Pressing, oilseed

Hydraulic Pressing. Batch pressing was the earliest commercial method of oil extraction. Hydraulic equipment replaced the mechanical operations and the method became known as hydraulic pressing (49). In open presses, oilseed meals were wrapped in cloths and placed between plates, which were then gradually... 

The edible oilseed protein industry is comparatively small and is restricted to peanut and soybean proteins. One company manufactures partially defatted peanut flours made by hydraulic pressing. The products contain 40—42% protein. Production estimates for edible soybean proteins in the United States in 1993—1994 (56) and wholesale prices as of November 1995 are given in Table 15. 

Eggers, R., Supercritical fluid extraction (SFE) of oilseeds/lipids in natural products, in Supercritical Fluid Technology in Oil and Lipid Chemistry, King, J.W. and List, G.R., Eds., AOCS Press, Champaign, IL. 1996, 35. 

Typically, full-fat flours are made by hammer milling the seed to pass through 80-mesh or smaller size screens. However, grinding of oilseeds containing over 25% oil results in sticky flours. Thus, partially-defatted peanut and sunflower seed flours are made by first screw pressing the seed to reduce the oil to 6-18% fat content. 

Knapp SJ, Crane JM (1999) Breeding advances and germplasm resources in meadowfoam a very long chain oilseed. In Janick J (ed) Perspectives on new crops and new uses. ASHS Press, Alexandria, VA, 225-233... 

Better and Davidsohn (23) reported that the susceptibility of proteins in oilseed presscaFe and solvent-extracted meal was strongly affected by heat treatment. Working with peanut and coconut presscake, they demonstrated that the stronger the heat treatment, the higher are the concentrations of pepsin required to make peptization more complete. This is an important fact to bear in mind when oilseed press or extraction residues are being used as raw materials for production of industrial protein. 

Westdal, P.H., Insect pests of sunflower, in Oilseeds and Pulse Crops in Western Canada A Symposium, Harapiak, J.T., Ed., Modem Press, Saskatoon, Saskatchewan, 1975, pp. 475-495. 

Continuous screw presses are used (1) for extracting fats and oils in small operations where investment capital or supplies of raw materials are limited and installation of a solvent extraction plant is impractical (2) to partially defat high-oil content seeds for easier handling in subsequent solvent extraction or hard pressing and (3) for extraction of animal flesh and bones, fish, and fleshy-type oilseeds such as palm fruit, olives, and copra (dried coconut meat ), and oilseeds. These machines have been generically referred to as expellers, but the Expeller trademark belongs to Anderson International Corporation, Cleveland, OH, successor to the company founded by Valerius D. Anderson who patented the first continuous screw press in 1899. 

Introduction of the expander has enabled extraction plants to handle additional seed species, with purchase of only minimal cleaning and dehulling equipment where needed. Prepress-solvent extraction facilities are being replaced by expander-direct solvent extraction equipment, leaving two basic extraction processes in modern large volume oilseed extraction plants expander-direct solvent extraction, and hard press for applications... 

Solvent extraction. The press cake emerging from a screw press still retains 3 to 15 percent of residual oil. More complete extraction is done by solvent extraction of the residues obtained from mechanical pressing. The greater efficiency obtained in the solvent extraction process encouraged the industry for direct application to oilseeds. In the United States and Europe, continuous extractor units are used in which fresh seed flakes are added continuously and are subjected to a counterflow of solvent by which intimate contact is achieved between the seeds and solvent. The common solvent for edible oil is commercial hexane or heptane, commonly known as petroleum ethers, boiling in the range of 146 to 156°F (63.3 to 68.9°C). After extraction, maximum solvent recovery is necessary for economical operation. The solvent is recovered by distillation and is reused. The extraction oil is mixed with prepress oil for refining. The extracted meals contain less than 1 percent of residual oil. 

Extruders. Extruders, or expanders, are widely applied in the oilseed industry, but mostly for press-cake conditioning in canola oil extraction, and for extruding soybean flakes into expanded collets for improved extraction yield. Extruders as cookers are used in some soybean extraction plants to achieve enzyme inactivation. Lusas investigated inactivation of enzymes during extrusion of soybean (69). Extruders could be used to pretreat canola seed to assist prepressing and to inactivate the enzymes however, commercial application of this process in canola industry is not known. 

T. Harper, in R. E. Wilson, ed.. Proceedings of the World Conference on Oilseed Processing and Utilization, AOCS Press, Champaign, Illinois, 2001, p. 25. 

P. J. Wakelyn and P. K. Adair, in S. S. Koseoglu, K. C. Rhee, and R. F. Wilson, eds.. Emerging Technologies, Current Practices, Quality Control, Technology Transfer, and Environmental Issues, Vol. 1, Proc. of the World Conference on Oilseed and Edible Oil Processing, AOCS Press, Champaign, Illinois, 1998, pp. 305-312. 

Many species in the Europhorbiaceae and Labiatae families produce seeds with a high content of oil and contribution of hnolenic acid of up to 76% (1). Flaxseed has been used for years in the production of paints, varnishes, inks, and linoleum. In food applications, flaxseed is more often used than oil because of its better stability and because of the presence of fiber, lignans, and a-linolenic acid (ALA), which have health benefits. Cold pressed flaxseed oil is not considered suitable for deep-frying, although Chinese use it in stir-frying (2). In this chapter, oilseeds of flax, perilla, camelina, and chia are discussed as sources of oils with elevated content of ALA. These oilseeds are produced in industrial quantities and can be considered as potential sources of new oils with specific nutritional and functional properties. 

D. K. Salunke and B. B. Desai, Postharvest Technology of Oilseeds, CRC Press, Boca Raton, Florida, 1986, p. 35. 

In India much oil is still sold by small mills that simply filter oil from the press and supply the product in small tins or even in the consumer s own vessel. Safflower production is by and large a neighborhood affair in India. While the government is encouraging more production of all types of oilseeds, sunflower, which has much wider adaptation than safflower, enjoyed spectacular increase in production in the 1990s. 

In Asia, sesame oil is obtained by pressing the roasted oilseeds and consumed as a naturally flavored oil without refining. In the western world, sesame oil is extracted by a multiple-step mechanical expeller and either the virgin oil or the... 

The modem commercial methods of oil extraction from oilseeds include (1) batch hydraulic pressing Oil seeds are expressed by hydraulic pressure to yield oil (2) continuous mechanical pressing Oil seeds are squeezed through a tapering outlet and oil is expressed by the increasing pressure and (3) solvent extraction Oil seeds are extracted with solvent followed by removal of solvent to yield oil. These methods are also employed in the extraction of sesame seeds with some modification. 

P. J. Wan and P. J. Wakelyn, eds.. Technology and Solvents for Extracting Oilseeds and Nonpetroleum Oils, AOCS Press, Champaign, Illinois, 1997. 

Mechanically Extracted Meals. Solvent extracted oilseed meals typically contain less than 1.5% residual fat unless the gums (hydrated phosphatides) or soapstock have been added back to the meal before the desolventizer-toaster or meal dryer. Mechanically extracted (expeller or screw-pressed) meals can contain 4—9% oil, which can be a significant calorie source in animal feeds. Fat contents of extracted meals are not part of the definition, although typical analyses are shown below. 

Cake or meal from oil extraction contains 40-50% protein when processed in a screw press and 56-60% protein after solvent extraction. Sesame products have a pleasant flavor and contain high levels of methionine and cysteine. The flour produced from sesame meal has a high nutritive value compared to other oilseed flours (75). 

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