School of Graduate Study Department of Chemical Engineering

2.2.1 Soy flour and grits
Mature, whole, yellow soybeans are used for human food production. They are cleaned,
preferably sorted into uniform size to minimize variations in processing, equilibrated to
10-12% moisture and cracked into six to eight pieces by using corrugated rolls.
Preheating enhances loosening of hulls from the cotyledons during cracking and aids
their removal by aspiration. The raw cotyledons are then milled into full-fat enzyme
active flour (Lusas and Riaz, 1995).
2.2.2 Defatted soy flour
Defatted soy flour is the most widely used soy ingredient in the baking industry. Among
soy products, it may be best source of Isoflavones and other micro-ingredients that have
been linked to positive health benefits, because it is the least processed form of soy. It
contains up to 50% protein, making it a more concentrated source of protein than full fat
soy flour (Riaz, 2000).
2.2.3 Soy protein concentrate
According to Berk (1992), historically, the need for the development of soybean protein
concentrates stemmed primarily from two considerations:
To increase protein concentration, and
To improve flavour.
To remove flatulent causing components
It is very difficult to avoid the occurrence of the green-beany flavour of soybeans in untoasted
full-fat or defatted soy flour, prepared in the conventional way. Beany flavour is
one of the major objectionable characteristics, limiting the use of conventional soy flours.
One of the objectives of the further processing of flours into concentrates is to extract the
particular components, which are responsible for the bitterness and beany taste. The
solvents used in the production of concentrates, also efficiently remove the flatusproducing
oligosaccharides of soybean flour, raffinose and stachyose (Berk, 1992).
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