This study aimed to determine the effect of pretreating defatted soy flakes with ultrasound on soy protein isolate (SPI) yield and functionality. Defatted soy flakes dispersed into water (16%, w/w) were sonicated for 30, 60 and 120 s at ultrasonic amplitudes of 21 and 84 lm pp (peak to peak amplitude in lm), representing low and high power, respectively. The power densities were 0.30 and 2.56 W mL -1 , respectively. The SPI yield increased by 13 and 34%, after sonication for 120 s at low and high power, respectively. The sonication of defatted soy flakes for 120 s at the higher power level improved the SPI solubility by 34% at pH 7.0, while decreasing emulsification and foaming capacities by 12 and 26%, respectively, when compared to control SPI. Rheological behavior of the SPI was also modified with significant loss in consistency coefficient due to sonication. Some of these results could be explained by the loss of the protein native state with increased sonication time and power.
further reduced GLS up to 99 and 98 %, respectively. Fiber levels increased due to the concentration effect of removing oligosaccharides and GLS.
AbbreviationsADF Acid detergent fiber CP Cold-pressed dw Dry weight GLS Glucosinolate GYE Glucose yeast extract HE Hexane-extracted LC-MS Liquid chromatography-mass spectrometry NDF Neutral detergent fiber PDA Potato dextrose agar q-tof Quadrupole time-of-flight rpm Revolutions per minute RS Residual sugar RP-HPLC Reverse phase high performance liquid chromatography SLR Solid loading rate Abstract The study goal was to determine the optimal fungal culture to reduce glucosinolates (GLS), fiber, and residual sugars while increasing the protein content and nutritional value of canola meal. Solid-state incubation conditions were used to enhance filamentous growth of the fungi. Flask trials were performed using 50 % moisture content hexane-extracted (HE) or cold-pressed (CP) canola meal with incubation for 168 h at 30 °C. Incubation on HE canola meal Trichoderma reesei (NRRL-3653) achieved the greatest increase in protein content (23 %), while having the lowest residual levels of sugar (8 % w/w) and GLS (0.4 μM/g). Incubation on CP canola meal Trichoderma reesei (NRRL-3653), A. pullulans , and A. pullulans (NRRL-Y-2311-1) resulted in the greatest improvement in protein content (22.9, 16.9 and 15.4 %, respectively), while reducing total GLS content from 60.6 to 1.0, 3.2 and 10.7 μM/g, respectively. HE and CP canola meal GLS levels were reduced to 65.5 and 50.7 % by thermal treatments while solid-state microbial conversion Mark Berhow: Mention of trade names or commercial products in this paper is solely for the purpose of providing specific information and does not imply endorsement by the U.S. Department of Agriculture (USDA). The USDA is an equal opportunity provider and employer.
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