University Of Nairobi

UNIVERSITY OF NAIROBI

DEPARTMENT:ENVIRONMENTAL AND BIOSYSTEMS ENGINEERING COURSE NAME:PROCESS AND FOOD ENGINEERING COURSE CODE :461 NAME:

MATILU URBANUS NDUNDA REG NO: F21/0026/2005

TERM PAPER TITLE:PROCESSING OF SUNFLOWER OIL SUBMITTED TO: MR. MUTAI EMMANUEL .K.

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TABLE OF CONTENTS 1. OBJECTIVE ……………………………………………………………………..3 2. LITERATURE REVIEW………………………………………………………3 3. INTRODUCTION…………………………………………….. ………………….4 4. BASIC PROCESSING TECHNIQUES …………………………………………6 5. INDUSRIAL PROCESSING …………………………………………………….10 (a) SEED CLEANING ………………………………………….. ………………….10 (b). SEED DECORTIFIOCATION …………………………………………………11 (c) CONDITIONING AND FLAKING ………………………………………………14 (d) BATCH AND CONTINOUS SOLVENT EXTRACTION……………………….15 (e) NEUTRALIZATION PROCESS……………………………………………………. 18 (f). BLEACHING PROCESS ………………………………………………………….18 (g) DEODORIZATION SECTION …………………………………………………….17 (h). DEWAXING ………………………………………………………………………..18 (I) PRESERVATIVE AND FLAVOR ADDITION ……………………………………..19 (J). PACKAGING………………………………………………………………………. 19

6. RECOMMENDATIONS AND CONCLUSIONS ……………………………………… 20 7.REFERENCE………………………………………………………………………………20

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1.OBJECTIVE To discuss various methods and processes involved during extraction of sunflower oil To conduct studies on the improved oilseed processing technology. To learn how different processing machines work e.g. decorticating machine

2.LITERATURE REVIEW The sunflower plant gets its name from following the sun. The flowers literally keep their face toward the sun from morning till night. It is tall, often branching, it has large heart-shaped leaves with yellow flowers and brownish black to red centers. Besides its beautiful ornamental qualities, the sunflower made up part of Native Americans diet; the sunflower is an important resource. The flower heads are boiled to extract oil. The seeds are crushed and sifted or the shells were roasted. Sunflower seeds could be eaten alone, made into bread, or combined with other foods. Besides consuming this plant, other uses are employed. The sunflower infusion can be used for prenatal infections and removal of warts. A traditional skin wash can be made, with the claim of anti-oxidant and anti-aging properties. This is patted on the face twice daily with reputed youth-preserving effects. Herbalists use this plant for treating coughs, bronchitis, sore throats, and kidney problems. A great deal of interest has recently been shown in sunflower seed as an oilseed crop. The introduction of new Russian seed varieties with higher oil content have helped to stimulate this interest, particularly in the flax and cottonseed growing areas. This paper presents background material pertinent to the subject of sunflower processing. Such things as seed structure and oil quality have been considered. Processing techniques currently used are discussed and comparisons made with the processing of other oilseeds. Brief mention is made of storage and handling of the seeds and oil. Extraction is discussed briefly, but since it is successful only if the seed is properly prepared, seed preparation and handling prior to extraction are stressed. Sunflower seeds are nearly 30% hulls and these hulls are high in crude fiber content. For this reason, dehulling and hull separation practices are important aspects of processing sunflowers. Expeller operating variables are also important where pre-pressing is part of the process. These processes are stressed. Direct solvent extraction and prepress solvent extraction methods are currently being used successfully. Features of both methods and their applicability are discussed along with seed preparation needed for each method.

