OIL AND FAT OIL AND FAT TECHNOLOGYTECHNOLOGY))

Abdul Moiz DOtaAbdul Moiz DOta

Handling & Storage of Handling & Storage of Oil-Bearing MaterialsOil-Bearing Materials

The handling and storage of oil-bearing materials The handling and storage of oil-bearing materials is one of the most important phases of oil seed is one of the most important phases of oil seed processing. processing.

The vegetable oils and feed industries are The vegetable oils and feed industries are dependent for successful operation upon dependent for successful operation upon obtaining high yields and product of good obtaining high yields and product of good quality from their raw material.quality from their raw material.

Excessive biological activity in the seeds, either Excessive biological activity in the seeds, either in the field prior to harvesting or subsequently in the field prior to harvesting or subsequently during storage, will result in a reduction both in during storage, will result in a reduction both in the quality and the yield of oil and meal. the quality and the yield of oil and meal.

The handling and control of the raw The handling and control of the raw materials for the oil seed industry can materials for the oil seed industry can be primarily characterized by the short be primarily characterized by the short harvest season, by the necessity to harvest season, by the necessity to move them into protected storage in move them into protected storage in minimum time, and by the required care minimum time, and by the required care before they can be processed. But they before they can be processed. But they can be treated and stored successfully can be treated and stored successfully with minimal deterioration long enough with minimal deterioration long enough to allow the processing industry to to allow the processing industry to operate throughout the year. operate throughout the year.

Sunflower seed, sSunflower seed, soybeans, cottonseed, oybeans, cottonseed, rape seedrape seed and other oil seeds are subject and other oil seeds are subject to damage primarily from biological to damage primarily from biological actions, which are accelerated by actions, which are accelerated by high high moisture content, foreign material, moisture content, foreign material, physical damage, and such adverse physical damage, and such adverse climatic conditions as frost or rain before climatic conditions as frost or rain before harvest. harvest.

Effects accompanying deterioration of seed Effects accompanying deterioration of seed during storageduring storage

Respiration :Respiration : In the presence of oxygen as the In the presence of oxygen as the oxidizing agent, organic food stuffs are oxidized to oxidizing agent, organic food stuffs are oxidized to form water and carbon dioxide as the end product.form water and carbon dioxide as the end product.

exothermic reactionexothermic reaction

CC6 6 HH1212OO 6 6 + O + O22 6 CO 6 CO2 2 + 6 H+ 6 H22O + energyO + energy

Respiration intensity;Respiration intensity;

Sound seed – low m.c. 0.1ml COSound seed – low m.c. 0.1ml CO2 2 /g seed.day/g seed.day

Damaged seed – high m.c. 5.0ml CODamaged seed – high m.c. 5.0ml CO2 2 /g seed.day/g seed.day

The respiratory quotientThe respiratory quotient, defined as the , defined as the ratio of carbon dioxide evolved to ratio of carbon dioxide evolved to oxygen absorbed, is an indication of the oxygen absorbed, is an indication of the class of substances undergoing class of substances undergoing oxidation. oxidation.

In aerobic respiration; In aerobic respiration; it is theoretically it is theoretically unityunity if the subctances if the subctances

are are carbonhydratescarbonhydrates, , but but less than unityless than unity if they are if they are proteins or proteins or

fatsfats, which are less rich in oxygen., which are less rich in oxygen.

Enzymes :Enzymes :

(a)(a)LipaseLipase.. This enzyme catalyzes the reaction; This enzyme catalyzes the reaction;

11 glycerol + 3 fatty acid triglycerid + 3 waterglycerol + 3 fatty acid triglycerid + 3 water 22

1 synthesis t.g 2 hydrolysis t.g1 synthesis t.g 2 hydrolysis t.g

(b) (b) Catalase and peroxidaseCatalase and peroxidase.. Both of these enzymes react Both of these enzymes react with hydrogen peroxide.Catalase will decompose with hydrogen peroxide.Catalase will decompose hydrogen peroxide while peroxidase utilizes it for hydrogen peroxide while peroxidase utilizes it for further oxidation.further oxidation.

2 hydrogen peroxide 2 water + oxygen2 hydrogen peroxide 2 water + oxygen

Influence of moisture content : Influence of moisture content :

Oil seeds are best stored at low moistures where Oil seeds are best stored at low moistures where respirotary and enzymic activities, germination respirotary and enzymic activities, germination and mold growth are inhibited. This maximum and mold growth are inhibited. This maximum acceptable moisture level is known as acceptable moisture level is known as “critical “critical moisture level (CML)moisture level (CML) ”. ”.

