oil extraction ppt_by-Santhosh..pptx

Edible oil extraction
Various methods





























Oil processing

1. Vidhyalaxmi group of educational institutions, Brahmavara DEPARTMENT OF FOOD TECHNOLOGY PRESENTATION OIL EXTRACTION MODERATOR Ms Rasmiya Lecturer Technology of Fat and Oil Products Presented by : Santhosh Kumar P S Second year BSc Ft

2. INTRODUCTION Edible oil processing covers the range of industrial processing that that start with the isolation of triglyceride oils and fats from raw materials of biological origin. This range includes those refining process that convert the crude oil into high quality oil products that are fit for human consumption and also the oil modification process that ensure that the physical properties if the fts and oils meat market requirements at minimal cost. Edible oil processing has 3 different stages. 1. Production of triglyceride oils. 2. Refining of oils. 3. Modification of oils.

3. Oil extraction Oil extraction is the isolation of oil from animal byproducts fleshy fruits such as the olive and palm, and oil seeds such as cotton seed, sesame seed, soybeans, and peanuts. oil is extracted by 3 general methods depending on the source or raw material and scale of operation. Rendering used animal products and oliaginous fruits. Mechanical pressing foroil bearing seeda and nuts. Extraction with volatile solvents , employed in large scale operations for more complete extraction then the pressing. Other advanced methods are also employed such as super critical fluid extraction, enzymatic extraction, microwave assisted extraction.

4. Pretreatment Before subjecting the seeds to extraction pretreatments are given to the seeds to facilitate easy oil extraction. Pretreatments are as follows.

5. Oil extraction techniques

6. Mechanical extraction of oil Expression Expression is the process of mechanically pressing liquid out of liquid-containing solids.

Screw presses, roll presses and mills, collapsible-plate and frame-filter presses, and hydraulic presses are examples of the wide variety of equipment available for expression processing. The efficiency of a mechanical-expression process cannot be equal to unity and, in actual operations, it seldom exceeds 90%. Oil seeds Oil content Sunflower 40-42 Soybean 13-25 Sesame 50-57 Peanut 43-45 Rapeseed 33-43 Mustard 25-60 Cottonseed 24-26 Coconut 40-45 Caster bean 35-55

7. Mechanical extraction of oil Mechanical oil extraction (expression) is a solid-liquid phase seperation method which is applied to cooked seed flakes.

• It can be executed by batch , mainly hydraulic, and by continous , mainly mechanical working presses .

This method usually uses an expeller press to give pressure on vegetables, nuts and seeds to cause the oil to run.

Usually the mechanical pressing method provides yields of only 65-70% of the oil; and 80% is considered very good. Most large commercial operations use a mild pressing operation to extract 60 to 70% of the oil, while the remainder is solvent extracted.

8. Pressing Cold pressing •High oil containing seeds such as sesame and peanuts and the oily pulps of olives yield free oil by the simple application of pressure.

• Oil of this type generally require no further processing.

•Sesame and peanut oils have a pleasant nutty flavor .

•Olive oil has a strong but well accepted flavour. However cold processing is not very efficient.

9. Hot pressing ✔The oil meals (seed residues from which oil has been removed) obtained after cold pressing techniques contained an excessive amount of valuable oil.

✔This lead to the development of more efficient presses such as the hydraulic batch press and the continuous spiral press or expeller.

✔These presses develop pressure of 1-15 tones per square inch leaving 4-5% oil in the meal.

✔Unfortunately such presses also develop excessive heat causing darkening of the oil and denaturation of the oilseed proteins.

10. Oil expellers used in Mechanical extraction Screw Press Hydraulic press

11. Advantages of mechanical extractions Relatively simple process. Lower initial capital cost.
No use of solvent. Drawbacks of mechanical extractions Low capacity.
High residual oil in the press cake (4 to 7 %).
High power requirements.
Higher maintenance and operator skill.

12. Factors affecting mechanical extraction of oil Factors Effect Pressure The more pressure is applied, the higher is the oil extraction yield. Temperature The heat coagulates the protein and reduces the viscosity of oil which increases the yield.
Prolonged heating at higher temperature causes hardening of material that reduces oil yield. Screw rotation speed Depending upon type of press and raw material, generally the increase in screw speed may either increases or decreases the yield of oil. Moisture content Low moisture content leads to a better yield of oil. Higher moisture results in poor oil recovery. Particle size Coarser the particle size higher the yield of oil.

13. Solvent extraction Basic principle The extraction of oil from oilseeds by means of non-polar solvents is, basically, a process of solid-liquid extraction.

The transfer of oil from the solid to the surrounding oil-solvent solution ( miscella ) involves three steps.

✓ Diffusion of the solvent into the solid,

✓ Dissolution of the oil droplets in the solvent, and

✓ Diffusion of the oil from the solid particle to the surrounding liquid.

14. Factors affecting solvent extraction • Physical characteristics of solids ✓ An open, porous structure of the solid material is preferable, because such a structure facilitates diffusion as well as percolation.
• Solvent ✓ A solvent having higher solubility is preferable. A low boiling point make the separation easier.
• Temperature ✓ The rate of extraction can be increased considerably by increasing the temperature in the extractor.
✓ Higher temperature means higher solubility of the oil, higher diffusion coefficients and lower miscella viscosity. * A number of processes like cooking, flaking have been proposed for increasing the porosity of oilseeds before solvent extraction.