3. INTRODUCTION 3

The many varieties of seeds and nuts can produce oils for food, nutraceuticals, skin care products, aromatherapies, biodiesel fuels, and industrial lubricants. This publication profiles the evolution of a cold-pressing and consulting business in the U.S. It also describes the basic processes involved in oil processing: seed cleaning, extraction, clarification, packaging, and storage. Sources for more information and equipment are included. sunflower facts The sunflower is a distinctive, flowering plant (Helianthus annus L.), the seeds of which contain a valuable edible oil that contains more Vitamin E than any other vegetable oil. Most sunflower oil is used in food products. The seeds of confection varieties of sunflower are also sold for human consumption and birdseed.U.S. sunflower oil crushers can deliver three types of sunflower oil, NuSun, Linoleic and High Oleic sunflower oil. NuSun is a mid-range oleic, 65 percent (monounsaturated) sunflower oil. It needs no hydrogenation and has a 9 percent saturated fat level. NuSun is extremely functional for frying applications and has a good balance of linoleic acid — an essential fatty acid that enhances the taste of products. Linoleic sunflower oil has about 69 percent polyunsaturated fat, 20 percent monounsaturated fat and 11 percent saturated fat. Linoleic sunflower oil is excellent cooking oil with a neutral taste. This enhances the taste of food rather than overpowering it. High Oleic sunflower oil has 80 percent or more oleic (monounsaturated) acid. This unique oil has many specialty applications. The confection sunflower industry is divided into three segments according to seed size and separated into groups. Processors of confection sunflower seed sell the seeds based on seed size. The largest size will go into the in-shell market, meaning the seed stays intact. The medium-sized seeds are usually hulled for the kernel market. The smallest size will go into the bird and pet feeding market. The sunflower industry continues to have adequate processing capacity to meet the demands of the domestic and international markets. The U.S. is recognized as having the highest quality of sunflower products. The processors have developed technology that currently surpasses any other supplier in both volume capacity and quality control standards. Several of the domestic processing plants have gone through major renovations, having added processing facilities to meet specific consumer requirements in areas such as refining and packaging of sunflower oil and roasting and flavoring of confection products. Common Varieties There are two types grown. The first is Oilseed. This small black seed is very high in oil content and is processed into sunflower oil and meal. It is also the seed of choice of most bird feeders. The second type is Non-oilseed (confectionery sunflower). This is a larger black and white striped seed used in a variety of food products from snacks to bread. Major Products There are three types of sunflower oil available; Mid-Oleic Linoleic and High Oleic sunflower oil. 4

All are developed with standard breeding techniques. They differ in oleic levels and each one offers unique properties. With three types of sunflower oil available, sunflower oil meets the needs of consumer and food manufacturers alike for a healthy and high performance nontransgenic vegetable oil. Confection sunflower seeds are normally black with white stripes and provide consumers with in-shell seeds and kernel. In-shell means the seed is left intact with the "meat" of the seed still in the shell. It is normally roasted and seasoned. It is eaten as a snack by cracking the shell with one's teeth, discarding the hull and eating the delicious morsel within. 'Chew and spit' is a great American pastime, especially at baseball games and other outdoor events. Kernel means the processor has mechanically removed the hull. The resulting kernel is now in a convenient form to be sold raw or roasted for snacking or as an ingredient.

Processes Used Confection sunflower seed is processed according to these steps: •

Seed preparation and cleaning

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Grading the seeds into large, medium and small sizes

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Seeds to be marketed as in-shell are bagged

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Seeds to be sold as kernel are hulled and then bagged

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Storage

Oil-type sunflower seed is normally processed according to these steps: • Seed Preparation and cleaning •

Dehulling

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Physical pressing of the sunflower seed with subsequent hexane extraction of the remaining oil in the meal

