The foaming capacity of protein is an important factor affecting the quality of a series of confectionery products such as bakery products and ice cream. As a mild, low energy-consuming, and highly specific method, enzymatic hydrolysis has been applied to improve the foaming capacity of protein. However, there are few review articles on the factors influencing the effect of enzymatic modification on the foaming capacity of proteins and the underlying mechanisms. Therefore, this article reviews the foaming and destabilization mechanisms of proteins and the factors influencing them, and explains the exact mechanisms behind the effects of enzymatic hydrolysis and the characteristics of enzymatic hydrolysates on the foaming capacity of proteins. We hope that this review provides a theoretical basis for further research on the foaming capacity of proteins.

In this study, soybean meal was hydrolyzed with alkaline protease. The effect of hydrolysis time on the structure, physicochemical properties and emulsifying properties of soybean meal peptides was investigated. Furthermore, a highly stabile oil-in-water (O/W) emulsion was prepared by using soybean meal peptides with the best emulsification properties. The results showed that as enzymatic hydrolysis progressed, the degree of hydrolysis (DH) gradually increased, and the emulsifying properties of soybean meal hydrolysate first increased and then decreased, reaching the maximum value at 2 h. The emulsion stability gradually decreased. With increasing of DH, the structure of soybean meal peptides gradually unfolded. The content of free amino groups in soybean meal hydrolysate increased, the content of total sulfhydryl groups changed, the surface hydrophobicity decreased, and the secondary structure changed from α-helix to random coil. The optimal process conditions were determined as 40 mg/mL, 0.1 and 8.0 for addition level of soybean meal hydrolysate, oil/water ratio and pH, respectively. The soybean meal hydrolysate adsorbed on the surface of oil droplets could act as a “protective layer”, resulting in good emulsion stability. This study provides new ideas for improving the emulsifying properties of soybean meal protein and also provides a theoretical basis for the development and application of soybean meal peptides in emulsion.

Inhibition of beta-site APP cleaving enzyme1 (BACE1) is one of the most promising therapeutic approaches for Alzheimer's disease. To find natural products for the treatment of Alzheimer's disease, absorption, distribution, metabolism, excretion and toxicity (ADMET) properties and in vitro BACE1 inhibitory activity of the peptides isolated from egg albumin were evaluated. Then, molecular docking and molecular dynamics simulation were used to explain the molecular mechanism of the interactions between BACE1 and peptides. The IC₅₀ value of peptide KLPGF, with satisfactory ADMET properties, against BACE1 was (8.30 ± 0.56) mmol/L. Molecular docking revealed that KLPGF contacted with the residues of BACE1's active sites through twelve hydrogen bonds interactions, two hydrophobic interactions, one electrostatic interaction, and two Pi-cation interactions. The 5 ns molecular dynamics simulations confirmed that the structure of KLPGF with BACE1 was stable. Peptide KLPGF contacted the residues Lys321, Asp228, and Asn233 with stable hydrogen bonds. KLPGF may be a potential anti-BACE1 candidate.

The egg white-derived hexapeptide TNGIIR inhibits angiotensin-converting enzyme (ACE) activity in vitro. In this work, molecular docking revealed that TNGIIR established hydrogen bonds with the S1 (Ala 354), S2 (Gln 281, His 513, Tyr 520 and Lys 511) and S1′ (Glu 162) pockets of ACE. In addition, the potential antihypertensive effect of the oral administration of TNGIIR in spontaneously hypertensive rats (SHR) was investigated, as was the effect of this peptide on the mRNA expression of ACE and angiotensin type 1 (AT1) and type 2 (AT2) receptors in renal tissue. The oral administration of TNGIIR (2, 10 and 50 mg/kg) for up to four weeks did not reduce the blood pressure of SHR, in contrast to captopril (10 mg/kg, orally), but attenuated the mRNA expression of ACE and AT1 receptor (as did captopril). In contrast, both TNGIIR and captopril enhanced the expression of AT2 receptor mRNA. There was no change in the circulating concentration of fAng Ⅰ, 10 amino acids, but a slight decrease (about 10%) was seen in the concentration of circulating angiotensin Ⅱ with TNGIIR and captopril.