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Response Surface Analysis (RSA) was used to study the effect of three variables, process temperature (120, 145 and 170"(Z), feed moisture content (20, 30 and 40%) and screw speed (800,900 and 1000 rpm) on extrudate characteristics. Unheated soybean flakes extruded under different conditions were subjected to Warner-Bratzler shear (WBS), water absorption (WA) measurements and residual trypsin inhibitor activity (TIA) assays. Low feed moisture contents induced higher internal heat production causing residual TIA in the product to be lower than expected, WA to increase and WBS to be independent of process temperature (at constant screw speed of 900 rpm). Variation of screw speed permitted the attainment of desired values of product characteristics when moisture and temperature had to be fixed.

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Five cultures of active lactose-fermenting yeasts were adapted to ferment concentrated ultrafiltrated cottage cheese whey permeates of high lactose levels (22-24%). The conditions for veast adaptation and the problems of standardizing the fermentation solution were investigated. Yeast adaptation with controlled lactose standarization of the cottage cheese permeates led to a high yield of alcohol by one strain of KIuy veromyces fragilis approximately 10% (v/v) ethanol in 15 days at 30°C.