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Degumming

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Refining

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Bleaching

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Dewaxing

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Deodorization

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Storage

4.BASIC PROCESSING STEPS raw material preparation Preparation of the raw material often includes removing husks or seed coats from the seeds and separating the seeds from the chaff. Information about seed cleaners designed for small-scale operations is often available from agricultural research stations doing small plot research with various crops. For instance, the U.S. Department of Agriculture (USDA) researchers working with flax in North Dakota buy some of their equipment from Seedburo, which will supply a catalog upon request. Almaco is another company that specializes in equipment for research, such as one- and two-row test plot combines and various types of stationary threshers. Extraction Oil can be extracted mechanically with an oil press, an expeller, or even with a wooden mortar and pestle – a traditional method that originated in India. Presses range from small, hand-driven models that an individual can build to power-driven commercial presses. Expellers have a rotating screw inside a horizontal cylinder that is capped at one end. The screw forces the seeds or nuts through the cylinder, gradually increasing the pressure. The material is heated by friction and/or electric heaters. The oil escapes from the cylinder through small holes or slots, and the press cake emerges from the end of the cylinder, once the cap is removed. Both the pressure and temperature can be adjusted for different kinds of feedstock. The ram press uses a piston inside a cage to crush the seed and force out the oil. Oils can also be extracted with solvents, but solvent extraction is a complex operation. The Intermediate Technology Development Group Technical Brief, Principles of Oil Extraction, describes several methods of extraction. It cautions that “solvent extraction is not suitable for small-scale processing because of high capital and operating costs, the risk of fire and explosions from solvents, and the complexity of the operation.” Waste management of solvents such as hexane is a problem as well. Clarification Clarification removes contaminants, such as fine pulp, water, and resins. You can clarify oil by allowing it to stand undisturbed for a few days and then removing the upper layer. If it needs further clarification, filter the oil through a fine filter cloth. Finally, you can heat the oil to drive off traces of water and destroy any bacteria. Having a very clean oil is very important in all uses, including biodiesel. Packaging and Storage Use clean, dry containers to package and store oils and help prevent rancidity. Sealed glass or 6

plastic bottles are adequate. Colored containers in a dark box help to increase shelf life. The shelf life of oil is usually 6 to 12 months, if it is properly packaged and kept away from heat and sunlight. Adding Value Adds Costs Although value-added processing can be a way to increase a farmer’s share of the farm product dollar, adding value doesn’t come free. At each step, the farmer is adding more work, buying additional equipment and supplies, and using more energy. For example, an automated Chinese oil press costs $5,000 and a Swedish Taby Press scaled for on-farm use is $9,000, based on price quotes in 2006 Information needs increase. Wholesaling or retailing culinary oil will require nutritional labeling. And depending upon the situation, liability insurance may become a must. A key point to remember is that adding value to any foods by processing increases safety risks, due to the increased handling. Therefore, rules and regulations are established by each state to protect the public health. In addition, the FDA regulates products going out of state. Farmers considering processed foods as a value-added business should contact their state health department before proceeding

Sunflower Seed Oil Using the Ram Press Enterprise Works Worldwide (EWW – formerly Appropriate Technology International) has supported a number of projects in Africa that process oilseeds using the ram press. The presses weigh about 45 pounds and can process 100 to 120 pounds of sunflower seeds per day. The extraction rate is 20 to 25 percent using the softer-shelled, high-oil-content sunflower varieties. The ram press can also be used for sesame, mustard, safflower seeds, and peanuts. Details on the use of the press are given in EWW’s manual Using and Maintaining the Ram Press. The information on pressing sunflower seed that follows is from that manual. Choose seed that has a soft shell and high oil content (40–45 percent oil). Most high-oil-content sunflower seeds are all black. Many striped seeds have little oil. To get some idea of how the seed will work in the press, try to crack it open with your fingers. This will not be difficult with soft seed. With hard seed, you may need to use your teeth. Now look at the kernel inside the shell. It should fill the shell completely. If the seed is much smaller than the inside of the shell, it was probably harvested too early. You will not get much oil from it. Put the kernel (without the shell) between your two thumbnails and squeeze. Did the kernel fall apart? Are there little smudges of oil on your thumbnails? If not, there may not be much oil in the kernel. (This is a very rough way of assessing seed. The manual also presents a more precise way to determine the percent of oil, but still encourages the practice of checking seeds with your fingers.) Check the different batches of seed you come across. In time you will get a feel for the differences. For successful pressing, the seed must be: • Dry. Moist seed will lead to low yields and clog the cage (a part of the press). Moist seed 7

may also get moldy. •

Clean. Fine dust in the seed may clog the cage. Chaff left in the seed will absorb some of the oil and keep it from getting squeezed out of the cage. Sand in the seed will wear the press out. Stones badly damage the piston.

