OIL-SEEDS

OIL-SEEDS COMPRISES AN ESSENTIAL PART OF OUR COUNTRIES ECONOMY. INDIA OCCUPIES A PROMINENT POSITION IN THE WORLD. BOTH REGARD TO AVERAGE AND PRODUCTION BY PRODUCING AN AVERAGE 20 MILLION TONNES OF OIL-SEEDS EVERY YEAR.

INDIA IMPARTS OUT OF WORLD RS. 12000 CRORES EVERY YEAR. THE PER CAPITA AVAILABILITY OF OIL AND FAT IN INDIA IS ABOUT 5KG WHICH IS FAR BELOW THAN RECOMMENDED AVERAGE REQUIREMENT OF 18KG. THE IMPROVEMENT IN OIL MILLING TECHNOLOGY CAN CERTAINLY CONTRIBUTE TO INCREASE AVAILABILITY OF EDIBLE OILS.

THE MAJOR OIL SEEDS ARE- OLIVE SEEDS, SUNFLOWER, COTTON SEEDS, GROUNDNUT, COCONUT AND MUSTARD SEED ETC.

OIL EXTRACTION:-

TO SUIT SPECIFIC CONDITIONS ONE OF THE THREE BASIC METHODS CAN BE MODIFIED OR COMBINED TO OBTAIN OIL FROM OIL SEEDS. COMMERCIALLY BASIC METHODS ARE-

1- BASIC HYDROLIC PRESSING:-

IN THIS OIL IS EXPRESSED BY HYDROLIC PRESSURE FROM MASS OF OIL BEARING MATERIAL.

2- CONTINUOUS MECHANICAL PRESSING:-

IN THIS THE OIL BEARING MATERIAL IS SQUEEZED THROUGH A TAPOURING OUTLET, BEING EXPRESSED BY THE INCREASING PRESSURE.

3- SOLVENT EXTRACTION:-

IN THIS OIL BEARING MATERIAL IS TAKE INTO SOLUTION WITH A SOLVENT. THE SOLUTION IS SEPARATED FROM INSOLUBLE RESIDUE AND OIL RECOVERED FROM THE SOLVENT SOLUTION. THE COMBINATION OF THESE PROCESS IS COMMERCIAL.

OPERATIONS ARE CONTINUOUS, MECHANICAL PRESSING (EXPELLING) WITH CONTINUOUS SOLVENT EXTRACTION AND BATCH HYDRAULIC PRESSING AND SOLVENT EXTRACTION WITH THE EXCEPTION OF COASTER WHICH REQUIRES SPECIAL TREATMENT AND EQUIPMENT CLEANING PROCEDURES AND OTHER OIL SEEDS CAN BE SIMILARLY PROCESSED.

WHEAT

WHEAT

NEXT TO RICE, WHEAT IS THE SECOND LARGEST IMPORTANT FOOD GRAIN OF INDIA.NEARLY  1/10 OF CROPPED AREA IS DEVOTED TO WHEAT. THE COUNTRIES PRODUCING MORE WHEAT THAN INDIA ARE- USA AND CHINA OVER 83% OF THE COUNTRIES. TOTAL WHEAT OUTPUT COMES FROM UP, PUNJAB, BIHAR, MP, HARYANA AND RAJASTHAN. DURING 1890-91 IT IS OCCUPIED AN AREA OF 240 LAKH TONNES OF WHEAT GRAIN.

STRUCTURE OF WHEAT GRAIN:-

THE GRAIN OF WHEAT CONSIST OF AN OUTER COVERING THE PERICARP AND TESTA WHICH IS HARD AND INDIGESTIBLE, AN ALLEURONE LAYER, WHICH CONTAINS A HIGHER PROPORTION OF PROTEIN THAN FLOUR, AN EMBRYO ATTACKED TO A SMALL STRUCTURE, THE SCHUTELUM AT THE LAYER END OF GRAIN AND FINALLY THE ENDOSPERM COMPERISING OF 85% OF THE WHOLE GRAIN FROM WHICH THE FLOUR IS DERIVED.

