Post harvest Technology:

Post harvest processing technology or Post harvest technology of agricultural products refers to the processes and treatments carried out on agricultural products   after it is harvested. It starts from the selection of proper harvest and ends with marketing.  The following operations such as threshing, drying, storage, parboiling, milling, sorting, grading, oil extraction, juice extraction, ginning, cold storage, packing, transport, marketing etc., included under this term. The purpose of post harvest processing is to maintain or enhance quality of the products and make it marketable.

It is an inter-discipline “science and technique” applied to agricultural produce after harvest for its production, conservation, processing, packaging, distribution, marketing, and utilization to meet the food and nutritional requirement of the people in relation to their needs. It has the capability to meet food requirement of growing population by eliminating avoidable losses, making more nutritive food items from low grade raw commodity by proper processing and fortification, converting low grade food and organic waste into nutritive cattle feed. It has potential to create rural agro industries.

Threshing

• Process of detaching grains from ear heads or from the plants
• Threshing can be achieved by three methods namely rubbing, impact and stripping
• Threshing loosens the grains and separates from the stalk

Principle

• Bases on the principle that when
  • Impact is given on crops, the grains are separated
  • The crop mass passes thru a gap between drum and concave, wearing or rubbing action takes place-separates grain from panicle
• Rupture of the bond between grains and ears is due to
  • Impact of beaters or spikes over grains
  • Wearing or rubbing action
• Strength of the bond between grain and panicles depends upon
  • Type of crop
  • Variety of crop
  • Moisture content of grain
  • Ripening phase of grain

Efficiency and quality of threshing  depends upon

• • Drum speed
  • No. of beaters
  • Gap between drum and concave
  • Quality & condition of plant mass fed to thresher
  • Direction of feeding
  • Rate of feeding

Methods

• Based on power
  • Manual – capacity varies from 30 to 50 kg/h
  • Power – capacity varies from 300 to 50 0kg/h

• Based on type of feeding
  • Throw-in
    • Entire crop is thrown into the cylinder
    • Major portion is threshed by initial impact or spikes of the cylinder
  • Hold-on
    • Holds the panicle end against the wire loop of the rotation

Based on flow of material

• • Through flow
    • Threshed straw and separated grain flow in a direction perpendicular to the axis of the threshing cylinder
  • Axial flow
    • Threshed straw and separated grain flow in a direction parallel to the axis of the threshing cylinder

Components of thresher

• Concave
• Threshing cylinder
• Cleaning unit

Concave
Concave shaped metal grating, partly surrounding the cylinder against which the cylinder rubs the grain from the plant or ear heads & thru which the grains fall on the sieve

Threshing cylinder

• Most important component of thresher
• Balanced rotating assembly comprising rasp beater bar or spikes on its periphery and their support for threshing the crop
• Types
  • Peg tooth
  • Wire loop
  • Rasp bar
  • Angle bar
  • Hammer mill

Types of threshing cylinder

Peg tooth

• The teeth on the concave & cylinder are so arranged that the cylinder teeth pass midway between the staggered teeth on the concave
• The clearance between the cylinder & the concave is adjusted according to the requirement
• As the stalks pass thru the clearance space, the grains get separated from the head due to impact action between the teeth

Wire loop

• Cylinder is studded with number of wire loops through out its outer periphery
• Mostly used on paddy thresher

Angle bar

• Cylinder is equipped with angle iron bars, helically fitted on the cylinder
• The bars have rubber pads on their faces
• The clearance between cylinder and concave unit at the entrance is from 13 mm to 19 mm and reduces to 6 to 9 mm only

Hammer mill type

• Beaters are in the shape of hammer mill
• Beaters are attached with the beater arm at the tip
• Beater arms are rigidly fixed to a hub which is mounted on main shaft

Rasp bar cylinder

• Cylinder has corrugated bars round it
• Threshing is accomplished between corrugated cylinder bars and stationary bars of the concave portion
• Rotating cylinder takes the grains out from the head as it is drawn over the bars on the concave unit
• Usually 6 to 8 bars are spirally fixed on the cylinder

Cleaning unit

• Function is to separate & clean the threshed grain
• Mainly consists of two or more oscillating sieves, a fan and air sucking duct known as aspirator
• Usually two ducts viz. primary and secondary duct
• Function of primary duct is to remove major portion of straw, dust and other foreign matter
• Secondary duct is used for final cleaning of the grain

Thresher with aspirator
Threshing efficiency

• The threshed grain received from all outlets with respect to total grain input expressed as percentage by mass
  • Efficiency = 100- % of unthreshed grain
• Factors affecting threshing efficiency
  • Peripheral speed of the cylinder
  • Cylinder concave clearance
  • Type of crop
  • Moisture content of crop
  • Feed rate

Cleaning efficiency
Efficiency = M/F X 100

• • M – Quantity of clean grain obtained from the sample taken at main grain outlet
  • F – Total quantity of sample taken at main grain outlet

Combine –Harvester-Thresher

• Machine designed for harvesting, threshing, separating, cleaning and collecting grains while moving through the standing crop
• Main functions are
  • Cutting the standing crops
  • Feeding the crop to threshing unit
  • Threshing the crops
  • Cleaning the grains from straw
  • Collecting the grains in a container

Combine-Harvester-Thresher

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Wind winnowing is an agricultural method developed by ancient cultures for separating grain from chaff. It is also used to remove weevils or other pests from stored grain. Threshing, the separation of grain or seeds from the husks and straw, is the step in the chaff-removal process that comes before winnowing. “Winnowing the chaff” is a common expression. In its simplest form it involves throwing the mixture into the air so that the wind blows away the lighter chaff, while the heavier grains fall back down for recovery. Techniques included using a winnowing fan (a shaped basket shaken to raise the chaff) or using a tool (a winnowing fork or shovel) on a pile of harvested grain
          Winnowing, the process of separating quality grains from chaff, is a crucial process in the cultivation of paddy. The traditional way of winnowing is making the dried grains fall from a height using shovels and a sieve. The quality grains which are heavy fall vertically while the weightless chaff and straw get blown away by the wind. Thus, winnowing is effective only when there is a wind. Farmers often have to wait for hours for the wind to blow before they could start the process of winnowing.
Grain winnower
          This machine winnows the paddy already threshed by a paddy thresher or other means.  It has a feeding hopper at the top to receive the threshed paddy with other impurities. It discharges the threshed paddy over a scalper and removes bigger size impurities. A blower provided at bottom sends a stream of air against the grain falling through the scalper, which separates the straw, chaff and other impurities. The dust, chaff and straw are collected separately and cleaned paddy is taken out through another outlet near the bottom of the unit. The capacity of unit is 625 kg/h and the unit is operated by one hp motor.

Paddy winnower
The machine winnows paddy already threshed by the paddy thresher or by other means. It has a feed hopper at the top to receive the threshed paddy, chaff and straw bit. A blower provided at the bottom sends a stream of air which separates straw, chaff and other impurities. The dust, chaff and straw come out through an opening and cleaned paddy is taken out through another spout.  The unit is continuous type and operated by one hp electric motor.

Paddy precleaner
Paddy precleaner is used to remove appendages, glumes and foreign matter. The pre-cleaner is provided with an aspirator, a rotating scalping sieve and horizontal reciprocating grading sieve. By suitably changing the sieve, it can also be utilized for other seeds. By using the pre-cleaner, the efficiency of cleaner cum grader is improved. It also removes both smaller and larger size impurities and the dust from the grain.  The capacity of the unit is 150 kg/h and it is operated one hp electric motor. The efficiency of the unit is 91%.

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Groundnut decorticator: Manually operated
            Hand operated groundnut decorticator consists of curved ‘L’ angle frame and four legs. A perforated sieve in a semi circular shape is provided. Seven cast iron peg assemblies are fitted in an oscillating sector. The groundnut pods are shelled between the oscillating sector and the perforated concave sieve. The kernels and husk are collected at the bottom of the unit. The clearance between the concave and oscillating sector is adjustable to decorticate pods of different varieties of groundnut. The sieve is also replaceable according to the variety of groundnut pods.