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Warm. Warm seed will yield the most oil for the least effort.

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To prevent the growth of mold, dry the seeds shortly after harvest

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Dried before it is bagged and stored. Very damp seed will feel humid when you bury your hand in it, especially if the seed is warm. If you heat your seed in the sun under a sheet of clear plastic, you may see moisture collecting beneath the plastic if the seed is too wet.

Seed that is slightly too damp may feel dry but will not press well. If it is too damp, but not yet moldy, it can be dried in the sun. (Never press moldy seed. It is not safe for human consumption.) Spread the seed out thinly on the ground, on plastic, or on roofing tin. At the end of the day, pile the seed up to keep it from absorbing moisture in the cool night air, and spread it out again in the morning. If there is any chance of rain, or if the morning dew is heavy, you will need to bag all the seed in the evening and put it back out the following morning. After two or more sunny days, the husks will be dry. Now bag the seed and store it for a week. In that time, the moisture in the seed will be drawn into the dry husk, and the entire seed will become evenly dry. Winnowing is a low-cost way to clean the seed. On a day when there is a steady breeze, spread a cloth on the ground. Drop the seeds from a container to the cloth. The chaff and dirt will blow away. The seeds will collect on the cloth. Any stones must be picked out by hand. If the sun is shining, the seed can be heated on a piece of roofing tin or some black plastic. Spread the seed thinly and evenly on the sheet. On a sunny day, it will be hot to the touch in 15 minutes. The seed should be at least 104°F, which is pleasantly warm to the touch. The yield will improve as the seed gets hotter, all the way up to 150°F, uncomfortably hot to the touch. The seed will heat faster on a black surface than on a light-colored surface. Some people also cover the seed with a sheet of clear plastic. This helps to hold heat in and make the seed hotter. If the sun is not shining, you can also heat the seeds on a stove. Put the seeds in a shallow pan over low heat for five minutes. You will need to stir the seeds often and be careful not to scorch them. Charred seeds will give the oil a bad taste. You can use a double boiler to make sure that the seeds do not burn. You will need two pots, one large and one smaller. Set the larger pot on the heat, with enough water to keep it from boiling dry. Set the smaller pot inside the big pot. The bottom of the small pot does not need to touch the water below. Put the seed in the smaller pot, stir it occasionally, and the steam from the boiling water will heat the seed without burning it. The seed should be ready in 15 minutes. The boiler works best if the smaller pot is almost the same size as the big pot. Then there is not too much room for the steam to escape from between them. This method does not require as 8

