School of Graduate Study Department of Chemical Engineering

2.5 Soybeans and soy Products Quality Attributes
There are a number of soybean characteristics that are important for end use and /or
storage. The level, plus presence of these characteristics, is generally referred to as
“Quality”. Not all soybeans are created equal. Soybean can vary widely in characteristics
desired for many soy foods and soy food application. High-quality soybeans have
desirable levels of certain characteristics or combination of characteristics. Such
characteristics include physical properties, chemical compositions, and functional
properties of soy products. (Brumm, 2006)
2.5.1 Physical Properties of soybeans
a) Hilum Color
Many processors want yellow-hilum soybean (also known as clear or white –hilum), as
the darker hila may affect the color or clarity of the final processed product. Certain soy
foods are made with yellow-hillum soybeans because it has been traditionally done so,
not necessarily because there is a negative impact from colored hila. The hilum color is a
genetic characteristic of a soybean variety. Hilum color is identified by visual inspection
(Brumm, 2006).
b) Seed Count
Larger seed counts (number of seeds per unit weight) correspond to smaller seeds.
Commodity-type soybeans are typically 6,000 to 7,300 seeds/kg. Tofu and soy milk
processors often want larger seeds of 4,400 to 5,500seeds/kg. Miso processors want
medium but uniform size beans. In some soy products, it is desirable to minimize the
amount of fiber. Larger seeds have fewer hulls and therefore less fiber can be obtained.
Seed count is a varietal characteristic that is influenced by growing conditions. Seed
count is determined by counting and then weighing (Brumm, 2006).
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