Enzyme‐assisted extraction of chicken skin protein hydrolysates and fat: Degree of hydrolysis affects the physicochemical and functional properties

Abstract

Enzyme‐assisted extraction (EAE) of oils/fats involves the disruption of the cell wall of source material using enzymes to facilitate the release of oil. When proteases are used as the enzyme, EAE ends in the extracted oil as well as the protein hydrolysates. Herein, the EAE (using a commercial protease, Alcalase) was exploited to obtain fat and protein hydrolysates from chicken skin. Degree of hydrolysis (DH, the percentage ratio of cleaved peptide bonds), which showed a logarithmic correlation with the reaction time, was found to affect the properties of the products. As the DH increased, the peptide chain length of protein hydrolysates decreased which was confirmed by SDS‐PAGE analysis. With the increase of DH, the emulsifying activity index, foaming capacity, and oil holding capacity of the hydrolysates decreased but the solubility and emulsion stability index increased (p < 0.05). The DPPH free radical scavenging activity of the hydrolysates increased with the DH up to DH = 39.62% but decreased thereafter (p < 0.05). EAE resulted in a rise in fat yield and the fat contained a higher amount of unsaponifiables and lower free fatty acids (FFA) content, as compared to the control treatment (No enzyme, 80°C, 2 h, p < 0.05). DH affected the fat yield and the unsaponifiables content of the fat, positively (p < 0.05). However, it did not affect the fat FFA content and iodine value (p > 0.05). Results obtained here showed DH can be used as an effective measure for controlling the physicochemical and functional properties of chicken skin protein hydrolysates and fat in the EAE process.

Functional, physicochemical, and structural properties of the hydrolysates derived from the abalone (Haliotis discus subsp hannai Ino) foot muscle proteins

“…Similarly, the solubility of chickpea protein isolates ( Lo, Kasapis, & Farahnaky, 2022 ) and that of lime seeds was the lowest at pH 4 – 5 ( Fathollahy et al, 2021 ). The solubility of proteins in water depends on the protein-protein, water-water, and water-protein interactions; and thermodynamically is a dynamic equilibrium ( Safar Razavizadeh, Farmani, & Motamedzadegan, 2022 ); when the pH of the solution is near or equal to the isoelectric point of protein, the net charges of protein molecules are small or equal to zero. Thus, the water-protein interactions weaken while the protein-protein interactions strengthen due to which aggregation occurs, leading to precipitation, and reduced solubility.…”

Enhancing activity of food protein‐derived peptides: An overview of pretreatment, preparation, and modification methods

“…Endogenous enzymes are responsible for cleaving peptide bonds within protein chains, whereas exogenous enzymes are capable of cleaving amino acids at the ends of protein chains (Fathollahy et al., 2021). In the last decade, exogenous enzymes have gained widespread use over endogenous enzymes due to their ability to provide better control of the hydrolysis reaction, resulting in shorter reaction times, a more consistent peptide composition, and the achievement of the same level of hydrolysis (Fathollahy et al., 2021; Safar Razavizadeh et al., 2022). Additionally, specific enzymes have been developed to hydrolyze certain types of amino acid bonds, such as trypsin for lysine and arginine, chymotrypsin for the cleavage of aromatic amino acids such as phenylalanine, tyrosine, and tryptophan, and enzymes like pepsin, which are capable of hydrolyzing multiple types of amino acid bonds (Mardani et al., 2023).…”

Characterization of Poultry Gelatins Prepared by a Biotechnological Method for Targeted Changes at the Molecular Level

“…The literature does not currently report the processing poultry stomachs into gelatins using proteolytic enzymes. However, procedures for the enzymatic cleavage of collagen from chicken skin [35], bones [36,37], livers [38], feet [29], and byproducts remaining after the production of mechanically deboned chicken meat [39,40] are known.…”