Studies of matrix interactions for the valorisation of the protein fraction of Okara, a food by-product with a high potential for biotechnological applications

Reduction of by-products and food wastage for the full use of natural resources is one of the main challenges the industrialized world must face nowadays. Okara is a by-product generated during soymilk or tofu production processes, annually produced in huge quantities, thus posing a significant disposal problem since, up to now, it has been mainly used as such in animal feeds or as industrial waste. Okara high protein content (about 25-40% on dry weight basis), makes this by-product still interesting and exploitable from a biotechnological point of view. Aim of the work is firstly to characterize the composition of the raw material, in order to define a rapid, cheap and efficient approach to extract and solubilize Okara proteins. Different extraction approaches have been compared for the selection of those with the best yield, considering their applicability in downstream processes as well. Results contribute to give new insights into the complex interactions that take place between the different constituents of the raw material, which has already undergone numerous physical-chemical transformations during food processing, with a particular focus on protein-protein interactions. In conclusion, the study of the complexity of all the components that are present in a transformed food is crucial to determine the best approaches to extract and isolate the valuable compounds present in it. Furthermore, the re-use of a food by-product gives an additional economical value to a product up to now treated as a waste.