Process For The Extraction Of Fats And Oils

Process for the extraction of fats and oils Abstract: A process for the extraction of fats and oils from natural substances using liquid propane as the solvent is described in which the extraction is carried out at a pressure of 10 to 30 bar and a temperature of 10° to 55° C. and the separation of the extracted fats and oils from the solvent is carried out by means of pressure reduction or/and temperature increase to ≤80° C. High quality products are isolated in this way in a good yield and under mild conditions. A process for the extraction of fats and oils from natural substances using liquid propane as the solvent is described in which the extraction is carried out at a pressure of 10 to 30 bar and a temperature of 10° to 55° C. and the separation of the extracted fats and oils from the solvent is carried out by means of pressure reduction or/and temperature increase to ≤80° C. High quality products are isolated in this way in a good yield and under mild conditions.

Edible Oil The extraction of oil and fat for food has always been an important part of human nutrition and culture. There is evidence that oil fruits such as poppies, rape and flax were cultivated as far back as the Neolithic period. The first oil mills appeared in the Minoan culture in 3500 bc while Chinese sources from 2800 b.c already mentioned soy and hemp as oil plants. The rapid growth in the population in europe in the 18th and 19th centuries was due solely to the industrial extraction of oils from plant seeds. Edible vegetable oils is one of the nutritional foundations on which western civilization is historically based. Current Trends 18.5 million tons of oil were produced from plants in 2004.Demand will rise quickly due to this oil's additional advantage as a substitute for mineral oil. The world's most important oil seed are now the soy bean, palm fruit, rape, sunflower, cottonseed and maize. Sunflowers, rape and maize are primarily cultivated, processed and consumed in Europe. Olives are also processed, but on the either small scale compared with other fruits, and are intended for direct consumption. Constituents, processing and origin Edible oil contributes unsaturated fatty acids to people's diet. The recommended daily intake of these fatty acids is 10 grams. Oils contains vitamins E, D, K and A. In particular, vitamin E is important as an antioxidant. Since these oil constituents are very sensitive, the process must be controlled very precisely.

A large number of products, for example palm oil, must be processed directly after harvesting in order to prevent spoilage. This leads to very harsh conditions for the plantations which are often located in inhospitable areas close to the Equator. Since harvesting is a seasonal business, the installed machines must be able to readily cope with these burdens on production and the difficult climatic conditions. Oil can not only be extracted from plants, but also from marine animals such as whales, herring or the liver of other fish. This oil is rich in unsaturated fatty acids. However, it is not sold commercially as a pure fish oil of waltran for use as edible oil. For this reason this will be not mentioned any further. Types of edible oil Commercial edible oils come from one specific plant or are a mixture of several plant oils. If oils have a specific plant name, they must stem from the pure unmixed oil of this plant. Mixed oils are called table oil, edible oil or vegetable oil. Mixed oils are mostly sold under a brand name. References to the utilized plant oils are only permissible if their type and proportion are shown on the label. Mixed oils are normally cheaper and more heat resistant than oils from a single plant. They can be easily used for all kitchen processing methods such as frying, baking or deep drying. The best known edible oil >Cottonseed oil >Dietary edible oil >Thistle oil >Peanut fat >Linseed oil

>Maized oil >Rapeseed oil >Saflor oil >Sesame oil >Sunflower oil

>Special oils >Wheatgerm oil

Edible oils can be produced either through cold processing (up to 40 °C) or hot pressing with extraction from oil seeds or fruits. The fruits and seeds from which the oil is extracted (oil fruits) are first cleaned and then crushed in rollers. The mush created during this process is then normally heated. The addition of chemical solvents finally "washes" the oil out of the heated mush, thus producing the raw oil. The raw oil contains unwanted substances which make it cloudy and spoil it, and may have a negative effect on taste. These substances include plant residues, sludge, slime and free fatty acids. In order to separate these substances from the oil, it is refined. During refining, different chemical and mechanical processes are used to clean, de-lime, de-acidify and de-color the raw oil and free it from unwanted odors. The edible oil thus produced is stable, which means that no solid constituents settle during storage. Refined oil is also clear and light, and ha a much more neutral taste and smell than untreated raw oil. Refining has no adverse effect on the valuable polyunsaturated fatty acids. Refined oils are suitable for the preparation of warm meals in the kitchen, like frying.

