Parameters Affecting Milling Qualities of Undefatted Soybeans (Glycine max, l. Merill) (1): Selected Thermal Treatment

In the developing countries animal proteins are very expensive and cannot meet with the protein requirement of the current explosive population trend hence, supplementing with plant protein is pertinent. Soybean, which is widely consumed when processed to flour and flour products, is one of the best substitutes if properly processed. This study, therefore, aimed at establishing the best thermal treatment among the commonly used methods that will conserve the protein content of soy flour maximally, result in high flour yield and acceptability. Four different methods: Roasting (ROA), Extrusion (EXT), Boil and Sun Dry (BSD) and Boil and Oven Dry (BOD), were used to prepare samples from Tax 1448 soybean variety obtained from International Institute for Tropical Agriculture (IITA) and mixed variety obtained from market. The samples were milled in an attrition mill and the flours obtained were subjected to proximate, sieve and organoleptic evaluations. The results of the experiment, showed a protein content of 40.5, 40.7, 40.1 and 40.3%, flour yields of 32.0, 3.7, 29.7 and 37.9%, and acceptability of 58.0, 61.0, 36.0, and 48.0% and protein content of 33.7, 34.4, 32.7 and 32.7%, flour yields of 17.0, 5.0, 14.1 and 12.3%, and acceptability of 64.0, 68.0, 48.0 and 60.0% for BOD, EXT, ROA and BSD respectively for Tax 1448 and mixed variety. These results indicated that BOD is a better method over others. EXT, though, has the highest acceptability and protein contents, these values (p < 0.05), have no significant difference from those of BOD. EXT however has a very low flour yield. This study has therefore established that BOD is the best of the commonly used domestic methods for producing acceptable soy flour of high protein content and flour yield.