Impact of the environmental conditions and substrate pre-treatment on whey protein hydrolysis: A review

• Published in: Critical reviews in food science and nutrition Vol. 57; no. 2; pp. 418 - 453
• Main Authors: Cheison, Seronei Chelulei, Kulozik, Ulrich
• Format: Journal Article
• Language: English
• Published: United States Taylor & Francis 22.01.2017; Taylor & Francis Ltd
• Subjects: Acid Protease A; Animals; Biocatalysis; Buffers; chemical structure; Chymotrypsin - chemistry; Chymotrypsin - metabolism; denaturation; Environmental conditions; environmental factors; Environmental impact; Enzymes; Enzymes, Immobilized - chemistry; Enzymes, Immobilized - metabolism; Food Additives - chemistry; Food Additives - isolation & purification; Food Additives - metabolism; Food Handling; Food science; heat; Hydrogen-Ion Concentration; Hydrolysis; ionic strength; lactose; Molecular structure; Osmolar Concentration; Pepsin A - chemistry; Pepsin A - metabolism; Peptide Fragments - chemistry; Peptide Fragments - isolation & purification; Peptide Fragments - metabolism; pH-stat; protein composition; Protein Conformation; Protein Denaturation; Protein Hydrolysates - chemistry; Protein Hydrolysates - isolation & purification; Protein Hydrolysates - metabolism; Proteins; Proteolysis; selective hydrolysis; Solubility; solvents; Temperature; Thermolysin - chemistry; Thermolysin - metabolism; thiols; Trypsin - chemistry; Trypsin - metabolism; whey protein; Whey proteins; Whey Proteins - chemistry; Whey Proteins - isolation & purification; Whey Proteins - metabolism; α-lactalbumin; β-lactoglobulin; Acid Protease A; Whey proteins; selective hydrolysis; α-lactalbumin; pH-stat; β-lactoglobulin
• ISSN: 1040-8398; 1549-7852; 1549-7852
• DOI: 10.1080/10408398.2014.959115

Proteins in solution are subject to myriad forces stemming from interactions with each other as well as with the solvent media. The role of the environmental conditions, namely pH, temperature, ionic strength remains under-estimated yet it impacts protein conformations and consequently its interaction with, and susceptibility to, the enzyme. Enzymes, being proteins are also amenable to the environmental conditions because they are either activated or denatured depending on the choice of the conditions. Furthermore, enzyme specificity is restricted to a narrow regime of optimal conditions while opportunities outside the optimum conditions remain untapped. In addition, the composition of protein substrate (whether mixed or single purified) have been underestimated in previous studies. In addition, protein pre-treatment methods like heat denaturation prior to hydrolysis is a complex phenomenon whose progression is influenced by the environmental conditions including the presence or absence of sugars like lactose, ionic strength, purity of the protein, and the molecular structure of the mixed proteins particularly presence of free thiol groups. In this review, we revisit protein hydrolysis with a focus on the impact of the hydrolysis environment and show that preference of peptide bonds and/or one protein over another during hydrolysis is driven by the environmental conditions. Likewise, heat-denaturing is a process which is dependent on not only the environment but the presence or absence of other proteins.