Simultaneous Extraction and Hydrolysis of Pumpkin Oilseed Cake Proteins Using Active Culture of Proteolytic Bacillus subtilis

Edible oil industry generates considerable quantities of oilseed cakes that require rational management. The inherent trait of these by-products is an exceptionally high protein content, the retrieval of which is of major interest. In the study, we described a method of simultaneous extraction an hydrolysis of pumpkin oilseed cake proteins, mediated by active culture of proteolytic Bacillus subtilis ATCC 6633. Our study aimed to assess the practicability of this application hitherto unexplored in the context of pumpkin material. The goal was to verify the feasibility of this method, to optimize process parameters, and to characterize its products.

A two-step methodology was used involving a Plackett–Burman screening design and regression modelling with artificial neural network in order to maximize the output of oilseed cake protein hydrolysis products. Characterization of hydrolysates comprised antioxidative potential determined with three methods (ABTS, DPPH, FRAP) and its dynamics, amino acid profile, and fatty acids composition.

The regression model incorporating substrate concentration and bacterial cultivation time allowed to define beneficial culture conditions for the protein extraction and hydrolysis process. The resultant hydrolysate exhibited significant antioxidant activity. The mild hydrolysis conditions maintained advantageous amino acid composition, as well as marginally altered fatty acids profile.

The proposed bacteria-mediated extraction and hydrolysis of pumpkin oilseed cake proteins presents a noteworthy and cost-effective alternative for the application of commercial peptidases in valorization of this by-product.