Fig. Groundnut decorticator: Manually operated
Groundnut decorticator: Power operated

The unit consists of a hopper, double crank lever mechanism, an oscillating sector with sieve bottom and blower assembly, all fixed on a frame. A number of cast iron peg assemblies are fitted ion the oscillating sector unit. The groundnut pods are shelled between an oscillating sector and the fixed perforated concave screen. The decorticated shells and kernels fall down through the perforated concave sieve. The blower helps to separate the kernels from the husk and the kernel are collected through the spout at the bottom. The shells are thrown away from the machine.

Fig. Groundnut decorticator: Power operated

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Maize sheller
The maize sheller consists of a bevel gear fixed adjacent to the shelling disc, which pulls the cob inside, while a spring loaded tongue which is provided above the bevel gear holds the cob tight against the shelling disc,. Shelling is accomplished with beating and shearing action of the cast iron projections present in the rotating shelling disc.  The shelled kernels with dust are passed through an air stream produced by a blower which separates the kernels. The cleaned kernels are collected at the bottom. The capacity of the unit is 500 kg of cob/h and it is operated by an one hp electric motor. 

Husker sheller for maize
            The machine consists of a hopper, rotor, sieve, blower, auger and an elevator. The removal of sheath and shelling of cob take place in the rotor sieve assembly. The shelled kernels are carried by the auger to one end and then elevated to the desired level for direct collection in bags. The capacity of the unit is 100 quintals per day. It is operated by 7.5 hp electric motor.

Castor sheller cum winnower
The machine consists of a teakwood cylinder and concave, a feed hopper, blower, sieve assembly and 2 hp electric motor. Unthreshed pods are retained on the top of sieve and come out from chute at the end of the sieve. Partially and completely shelled one pass through the top sieve. The middle sieve retains the partially shelled pods and allows the shelled beans to pass through. The partially shelled pods come out from chute at the end of middle sieve. The lighter hulls are blown out by the blast of air form the blower. The shelled bean comes out form the chute at the middle of the bottom perforated sheet. The perforations allow sand particles; weed seed etc., to be sieved out of the threshed castor bean. Capacity of the unit is 250 kg/h.

Fig. Castor Sheller cum winnower

Castor Sheller
The sheller consists of a wooden ribbed cylinder of 320 mm length and 380 mm diameter, concave, cylinder cover, feeding chute discharge cute, drive mechanism and crank. The clearance between the concave and cylinder adjustable depending on the size of bean. Shelling drum is operated by crank through a gear unit which shells the castor pods. Manual clearing is done. The unit is operated by two labours. Capacity of the unit is one quintal per day.

Fig. Castor Sheller

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• Permits long time storage of grain without deterioration
• Permits continuous supply of product thro’ out the year
• Permits early harvest which reduces field damage and shattering loss
• Permits the farmers to have better quality product
• Makes products available during off season

Drying theory

• Convection process in which moisture from a product is removed
• The water content of agricultural product is given in terms of moisture content
• They gain or loose moisture as per the atmospheric conditions
• Moisture migration into or from a product is dependent on the difference of vapour pressure between atmosphere and product
• If the vapour pressure of grain is greater than atmospheric vapour pressure, transfer of moisture from grain to atmosphere takes place
• If the atmospheric vapour pressure is greater than grain vapour pressure, grain absorbs moisture from  atmosphere

Drying rate periods
Divided into 3 periods

• • Constant rate period
  • First Falling rate period
  • Second falling rate period

Constant rate period

• Moisture migration rate from inside of product to its surface is equal to the rate of evaporation of water from surface
• This period continues till critical moisture content is reached
• Critical moisture content: Moisture content of a product where constant rate drying ceases and falling rate starts
• This period is very short for agricultural products
• Drying of sand and washed seeds takes place in constant rate period

Falling rate period

• Most of the agricultural products are dried in falling rate drying period
• Movement and diffusion of moisture in interior of grains controls the entire drying process

Controlled by

• Migration of moisture from interior of grains to upper surface due to water vapour diffusion
  • Removal of moisture from the surface
• Divided into two periods
  • First falling rate period
  • Second falling rate period

First falling rate

• Unsaturated surface drying
• Drying rate decreases because of the decrease in wet surface area
• Fraction of wet surface decreases to zero, where first falling rate ends

Second falling rate

• Sub surface evaporation takes place & it continues until the equilibrium moisture content is reached

Mechanism of drying process

• Movement of moisture takes place due to
  • Capillary flow – Liquid movement due to surface forces
  • Liquid diffusion – Liquid movement due to difference in  moisture concentration
  • Surface diffusion – Liquid movement due to moisture diffusion of the pore spaces
  • Vapour diffusion – vapour movement due to moisture concentration difference
  • Thermal diffusion – vapour movement due to temperature difference
  • Hydro dynamic flow – water and vapour movement due to total pressure difference

Thin layer drying

• Process in which all grains are fully exposed to the drying air under constant drying conditions i.e. at constant air temp. & humidity.
• Up to 20 cm thickness of grain bed is taken as thin layer
• All commercial dryers are designed based on thin layer drying principles
• Represented by Newton’s law by replacing moisture content in place of temperature

M-Me/Mo-Me = e -Kq
M – Moisture content at any time q, % db
Me- EMC, %db
Mo – Initial moisture content, %db
K – drying constant
q – time, hour

Deep bed drying

• All grains are not fully exposed to the same condition of drying air
• Condition of drying air changes with time and depth of grain bed
• Rate of airflow per unit mass of grain is small
• Drying of grain in deep bin can be taken as sum of several thin layers
• Humidity & temperature  of air entering & leaving each layer vary with time
• Volume of drying zone varies with temp & humidity of entering air, moisture content of grain & velocity of air

Deep bed drying characteristics at different depths
Continuous flow dryer

•  Columnar type dryer in which wet grains flow from top to the bottom of the dryer
• Two types
  • Mixing
  • Non-mixing

Mixing

• Grains are diverted in the dryer by providing baffles
• Use low air flow rates of 50-95 m3/min/tonne
• Zig-zag columns enclosed by screens are used  to achieve mixing
• High drying air temperature of 65°C is used

Baffle dryer

• Continuous flow mixing type dryer
• Consists of receiving bin, drying chamber fitted with baffles, plenum fitted with hot air inlet
• Baffles are fitted to divert the flow & also for mixing
• Grain fed at the top & move downward in a zig-zag path where it encounters a cross flow of hot air
• Bucket elevator is used to recirculate the grain till the grain is dried to desired moisture level
• Uniformly dried product is obtained

Mixing type baffle dryer
Non-mixing

• Grains flow in a straight path
• Baffles are not provided and drying takes place between two parallel screens
• High airflow rates can be used
• Drying air temp. of 54°C is used

• Feed hopper
• Plenum chamber
• Exit air
• Dry grain outlet
• Screened grain column

Continuous flow dryer (Non-mixing)
Recirculatory Batch dryer

• • • • • Continuous flow non mixing type
        • Consists of 2 concentric circular cylinders, set 15-20 cm apart

Bucket elevator is used to feed & recirculated the grain
Centrifugal blower blows the hot air into the inner cylinder, acts as a plenum
Grain is fed at the top of the inside cylinder; comes in contact with a cross flow of hot air
The exhaust air comes out through perforations of the outer cylinder
Grain is recirculated till it is dried to desired moisture content
Drying is not uniform as compared to mixing type

Recirculating batch dryer

LSU dryer

• • Developed at Louisiana state university (LSU)
  • Continuous mixing type dryer
  • Developed specifically for rice to ensure gentle treatment, good mixing & good air to grain contact
  • Consists of rectangular chamber, holding bin, blower with duct, grain discharging mechanism and air heating system
  • Layers of inverted V shaped channels are installed in the drying chamber; heated air is introduced through these channels at many points
  • Alternate layers are air inlet & outlet channels; arranged one below the other in an offset pattern
  • Inlet port consists of few full size ports & two half size ports; all ports are of same size arranged in equal spacing
  • Ribbed rollers are provided at the bottom of drying chamber for the discharge of grain
  • Capacity varies from 2-12 tonnes
  • Recommended air flow rate is 60-70 m3/min/tonne
  • Air temp. are 60 &85°C for raw & parboiled paddy
  • Uniformly dried product can be obtained
  • Can be used for different types of grain
  • High capital investment

LSU Dryer

Garner Duct Dry material outlet Hopper Continuous flow Door Roof

LSU Dryer
Tray driers

• In tray dryers, the food is spread out, generally quite thinly, on trays in which the drying takes place.
• Heating may be by an air current sweeping across the trays, or heated shelves on which the trays lie, or by radiation from heated surfaces.
• Most tray dryers are heated by air, which also removes the moist vapours.