The moisture content of the nonoil portion of the The moisture content of the nonoil portion of the seed rather than the whole seed is the important seed rather than the whole seed is the important factor in oil seed deterioration. factor in oil seed deterioration.

CML is relatively high for seeds of low oil CML is relatively high for seeds of low oil content.content.

CML is relatively low for seeds of high oil CML is relatively low for seeds of high oil content.content.

Safe humidity for starchy food grains Safe humidity for starchy food grains

16%16%

Oil content of soybean ……. 22%Oil content of soybean ……. 22%

Non-oily part of soybean ……. 78% Non-oily part of soybean ……. 78%

Critical moisture level 0.78 x 16% = Critical moisture level 0.78 x 16% = 12.5%12.5%

CML of oil seedsCML of oil seeds

Hulls (%) Fat (%) CML(%)Hulls (%) Fat (%) CML(%)

Rape seedRape seed 14 40 7.0 14 40 7.0

Palm kernelPalm kernel - 52 8.0 - 52 8.0

Sunflower seedSunflower seed 28 43 8.5 28 43 8.5

CottonseedCottonseed 48 18 10.0 48 18 10.0

Soya beansSoya beans 8 20 12.0 8 20 12.0

Influence of temperature.Influence of temperature.

In the case of soya beans and similar oilseeds where In the case of soya beans and similar oilseeds where deterioration appears to b primarily a result of the deterioration appears to b primarily a result of the growth of microflora, the storage temperature does growth of microflora, the storage temperature does not appear to be a major factor. not appear to be a major factor. However, temperature However, temperature is very important factor in storage of cotton seed. The is very important factor in storage of cotton seed. The respiration of cotton seed is markedly temperature-respiration of cotton seed is markedly temperature-dependentdependent. . The insulating effect of linters on The insulating effect of linters on cottonseed contributes to the peculiar tendency of cottonseed contributes to the peculiar tendency of this seed to heat in storage. this seed to heat in storage.

It is because of the undesirable effect of high It is because of the undesirable effect of high temperature that most seed houses are equipped with temperature that most seed houses are equipped with aeration ducts and large ventilating blowers to cool aeration ducts and large ventilating blowers to cool the seed. the seed.

Storage methodStorage method Warehouses (Muskogee type seed Warehouses (Muskogee type seed

houses)houses)Bulk storage in warehouses on flat floors Bulk storage in warehouses on flat floors

has the advantage of easy control of oil has the advantage of easy control of oil seeds, like cottonseeds, sunflower seeds, like cottonseeds, sunflower seed, corn germ, further meals etc. To seed, corn germ, further meals etc. To prevent self heating or autocombustion prevent self heating or autocombustion of the seeds, recycling by horizantal and of the seeds, recycling by horizantal and vertical transportation means is vertical transportation means is recomended.recomended.

Muskogee type seed storeMuskogee type seed store

Belt conveyer

Section through storage building

Oil seed

Oil seed bulk

Preparation of Oil-bearing Preparation of Oil-bearing MaterialsMaterials

Cleaning foreign materials

Delinting for cottonseed lints

Dehulling hulls

Flaking

Cooking moist

CLEANING

Cleaning is important not only to ensure the good quality of the final products oil and meal but also to avoid premature wear of the preparation equipment.

The removal of foreign materials from oil seeds is done by cleaning machines working on mechanical, pneumatic and magnetic principles.

Cleaning machines;ScreensAspiratorsMagnetsShape sorters

SCREENSSCREENS

Screening is the seperation of mixtures of Screening is the seperation of mixtures of different sizes into fractions; the portion different sizes into fractions; the portion staying behind being oversize, the staying behind being oversize, the portion passing through being portion passing through being undersize.undersize.

Rotating screensRotating screens Vibrating screensVibrating screens

Drum screen

Vibrating screenVibrating screen

ASPIRATORSASPIRATORS

In order to seperate impurities or fractions In order to seperate impurities or fractions of different density, pneumatic means, of different density, pneumatic means, like air nozzles and aspirators are used.like air nozzles and aspirators are used.

