Concentrates oilseed processing

The most important phospholipid concentrates are those resulting from oilseed processing. Oilseeds are heated to high temperatures with application of steam. Lipoproteins... 

The sohd can be contacted with the solvent in a number of different ways but traditionally that part of the solvent retained by the sohd is referred to as the underflow or holdup, whereas the sohd-free solute-laden solvent separated from the sohd after extraction is called the overflow. The holdup of bound hquor plays a vital role in the estimation of separation performance. In practice both static and dynamic holdup are measured in a process study, other parameters of importance being the relationship of holdup to drainage time and percolation rate. The results of such studies permit conclusions to be drawn about the feasibihty of extraction by percolation, the holdup of different bed heights of material prepared for extraction, and the relationship between solute content of the hquor and holdup. If the percolation rate is very low (in the case of oilseeds a minimum percolation rate of 3 x 10 m/s is normally required), extraction by immersion may be more effective. Percolation rate measurements and the methods of utilizing the data have been reported (8,9) these indicate that the effect of solute concentration on holdup plays an important part in determining the solute concentration in the hquor leaving the extractor. 

Seed-Meal Concentrates and Isolates. Seed-meal protein products include flours, concentrates, and isolates, particularly soy protein products. These can be used as extenders for meat, seafood, poultry, eggs, or cheese (see Soybeans and other oilseeds). Detailed information on soybean and other seed-meal production processes is available (13,14,18). 

Oilseed proteins are used as food ingredients at concentrations of 1—2% to nearly 100%. At low concentrations, the proteins are added primarily for their functional properties, eg, emulsification, fat absorption, water absorption, texture, dough formation, adhesion, cohesion, elasticity, film formation, and aeration (86) (see Food processing). Because of high protein contents, textured flours and concentrates are used as the principal ingredients of some meat substitutes. 

Use of some oilseed proteins in foods is limited by flavor, color, and flatus effects. Raw soybeans, for example, taste grassy, beany, and bitter. Even after processing, residues of these flavors may limit the amounts of soybean proteins that can be added to a given food (87). The use of cottonseed and sunflower seed flours is restricted by the color imparted by gossypol and phenoHc acids, respectively. Flatus production by defatted soy flours has been attributed to raffinose and stachyose, which are removed by processing the flours into concentrates and isolates (88). 

Whole oilseeds and legumes and their derivatives (defatted flours, and protein concentrates and isolates) are used in traditional foods as sources of protein and for their texture-modifying functions. This article reviews, on a comparative basis, processes for preparation of vegetable food proteins, compositions and characteristics of the resulting food ingredients, and their functionalities and uses in traditional foods. 

A flowsheet for preparation of glandless cottonseed full-fat kernels and subsequent processing of defatted flours and concentrates and isolates is shown in Figure 1. This scheme, with specialized adaptations depending upon oilseed species, is typical for processing of all oilseeds. 

Rapeseed. one of the five most widely produced oilseeds, is cultivated mainly in India. Canada, Pakistan, France, Poland, Sweden, and Germany. Past objections to using rapeseed as a source of edible protein has been its content of deleterious glucosinolales. Considerable research has been conducted in Sweden to develop a rapeseed protein concentrate. The first full-scale production plant using a new process was installed in Alberta, Canada. The plant, with a capacity of 5000 tons/year produces a material containing 65% protein. Rapeseed is rich in essential amino acids, with exception of methionine, which soybeans also lack. 

The sohds remaining after fat removal are generally rich in protein and find a ready market in animal feeds. Some oilseed solids, especially soybean, go into human foods as flours, concentrates, textured particles, or protein isolates. Some oilseed sohds contain toxins or allergens that make them unfit for animal feeds tung nut and castor bean, for example. Unless treated, these solid residues go into fertilizers. Various processes have been developed to remove or chemically destroy undesirable compounds (10). One process developed at Texas A M University for UNIDO (11, 12) uses a chemical additive and extrusion to detoxify and deallergenate castor meal making it suitable for animal feed. 

In one process, the inventor has reported that sugars from oilseed meals are readily fermented to form ethanol (80). With soybeans, the concentration of fermentable sugars can constitute 12% of the meal weight. These sugars could readily be fermented to produce enough ethanol for esterification of oil from the seed. However, it is improbable that seeds with higher oil contents would produce sufficient ethanol from fermentation to esterify the oils present. 

Several processes for the manufacture of protein concentrates or isolates for aquaculture have also been developed. These technologies yield nondenatured proteins with better digestibility for fish nutrition. Membrane separation techniques are used to separate oilseed components, remove antinutritional factors, and fractionate protein for fish feed production. 

However, various technologies have been developed that utilise extractions from oilseed meals and pulses as the raw material for the production of flours, protein isolates and protein concentrates. These technologies are mainly used in the processing of soybeans and, to a lesser extent, in the processing of peanuts, cotton, lupine and other oilseed meals. Additional sources of protein are whey, fishmeal and others. The final products can be various mixtures rich in proteins (often enriched by minerals and vitamins), which are mainly used in less-developed countries. 

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