Defatted flours, oilseed

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. 

Dabrowski, K.J. and Sosulski, F.W. 1984. Composition of free and hydrolysable phenolic acids in defatted flours of ten oilseeds. J. Agric. Food Chem. 32, 128-130. 

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. 

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). 

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. 

Rokey, G.J. G.R. Huber I. Ben-Gera. Extrusion-cooked and textured defatted soybean flours and protein concentrates. Proceedings of the World Conference on Oilseed Technology and Utilization T.H. Applewhite, Ed. American Oil Chemists Society Champaign, IL, 1993 pp. 290—298. 

The flours highest in protein are those made from defatted fish and from the defatted oilseed meals (cottonseed, peanut, soybean, and sunflower). It is noteworthy that these flours are currently being used around the world as protein supplements. 

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