much attention and stirring, and you will not spoil any seed from accidental charring, but it uses more fuel. The seed is now ready to be pressed. The pressing operation is described in detail in the manual, complete with diagrams. Rita Laker-Ojok, a former EWW staffer who worked in Africa, cautions that knowing how to use the press is important, especially regarding pressure adjustments. Correct adjustment allows the “cake,” or meal, to come out; too much pressure may cause a jam. According to Laker-Ojok, the sunflower oil produced is very high quality. It can be further processed, or clarified, in one of three ways. The simplest is to let it settle for a week. The oil can also be mixed with a little water and salt and boiled for 10 minutes. This changes the taste slightly. Or the oil can be filtered through paper or cloth. Seed Cake or Meal—Valuable By-product Seed cake is a valuable by-product of pressing. Sesame seed cake is valuable as a human food. Sunflower seed cake is not suitable for people, but it makes a good addition to chicken, pig, or cattle feed. Since sunflower seed cake has all the seed hulls in it, it is very fibrous. The ram press does not get all the oil out of the cake; it is oilier than most feed additives. It is quite high in crude protein, but contains very few carbohydrates. It should be used as a feed additive, not a feed by itself. The EWW manual describes feed rations for commercial broiler chickens, cows, and pigs that include sunflower seed cake. Proper storage of both seed and seed cake is extremely important. Seed must be protected from moisture, rodents, and insects. Very moist seed will rot. Even if your seed is not moist enough to rot, it may be moist enough to grow mold. This is a problem for two reasons. First, moldy seed cake does not taste good to animals. They may not be willing to eat moldy feed. Worse, some kinds of mold make mycotoxins such as aflatoxin. These poisons can make people and animals sick. Some of the poisons from moldy seed will end up in the oil, but most remain in the seed cake. They can also get into the meat, eggs, and especially the milk of the animals that eat the cake. Mold spores (seeds) are present in all crops. Molds grow best in warm, humid weather. To prevent the growth of mold, dry the seeds shortly after harvest. Even dry seed can quickly get damp by being in contact with damp earth. Once the seed is dried and bagged, it must be stored carefully to keep it from taking up moisture. The moisture content of the seed should be no higher than 10 percent. To test for moisture, weigh a sample of seed or cake, and then heat the sample in an oven at 300°F for one hour. Reweigh the sample. The weight lost in the oven is equal to the moisture content of the original sample, and the percentage can be calculated: divide the weight lost by the original weight and multiply by 100

Komet Oil Expellers Komet Vegetable Oil Expellers are manufactured by IBG Monforts in Germany, whose range of products covers small hand-operated as well as industrial machines. According to the product literature, Komet oil expellers feature a special cold pressing system with a single conveying 9

screw to squeeze the oils from various oil-bearing seeds. The machines operate on a gentle mechanical press principle that does not involve mixing and tearing of the seeds. Virtually all oilbearing seeds, nuts, and kernels can be pressed with the standard equipment without adjusting the screws or oil outlet holes. The vegetable oil produced needs no refining, bleaching, or deodorizing, as long as the natural taste, smell, and color are acceptable. Generally, any sediment in the oil will settle to the bottom of the collecting vessel after approximately 24 hours and form a hard cake. You can then pour the oil through a paper or textile filter to remove any remaining impurities. Since the vegetable oil will not reach temperatures higher than approximately 100 to 120°F, all its vital components will be preserved. Therefore, it is excellently suited for natural nutrition. As long as the oil is stored in a dark, cool place, it will have a long shelf life. You must precondition the seeds before extraction. Big nuts, kernels, and copra (dried coconut meat) have to be crushed to the size of peas on the Comet Cutting Machine “System Crusher.”

5. INDUSTRIAL PROCESSING

SEED CLEANING

A mechanical system consisting of reels or shakers both with perforated metals or screens which are simple in that the material flows over the tray /drum of the machines ,with the small foreign matter removed by sifting through the metal as the seeds fall through .magnets for removal of metals should be located in the strategic spots and installed for easy access for cleaning .A pneumatic system consisting of vacuum boxes is sometimes used .It has air separators or aspirating nozzles where the light materials are pulled through and the heavies (specifically the oil-bearing sunflower seeds) are gravitated out.

When cleaning it is easy to remove large particles but when removing the fine foreign matter such as lint, dust or sand, these tend to adhere to some materials and cleaning becomes more of a problem .Also certain foreign matter is of the same size and density as of the material being cleaned or 10

separated, It cannot be separated by perforated metal as it is of the same size and it cannot be separated by air as it is the same density

FIGURE: WINNOWING MACHINE

DECORTICATION (HULLING OF OILSEEDS) Hulling is a process of removing hulls from the oil bearing seeds for obtaining high quality edible oil by the processing of kernels. This reduces fibrous content of the meal and increases the marketability as stock feed. About 99% of oil is stored naturally in kernels and the hulls contain not more than 1% oil. If the hulls are not removed they reduce the total yield of oil by absorbing or retaining oil in the pressed cake. In addition to this the wax and colorings matters present in the hulls get mixed with the expressed edible oil. This necessitated the refining process, and therefore, increase the production cost of edible oil. Moreover, processing oilseeds without dehulling reduces the capacity of the extraction equipment in addition to more repair and maintenance charges.

