PROTEINS EXTRACTION FROM WHOLE SOYBEAN FLOUR : INFLUENCE OF MIXING RATE ON YIELD AND QUALITY

Proteins are essential to human nutrition and health. While animal proteins have been considered to be the primary dietary protein source for decades, there has been a paradigm shift recently on the dietary consumption patterns among the general population towards plant-based food proteins. As a result, plant protein production in the food industry has remarkably increased (Qin et al, 2022). Soy protein from soybeans, historically identified in the Asian region, is considered as an important food source to meet protein demand for the human body (Rizzo et al, 2018). Soybean flour can contain up to more than 40% protein and protein concentrates or isolates (with typically more than 70 and 90% protein content, respectively) can be obtained through appropriate extraction processes. In most cases, defatted soybean flour is used as starting material, but the use of hexane as extraction solvent may lead to protein denaturation and solvent residues. On the other hand, starting from whole soybean flour, makes difficult the separation of fat and protein fractions and still, the presence of fat in the extracted proteins may enhance their emulsifying properties. In this work soy proteins were extracted from whole soy flour through a conventional process consisting in an alkaline extraction step followed by acid precipitation. Four different mixing systems in the alkaline extraction step were applied in order to investigate their influence on protein and fat extraction yield, on purity of final proteins (protein, free and bound fat content) and on technological properties (gelling and emulsifying capacity) of the extracted proteins.