IT IS IMPORATANT TO MENTION THAT THE MILLING OF WHEAT IS A PHYSICAL PROCESS. THE COMPOSITION OF BRAN, EMBRYO AND ENDOSPERM IN WHEAT IS GIVEN BELOW-

BRAN – 12%

GERM – 3%

ENDOSPERM – 85%

COMPOSITION OF WHEAT:-

MOISTURE – 10-13%

CARBOHYDRATE – 69%

PROTEIN – 8-13%

FAT – 2%

FIBRE – 3%

QUALITY TEST FOR WHEAT:-

1)- TEST WEIGHT:-

IT IS MOST WIDELY USED CRITERIA FOR FINDING WHEAT QUALITY FACTORS AFFECTING WEIGHT IN WHEAT.

SHAPE

SIZE

DENSITY

MOISTURE CONTENT

IN INDIA THE WEIGHT IS MEASURED IN TERMS OF KG/HECTO LITRE.

TEST WEIGHT= WEIGHT/UNIT VOLUME

VOLUME IS MEASURED IN TERMS OF WINCHESTER BUSHEL.

1 KG HECTO LITRE= 1 WINCHESTER BUSHEL * 1.287

2)- THOUSAND KERNEL WEIGHT:-

IT IS DEFINED AS THE WEIGHT OF 1000 KERNELS OF WHEAT. THE PROPERTY GIVEN AN IDEA ABOUT THE SOUNDNESS OF WHEAT.

PROCEDURE:-

RANDOMLY SELECT 1000 KERNELS FROM THE GIVEN SAMPLE WEIGH THEM AND WEIGHT BY 100. TAKE ATLEAST 5 READING AND THEN TAKE AVERAGE.

3)- GRAIN HARDNESS:-

HARDNESS CAN BE MEASURED BY GRAIN HARDNESS OR BY PEARLING INDEX. HARD THE WHEAT MEANS CONTAIN MORE PROTEIN CONTENT.

HARDNESS α PROTEIN CONTENT

WHEAT MILLING:-

THE WHEAT MILLING PROCESS CONSISTS OF 5 MAIN PRODUCTS.

1-       RECEPTION AND STORAGE OF WHEAT.

2-      CLEANING

3-      TEMPRING OR CONDITIONING

4-      MILLING OF WHEAT INTO FLOUR

5-      STORAGE OF FINISHED PRODUCTS.

1)-  RECEPTION AND STORAGE OF WHEAT:-

WHEAT SELECTION IS IMPORTANT TO THE FLOUR MILLER WITHOUT SOUND WHEAT (DRY UNSPOTTED AND FREE FROM CONTAMINATION) THE MILLER IS PRWERLESS TO PRODUCE ADEQUATE PRODUCED.

WHEAT IS STORED AT MILL IN LARGE CONCRETE. BEFORE STORAGE THE WHEAT IS UNDERGOES A PRELIMINARY CLEANING AND DRYING TO REMOVE THE GROSS IMPURITIES AND FOREIGN MATERIAL AND TO REMOVE MOISTURE IF NECESSARY SO THAT THE WHEAT CAN BE STORED WITHOUT HEATING.

WHEAT MUST BE KEPT DRY NORMALLY NOT HIGHER THAN 14.5% MOISTURE.

2)- CLEANING:-

SINCE THE GRAIN IMPURITIES HAVE ALREADY BEEN REMOVED AT THE STORAGE LINES THE TECHNIQUES USED IN THE CLEANING HOUSE IS MORE REFINED. HERE, THE WHEAT IS CLEANED BY REMOVING LOOSE FOREIGN MATERIAL AND DIRT, ADHERING TO SURFACE OF THE GRAIN. WHEAT IS WEGHED AS IT ENTERS THE CLEANING HOUSE AND THERE FORE GOES THROUGH A SEPARATOR, WHICH IS SET TO REMOVE FINE IMPURITIES AND DUST, SMALL PIECES OF STICKS, STONES, SAND AND DUST ARE SHIFTED AWAY AND LIGHT IMPURITIES SUCH AS WHEAT CHOFF ARE REMOVED BY AIR CURRENT. AFTER THIS WHEAT IPASSES OVER MAGNETIC SEPARATOR TO RAMOVE BITS OF ADVENTITIOUS METAL WHICH MAY HAVE FORMED THEIR WAY INTO THE WHEAT MIX. NEXT STEP OF DIRT FROM SURFACE OF WHEAT BY SCORING.