Except for the hullers or cracking rolls,separation of hulls from meats is accomplished with the same basic type of machinery as is used in seed cleaning,reels,shakers,pneumatic systems ,vacuum boxes,air separators or a combination of some or all .These machines can be built into one unit called a decorticator or they can be several machines and be called decorticating machinery or de-hulling and separating machinery separating hulls from seeds is normally a simple process when storage and drying as for each seed has been properly handled. The first step in dehulling is to crack the husks with machines called hullers i.e. bar hullers, impact hullers, disk hullers, cracking rolls and hammer mills.The idea is to use the most practical machine for the type or kind of seed being cracked which will cut the hull for the best separation of meat and hull

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With certain seeds it is best to crack into quarters and eighths .Specifically with the sunflower it is best to cut as course as possible preferably in halflengthwise, leaving two sides .This allows the meat to fall out with a minimum of fines.

Generally any meal with desired protein or fiber content can be produced relatively easy .Sunflower can be successfully decorticated to produce a good finished product .Sunflower can be produced with a residual oil in finished hulls from 1 to 4 ⁰/₀ and protein of 33-46 percent including 12 percent fiber

A small size decorticating machine is shown below. The machine design is simple and it works on the principle of gravity. The machine has a double walled, hallow disc, which is fitted with three blades. The design of the disc is like a rotor being used in tube-wells for the sucking of oil from the well. When rotor inside the machine rotates at high speed (3200 rpm.) it sucks seeds through a small hole from one side of it, around the exal. The seed is then thrown with great force against the rubber lined slanting walls of the cylinder. The mixture of kernel and hull is separated by means of a winnowing machine.

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FIG.DECORTICATION MACHINE The machine is simple and could be adopted in the rural areas for the decortication of sunflower seeds. The machine is not good for safflower seeds even operating the disc at double the rpm. (4600). Therefore, new design of a suitable size for rural areas could be investigated for safflower seeds. The use of small size decorticating machine at the village level would help in mobilizing the farmers to grow more of sunflower and safflower seeds.

CONDITIONING AND FLAKING Manufacturers in the decorticating end of oil bearing seed processing generally leave conditioning and flaking to the manufacturers of extraction 13

machinery .A conditioner is used in many mills especially for best flaking of dry meats before flaking or crushing so that the moisture can be added and proper flaking can be accomplished. Conditioners can be of vertical staked kettle type or horizontal rotary type. These both are jacketed and heated with steam ,with an arrangement to eject live steam or water into the meats which will aid in absorption of moisture by the meats. Flaking of seeds is accomplished in flaking rolls with a pair of smoothrools running against each other on a horizontal plane ,one roll is fixed and the other is adjustable to produce flakes of desired thickness Crushing is accomplished in crushing rolls,generally five rolls high stacked on top of one another.Flake thickness is acquired by weight and RPM of rolls.The kind of seeds to be processed and the processing itself will govern the best kind of rolls to be used.Many mills have substituted flaking for crushing rolls and this work satisfactorily achieved with hydraulic roll adjustment. Adjustment should be checked to give finished flake thickness as required for best extraction. The moisture of flakes should be checked oftenly as required for proper operation. Meat bin is essential as meat overflow to assure adequate flow of meat at all times to roll. Empty rolls should not be operated as this can result to damage, scraper should be properly adjusted to ensure clean rolls so as not to overload motors or damage rolls