Fluidized Bed Dryers
In a fluidized bed dryer, the food material is maintained suspended against gravity in an upward-flowing air stream.
Heat is transferred from the air to the food material, mostly by convection

Pneumatic Dryers

• In a pneumatic dryer, the solid food particles are conveyed rapidly in an air stream, the velocity and turbulence of the stream maintaining the particles in suspension.
• Heated air accomplishes the drying and often some form of classifying device is included in the equipment.
• In the classifier, the dried material is separated, the dry material passes out as product and the moist remainder is recirculated for further drying

 Rotary Dryers

• The foodstuff is contained in a horizontal inclined cylinder through which it travels, being heated either by air flow through the cylinder, or by conduction of heat from the cylinder walls.
• In some cases, the cylinder rotates and in others the cylinder is stationary and a paddle or screw rotates within the cylinder conveying the material through.

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Storage structures
Storage – to maintain the quality of grain after harvest for

• Maintaining the supply of grain
• Taking advantage of higher prices

Two methods of grain storage

• Bag storage
• Loose in bulk storage

The choice based on the local factors

• Type of grain
• Duration of storage
• Value of grain
• Climate
• Transport system
• Cost and availability of labour
• Cost and availability of bags
• Incidents of rodents and certain types of insects

Bag and bulk storages

Traditional storage structures- (Bulk type)
Bukkhari type

• Cylindrical in shape
• Made of mud or combination of mud and split bamboo
• Raised above the ground by wooden or masonry platform
• Floor
• Walls
• Roof
• Improved type – same structure
• Rat proofing cones
• Grains – wheat, gram, paddy, maize and sorghum
• Capacity – 3.5 – 18 t

Kothar type

• Store – paddy, maize, sorghum, wheat
• Capacity – 9-35 t
• Structure – box
• Improved Kothar – 5cm thick wooden planks and beams
• No gap between the planks 

Morai type

• Grains – paddy, maize, sorghum
• Capacity – 3.5 – 18 t
• Shape- inverted truncated cone

Modern storage structures

• Bagged storage system
• Silo storage system
• Air tight storage system
• Aerated storage system
• Low temperature storage system
• Controlled atmosphere storage system
• Damp grain storage system with chemicals

Bagged storage system

• Storage capacity is from 25 tonnes
• Generally the length is about twice the width or greater
• The entire structure should be moisture proof
• Large size doors of 2.4 x 2.4 m and top ventilators
• Each door is provided with a light overhanging hood
• It should be provide with ventilators – having wire netting and shutter

Bag Storage structure

Damp proof floor
1) 15 cm thick layer of gravel and sand well rammed at the bottom
2) 12.5 cm thick layer of stone or brick ballast or double layer of brick
3) 10 cm thick layer of cement concrete (1:4:8)
4) 1.25 cm thick bitumen mixed with sand
5) 4 cm thick layer of cement concrete (1:2:4)
6) 2.5 cm thick layer of cement concrete (1: 1 1/2: 3)

The walls are made of bricks or stone laid either in lime mortar (1:2), cement mortar (1:6)
Thickness of the wall is either 37.5 or 45 cm
The height of the walls on which trusses are kept: 5.5 m
Roof
Either gabled or flat roof
Gabled roof is covered with corrugated sheet
Flat roof is more durable – either reinforced brick or concrete – 10 to 12.5 cm thick
The terracing on the roof is made of brick ballast, surkhi, and lime ( 3.5: 1:1)

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Impurities in Freshly Harvested Fruits

• Field Soil
• Dust and surface microorganism
• Fungicide / insecticide etc
• Sap
• Black spots

Fruit and Vegetable Cleaning Machine
Specifications
Capacity                      : 20 kg/batch
Power requirement     : 1 person
RPM                            : 20 – 30 rpm
Fruit and vegetable     : Most fruits &   vegetable inclusive mango & tomato
Foreign matter removal          :
Field Soil, Dust and surface microorganism, Fungicide / insecticide, Sap, Black spots etc

Multifunctional cleaning machine

            The machine is a multifunctional fruit and vegetable cleaning equipment with bubbles, spraying and brush available in cleaning with features such as highly cleanness, energy-saving, water-saving, stable and reliable. This equipment is suitable for cleaning fruits and vegetables. It is easy to operate, convenient in maintenance and wiring.
Fruit cleaning machine

               The equipment is suitable for cleaning of ball-shape or oval-shape fruits and vegetables. The fruits and vegetables rotate continuously in all directions randomly. Brushing and spraying is in effect at a same time, with features such as high cleanness. The machine is easy to operate, convenient in maintenance and wiring.
Brush Type Vegetable & Fruit Cleaning Machine

Production capacity
Apple 30T/h
Watermelon 10T/h
Carrot 8T/h
Orange 35T/h
The fruit and vegetable raw materials are making irregular rotation under the effect of rotary brush roller to carry out spraying and brushing simultaneously. The brush is made of high temperature resistant nylon wire through two kinds of technologies such as hair planting and stainless steel winding.
a) Brush fruit cleaning machine for apple and fruits
b) Brush clearing machine for watermelon
c) Brush cleaning machine for carrot vegetable
d) Brush cleaning machine for citrus fruit

Surf Type Fruit Cleaning Machine

The equipment is mainly composed of water cabinet, material turning device, fan and lifter etc. It is widely used for soft washing of fruit and vegetable raw materials. The lifter can be made of complete stainless steel and engineering plastic. It can be additionally provided with spray cleaning device.

Roller with Brush Cleaning Machine

           The fruit washing equipment consists of a roller with brush washing (cleaning) machine for washing fruits and vegetables. Roller with brush washing machine is made up of stainless steel tube and brush. The brush is made of polyethylene, and will make revolution as the movement of stainless steel chain. Fruits are driven to circumvolve and washed by brush. At the same time, the bad or rejected fruits are picked up by manual and then sent away by scrap conveying device.
Rolling Drum Brush Washing Machine

The fruit washing equipment consists of a rolling drum brush washing (cleaning) machine for washing root vegetables. Rolling drum brush washing machine is made up of electric motor, water pump, roller drum, supporter, riding wheel, brush, water spraying tubes, feeding funnel, cover board, water box, transmission shaft, supporter for motor, electric control switches, and other parts.

Roller drum is driven to rotate by chain wheel of electric motor through stainless steel chain. When materials enter into the rotating roller drum, they are washed by spraying water and brush. There are two water boxes in our rolling drum brush washing machine. One is used to hold fresh water, and the other with filtering net in it is to recycle water.

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Sorting Bench IARI Fruit and Vegetable Grader

Divergent roller type fruit sorting machine for lemon and sapota, MPKV, Rahuri

Divergent rails/slit size mango grader.CISH, Lucknow

Mango grader

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Unit operation in which the average size of solid pieces of food is reduced by the application of

• • grinding
  • compression
  • impact forces

Related terms

• Homogenization or Emulsification
  • Reduction in size of globules of immiscible liquids
• Atomization
  •  Size reduction of liquids by droplets
• Extrusion, Agglomeration or Forming
  • Size enlargement

Benefits in food processing

• • • Increase in the surface area to volume ratio of the food 
    • Increases the rate of drying, heating or cooling
    • improves the efficiency and rate of extraction of liquid components
    • Eg. Fruit juice, cooking oil extraction
    • When combined with screening, a predetermined range of particle sizes is produced which is important for the correct functional or processing properties of some products
    •  Eg. Icing sugar, spices, corn starch
    • A similar range of particle sizes allows more complete mixing of ingredients
    • Eg. Dried soup and cake mixes

Methods

• • • • Chopping, cutting, slicing and dicing
      • Large to medium (Cheese and sliced fruit for canning)
      • Medium to small (Diced carrot)
      • Small to granular (minced meat, flaked fish or nuts and shredded vegetables)
      • Milling to powders or pastes
      • Grated products
      • Emulsification and homogenization