THE FINAL CLEANING STEP IS A WATERMARK. THE WATER DISSOLVES THE DIRT AND PERMITS STONES AND BITS OF MEATAL TO SINK.

3)- TEMPERING OR CONDITIONING:-

TEMPERING REFERS TO THE ADDITION OF WATER TO THE BRAN AND ENDOSPERM. THE BRAN BECOMES TOUGH AND RUBBERY WHILE THE ENDOSPERM BECOME LESS VITEROUS. THIS IMPROVES MILLING EFFICIENCY.

TEMPERING INVOLVES ADDING WATER TO VOICE THE MAOISTURE TO 15-18% FOR HARD WHEAT AND 14.5-17% FOR SOFT WHEAT AND ALLOWING WHEAT TO BE INTEMPERING BINS FOR PERIOD OF 18-72 HOURS. DURING THIS TIME THE WATER ENTERS THE BRAN AND DIFFUSE INWARDS CAUSING. THE BRAN TO LOOSE ITS VIABLE CHARACTERISTICS AND TO BECOME LEATHERY IN TEXTURE.

CONDITIONING IN CONTRAST TO TEMPERING ALWAYS INVOLVES THE USE OF WHEAT SINCE QUICK DIFFUSION OF WATER INTO ENDOSPERM AS WELL AS THE BRAN IS THE PURPOSE. WHEAT CONDITIONERS INVOLVE  FOR SECTIONS. THE FIRST SECTION HEATS THE WHEAT TO THE PROPER TEMPERATURE (AS HEAT AFFECTS QUALITY OF GLUTEN, SO NORMALLY TEMPERATURE OF 45⁰C CANNOT BE EXCEES).

THE SECOND SECTION ADDS MOISTURE AND HOLDS THE WHEAT FOR THE PROPER TEMPERATURE. THE THIRD SECTION COOLS THW WHEAT AT ROOM TEMPERATURE AND THE FINAL SECTION ROVIDES A HOLDING BIN WHERE THE MOISTURE IN WHEAT IS ALLOWED TO EQUILIBRATE BEFORE MILLING.

4)- WHEAT GRINDING:-

THE GRINDING OF WHEAT IS DONE BETWEEN PAIRS OF ROLLS SINCE THEY ARE MOVING IN OPPOSITE DIRECTIONS MOVING AT DIFFERENT RATE OF SPEED ONE FROM THE OTHER AND SET WITH AN APPRECIABLE GAP BETWEEN THEM, DO NOT GRIND THE WHEAT PRIMARILY BY CRUSHING THE REDUCTION OF WHEAT SIZE BY SHEARING FORCES WHICH BECAUSE OF THE SET OF THE ROLL RUNS ABOUT 25 TIMES FASTER THAN THE SLOWER ONE AND AT SPEEDS FROM 250-450 RPM.

HERE, THE ROLLER MILLING AREA IS DIVIDED INTO 2 SECTIONS, THE BREAK SECTION AND THE REDUCTION SECTION. IN THE FIRST SYSTEM, THE BRAN IS BROKEN OPEN AND THE ENDOSPERM IS MILLED AWAY. ROLLS IN SECOND SYSTEM ARE REDUCTION ROLLS WHICH ARE SIMILAR TO THE BREAK ROLLS EXCEPT THAT THEIR SURFACES IS NORMALLY SMOOTH RATHER THAN CORRUPTED. AFTER EACH REDUCTION OF ENDOSPERM THE FLOUR IS SHIFTED AWAY FROM THE UNDERGROUND ENDOSPERM CHANNELS WHICH ARE RETURN TO THE SECOND ROLL AND PROCESS IS REPEATED.

5)- STORAGE OF FINISHED PRODUCT:-

NOW ATLEAST FLOUR IS PACKAGED IN WELL MANNER ANS STORE IN STORE HOUSE.

PHYSIOCHEMICAL TEST OF WHEAT FLOUR:-

THE GENERAL TEST WHICH ARE CONDUCTED TO SPECIFY THE WHEAT FLOUR ARE-

1- MOISTURE CIONTENT

2- PROTEIN

3- FIBRE

4- COLOUR

5- GLUTEN CONTENT

6- AMYLOSE ACTIVITY

7- SEDIMENTATION VALUE

8- POLSHENKE VALUE

USE OF FLOUR:-

1- WHEAT FLOUR IS USED TO PREPARE VARIOUS WHEAT PRODUCTS SUCH AS BREAD, COOKIE, BISCUITS, CRUCKER, CAKES, PARTY ETC.