BATCH AND CONTINOUS SOLVENT EXTRACTION Two physical processes are used for the removal of oil from seeds. One is called ‘solution extraction’ and the other ‘diffusion extraction’. In batch type solvent extraction plants, a diffusion process takes place. Due to their high steam and labor requirements, such plants are being steadily replaced with continuous solvent extraction plants, whose main component is the extractor which can either of the immersion or percolation type. The combined use of these two types of extractor makes it possible to extract oil directly from oil seeds, even if they have high oil content, with no need for

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continuous screw presses or expellers. Comparative data on the processes in common use are discussed below

REMOVAL OF OIL FROM OIL SEEDS IN BATCH AND CONTINUOUS AND SOLVENT EXTRACTION PLANTS The removal of oil from oil-bearing sunflower seed calls for a careful study of their nature and main characteristics, among which the following deserve particular attention; oil content,particle size and preparation of the material .It is upon these factors that selection of the most suitable type of equipment should be based .Extraction o oil from sunflower seed is usually done by pressing by means of screw presses or by extraction with volatile solvents. Solvent extraction plants can be of the batch or continuous type. In their turn, continuous plants can be percolation plants, immersion plants or direct extraction plants. High oil sunflower seeds are extracted into two stages ;pre-pressing and solvent extraction or as has been the case in a single step by continuous direct solvent extraction system. During the contact time between seed and solvent ,two extraction processes occur simultaneously one faster than the other ,infact it can be verified that the larger proportion of readily available oil is derived from oil bearing cells broken in the preliminary processes of grinding,cooking,pressing, or flaking whereas the smaller portion that is most difficult to extract is in the intact or only ruptured cells. Removal of oil from the latter cells requires a longer time and takes place by osmosis. The oil contained in the cells tends to pass through the cell wall into the oil solvent solution of lower concentration .As a result two processes may be distinguished which are called ‘solution extraction’-when the oil is obtained from the ruptured cells and ‘diffusion extraction’-when the oil is derived from the cells that remain intact.

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PREPARATION PROCESS Preparation means breaking the cell wall of seeds to get oil out or solvent into the cells .From the standpoint of equipment design,each cell must be treated by the necessary mechanical forces to break the cell wall.This requires size reduction of the seeds first,which is normally performed in flutedroller mills .the actual breaking of cells is achieved through roller mills where each seed is exposed to the necessary pressure to break its cell wall.

SEPARATION PROCESS The properly prepared seed passes through a separation process ,aside from technical details of the different designs ,they are basically the same ,as 16

they have to meet the same requirements which includes ;Drawing in the material ,compressing the material, forming a porous structure in the solid material ,self filtration of the oil through the fines of solid material and no overheating of the organic matter at any place in the press. The performance of any kind of screw press can be characterized by a pressure over length of cage curve, which indicates the effectiveness of the pressing process. There are basically two different designs of extractors; the percolation type and the immersion type. With the percolation type, the solid material forms a fixed bed, where good drainage of the fluid phase is a main requirement .Therefore size reduction of the seed must not go too far, so that the pressure drop may be kept low .

DEODORIZING SECTION This is the process whereby the odors and flavours of oils are removed ,resulting in a brand finished product .Other compounds are stripped off at the same time;these includes some pigments and sterols and other waxes .Altough deodorized oil is theoretically completely odorless and flavourless ,the various types of oils do have characteristic flavours which are distinguishable to an experienced taster.This may be due to traces of residual matter or oxidation or polymerization of the oil after deodorization even to the smallest degree. By chemical analysis ,deodorized oils have a peroxide value of zero as heat destroys these compounds.On storage oils begin to develop peroxides slowly.If the oils had been badly oxidized before deodorization they will have poor stability after deodorization The biggest problem in deodorization is in potential leakage of air into the system.deodorizers are large with high capacity vacuum pumps.Small leaks are not easily detected,when they become sufficiently large the deodorized oil darkens,develops a bad odor and flavor.The final step in dodorizationis the addition of citric acid to the oil,it is usually added as a water solution under vacuum so that the water is evaporated off.The citric acid as a metal scavenger,especially for traces of copper and iron which acts as a pro-oxidants for oil.The maximum amount of citric acid permitted is 0.01 percent. 17