Theory
Three types of forces

• • Compression
  • Impact
  • Shearing or Attrition forces

            Stress is applied to a food; the resulting internal strains are first absorbed to cause deformation of the tissues. Amount of energy needed to fracture a food is determined by its hardness and tendency to crack – in turn depends on the structure of the food. Fewer the lines of weakness in a food, the higher are the energy input needed to cause fracturing. Harder foods absorb more energy and require a greater energy input to create fractures. Extent of size reduction, the energy expanded and the amount of heat generated in the food depend on both the size of the forces that are applied and the time that food is subjected to the forces. Compression forces are used to fracture friable or crystalline foods. Combined impact and shearing forces are necessary for fibrous foods. Shearing forces are used for fine grinding of softer foods.
Factors influencing the energy input

• Moisture content
  • Wheat is conditioned to optimum moisture content
  • Maize is thoroughly soaked and wet milled for complete disintegration
• Heat sensitivity of the food
  • Determines the permissible temperature rise and the necessity to cool the mill
  • Liquid N2 or solid CO2 are mixed with foods before milling to cool the product and to retain volatiles
• Quantum of the forces that are applied
• Time that food is subjected to the forces

Equations for energy requirement determination
Kicks law

• • Energy required to reduce the size of particles is directly proportional to the ratio of the initial size of a typical dimension to the final size of that dimension

E = Kk ln (Df/Dp)
E – Energy required per mass of feed
Kk – Kick’s constant
Df – Average initial size of feed
Dp – Average size of product
Df / Dp – Size reduction ratio

• Coarse grinding has RRs below 8:1
• Fine grinding  can exceed 100:1
• Grinding of coarse particles in which the increase in surface area per unit mass is relatively small, Kick’s Law is a reasonable approximation
• Rittinger’s law
  • States that the energy required for size reduction is proportional to the change in surface area of the pieces of food

• E = KR       1            1

                            Dp         Df

•  KR – Rittinger’s constant
• For the size reduction of fine powders, in which large areas of new surface are being created, Rittinger’s Law fits the experimental data better.

Bond’s law

• The work required to form particles of size Dp from very large feed is proportional to the square root of the surface to volume ratio of the product
• P/f = 0.3162 wi   1             1

                                    ÖDp       Ö Df

P – Power in kW
f – feed rate, t/hr
Dp – 80% of the product passes through mesh of dia Dp, mm
Df – 80% of feed passes through mesh of dia, Df, mm
Wi – Work index
Gross energy requirement in kilowatt-hour per tonne of feed needed to reduce a very large feed to such a size that 80% of the product passes through a 100 micro meter screen 

• An ideal size reduction equipment should fulfill the following conditions
  • Large capacity
  • Should yield a pre desired sized product or range of size
  • Small power input requirement per unit of product handled
  • Easy & trouble free operation
• Amount of power required to create smaller particles
• Desired uniformity of size
• Work required to strain the material is temporarily stored in the form of mechanical energy of stress.
• When external force exceeds the amount of stored mechanical energy, the material is disturbed beyond its strength and finally broken in to fragments – results in creation of new surface
• Solids have a certain amount of surface energy, thus for creation of new surface, work is required and supplied by the release of stress energy when material breaks.
• Stress energy excess of the new surface energy create is converted into heat energy.

Grinding

• Classified in to two
• Plain grinding
  • Milled to a free flowing meal consisting of sufficiently uniform particle size
• Selective grinding
  • Grinding operation is carried out in various stages depending upon the differences in structural and mechanical properties of components of grain

Degree of grinding

• Ratio of the overall surface area of the ground product to the overall surface area of the feed

Dg = Sp/Sf
Dg – degree of grinding         
Sp – Overall surface area of product
Sf – Overall surface area of feed
Milling efficiency

• Product of coefficient of hulling (E hulling )and coefficient of wholeness of kernel (E wk)
• Coefficient of hulling
  • Percentage of the hulled grains obtained from the total amount of grain input
• Coefficient of Wholeness of kernel
  •  Ratio of the amount of kernel, crushed grains and mealy waste obtained by any milling system

Size reduction machinery

• Crushers
• Grinders
• Fine grinders
• Cutting machines

Crushers

• Squeeze or press the material until it breaks
• Mostly used to break large pieces of solid materials into small lumps
• Use of crushers in agricultural operations is limited

Types

• • Jaw crushers
  • Gyratory crushers

Jaw crusher

• Feed is admitted between two jaws, which are open at the top like V
• One of the jaws is fixed and vertical, while the other is the swinging jaw
• This jaw reciprocates in a horizontal plane and makes the angle of 20-30° with the fixed jaw
• Movable jaw is operated by an eccentric unit so as to impart great compressive force
• Solids which has to be broken is caught between the two jaws
• Large lumps of solid materials are caught between the upper parts of the jaws
• Subsequently broken and dropped into the narrower space below
• Broken pieces are further reduced next time when jaws come closer.
• No. of strokes given to the movable jaw ranges between 250 to 400 times per minute

Gyratory crusher

• Jaws between which the solid materials fed are circular
• Material is being crushed at all times at some point
• Solids are caught between V shaped space between the head and casing
• Material is repeatedly broken in sufficiently small pieces to pass out from the bottom.
• Speed of crushing ranges between 125 to 425 gyrations per minute
• Discharge from the gyratory crusher is continuous
• Less maintenance is required as compared to jaw crusher
• Power requirement is low

Crushing rolls

• Mainly used for extraction of juice from sugarcane
• Two types
  • Smooth roll crusher
  • Serrated or toothed roll crusher

Smooth roll crusher

• Two heavy smooth faced roll rotating towards each other at same speed on parallel horizontal axes
• Size of the material caught by the rolls depends upon the coefficient of friction between the material and the roll surface
• Dp = 0.04R + g

Dp – maximum size of particle
R – roll radius
g – half of the width of gap between the rolls

• Used to make grits or meal from food grains
• One of the rolls should be spring loaded to avoid any damage to roll surface
• Extensively used for making food grains flakes

Serrated or toothed roll crusher

• Rolls are serrated as per need
• Much more versatile than smooth roll crusher
• Best example – Break and reduction rolls of wheat milling
• Disintegrators are toothed roll crushers in which the corrugated rolls are rotating at different speeds
• Size reduction is by compression, impact and shear and not by compression alone, as in the case of smooth roll crushers
• Can accommodate larger particles than smooth roll crushers

Crushing efficiency

• Ratio of the surface energy created by crushing to the energy absorbed by the solid

Grinders

• Used to mill the grains into powder
• Types
  • Attrition mill
  • Hammer mill
  • Impactors
  • Rolling compression mill

Attrition mill

• Also known as burr mill
• Grains are rubbed between the grooved flat faces of rotating circular disks
• Axis of the roughened disks may be horizontal or vertical
• One plate is stationary and fixed with the body of the mill while the other one is rotating disk
• Material is fed between the plates and is reduced by crushing and shear
• Mills with different patterns of grooves, corrugations on the plates perform a variety of operations
• Overfeeding
  • lowers grinders performance
  • Increases heat generation during milling
• Disks are 20-137 cm in dia and operated at 350 to 700 rpm

• Used for making whole grain and dehusked grain flour
• Use in spice grinding is limited
• Double runner disks type attrition mills are also available
• Used for grinding of soft materials
• Both disks are driven at high speed in opposite direction
• Operated between 1200 to 7000 rpm
• Capacity is large

Salient features

• Fineness of grinding is controlled by the type of plates and the gap between them
• Spacing between the plates is adjustable
• Arrangement is spring loaded
  • to avoid damage to plates in case of overloading
  •  to overcome the damage to plates by foreign material coming along with the feed
• Lower initial cost
• Lower power requirements

Hammer mill

• Used for various types of size grinding jobs
• Size reduction takes place by impact force
• Consists of high speed rotor rotating inside a cylindrical casing
• Shaft is usually kept horizontal

• Materials are fed into the mill from the top of the casing and is broken by the rotating hammers and fall out through a screen at the bottom
• Feed is broken by the fixed or swinging hammers, pinned to a rotor
• Hammers are rotated between 1550 to 4000 rpm, strike and grind the material until it becomes small enough to pass through the bottom screen