2- FOR MAKING READY TO EATEN EASY TO MAKE OR OTHER CONVENIENT FOODS.

RICE GRAIN

RICE GRAIN- QUALITY, TEST, MILLING AND 

USES OF RICE

STRUCTURE OF RICE

THE RICE GRAIN CONSIST OF AN OUTER PROTECTIVE COVERING, THE HULL (HUSK) AND THE EDIBLE RICE CARYOPSIS OF FRUIT (BROWN, CARGO, DEHULLED OR DEHUSKED RICE). BROWN RICE CONSISTS OF THE OUTER LAYERS OF PERICARP SEED COAT AND NUCELLUS, THE GERM OR EMBRYO WHICH ARE MATERNAL TISSUE AND THE ENDOSPERM. THE ENDOSPERM CONSISTS OF THE ALEURSOME LAYER, THE SUBALLEURONE LAYER AND THE STARCHY  OR INNER ENDOSPERM PIGMENT IS CONFINED TO PERICARP. THE ALLEURONE LAYER ENCLOSES THE EMBRYO.

THE INEDIBLE HULL CONSTITUTE 16-20% (MEAN 20%) OF THE ROUGH RICE WEIGHT. BROWN RICE CONSISTS OF 1-2% PERICARP, 4-5% ALLEURONE, NUCELLUS AND SEED COAT, 1% EMBRYO, 2% SCUTELLUM AND 90-91% ENDOSPERM. THE ALLEURONE AND EMBRYO CELLS ARE RICH IN PROTEIN BODIES CONTAINING GLOBOIDS AND PHYTATE BODIES AND IN LIPID BODIES.

THE ENDOSPERM CELLS ARE THIN WALLED AND PACKED WITH AMYLOPLASTS CONTAINING POLYHEDRAL COMPOUND. STARCH GRANULES ABOUT 3-9 MICRO METER IN SIZE. PROTEIN OCCURS MAINLY IN THE FORM OF LARGE(1-2 MICRO METER) AND SMALL (0.5-0.8 MICROMETER) SPHERICAL; PROTEIN BODIES AND CRYSTALLINE PROTEIN BODIES SPHERICAL PROTEIN BODIES ARE RICH IN PROLAMINE (ALCOHOL SOLUBLE PROTEIN) & CRYSTALLINE PROTEIN BODIES ARE RICH IN GLUTELIN (ALKALI SOLUBLE PROTEIN), SPHEROSOMES ARE PRESENT IN SUBALLEURONE OR TWO OUTERMOST CELL LAYER.

VARIOUS PARAMETERS USED TO JUDGE THE QUALITY OF RICE ARE:-

·          

      ALKALI SCORE

·         WATER UPTAKE

·         COOKING QUALITY

·         DIMENSIONS

·         COLOR

·         1000 KERNEL WEIGHT

·         BULK DENSITY

·         TRUE DENSITY

·         PERCENT POROSITY

·         SURFACE AREA

ALKALI SCORE:-

IT HELPS IN DETERMINING THE APPROXIMATE GELATINIZATION TEMPERATURE OF THE GIVEN VARIETY OF RICE. IN THIS 8 OR 10 KERNALS ARE PLACED IN KOH SOLUTION, FOR 24 HOURS OR OVERNIGHT. KOH TRIES TO BREAK THE KERNEL. OBSERVED HOW MANY  KERNELS ARE DISINTEGRATED & CALCULATE PERCENT DISINTEGRATION. IF DISINTEGRATION IS MORE , GELATINIZATION TEMPERATURE IS LESS & RICE IS OF LOW QUALITY.

PROCEDURE:-

·         TAKE 8 RICE KERNALS AND KEEP THEM SYMMETRICALLY ON THE PETRIPLATE.

·         ADD 1.8% KOH SOLUTION ENOUGH TO COVER THE KERNELS OR IMMERSE THE KERNEL.

·         PLACE THE COVER OF PETRIPLATE.

