Valorization of an Abundant Slaughterhouse By-product as a Source of Highly Technofunctional and Antioxidant Protein Hydrolysates

Chicken blood meal (CBM) is a slaughterhouse by-product of great environmental concern, rich in protein and iron, mainly used as animal feed and fertilizer. In this work, the valorization of CBM as a source of protein hydrolysates (CBMH) is proposed. The hydrolysis reaction conditions were assessed using a Doehlert experimental design. Samples of CBMH were thus prepared at optimal conditions: T = 54 °C, pH 8.5 and enzyme-to-substrate ratio (E/S) = 6.5% with different reaction durations in order to study the impact of the degree of hydrolysis (DH) on the properties of the product. The characteristics studied in the hydrolysates were among others: chemical structure, technofunctional properties [compared to those from soy protein isolate (SPI)] and antioxidant activity. CBMH samples displayed MW < 14.4 kDa, increasing heme content correlated with their color parameters, formation of hygroscope aggregates and enhanced thermal stability. UV-spectroscopy, infrared spectroscopy and circular dichroism confirmed the conformational changes in CBMH to be dependent on the DH. Compared to CBM, CBMH had improved oil holding capacity that decreased with the DH. CBMH foams exhibited better behavior at neutral pH than those from SPI. Moreover, CBMH emulsions displayed lower emulsifying activity and higher but decreasing emulsifying stability. CBMH samples displayed antioxidant activity (FRAP, DPPH and ABTS), whereas only the FRAP values suffered a negative impact due to the extended hydrolysis. The results suggest that the valorization of CBM can be achieved via hydrolysis, resulting in potential ingredients for the food, cosmetic and pharmaceutical industries.