• Fineness of grinding is controlled by the screen size
• There is less chances of damage of hammer in swinging hammer mill
• Can grind tough fibrous solids, steel chips, food grains, hard rock etc.
• Assumed to reduce size by impact of hammers

Salient features

• Simplicity and versatility in design
• Less chances of damage due to foreign objects
• High power requirement
• Capacity and power requirement depend on the nature of feed to be ground
• Used for poultry feed grinding, spices grinding
• Suitable for grinding of wet sorghum and millets
• Also used for potato, tapioca, banana flour making

Ball mill

• Cylindrical or conical shell slowly rotating about a horizontal axis.
• Half of its volume is filled with solid grinding balls
• Shell is made of steel lined with high carbon steel plate, porcelain or silica rock.
• Size reduction is achieved by impact of the balls when they drop from near the top of the shell
• Energy consumed in lifting the balls is utilized for grinding job
• When the ball mill is rotated , the balls are carried by the mill wall nearly to the top
• Balls are released by the gravitational pull and drop to the bottom and picked up again
• Centrifugal force keeps the ball in contact with the mill wall.
• Due to centrifugal force, if the speed of rotation of mill is faster, the balls are carried to more distance.
• Centrifuging: In case of too high speed, balls stick to mill wall and are not released

Critical speed: Rotational speed at which centrifuging occurs

• At this speed, no impact occurs hence little or no grinding results
• Operating speed must be kept less than the critical speed
• Speed at which the outermost ball released from the mill wall depends on the interaction of gravitational and centrifugal forces
• Critical speed can be determined by
• nc = 1/2╥Ög/R-r

nc = critical speed, revolution/sec
g= acceleration due to gravity, 9.8 m/s2
R- radius of the mill, m
r = radius of the ball, m

Roller mills

• Roller mills are similar to roller crushers
• They have smooth or finely fluted rolls, and rotate at differential speeds.
• They are used very widely to grind flour.
• Because of their simple geometry, the maximum size of the particle that can pass between the rolls can be regulated.
• If the friction coefficient between the rolls and the feed material is known, the largest particle that will be nipped between the rolls can be calculated, knowing the geometry of the particles.

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Evaporation is an operation used to remove a liquid from a solution, suspension, or emulsion by boiling off some of the liquid. It is thus a thermal separation, or thermal concentration, process. We define the evaporation process as one that starts with a liquid product and ends up with a more concentrated, but still liquid and still pumpable concentrate as the main product from the process. There are actually a few instances where the evaporated, volatile component is the main product, but we will not discuss that here.

            In most cases it is essential that the product be subject to minimal thermal degradation during the evaporation process, requiring that temperature and time exposure must be minimized. This and other requirements brought on by the physical characteristics of the processed product have resulted in the development of a large range of different evaporator types. Additional demands for energy efficiency and minimized environmental impact have driven development toward very innovative plant configurations and equipment design.

            In the field of thermal separation / concentration technology, evaporation plants are widely used for concentration of liquids in the form of solutions, suspensions, and emulsions. The major requirement in the field of evaporation technology is to maintain the quality of the liquid during evaporation and to avoid damage to the product. This may require the liquid to be exposed to the lowest possible boiling temperature for the shortest period of time. This and numerous other requirements and limitations have resulted in a wide variation of designs available today. In almost all evaporators the heating medium is steam, which heats a product on the other side of a heat transfer surface. The following list contains the descriptions of the most common types of evaporators.

1. Falling Film Evaporators
2. Rising Film Evaporators
3. Forced Circulation Evaporators
4. Plate Evaporators
5. Thermal and Mechanical Vapor Recompression (TVR & MVR)

Typical evaporator applications:
 Product concentration
 Dryer feed pre-concentration
 Volume reduction
 Water / solvent recovery
 Crystallization

Falling Film Evaporators
            In falling film evaporators, liquid and vapors flow downwards in parallel flow. The liquid to be concentrated is preheated to boiling temperature. An even thin film enters the heating tubes via a distribution device in the head of the evaporator, flows downward at boiling temperature, and is partially evaporated. This gravity-induced downward movement is increasingly augmented by the co-current vapor flow.
            Falling film evaporators can be operated with very low temperature differences between the heating media and the boiling liquid, and they also have very short product contact times, typically just a few seconds per pass. These characteristics make the falling film evaporator particularly suitable for heat-sensitive products, and it is today the most frequently used type of evaporator.

Fig. 1. Falling Film Evaporator

However, falling film evaporators must be designed very carefully for each operating condition; sufficient wetting of the heating surface by liquid is extremely important for trouble-free operation of the plant. If the heating surfaces are not wetted sufficiently, dry patches and incrustations will occur; at worst, the heating tubes will be completely clogged. In critical cases extending or dividing the evaporator effects, keeping the advantages of single pass operation, can increase the wetting rate. The proper design of the liquid distribution system is critical to achieve full and even product wetting of the tubes.  Because of the low liquid holding volume in this type of unit, the falling film evaporator can be started up quickly and changed to cleaning mode or another product easily.  Falling film evaporators are highly responsive to alterations of parameters such as energy supply; vacuum, feed rate, concentrations, etc. When equipped with a well-designed automatic control system they can produce a very consistent concentrated product. The fact that falling film evaporators can be operated with small temperature differences makes it possible to use them in multiple effect configurations or with mechanical vapor compression systems in modern plants with very low energy consumption.

Rising Film Evaporators

            These operate on a “thermo-siphon” principle. Feed enters the bottom of the heating tubes and as it heats, steam begins to form. The ascending force of this steam produced during the boiling causes liquid and vapors to flow upwards in parallel flow. At the same time the production of vapor increases and the product is pressed as a thin film on the walls of the tubes, and the liquid rises upwards.

            Fig.2. Rising Film Evaporator

This co-current upward movement has the beneficial effect of creating a high degree of turbulence in the liquid. This is advantageous during evaporation of highly viscous products and products that have a tendency to foul the heating surfaces. Usually there must be a rather high temperature difference between the heating and boiling sides of this type of evaporator. Otherwise the energy of the vapor flow is not sufficient to convey the liquid and to produce the rising film. The length of the boiling tubes will typically not exceed 23 ft. This type of evaporator is often used with product recirculation, where some of the formed concentrate is reintroduced back to the feed inlet in order to produce sufficient liquid loading inside the boiling tubes.

Forced Circulation Evaporator
Forced circulation evaporators are used if boiling of the product on the heating surfaces is to be avoided due to the fouling characteristics of the product, or to avoid crystallization. The flow velocity in the tubes must be high, and high-capacity pumps are required. The circulating liquid is heated when it flows through the heat exchanger and then partially evaporated when the pressure is reduced in the separator, cooling the liquid to the boiling temperature corresponding to this pressure.

Fig. 3. Forced Circulation Evaporator

The liquid is typically heated only a few degrees for each pass through the heat exchanger, which means the recirculation flow rate has to be high. This type of evaporator is also used in crystallizing applications because no evaporation, and therefore no concentration increase, takes place on the heat transfer surface. Evaporation occurs as the liquid is flash evaporated in the separator/flash vessel. In crystallizer applications this is then where the crystals form, and special separator designs are used to separate crystals from the recirculated crystal slurry.  The heat exchanger (in evaporator parlance sometimes called the “calandria”) can be arranged either horizontally or vertically depending on the specific requirements in each case.

Methods of Operation of Evaporators

1. Single-effect evaporators

 A simplified diagram of a single-stage or single-effect evap­orator is given in
Fig.1. The feed enters at TF K and saturated steam at Ts enters the heat-exchange section. Condensed steam leaves as condensate or drips. Since the solution in the evaporator is assumed to be completely mixed, the concentrated product and the solution in the evaporator have the same composition and temperature Tt, which is the boiling point of the solution. The temperature of the vapor is also Tt, since it is in equilibrium with the boiling solution. The pressure is P1, which is the vapor pressure of the solution at Tt.
If the solution to be evaporated is assumed to be dilute and like water, then 1 kg of steam condensing will evaporate approximately 1 kg of vapor. This will hold if the feed entering has a temperature TF near the boiling point.
The concept of an overall heat-transfer coefficient is used in the calculation of the rate of heat transfer in an evaporator. The general equation can be written

                                               (1)

where q is the rate of heat transfer in W, U is the overall heat-transfer coefficient in W/m2. K, A is the heat-transfer area in m2, Tsk is the temperature of the condensing steam in K, and Tl is the boiling point of the liquid in K.