·         KEEP IT FOR OVERNIGHT.

·         NOTE DOWN THE MICRO-ORGANISMS OF KERNELS DISINTEGRATED.

FORMULA USED:-

ALKALI SCORE= NUMBER OF KERNEL DISINTEGRATED/TOTAL NUMBER OF KERNELS*100

GELATINIZATION TEPERATURE α 1/ALKALI SCORE

COOKING QUALITY:-

COOKING QUALITY REVEALS THE QUALITY DEPENDING UPON THE TYPE OF KERNELS. COOKING QUALITY IS DEFINED W.R.T MANY CHARACTERISTICS SUCH AS TIME OF COOKING, SWELLING CHARACTERISTICS, COLOR, PASTYNESS. RAW RICE TAKES 15-20 MINUTES TO BECOME FULLY COOK IN BOILING WATER WHEREAS PARBOILED RICE TAKE 30 MINUTES FOR SOME DEGREE OF SOFTNESS. RAW RICE COOKED BEYOND 20 MINUTE BECOME PASTY.

PROCEDURE:-

·        SIX BEAKERS HAVING 50 ML OF WATER ARE TAKEN AND BOILED OVERFLAME.

·         WHEN WATER STARTS BOILING ADD 2 GM OF RICE IN EACH.

·         WITHDRAW IT FROM FLAME AFTER TIME INTERVALS OF 4, 8, 12, 20, 22, AND 24.

·         NOTE THE NATURE OF THE RICE KERNELS.

WATER UPTAKE:-

WATER UPTAKE IS DEFINED AS GRAMS OF WATER OBSERVED BY ONE GM OF RICE. IT IS A PARAMETER USE TO FIND OUT COOKING QUALITY.

PROCEDURE:-

·         TAKE 4 TEST TUBES HAVING 20 ML OF WATER IN EACH.

·         IMMERSE IT IN WATER BOTH TILL THE TEMPERATURE OF THE TEST TUBE WATER REACHES TO 80⁰C.

·         ADD 2 GM OF RICE IN EACH TEST TUBE AND KEEP IT FOR 25 MINUTES.

·         TEST TUBES ARE COOLED AND EXCESS OF WATER ID DRAINED.

·         WEIGH THE RICE TO CALCULATE WATER ABSORBED.

FORMULA USED:-

WATER UPTAKE= FINAL WEIGHT- INITIUAL WEIGHT/INITIAL WEIGHT*100

% WATER ABSORBED= GM OF H2O ABSORBED/GM OF RICE*100

DIMENSIONS:-

THIS INCLUDES LENGTH AND BREADTH OF RICE. DIMENSIONS GIVE AN IDEA ABOUT THE QUALITY OF RICE. LONG AND THIN RICE IS OF GOOD QUALITY AS COMPARED TO THICK AND SMALL RICE.

PROCEDURE:-

LENGTH:-

FOR FINDING THE LENGTH WE USE VERNIER CALLIPER. TAKE 10 KERNELS FROM EACH OF THE SAMPLE AND FIND THE LENGTH THEN TAKE THE AVERAGE. THE LEAST COUNT OF VERNIER CALLIPER IS 0.1.

BREADTH:-

FOR FINDING THIS SCREW GUAGE IS USE. TAKE 10 KERNELS FROM EACH SAMPLE AND THEN TAKE THE AVERAGE. THE LEAST COUNT OF SCREW GUAGE IS 0.001.

COLOUR:-

COLOR IS A HERIDATORY NFACTOR AND DEPENDS UPON THE TYPE OF PROCESSING AND DEGREE OF MILLING COLOR OF RICE IS WHITE TO YELLOWISH.

1000 KERNEL WEIGHT:-

IT IS DEFINED AS THE WEIGHT OF 1000 KERNELS OF RICE. THE PROPERTY GIVES AN IDEA ABOUT THE SOUNDNESS OF RICE.

PROCEDURE:-

RANDOMLY SELECT 1000 KERNELS FROM THE GIVEN SAMPLE WEIGH THEM AND THE WEIGHT BY 100. TAKE ATLEAST 5 READINGS AND THEN TAKE AVERAGE.