15. Choice of solvent An ideal solvent for the extraction of oil from oil seeds should possess the following properties
✔ Good solubility of the oil. ✔ Poor solubility of non-oil components.
✔ High volatility (i.e. Low boiling point), so that complete removal of the solvent from the miscella and the meal by evaporation is feasible and easy.
✔ The boiling point should not be too low, so that extraction can be carried out at a somewhat high temperature to facilitate mass transfer.
✔ Low viscosity.✓ Low latent heat of evaporation, so that less energy is needed for solvent recovery.
✔ Low specific heat, so that less energy is needed for keeping the solvent and the miscella warm.
✔Chemically inert to oil and other components of the seed flakes.
✔Absolute absence of toxicity and carcinogenicity, for the solvent and its residues.
✔ Non-inflammable, non-explosive, non-corrosive.
✔Commercial availability in large quantities and low cost.

16. Advantages and disadvantages of the solvent extraction process Advantages ⚫ High oil yield as compared to mechanical extraction. .
⚫ Spends lower production cost and requires less time. Disadvantages ⚫ The expeller pressed oil is cleaner more pure oil, higher in natural colors and flavors compared to the solvent extracted oil.
⚫ Requirement of large volume of solvent, pressure requirements, etc.
⚫ High construction cost of extraction and refining workshop.
⚫ High maintenance cost.
⚫ Residual oil content in meal.

17. Types of extractors Solvent extractors are of two types Batch type ✓ In batch processes, a certain quantity of flakes is contacted with a certain volume of fresh solvent.
✓ The miscella is drained off, distilled and the solvent is recirculated through the extractor until the residual oil content in the batch of flakes is reduced to the desired level. Continuous type ✓ Both the oilseeds and the solvent are fed into the extractor continuously.
✓ The different available types are characterized by their geometrical configuration and the method by which solids and solvents are moved, one in relation to the other.
* Continuous solvent extractors are of two types
✓ Percolation type
✓ Immersion type

18. Simplified flow diagram of a hexane extraction process

19. Supercritical Fluid Extraction Public concerns and government scrutiny about the environmental and human health hazards of organic solvents and residues in oil/oilseed-derived products have catalyzed the search for alternative solvents for edible oil processing. Ethanol, isopropyl alcohol, acetone, iso -hexane and supercritical fluids (SCF) have been studied as alternative solvents. SCF technology has been examined as an alternative technique for the conventional oil and oilseed processing methods for more than two decades. The supercritical carbon dioxide (SC-CO2) technique, which utilizes carbon dioxide above its critical pressure (7.3 Mpa ) and temperature (31°C) as solvent, has been the choice for the majority of edible applications. The unique advantage of SC-CO2 is the easy removal of solvent from the extract. When pressure is released from the system, carbon dioxide returns to the gas phase and oil precipitate s out from CO2-oil mixture. Carbon dioxide is recycled; hence, CO2 released from the system is not an environmental issue. Although industrial applications of SC-CO2 technology have been growing steadily, currently most of the applications involve high-value products. The economic feasibility of SC-CO2 based processes is still hampered by the capital cost of high pressure vessels. However, cost saving can be realized from simplified separations and the lower solvent cost of supercritical fluids. The nontoxicity of SC-CO2 and significantly reduced waste streams from the process makes this technology unique in terms of meeting increasingly stringent health and environmental regulations.

20. Flow diagram of a supercritical carbon dioxide extraction system.

21. Aqueous enzymatic extraction •The extraction of oil from edible and non-edible oilseeds by solvent extraction step by mechanical and chemical for industrial purpose. Normally, hexane is used as a solvent. •In the past, due to use of hexane, there is chances of environmental pollution and low oil yield. So use of hexane was reduced. •The present scenario to be changing. Interest in aqueous Enzymatic extraction processes has been becoming popular due to its environmental concern. An aqueous process is looked upon as ecofriendly technology for oil extraction.

22. Other advantages of the aqueous Enzymatic extraction process compared with solvent-based processes include: (I) Higher extraction of edible and non-edible oil and protein (2) Minimum damage of protein during extraction, and (3) Good process safety due to the minimum fire risk and explosion. Due to the solvent recovery step is elimination, aqueous extraction processes may be more cost effective.

23. The enzymatic hydrolysis process is the pretreatment of oilseeds with enzymes. This leads to a quick softening of oilseed coats. In other words, enzymes digest the complex cell walls of oil seeds which increases their permeability leading to better oil extraction. They open up oil cell walls and break the complex lipoprotein and lipo -polysaccharide molecules into small parts which can be processed further. These lead to a release of oil from lipid bodies trapped between carbohydrate and protein structures within the seeds. Enzymatic extraction of oil requires certain factors like temperature, optimum pH levels, moisture, grinding, and reduced size of oilseeds for their efficient working. This leads to efficient and increased extraction of oil with a higher concentration of nutrients. Utilizing enzymes for oil extraction is an eco-friendly process that reduces BOD (Biological Oxygen Demand) by 75% and COD (Chemical Oxygen Demand) up to 45% of the residue and wastewater generated. Enzyme extraction also lowers acid development and oxidation which may occur during further processing and storage.

24. Enzymes Used in Oil Extraction Different enzymes are used depending on the oilseeds and the extraction process used for oil recovery. Enzymes such as proteases, cellulases , and hemicellulases are used for improved recovery of oil from solvent and expellers extraction methods. Pectinase and cellulase are the most effective enzymes that increase oil recovery by nearly 20%. Enzymatic extraction of oil should primarily contain a combination of several enzymes like cellulases , hemicellulases , pectinases, and proteases. Other enzymes used for the extraction of edible oils could include polygalacturonase , alpha-amylase, carbohydrases , and galactomanase .