           
Single-effect evaporators are often used when the required capacity of operation is relatively small and/or the cost of steam is relatively cheap compared to the evaporator cost. However, for large-capacity operation, using more than one effect will markedly reduce steam costs.
2. Forward-feed multiple-effect evaporators
A single-effect evaporator as shown in Fig.1 is wasteful of energy since the latent heat of the vapor leaving is not used but is discarded. However, much of this latent heat can be recovered and reused by employing multiple-effect evaporators. A simplified diagram of a forward-feed triple-effect evaporation system is shown in Fig.2. If the feed to the first effect is near the boiling point at the pressure in the first effect 1 kg of steam will evaporate almost 1 kg of water. The first effect operates at a high-enough temperature so that the evaporated water serves as the heating medium to the second effect. Here, again, almost another kg of water is evaporated, which can be used as the heating medium to the third effect. As a very rough approximation, almost 3 kg of water will be evaporated for 1 kg of steam for a three-effect evaporator. Hence, the steam economy, which is kg vapor evaporated/kg steam used, is increased. This also approximately holds for a number of effects over three. However, this increased steam economy of a multiple-effect evaporator is gained at the expense of the original first cost of these evaporators.

Fig 2. Double effect evaporator – forward feed

In forward-feed operation as shown in Fig.2, the fresh feed is added to the first effect and flows to the next in the same direction as the vapor flow. This method of operation is used when the feed is hot or when the final concentrated product might be damaged at high temperatures. The boiling temperatures decrease from effect to effect. This means that if the first effect is at P1= 1 atm abs pressure, the last effect will be under vacuum at a pressure P3.

3. Backward-feed multiple-effect evaporators

In the backward-feed operation shown in Fig.3 for a triple-effect evaporator, the fresh feed enters the last and coldest effect and continues on until the concentrated product leaves the first effect. This method of reverse feed is advantageous when the fresh feed is cold, since a smaller amount of liquid must be heated to the higher temperatures in the second and first effects. However, liquid pumps are used in each effect, since the flow is from low to high pressure. This method is also used when the concentrated product is highly viscous. The high temperatures in the early effects reduce the viscosity and give reasonable heat-transfer coefficients.
4. Parallel-feed multiple-effect evaporators
Parallel feed in multiple-effect evaporators involves the adding of fresh feed and the withdrawal of concentrated product from each effect. The vapor from each effect is still used to heat the next effect. This method of operation is mainly used when the feed is almost saturated and solid crystals are the product, as in the evaporation of brine to make salt.

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U.S. FOOD SAFETY SYSTEM
            The Food and Drug Administration (FDA) is charged with protecting consumers against food that is impure, unsafe, produced under unsanitary conditions, or fraudulently labeled. Through its Center for Food Safety and Applied Nutrition (CFSAN) and the Office of Regulatory Affairs (ORA), the FDA regulates both domestic and imported foods, except meat and poultry and processed eggs and has primary responsibility for enforcing food safety laws including food import and export regulations. (FDA. 2001) Some of the activities of the FDA with particular impact on imported produce include

• Inspecting food production establishments and food warehouses and collecting and analyzing samples for physical, chemical, and microbial contamination.
• Establishing good agricultural practices and good manufacturing practices and other production standards, such as plant sanitation, packaging requirements, and Hazard Analysis and Critical Control Point programs.
• Sampling and inspection of imported foods.
• Working with foreign governments (and with FDA counterparts in these countries, if they exist) to ensure safety of imported foods.
• Taking appropriate enforcement actions.
• Educating industry and consumers on safe food handling practices.

            The Centers for Disease Control and Prevention (CDC) work closely with state and local public health epidemiologists and laboratories to identify illnesses and clusters of illnesses that may be food borne. CDC surveys and studies various environmental and chronic health problems and administers national programs for prevention and control of vector-borne diseases (diseases transmitted by a host organism) and other preventable conditions.( CDC. 1999)
The U.S. Department of Agriculture (USDA) has several agencies that may play a role in assuring food safety by establishing the safety of imported fruits and vegetables.

• The Agricultural Marketing Service (AMS) carries out a wide range of programs aimed at facilitating the marketing of agricultural products, assuring consumers a quality food supply, and ensuring fair trading practices. Certain agricultural commodities (including fresh tomatoes, avocados, mangoes, limes, oranges, grapefruit, green peppers, Irish potatoes, cucumbers, eggplants, dry onions, walnuts and filberts, processed dates, prunes, raisins, and olives in tins) must meet United States import requirements relating to grade, size, quality, and maturity. These commodities are inspected and the AMS must issue an inspection certificate to indicate import compliance.
• The Foreign Agricultural Service (FAS) has primary responsibility for the USDA’s overseas programs, including market development, international trade agreements and negotiations, and the collection of statistics and market information.
• The Food Safety and Inspection Service (FSIS) regulates meat, poultry and egg products and maintains a comprehensive system of import inspection and controls.
• The Economic Research Service (ERS) provides estimates of costs of food borne disease and conducts benefit/cost analyses of alternative regulatory options.
• USDA’s Animal and Plant Health Inspection Service (APHIS) inspects imported agricultural products for disease and pests which might infect plants and animals. Through monitoring activities at airport terminals, seaports, and border stations, it guards U.S. borders against the entry of foreign agricultural pests and diseases.

            U.S. Environmental Protection Agency (EPA) includes regulating pesticides and assuring that drinking water meets standards for health. Through the Office of Pesticide Programs (OPP), EPA determines the safety of new pesticide products, sets tolerance levels for pesticide residues in foods.
INTERNATIONAL FOOD LAWS AND REGULATIONS
          Sanitary (human and animal health) and phytosanitary (plant health) standards are necessary to ensure that food is safe for consumers, to prevent the spread of pests and diseases among animals and plants and to ensure fair practices in trade. In recent years, world food trade has been profoundly altered by the adoption of agreements that provide a more precise framework for trade, and define the rights and the obligations of all partners. These agreements served to strengthen the status of institutions like the Codex Alimentarius Commission and the International Plant Protection Convention since these were used as a basis for harmonization.
THE URUGUAY ROUND AGREEMENTS
          The Uruguay Round of Multilateral Trade Negotiations, which concluded in 1994, established the World Trade Organization (WTO) to replace the General Agreement on Tariffs and Trade (GATT). The Uruguay Round negotiations were the first to deal with the liberalization of trade in agricultural products, an area excluded from previous rounds of negotiations. They also included negotiations on reducing non-tariff barriers to international trade in agricultural products and concluded with two binding agreements: the Agreement on the Application of Sanitary and Phytosanitary Measures (SPS Agreement) and the Agreement on Technical Barriers to Trade (TBT Agreement). The Agreement on the Application of Sanitary and Phytosanitary Measures confirms the right of WTO member countries to apply measures necessary to protect the life and health of humans, animals and plants (FAO, 2000).
          The Agreement on Technical Barriers to Trade was established with the objective of preventing the use of national or regional technical requirements, or standards in general, as unjustified barriers to trade (FAO, 2000). The agreement covers standards relating to all types of products including industrial and agricultural products. Not covered are food standards related to sanitary and phyto sanitary measures. It includes numerous measures designed to protect consumers against deception and economic fraud. Examples of food standards covered by the TBT Agreement are those related to quality and labeling. The TBT Agreement basically provides that all technical standards and regulations must have a legitimate purpose and that the impact or cost of implementing a standard must be proportional to the purpose of the standard. It also says that if there are two or more ways of achieving the same objective, the least trade-restrictive alternative should be followed. The agreement also places emphasis on international standards and WTO members are obliged to use international standards or parts of them except where the international standard would be ineffective or inappropriate in the national situation. The TBT Agreement does not include a program for harmonizing national standards.
CODEX ALIMENTARIUS
          The adoption of the SPS and TBT Agreements resulted in new emphasis and importance being placed on the work of Codex in establishing international food quality and safety standards.
Codex Alimentarius
The purpose of Codex is

• to guide and promote the elaboration of definitions and requirements for foods and assist in their harmonization
• to facilitate world trade
• to promote consumer protection