MAGNETSMAGNETS

Permenant or electromagnets enclosed in Permenant or electromagnets enclosed in a rotating aluminium drum are used in a rotating aluminium drum are used in feeders to distribute the material feeders to distribute the material uniformly over the whole active width of uniformly over the whole active width of the drum.The magnetic material collected the drum.The magnetic material collected is removed by a blade on the ono-is removed by a blade on the ono-magnetized half and, in this way, it magnetized half and, in this way, it remains seperated even in the case of remains seperated even in the case of power failurepower failure

Self cleaning rotary magnetsSelf cleaning rotary magnets

Seed inletaspirator

Rotating drum

Stationary magnet

İron parts

Cleaned seed

DELINTINGDELINTING

(for cottonseed) (for cottonseed)

cottonseed

lints (8-12%)

Hull (40-45%)

Delinting process to remove the remaining lint from cotton seed

Aims of delinting : 1)increase oil yield 2)obtain first- and second- cut linters

DelinterDelinter

Cutting operationCutting operation

cottonseed

saws

brush

delinted seed

cut lints

seed feeder

Saw teeth

MMethod of delinting cotton seed ethod of delinting cotton seed comprises comprises the steps of passing the the steps of passing the cotton seed through a saw delinter to cotton seed through a saw delinter to remove a substantial portion of the remove a substantial portion of the lint, preferably at least 40%, and lint, preferably at least 40%, and thereafter passing the partially thereafter passing the partially delinted seed through a brush delinter delinted seed through a brush delinter to remove substantially all of the to remove substantially all of the remaining lintremaining lint..

Cottonseed Delinting EquipmentCottonseed Delinting Equipment

DEHULLINGDEHULLINGDehulling is a process of removing hulls from the oilseeds Dehulling is a process of removing hulls from the oilseeds

for obtaining high quality edible oil by the processing of for obtaining high quality edible oil by the processing of kernels. This reduces fibrous content of the meal and kernels. This reduces fibrous content of the meal and increases the marketability as stock feed. About 99% of oil increases the marketability as stock feed. About 99% of oil is stored naturally in kernels and the hulls contain not is stored naturally in kernels and the hulls contain not more than 1% oil.more than 1% oil.

If the hulls are not removed they reduce the total yield of oil If the hulls are not removed they reduce the total yield of oil by absorbing or retaining oil in the pressed cake. In by absorbing or retaining oil in the pressed cake. In addition to this the wax and colouring matters present in addition to this the wax and colouring matters present in the hulls get mixed with the expressed edible oil.the hulls get mixed with the expressed edible oil. This This necessitated the refining process, and therefore, increase necessitated the refining process, and therefore, increase the production cost of edible oil. the production cost of edible oil.

Moreover, processing oilseeds without dehulling reduces the Moreover, processing oilseeds without dehulling reduces the capacity of the extraction equipment in addition to more capacity of the extraction equipment in addition to more repair and maintenance chargesrepair and maintenance charges. .

Approximate Hulls and Kernels Percentage in different Approximate Hulls and Kernels Percentage in different seedsseeds

% oil% oil

% kernel % hull% kernel % hull whole kernel husk whole kernel husk

Cottonseed 55 45 19 30 1-2Cottonseed 55 45 19 30 1-2

Rapeseed 82 18 42 - -Rapeseed 82 18 42 - -

Sunflower 75 25 22-36 36-55 1-2 Sunflower 75 25 22-36 36-55 1-2

Soybean 93 7 18 19 0.6Soybean 93 7 18 19 0.6

HULLERHULLERThe hulling machines used for the The hulling machines used for the

decortication of medium-sized oil decortication of medium-sized oil seeds with a flexible seed coat, such seeds with a flexible seed coat, such as cottonseed, sunflower seed and as cottonseed, sunflower seed and peanuts, are of two principle types;peanuts, are of two principle types;

Bar hullersBar hullers Disc hullersDisc hullers

Bar hullerBar hullerThe rotating member of a bar huller is a cylinder equipped on its The rotating member of a bar huller is a cylinder equipped on its

outer surface with a number of slightly projecting, outer surface with a number of slightly projecting, longitudinally placed, sharply ground, square-edged knives or longitudinally placed, sharply ground, square-edged knives or bars.Opposed to the cylinder over an area corresponding to bars.Opposed to the cylinder over an area corresponding to about one-third of its surface is a concave member provided about one-third of its surface is a concave member provided with similar projecting bars.The seed are fed between the with similar projecting bars.The seed are fed between the rotating cylinder and the concave member, and the hulls are rotating cylinder and the concave member, and the hulls are siplitted as the seeds are caught between the opposed siplitted as the seeds are caught between the opposed cutting edges.The clearence between the cutting edges may cutting edges.The clearence between the cutting edges may be adjusted for seed of different sizes. be adjusted for seed of different sizes.

seed

Bars (concave surface 1/3)

Square-edged knives

Disc hullerDisc huller

The disc huller consists of vertically mounted discs, The disc huller consists of vertically mounted discs, one of which is stationary and the other one of which is stationary and the other rotating.The seeds are fed to the center of the rotating.The seeds are fed to the center of the discs and are discharged at their periphery by discs and are discharged at their periphery by centrifigal force.centrifigal force.

seedsRotating disc

Stationary disc

Adjust according to seed size

The moisture content of seed effects the The moisture content of seed effects the efficiency of dehulling operation.efficiency of dehulling operation.