Presses or beaten: Differences in oil quality Cold-pressed or cold beaten oil is obtained solely through pressing and subsequent filtering of the oil fruits. Pressing of the oil fruits may produce heat which has an unfavorable effect on the quality of the oil. The oil press is therefore cooled to ensure high quality oil. The oil is only cleaned in special filter systems. The quality of cold pressed oil is very high since all the valuable substances originally contained in the oil fruit are preserve due to the gentle production method. Cold-pressed oil is characterized by a strong taste and intensive color. It can be called "natural" or "natural pure". Cold-pressed oil is suitable for the preparation of cold meals and salads. Since it does not contain any preservatives, it should be used up quickly. Cold-pressed oils are not suitable for frying. From an ecological viewpoint, cold pressing uses less energy but only has a yield of between 10 % and 30 %. By comparison, hot pressing uses a great deal of energy but has a yield of 99.5%. Principles of oil extraction Oil is extracted from a number of fruits, nuts and seeds for used in cooking and soap making or as an ingredient in other foods such as baked or fried goods. Oil is a valuable product with universal demand, and the possible income from oil extraction is therefore often enough to justify the relatively high cost setting up and running a small-scale oil milling business. Raw material preparation Oil seeds and nuts should be properly dried before storage, and cleaned to remove sand, dust, leaves and other contaminants. Fruits should be harvested when fully riped, cleaned and handled carefully to reduce bruising and splitting. All raw materials should be sorted to remove stones etc. and especially moldy nuts, which can cause aflatoxin poisoning. When storage is necessary, this should be in weatherproof, ventilated rooms which are protected against birds, insects and rodents. Some

raw materials (like groundnuts, sunflower seeds) need dehusking (or decorticating). Small manual machines are available to give higher production rates than manual dehusking.

Dehusking is important to give high yields of oil and reduce the bulk of material to be processed but in groundnut oil extraction about 10% by weight of husk should be added back to the nuts to allow oil to escape more freely from the press.

Coconut is dehusked and split by skilled operators as this is faster than the available small-scale machines. Most nuts need grinding before oil extraction to increase the yield of oil. Small mills are available for grinding copra, palm kernels and groundnuts.

the oil yield. Other oilseeds and nuts are usually processed cold provided that their moisture content is below about 70%.

Some seeds (like groundnuts) are conditioned by heating to 80-90 °C using a seed scorcher and all oilbearing materials need to have the correct moisture content to maximize Methods of Extraction These are basically three methods of removing oil from the raw materials: solvent extraction, wet processing or dry processing. 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 process. Equipment for wet or dry processing is available at different scales of operation from household to industrial scale. Traditional methods of extraction are described below, followed by higher output manual machines and mechanized extraction. Traditional methods Oil is extracted from fresh coconut, olives, palm fruit sheanut etc. by separating the flesh and boiling it in water. Salt is added to break the emulsion and the oil is skimmed from the surface. In palm oil processing the fruit is first heated in a digester.

Manual methods. Oil can be extracted by pressing softer soil seeds and nuts, such as groundnuts and shea nuts, whereas harder, more fibrous materials such as copra and sunflower seed are processed using ghanis. Pulped or ground materiall is loaded into a manual or hydraulic press to squeeze out the oil-water emulsion.This is more efficient at removing oil than traditional hand squeezing,allowing higher production rates. Fresh coconut meal is removed from the shell using a manual reamer or a motorised reamer. The fine particles are pressed in a similar wayto extract the oil emulsion. The emulsion is broken and the oil is then separated and clarified

Presses = have a number of different designs, which can be grouped into screw or hydraulic press operation. Both types can be manual or motor driven. In all types, a batch of raw materials is placed in a heavy-duty perforated metal 'cage' and pressed by the movement of a heavy metal plunger. The amount of material in the cages varies from 5-39 kg with an average of 20 kg. Layer plates can be used in larger cages to reduce the thickness of the layer of raw material and speed up removal of oil. The pressure should be increased slowly to allow time for the oil to escape. Srew types are more reliable than hydraulic types but are slower and produce less pressure. Exept where a lorry jack is used,

hydraulic types are more expensive, need more maintenance, and risk contaminating oil with poisonous hydraulic liquid.

Ghanis = are widely used in asia but less so in other areas. A heavy wooden or metal pestle is driven inside a large metal or wooden mortar. The batch of raw material is ground and pressed and the oil drains out. They have relatively high capital and maintenance costs and need skilled operators to achieve high oil yields. Mechanised Extraction Motorised presses are faster than manual or animal types but are more expensive. Motorised ghanis are also available, but their higher capital and operating costs require a larger scale of production for profitability.

Expellers = are continous in operation and work by grinding and prssing the raw materials as it is carried through a barrel by a helical screw. The pressure inside the barrel, and hence the yield of oil,are adjusted using a 'choke' ring of the outlet. The equipment has higher production rates than similar sized presses but is more expensive to buy and operate. Although manual expellers are available, small scale oil millers more often use powered equipment to reduce the time and labour involve in processing. Some designs also have an electric heater filted to the barrel to increase the rate of oil extraction.

The production rate using prsses and ghanis depends on the size of the equipment and the time taken to fill,press and empty each batch. The production rate of expellers depends on the size of the equipment, the speed of the screw and the setting of the choke.