BULK DENSITY:-

BULK DENSITY IS A WEIGHT OF KNOWN QUANTITY OF CEREALS. IT GIVES THE SOUNDNESS OF GRAIN WITH THE HELP OF BULK DENSITY, ONE CAN CALCULATE THE SURFACE AREA REQUIRED TO STORE A PARTICULAR OF RICE.

PROCEDURE:-

TAKE A MEASURING CYLINDER WITH THE RICE BY FIRST FILLING THE CYLINDER UPTO 25 ML, THEN TO 50 ML AND ATLEAST 75 ML AS THE DENSITY IS MASS/VOLUME. PUTTING THE  VALUE IN THE FORMULA FIND THE VALUES FOR BULK DENSITY.

TRUE DENSITY:-

TRUE DENSITY IS FOUND BY DIPPING 10 GM OF SAMPLE TO 50 ML TOULENE SOLUTION.

FORMULA USED:-

TRUE DENSITY= WEIGHT OF SAMPLE/ FINAL VOLUME-INITIAL VOLUME

% POROSITY:-

IT IS CALCULATED BY USING TRUE DENSITY AND BULK DENSITY.

FORMULA USED:-

% POROSITY= TRUE DENSITY- BULK DENSITY/ TRUE DENSITY* 100

MILLING OF RICE:-

STEPS OF RICE MILLING:-

RECEIVING:-

ROUGH RICE (PADDY RICE) WHICH CONSISTSOF 50% OR MORE KERNELS FROM WHICH THE HULL HAVE NOT BEEN REMOVED IS RECEIVED AT RICE MILL IN BULK OR SACKS.

DRY CLEANING:-

INCOMING RECEIPTS MUST BE CAREFULLY SORTED SO THAT DIFFERENT GRADES, VARIETIES AND GRAIN SIZES CAN BE PROCESSED IN A SEPARATE LOTS. PROCESSING MACHIENERY IS ADJUSTABLE SO THAT VARYING CHARACTERISTICS OF THE INCOMING MATERIAL CAN BE ACCOMODATED IN A SERIES OF MECHANICAL AND PNEUMATIC OPERATIONS CHAFF, LUMPS OF MUD AND DIRT, FOREIGNSUBSTANCES, GRAVEL, WEEDSEEDS AND ANY OTHER DEBSIS LEFT OVER FROM PRIOR THRESHING ARE REMOVED.

SHEILLING:-

THE RICE IS PASSED THROUGH SHELLER FOR THE REMOVAL OF HULLS. ALTHOUGH HULLING STONES MAY BE USED, MOST (MODERN FACILITIES), THE SHELLER CONSISTS OF PAIRED RUBBER ROLLS WHICH TURN AT DIFFERENT SPUDS SO THAT AS THE KENELS PASS THROUGH THE MACHINE A TEARING OR PULLING AND SLIGHT CRUSHING (CRACKING) ACTION TAKES PLACE. SHELLERS ARE USED IN TANDOM WITH RECYCLING BETWEEN MACHINES TO EFFECT FINAL QUALITY CONTROL. IN THESE OPERATIONS AND THROUGH OUT ALL MILLING OPERATIONS, A MAJOR CONCERN IS THAT OF AVOIDING KERNEL BREAKAGE. AFTER HULLING THE PRODUCT IS KNOWN AS BROWN RICE.

SEPERATING:-

DUST AND HUSKS ARE REMOVED PNEUMATICALLY IN WHAT IS CALLED A FANNING MACHINE. THE HULLS MAY BE CONSUMED AS FUEL AT THE MILLING FACILITY OR COLLECTED AND MARKETED FOR USE AN INSULATION AS A SOURCE OF FURFURAL FOR CHEMICAL MANUFACTURER, AS PACKING AND SOIL MULCHING MATERIAL. EVEN WIH PRIOR SHELLING IN TANDOM SOME UNHULLED KERNELS WILL GET THROUGH. THESE ARE RECYCLED BACK TO THE SHELLING LINE. THE SEPARATION MACHINE IS SOME TIME CALLED AS PADDY MACHINE.

