Effect of Storage Temperature and Materials on Protein Quality and Functional Properties of Soybeans

ABSTRACT This study investigated the impact of storing two soybean varieties (SC Semeki and Uyole Soya 2) in polypropylene and PICS bags at 15°C and 25°C, with analyses at 30‐day intervals for 3 months, on the retention of their protein content, amino acid profiles, and the functional properties of their protein isolates. The study indicates that using polypropylene bags at 25°C was not effective in maintaining the nutritive quality during storage. This led to a decrease in protein content of 3.85% and 5.19% and a decrease in PS of 12.47% and 7.32% in SC Semeki and Uyole soya 2, respectively. In contrast, similar settings led to an increase of emulsifying capacity by 40% and 41% and oil absorption capacity by 18% and 28% in SC Semeki and Uyole Soya 2, respectively. On the other hand, results from amino acid analysis indicated a higher retention in amino acids with the use of PICS bags (12/17) compared to polypropylene bags (3/17). Similarly, majority of amino acids were retained better at 15°C (6/17) compared to 25°C (2/17). Therefore, the use of PICS bags at low temperatures (15°C) is highly recommended for preserving nutritional quality and functional properties of SPI in comparison.