            The name Codex Alimentarius is taken from Latin and translates literally as “food code” or “food law”. The Codex Alimentarius is a series of food standards, codes and other regulations adopted by the Codex Alimentarius Commission (CAC) that countries can use as models in their domestic food legislation and regulations, and which can be applied to international trade. Codex provides the assurance that any foods produced according to its codes of hygienic practices and complying with its standards are safe and nutritious and offer adequate health protection. The CAC was created in 1962 by two United Nations organizations, the Food and Agriculture Organization (FAO) and the World Health Organization (WHO). Its main purpose is to promote consumer protection and to facilitate world trade in foods through the development of food standards, codes of practice and other guidelines (FAO/WHO, 1999). Since its inception, the CAC has been responsible for implementing the Joint FAO/WHO Food Standards Program (FAO, 2000).
          The CAC is an intergovernmental body with a current membership of 165 Member governments. Membership is open to all Member Nations and Associate Members of FAO and WHO. In addition, observers from international scientific, food industry, food trade and consumer associations may attend sessions of the Commission and of its subsidiary bodies. While observer organizations can fully participate in the proceedings of the meeting, by statute, only Member governments can participate in any decision process. To facilitate international trade, it has been necessary for efforts to be made to harmonize food standards. Those involved in harmonization efforts recognized that countries have the right to adopt standards they feel are appropriate to protect human, animal and plant health and the environment. They also have the right to take the steps necessary to assure these standards are met. However, preventing these standards from becoming barriers to trade is important to promote trade between countries (FAO, 1998).
          The Codex Alimentarius is a series of food standards, codes and other regulations adopted by the Codex Alimentarius Commission (CAC) that countries can use as models in their domestic food legislation and regulations, and which can be applied to international trade. Codex provides the assurance that any foods produced according to its codes of hygienic practices and complying with its standards are safe and nutritious and offer adequate health protection.The Codex Committee on Food Hygiene is currently developing a code of hygienic practice for fresh fruits and vegetables entitled “Draft Code of Hygienic Practice for Fresh Fruits and Vegetables”. This draft code addresses GAPs and GMPs that will help control microbial, chemical, and physical hazards associated with all stages of the production of fresh fruits and vegetables from primary production to packaging. To facilitate international trade, harmonization of food standards is necessary to prevent these standards from becoming barriers to trade between countries.
INDIAN STANDARDS
          There are a number of food laws being implemented by various Ministries/Departments. These are primarily meant for two purposes namely  (1) Regulation of Specifications of food and (2) Regulation of Hygienic condition of Processing/Manufacturing. Some of these food laws are mandatory and some are voluntary. The details of various food laws in operation in India are as under:-
A. Food Laws
The main Acts/Regulations/Control orders to regulate trade

• Prevention of Food Adulteration Act 1954
• Plant Quarantine (Regulation of Import into India) Order, 2003
• Meat Food Product Order 1973
• Milk And Milk Product Order 1992
• Bureau Of Indian Standards Act, 1986
• Standards On Weight And Measurement Act, 1976
• Livestock Importation Act, 1898
• AGMARK Act ,1937
• The Infant Milk Substitutes, Feeding Bottles and Infant Foods Act ,1992
• Export (Quality Control and Inspection) Act, 1963
• Essential commodities Act,1955
• Indian Explosives Act,1884
• Energy Conservation Act, 2001

1. Prevention of Food Adulteration Act (Ministry of Health)
          The Act lays down specifications for various food products and is mandatory. The Ministry of Health in 1995 had constituted a Task Force. This Task Force recommended that there should be emphasis on good manufacturing practices instead of detection of adulteration and prosecution. It also expresses concern about lack of laboratory equipments and quantified persons. In addition it also suggested that the name of PFA Act be changed to Food Safety Act.
2. Agriculture Produce (Grading & Marking) Act (Ministry of Rural development)
          This Act is commonly known as AGMARK and is voluntary. The Act lays down the specifications for various agricultural commodities including some processed foods.
3. Laws being operated by Bureau of Indian Standards (BIS)
          BIS is the largest body for formulating standards for various food items. These standards are also voluntary.
4. Essential Commodities Act
          A number of quality control orders have been issued under Essential Commodities Act such as FPO, MMPO, Meat Product Order and Vegetable Oils Control Order. These orders are mandatory and primarily meant for regulating the hygienic conditions. They need to be clubbed under one order which may called Food Products Order.
B. Harmonization of Food Laws
          The review of multiple laws is necessary to have a uniform and logical approach for regulating the quality of food. The following action is being taken by various Ministries:-
1. The Ministry of Civil Supplies & Consumer Affairs has brought out a paper for consideration of Committee of Secretaries (COS). The paper recommends that BIS should formulate standards for all food items in the country. This will be a major step towards harmonization of food laws and is still under consideration of COS for finalization.
2.   The Task Force had advocated promotion of food safety and quality. The Task Force has further made following suggestions

• • Food Regulation Authority (FRA) be set up to formulate and update food standards for domestic and export market.
  • FRA should replace the PFA to conform to international standards. The Task Force has given ten specific recommendations such as provision of storage, simplification of sampling procedure, simplification of procedure for nominee, time limit for prosecution, standard methods of analysis to be prescribed, penalty should graded according to the gravity of offences and provision of adequate/infrastructure and laboratories.
  • Harmonization of Indian standard with quality norms of Codex and WTO.
  • The Central Committee of food Standard (CCFS) should be replaced by FRA Governing Body for expeditious decisions.

THE FOOD SAFETY AND STANDARDS BILL, 2005

            A Bill to consolidate the laws relating to food and to establish the Food Safety and Standards Authority of India for laying down science based standards for articles of food and to regulate their manufacture, storage, distribution, sale and import, to ensure availability of safe and wholesome food for human consumption and for matters connected therewith or incidental thereto. The Central Government shall, by notification, establish a body to be known as the Food Safety and Standards Authority of India to exercise the powers conferred on, and to perform the functions assigned to, it under this Act. The Food Authority shall consist of a Chairperson and the following twenty-two members out of which one third shall be women, namely
1.  Seven Members, not below the rank of a Joint Secretary to the Government of India, to be appointed by the Central Government, to respectively represent the Ministries or Departments of the Central Government dealing with

• Agriculture
• Commerce
• Consumer Affairs
•  Food Processing
•  Health
•  Legislative Affairs
• Small Scale Industries who shall be Members ex officio

2. Two representatives from food industry of which one shall be from small scale industries;
3.   Two representatives from consumer organizations
4.   Three eminent food technologists or scientists
5.   Five members to be appointed by rotation every three years, on each in seriatim from the Zones as specified in the First Schedule to represent the States and the Union territories.
6.   Two persons to represent farmers’ organization.
7.   One person to represent retailers’ organizations.
REFERENCES
CDC. 1999. PulseNet. The National Molecular Subtyping Network in Place to Combat Foodborne Illness. Press Release. Updated 2/18/99. Available via the Internet at http://www.cdc.gov/ncidod/dbmd/pulsenet/pulsenet.htm
FAO. 1998. Food Quality and Safety Systems. A Training Manual on Food Hygiene and the Hazard Analysis and Critical Control Point (HACCP) System. Food Quality and Standards Service, Food and Nutrition Division,Food and Agriculture Organization of the United Nations.
FAO. 2000. Manual on Multilateral Trade Negotiations on Agriculture: A Resource Manual. SPS and TBT Agreements. FAO, Rome. 2000.
FAO/WHO. 1999. Understanding the Codex Alimentarius. Available via the Internet at http://www.fao.org/docrep/w9114e/w9114e00.htm
FDA. 1999. Import Program System Information. Food and Drug Administration,Office of Regulatory Affairs. Available via the Internet at http://www.fda.gov/ora/import/ora_import_system.htm
FDA. 2001. Requirements of Laws and Regulations Enforced by the U.S. Food and Drug Administration. Available via the Internet at http://www.fda.gov/opacom/morechoices/smallbusiness/blubook.htm#baseinfo.
FRUIT PRODUCTS ORDER (FPO) REGULATIONS IN FOOD SAFETY
INTRODCUTION
The Food Safety and Standards Act, 2006
         An Act to consolidate the laws relating to food and to establish the food Safety and Standards Authority of India for laying down science based standards for articles of food and to regulate their manufacture, storage, distribution, sale and import, to ensure availability of safe and wholesome food for human consumption and for matters connected therewith or incidental thereto.”
The following laws were consolidated:

1. The Prevention of Food Adulteration Act, 1954 (37 of 1954)
2. The Fruit Products Order, 1955
3. The Meat products Order, 1973
4. The Vegetable Oil Products (Control) Order, 1947
5. The Edible Oils Packaging (Regulation) order, 1998
6. The Solvent Extracted Oil, De oiled Meal, and Edible Flour (Control) Order, 1967
7. The Milk and Milk Products Order, 1992
8. Any other order issued under the Essential Commodities Act, 1955 (10 of 1955) relating to food

“Food Safety” means assurance that food is acceptable for human consumption according to its intended use.
“Food Safety Management System” means the adoption of Good Manufacturing Practices, Good Hygienic Practices, Hazard Analysis and Critical Control Point and such other practices as may be specified by regulation, for the food business”
THE FOOD SAFETY AND STANDARDS AUTHORITY OF INDIA
          As per the Gazette notification of India under S.O.2127 dated 28.08.2008, the activities of FPO have been transferred to the Food Safety and Standards Authority of India from 01.12.2008 onwards.
Duties and Functions of Food Authority

1. To regulate and monitor the manufacture, processing, distribution, sale and import of food so as to ensure safe and whole some food
2. To specify the standards and guidelines in relation to articles of food and specifying an appropriate system for enforcing various standards notified under this Act
3. Accreditation of certification bodies in certification of food safety management system for food businesses
4. Enforcement of quality control in relation to any article of food imported into India
5. To provide scientific advice and technical support to the Central Government and the State Governments in matters of framing the policy and rules in areas which have a direct or indirect bearing on food safety and nutrition.

ABSTRACTS OF FRUIT PRODUCTS ORDER, 1955.

CLAUSE 4(1): No person shall carry on the business of manufacture of Fruit & Vegetable Products except and in accordance with the terms of an effective licence granted to him under this order.
CLAUSE 5(2): The following fee being appropriate fees shall be payable for one term or part thereof to be paid ONLY WHEN INSTRUCTED BY THIS OFFICE.

NOTE:

• Area occupied by Machinery shall not be more than 50% of manufacturing area.
• WATER: Every licensee shall arrange for atleast l Kilo litre per day of potable water and its availability. Water shall be adequately increased as per production. Free flowing pipe water supply shall be made available to the processing hall.
• The workers engaged in Fruit & Vegetable processing shall be got medically examined for their fitness to ensure that they are not suffering from any contagious diseases.
• For Large/Small Scale B category units, a qualified CHEMIST shall be appointed as QUALITY CONTROL INCHARGE.
• All the workers engaged in the production of Fruit & Vegetable products shall be provided with clean APRONS AND HEADWEARS.

FRUIT PRODUCTS ORDER (FPO) 1955

• Constituted under Section3 of Essential Commodities Act
• Aims at regulating Sanitary & Hygienic conditions in the manufacture of Fruit Products.
• Mandatory for all Manufacturers of Fruit and Vegetable Products to obtain a licence under FPO.
• Implemented by the Food Safety and Standards Authority of India through Directorate of Fruit & Veg. Processing at its Regional Offices.

Products covered under FPO 1955

• All types of Processed Fruit and Vegetable products (eg:- Pickles,Jams,juices etc..)
• Sweetened aerated water
• Non- Fruit Vinegar & Non- Fruit Syrup.

Important Clauses under FPO-1955

• Clause-4:- No person shall carry on the business of a manufacturer except under and in accordance with the items of an effective licence granted to him under this order in Form-B.
• Clause-5:- Every application for grant of licence under Cl.4 shall be made in duplicates to the licensing officer in Form-A and shall be accompanied by a fee of such amount as is appropriate to the each of the clause of licence.
• Clause-7:-Every manufacturer shall manufacture fruit products in conformity with the sanitary requirements and the appropriate standard of quality and composition specified.
• Clause-9:- Every Manufacturer shall submit by the 31st of January of every year to the licensing officer a return in duplicate in Form-C in respect of each class of Fruit products manufactured, sold and exported by him during the previous term.
• Clause-12:- every manufacturer to whom any directions or order is issued in pursuance of any provision of this order shall be bound to comply with such directions or order any failure shall be deemed to be a contravention of the provisions of this order.

Documents to be submitted for grant of FPO license

• • • Application in Form A (Copy enclosed)
    • Plan of the factory showing the dimensions in metres /sq.metres duly ear-marking the area for Processing, raw-materials store & finished goods Store.
    • List of Machinery and Equipments showing the Capacity, Horse-power Used, Number and Source of supply of each Machine.
    • Proof of possession of factory premises – Rental/Lease Agreement and Property Tax receipt indicating Name of Owner &  address of unit .
    • N.O.C.  from the Local Government Authority.
    • Water Analysis Report –Chemical & Bacteriological, from Public Health Laboratory /GOVT. APPROVED LABORATORY and the report should indicate that the water has been drawn from the factory premises either by The representative of the laboratory or by the Public Health Authority. Under remarks column, it shall clearly indicate that the water is fit for drinking purpose /Potable.

CLAUSE 7
          Every manufacturer shall manufacture fruit products in conformity with the sanitary requirements and appropriate standards of quality and composition specified in the Second Schedule of this Order.
THE SECOND SCHEDULE (see Clause 7)
PART 1 (A): SANITARY REQUIREMENTS OF A FACTORY OF FRUIT PRODUCTS

• The premises shall be adequately lighted, ventilated & cleaned by white washing/ colour washing or oil painting.
• Windows and doors shall be fly proofed, doors fitted with automatic closing springs. Roof shall be permanent.  Floor cemented.
• The equipment and the factory shall not be used for manufacture of repugnant products like fish, meat, eggs etc., However, permission may be granted a special case if arrangements are made for disinfection of premises after changing from meat products to fruit products (One month idle gap will be required for change over).
• The premises shall be located in a sanitary place with open  surroundings, preferably in industrial area/estates. The premises shall not be used as or communicated directly with Residence.
• Adequate arrangements for cleaning equipments, machinery, Containers, tables and raw materials shall be provided.
• Copper, brass or iron equipments, containers or vessels are not permitted , in the preparation, packing or storage of fruit Products.
• The water used shall be potable and shall be got examined Chemically and bacteriologically by a Public Health Laboratory (if no municipal water is available at the premises). The water sample should be drawn for such examination by the Public Health Authority of the area where the premises is located or should be drawn in the presence of the above authority. Free flowing tap water of 1 kilo litre per day shall be made available.
• Adequate drainage system and provisions for disposal of refuse shall be made.
• Sufficient number of laterine & urinals shall be provided for workers.
•  Wherever cooking is done on open fire, proper outlets for the smoke/steam etc., like chimney, exhaust fan etc., shall be provided.
•  The workers engaged in the factory shall be healthy and shall be medically examined, inoculated and vaccinated, whenever required.
•  The workers shall be provided with aprons, head-wears, gloves etc., and shall be personally neat and tidy.
  Grant-in-aid: For setting up or up gradation of food processing units, Ministry of Food Processing Industries is giving grants. More details can be obtained from the Ministry’s web site – www/mofpi.nic.in

Office Details:
The enforcement of FPO 1955, is being carried out from four regional offices located at

• New Delhi
• Mumbai
• Kolkatta
• Chennai
• Guwahatti

The jurisdiction of our office covers Southern States of India i.e. Tamil Nadu, Kerala, Karnataka, Andhra Pradesh, Pondicherry and Lakshadweep.
Southern Regional Office is located at
Office of the Deputy Director(F&VP)
Food Safety And Standards Authority Of India,
C-1-D, Rajaji Bhawan, Besant Nagar,
Chennai-600 090
Tel:- 044-24912421, Fax:- 044-24463569
Address of the Food Safety and Standards Authority of India
Food Safety and Standards Authority of India
Ministry of Health and Family Welfare, Government of India,
FDA Bhawan,Kotla Road, New Delhi-110002
Website: www.fssai.gov.in;  Tel: 011-23220992

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