NEUTRILIZING SECTION In small plants,it is very possible that batch neutralizing is being used.Here the skill of the refiner is most important ;even though problems may still occur (a) Detorioration of neutralized oil may occur if the oil is stored –The risk can be reduced by washing and drying the oil after the refining process .Drying can be done either in a separate vacuum vessel or in the vacuum bleacher.If any excess moisture remains it will increase the chancs of deterioration(oils should be dried down to less than 0.1 percent moisture) (b)Poor oil yield may be nothing more than careless operation of the swing pipe in the neutralizing task.The operator cannot guess but actually obsrve the oil being drawn off from the top of the tank.

8.BLEACHING SECTION In this section whether it be batch or continuous ,the selection of bleaching earth is of importance.The process will rely upon recommendations of the suppliers of bleaching earth and upon the advice of the laboratory technician.To avoid other problems in bleaching; (i)Oil to be bleached should be dry or it will reduce the efficiency of the bleaching clay and cause blinding of the filter cloth. (ii)During the start up cycle of the filter presss or the tank type filter ,care must be taken to see the initial cloudy oil is returned to the bleaching unit rather than pumped to the bleaching oil storage tank.

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DEWAXING Sunflower oil becomes cloudy on being chilled since it contains waxes.Sunflower seed oil is cooled rapidly through a heat exchanger to 10⁰C. but must be held for 24 hours in a grain tank before filtration .Filter aid must be used in all dewaxing operations .The process of dewaxing and refining sunflower oil involves mixing together with a low shear agitator held for about 30 minutes as an mulsion and then treated with a dilute aqueous solution of phosphoric acid which catalyzes breakdown of the emulsion. The wax free oil is separated from the foots or soapstock which contains the waxes to be removed by passing the entire mass through a continuous centrifuge.Temperature of oil and water must not exceed 7 ⁰C during the entire operation.

PRESERVATIVES AND FLAVOUR ADDITION Salt and vinegar are excellent preservatives though they are added to foods as preservatives .Citric and malic acids are also permitted under specific conditions .They are added to sunflower oil to make it last for long without spoilage. Pigments used for fat and oil products are usually soluble and in the yellow to reddish orange. The carotenoids are practically the only oil soluble colors approved for use.These includes carotenes,bixin and apo-6 carotenal.The flavours used sunflower cooking oils are described as butter-like.The choice blend of flavours depend on the use to which it is put.The prescence or aabscence of an aquous phase in the system has a profound effect on the odor and flavor characteristics of the products involved.

PACKAGING Proper packaging involves the correct size and shape of the container and the material from which the container is made.Plastic bottles and cans are used to hold sunflower oil ,convenience of use is also a factor and is 19

considered as part of attractiveness of the container .Sunflower oil is packaged under a nitrogen blanket to reduce the potential development of oxidative rancidity. Under normal circumstances oils are sensitive to light which catalyzes oxidation reaction thus they should be packed in dark glasses/plastic containers in order to protect the oil and extend its half-life, however the consumer prefers clear containers

RECOMMENDATIONS The finally processed oils should be kept in a closed vessel in an atmosphere that excludes oxygen and moisture and where temperatures are controlled at minimum levels. The technology of sparging and blanketing finished oils with nitrogen during storage and transfer from vessel to vessel is essential. Finished oils can be deteriorated by atmospheric adultrants,internal contamination by water and soaps, overheating and by exposure to oxygen; thus care must be taken to avoid all these. 7.REFERENCES 1. Processed plant protein foods-united states department of agriculture 2. The essential oils- by Ernest Guenther, Ph.D. 3. Introduction to food processing -by P.Jelen-professor of food science university of Alberta 4. Edible oil processing –By Wolf Hamun and Richard J Hamilton

5. Internet

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