Wet seedsWet seeds are difficult to split cleanly are difficult to split cleanly and may clog the huller.and may clog the huller.

If If the seeds are very drythe seeds are very dry, the kernels , the kernels may disintegrate excessively.may disintegrate excessively.

Universal dehullingUniversal dehullingSeedSeed

First huller (coars huller)First huller (coars huller)

Hull beaterHull beater

KernelKernel HullHull Uncut seedUncut seed

Second hullerSecond huller

Hull beaterHull beater

KernelKernel HullHull UncutseedUncutseed

FLAKING

The extraction of oil from oil seeds, either by mechanical extraction or solvent extraction, is facilitated by reduction of the seed to small particles.

Flaking is achieved on corrugated roll stands. Cracking mills with one or two pairs of rolls are used.

Hammer mills are used for certain raw

materials like palm kernel.

Crushing rollsCrushing rollsA roll assembly commonly used for the reduction of oil A roll assembly commonly used for the reduction of oil

seeds consists of a series of five rolls placed one seeds consists of a series of five rolls placed one above the other. The seed is introduced by a feeding above the other. The seed is introduced by a feeding mechanism between the two top rolls.Seed travels mechanism between the two top rolls.Seed travels from the top to the bottom of the system, hence it is from the top to the bottom of the system, hence it is rolled four times.rolled four times.

Corrugated roll

Speed 0.05 m/sec

knife

Smooth rolls

kernel

flake

Crushing rolls

COOKING – HEAT TREATMENTCOOKING – HEAT TREATMENTEffects of cooking process on the physical Effects of cooking process on the physical

and chemical properties of oil seeds;and chemical properties of oil seeds; The oil droplets in the oil seed are The oil droplets in the oil seed are

ultramicroscopic in size. Because of the ultramicroscopic in size. Because of the increase in temperature they come increase in temperature they come together and form larger droplets to flow together and form larger droplets to flow from the seed.from the seed.

Heating of the seeds causes the protein Heating of the seeds causes the protein to denature and as a consequence, the to denature and as a consequence, the emulsion to break and the oil to seperate emulsion to break and the oil to seperate from the solid surface of the seed.from the solid surface of the seed.

Cooking of the seed gives the seed mass Cooking of the seed gives the seed mass the proper plasticity for efficient the proper plasticity for efficient pressing.pressing.

Insolubulization of phosphatides and Insolubulization of phosphatides and other impurities.other impurities.

Destruction of molds and bacteria.Destruction of molds and bacteria. Increase of the fludility of the oil through Increase of the fludility of the oil through

increase in temperature.increase in temperature. In the case of cottonseed, detoxification In the case of cottonseed, detoxification

of gossypol or related substances.of gossypol or related substances.

A four – high stack cookerA four – high stack cookerThe cooking of oil seeds is usually carried out in “stack cookers”.These The cooking of oil seeds is usually carried out in “stack cookers”.These

consist of a series of four to eight closed, cylindirical kettles. Each consist of a series of four to eight closed, cylindirical kettles. Each kettle is normally jacketed for steam heating on the bottom and is kettle is normally jacketed for steam heating on the bottom and is equipped with a sweep-type stirrer mounted close to the bottom.There equipped with a sweep-type stirrer mounted close to the bottom.There is an automatically operated gate in the bottom of all kettles. The top is an automatically operated gate in the bottom of all kettles. The top kettle may be provided with spray jets for the addition of moisture to kettle may be provided with spray jets for the addition of moisture to the seed, and each of the lower kettles is provided with an exhaust the seed, and each of the lower kettles is provided with an exhaust pipe with natural or forced draft for the removal of moisture, thus it is pipe with natural or forced draft for the removal of moisture, thus it is possible to control moisture content of the cooked seed.possible to control moisture content of the cooked seed.

Direct steam

Sweeper-type stirrer

Exhaust pipe

T (0C)

Cooked flakes

Seed flakes

gates

2-3.5 m diameter

50-70 cm high

STACK COOKER

Cooking of cottonseed Cooking of cottonseed

DetoxificationDetoxification

Before cooking, moisture 12.% Before cooking, moisture 12.%

Cooking time 90 mnCooking time 90 mn

Final cooking temperature 115 Final cooking temperature 115 00CC

Final moisture 3%Final moisture 3%

Conventional preparation system