BRAN REMOVAL:-

THE BRAN LAYERS ARE REMOVED. THE INNERMOST OR POLISH LAYER MAY REMAIN. THIS MACHINE IS AN ADAPTATION OF THE MACHINE USED TO HULL COFFEE AND HENCE IN THE TRADE IT IS COMMONLY REFERRED TO, THROUGH INCORRECTLY AS A HULLER. IN A SERIES OF RUBBING ACTIONS, THE BROWN COAT IS REMOVED AND ASPIRATED AWAY TO A BRAN COLLECTOR. AT THIS POINT THE PRODUCT IS KNOWN AS UNDERMILLED RICE. IN SOME PLANTS,  PEARLING OPERATION MAY FOLLOW. THIS ESSENTIALLY IS A REFINEMENT OF BRAN REMOVAL OPERATION. MOST RICE BRAN IS USED IN ANIMAL FEEDS.

BRUSHING:-

THE RICE PRODUCTS TO BRUSHING MACHINE WHERE IT IS SCOURED TO REMOVE THE INNER MOST BRAN COAT, ALSO KNOWN AS POLISH. THIS MACHINE CONSISTS OF A RAPIDLY REVOLVING VERTICAL CYLINDER EQUIPPED WITH OVERLAPPING PIECES OF HIDE.  A HIGH POLISH IS IMPOTED TO THE SURFACE OF RICE AND THE PRODUCT IS CALLED POLISHED RICE. THE POWDERY POLISH SUBSTANCES (MOSTLY CHO) IS COLLETED AND IS ALSO USED IN ANIMAL FEED.

TRUMBLING:-

POLISHED OR UNCOATED RICE MAY BE MARKETED AT THIS POINT, OR THE PRODUCT MAY BE PASSED TO TRUMBLING MACHINES, WHERE THE KERNELS ARE COATED WITH GLUCOSE AND TALE. THE COATING IS PREFERRED BY SOME MARKETS AND DOES NOT DETRACT FROM THE NUTRITIONAL VALUE OF THE PRODUCT.

SCREENING AND SEPERATNG:-

IN SCREENING AND SEPERATING THE WHOLE RICE KERNELS, BROCKERS AND RICE FLOUR ARE SEPERATED, THEN THEY ARE GRADED PACKAGED SEPERATELY AND MARKETED.

USES OF RICE:-

1.       RICE IS USED AS A STAPLE FOOD IN MANY COUNTRIES.

2.       RICE WITH A LOW STARCH GELATINIZATION IS  PREFERRED  IN RICE PUDDING, BREADS & CAKES & BEER ADJUNCTS, THIS ALLOWS STARCH GELATINIZATION AT LOWER PROCESSING TEMPERATURES, PARTICULARLY IN THE PRESENCE OF SUCROSE.

3.       WARY AND LOW AMYLOSE RICES ARE PREFERRED FOR RICE WINE(FOR HIGHER ETHANOL YEILD) AND IN FROZEN SAUCES, DESSERTS AND SWEETS BECAUSE OF THE SLOW STALING RATE.

4.       RICE BY PRODUCTS INCLUDING THE OUTER BRAN LAYERS, GERM AND POLISH ARE THE POTENTIAL SOURCE OF FOOD FOR HUMANS, THESE BY PRODUCTS ACCOUNTS FOR APPROX 10% OF PADDY RICE WEIGHT.

5.       THE HULLS OF THE RICE MAY BE CONSUMED ASFUEL AT THE MILLING FACILITY, OR COLLECTED AND MARKETED FOR USE AS INSULATION, AS A SOURCE OF FURFURAL FOR CHEMICAL MANUFACTURES, AS PACKING AND SOIL MULCHING MATERIAL.

6.       RICE-BRAN IS USED AS ANIMAL FOOD.

7.       RICE-FLOUR (GLUTINOUS AND WARY) IS USED FOR THICKENING OF VARIOUS PRODUCTS SUCH AS GRAVIES, WHITE SAUCES ETC.

8.       IN INDIA, SEVERAL TYPES OF DISHES ARE PREPARED FROM RICE FLAVORED WITH SPICES AND OTHER INGREDIENTS . OTHER RICE PREPARATIONS INCLUDE PARCHED RICE, PUFFED RICE AND FERMENTED PREPARATION LIKE IDLI AND DOSA.