Determination of unsafonifiable matter The unsafonifiable matter is defined as the substance soluble in an oil which after saponification are insoluble in water but soluble in the solvent used for the determination. It includes lipids of natural origin such as sterols, higher aliphatic alcohols, pigments, vitamins and hydrocarbons as well as any foreign organic matter non-volatile at 100 degree celcius (like mineral oil) which maybe present. Light petroleum or diethyl ether is used as a solvent but in most cases result will differ according to the solvent and generally the use of diethyl ether will give a higher result. Apparatus: 1. Flat bottom flask or connical flask with a ground glass joint,250 ml. 2. Air condenser 1 m long to fit the flask 3. Separating funnel, 500 ml Reagents: 1. Alcoholic potassium hydroxide solution: dissolve 7-8g of potassium hydroxide in an equal quantity of distilled water and add sufficient aldehyde free ethyl alcohol and make up to 100 ml. 2. Ethyl alcohol:95 percent 3. Phenolphthein indicator solution: Dissolve one gram of phenolphthlein in 100 ml of ethyl alcohol. 4. Petroleum ether(40-60 degree celcius): analytical reagent grade 5. Aqueous alcohol:10 percent of ethyl alcohol in water

6. Standard sodium hydroxide solution: approximately 0.02N 7. Acetone: analytical reagent grade 8. Anhydrous sodium sulphate Procedure: Weigh accurately 5 g of well mixed oil/fat sample into a 250 ml conical flask. Add 50 ml of alcoholic potassium hydroxide solution. Boil the content under reflux air condenser for one hour or until the saponification is complete (complete saponification gives a homogeneous and transparent medium). Take care to avoid loss of ethyl alcohol during the saponification. Wash the condenser with about 10 ml diethyl alcohol. Transfer the saponied mixture while still warm to a separating funnel, wash the saponification flask first with some diethyl alcohol and then with cold water, using a total of 50 ml of water to rense the flask,cool to 20-25 degeree celcius,add to the flask 50 ml petroleum ether,shake vigorously and allow the layers to separate. Transfer the lower soap layer into another separating funnel and repeat the ether. Some oils high inunsaponifiable matter like marine oils,may require more than three extractions to completely remove unsaponifiable matter. Wash combined ether extract three times with 25 ml portions of aqueous alcohol followed by washing with 25 ml. portions of distilled water to ensure ether extract is free of alkali (washing are no longer alkaline to phenolphthlein).transfer ether solution to 250 ml beaker,rinse separator with ether and rinsings to main solution.Evaporate to about 5 ml and transfer quantitatively using several portions of etther to 50ml erlenmeyer flask previously dried and weighed. Evaporate ether.When all ether has been removed add 23 ml acetone and while heating on steam or water bath completely remove solvent under a gentle air. To remove last traces of ether,dry at 100 degree celcius for 30 min tll constant weight is obtained. Dissolve residue in 5o ml of warm ethanol which has been neutralised to a phenolphthlien end point.Titrate with 0.02 N NaOH.

Calculation: Weight in g of the free fatty acids in the extracts as oleic acid=0.282 VN Where V=Volume in ml of standard sodium hydroxide solution N=Normality of standard sodium hydroxide solution Unsaponifiable matter= 100(A-B) / W where A=weight in grams of the residue B= weight in grams of the free fatty acids in the extracts W= weight in grams of the sample. Determination of Acid Value Definition: The Acid Value is defined as the number of mg of potassium hydroxide required to neutralized the free fatty acid present in one gram of fat. It is a relative measure of raincidity as free fatty acids are noemally formed during decomposition of oil glycerides. The value is also expressed as percent of free fatty acids calculated as oleic acid. Principle: The acid value is determined by directly titrating the oil/fat in an alcoholic medium against standard potassium hydroxide/sodium hydroxide solution. Analytical Importance: The value is a measure of the amount fatty acids which have been liberated by hrdrolysis from the glycerides due to the action of moisture,temperature and/or lypolytic enzyme lipase.

Apparatus: 250 ml conical flasks. Reagents: 1. Ethyl alcohol -95 % alcohol or rectified spirit neutral to phenolphthlein indicator. 2. Phenolphthelein indicator in solution=Dissolve one gram of in 100 ml of ethyl alcohol. 3. Standard aqueous potassium hydroxide solution 0.1 or 0.5 N. The solution should be colorless and stored in a brown glass bottle. Procedure: Mixed the oil or melted fat thoroughly before weighing. Weigh accurately about 5-10 g of cooled oil sample in a 250 ml conical falsk and add 50 ml -100 ml of freshly neutralised hot ethyl alcohol and about one ml of php indicator solution. Boil the mixture for about five minutes and titrate while hot against standard alkali solution shaking vigorously during the titration. The weight of the oil/fat taken for the stimation and the strength of the alkali used for titration shall be such that the volume of the alkali required for the titration does not exceed 10 ml. Calculation: Acid Value=56.1 VN / W where V= Volume in ml of standard potassium hydroxide or sodium hydroxide used N= Noemality of the potassium hydroxide solution or sodium hydroxide solution W= weight in g of the sample The acidity is frequently expressed as free fatty acid for which calculation shall be Free Fatty Acids as oleic acid %/wt= 28.2 VN / W

Acid Value=% fatty acid (as oleic)x 1.99