RANCIDITY

What is rancidity?
 Rancidity is the development of unpleasant smells in fats and oils, which are often accompanied by changes in their texture and appearance.Two types of rancidity: Hydrolytic rancidity Oxidative rancidity (auto-oxidation) 

 Hydrolytic rancidity
 Caused by the breaking down of a lipid into its component fatty acids and glycerol.
 C-O-CO-R + H2O → C-O-H + HO-CO-R
 Occurs more rapidly in the presence of enzymes such as lipase, and with heat moisture
 The water present in the food and the high temperature will increase the rate of hydrolysis to fatty acids.
 The free fatty acids have an unpleasant smell giving a rancid smell and taste to milk and butter that have been stored for too long. Longer chain acids are less volatile, so the smell is less noticeable. 

 Oxidative rancidity (auto-oxidation)
 Occurs due to the oxidation of fatty acid chains typically by the addition of oxygen across the C=C bond in unsaturated fatty
 The process proceeds by a free radical mechanism catalysed by light in the presence of enzymes or metal ion
 The complex free radical reactions will produce a wide variety of products, many of which have unpleasant odours or tastes
 In highly unsaturated lipids, such as fish oils oxidative rancidity can be a major problem

 Ways to minimize rate of rancidity
 Packaging 
- Opaque packaging and coloured glass bottles will reduce light induced oxidative rancidity. 
- Gas impermeable wrapping film will reduce the exposure of the product to oxygen and water vapour in the air. 
- Free space in the container should be kept to minimum to reduce the amount of oxygen and water vapour present. The best way is to use vacuum packaging or fill the package with inert gases. 
-Example: Potato crisps which are usually packed in thick foil packets filled with nitrogen.

 Storage 
- Refrigeration will reduce the rate of most reactions that produce rancidity. 
- Storing fat and oil rich foods in the dark will reduce the rate of photo-oxidation, which is less affected by temperature. 
- Reducing the water level content of the foods (such as drying or smoking) and then storing them away from moisture helps to reduce hydrolytic rancidity and discourage the growth of micro-organisms. 

 Additives 
- The process of salting and having a high sugar content (as in preserves) will reduce the amount of water in the foodstuff via osmosis. 
- The rate of hydrolytic rancidity will also be reduced as well as making the environment less suitable for the growth of micro- organisms. 
- Sulfur dioxide and sodium sulfites (used with fruit products), along with sodium and potassium nitrites (used in curing meats) are examples of reducing agents that function to prevent the oxidative reactions that will lead to browning of many substances when stored too long. 

 Anti-microbial agents 
- Many organic acids and their salts are added to discourage the growth of moulds and bacteria in foods. 
- Examples : → addition of benzoic acid and sodium benzoate to fruit juices 
                    → addition of propanoic acid along with its sodium and calcium salts to bread and cheese 

 Traditional methods to extend shelf life of foods
• Pickling 
- The use of vinegar creates an environment that is too acidic for micro-organisms 

 Fermentation 
- Ethanol is produced which limits the growth of bacteria 
- Wine keeps much better than fresh fruit juice and distilled spirits - Higher alcohol concentration will last longer

 Salting 
– reduces amount of water• Preserves 
– high sugar content will also reduce the amount of water.

What is shelf life?

What is shelf life?
 Length of time a product can be stored until degradation occurs.>Foodstuffs will gradually degrade, (growth of organisms) 
 >undesirable and unfit for consumption 
 >changes in flavour, smell, texture, and appearance

 Factors that affects the food shelf-
 1) Changes in water content (result of contact with the air) 
example : -moist foods becoming dry -dry food absorb water vapour from air, become moist, vulnerable to microbial degradation 
>Increase exposure to air , increase the rate of oxidation 
 -decrease in nutrient value, discolouration of the surface, rancidity. 

 2) Chemical reaction 
>result in pH changes, development of other undesirable flavours, colour changes in food, decrease in nutritional value. 

3) Light 
>provides energy for photochemical reaction to occurs. 
>rancidity, fading of the colour, oxidation of the nutrients (vitamins). 

4) Temperature 
>increase in temperature, increase in the rate of degradation of food. 
>water molecules will either chemically bonded to carbohydrate or protein polar group. 
>changes in temperature, change in the force of attraction between carbohydrates or protein chain with water molecules. 
>influence how much water molecules it can hold. Thus affecting texture, softness of the food.