Effects of Bromelain and Trypsin Hydrolysis on the Phytochemical Content, Antioxidant Activity, and Antibacterial Activity of Roasted Butterfly Pea Seeds

Butterfly pea (Clitoria ternatea L.) is a traditional medicinal and edible herb, whose health-promoting benefits have been attributed to its phenolic constituents. In this study, the effects of enzymatic hydrolysis on total phenolic content (TPC) and total flavonoid content (TFC), antioxidant (2,2’-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and ferric reducing antioxidant power (FRAP)) and antibacterial activities of raw and roasted (200 °C, 10–20 min) butterfly pea seeds were investigated. Roasting reduced the yield of seed aqueous extracts, but it increased the TPC and FRAP values, hence the reducing ability, of the extracts. Bromelain hydrolysis enhanced the TPC and TFC of the roasted seeds up to 2- and 18-fold higher, respectively. Trypsin hydrolysis drastically increased the TPC, but not TFC, of roasted seeds; trypsin-hydrolyzed, 20 min roasted sample had the highest TPC (54.07 μg gallic acid equivalent (GAE)/mg) among all samples. Bromelain hydrolysis significantly improved the antioxidant activity of the roasted seed samples, where the antioxidant activity of bromelain-hydrolyzed, 20 min roasted sample was about 50% greater than the non-hydrolyzed 20 min roasted sample. Trypsin hydrolysis raised the FRAP values of the 20 min roasted sample to 70.28 mg Fe(II) equivalent/g, the highest among all samples. Nevertheless, trypsin only weakly elevated the ABTS scavenging activity of the roasted samples, showing no enhancement of the DPPH scavenging activity. On the other hand, only bromelain hydrolysates of raw and 10 min roasted seeds were active against Staphylococcus aureus. Taken together, bromelain hydrolysis can be used to enhance the extractable phytochemical contents and antioxidant activity of roasted butterfly pea seeds.

Antioxidative Peptides from Proteolytic Hydrolysates of False Abalone (Volutharpa ampullacea perryi): Characterization, Identification, and Molecular Docking

Antioxidative peptides were produced from false abalone (Volutharpa ampullacea perryi) using enzymatic hydrolysis. Trypsin produced the most bioactive hydrolysates with the highest scavenging ABTS+• free radicals compared to pepsin, alcalase, neutrase, and flavourzyme. The response surface methodology studies on trypsin hydrolysis indicated that the hydrolysis temperature, time, and pH were interacted with each other (p < 0.05), and the optimal conditions were hydrolysis at 51.8 °C for 4.1 h, pH 7.7 and the maximum predicted hydrolysis degree was 13.18% and ABTS+• scavenging activity of 79.42%. The optimized hydrolysate was subjected to ultrafiltration fractionation, and the fraction with MW < 3 kDa showed the highest ABTS+• scavenging activity. There were 193 peptide sequences identified from this peptide fraction and 133 of them were successfully docked onto human myeloperoxidase (MPO), an enzyme involved in forming reactive oxidants in vivo. The highest scored peptide, no. 39, consists of DTETGVPT. Its structure and molecular interactions with MPO active site were compared with previously characterized peptide hLF1-11. The interactions between peptide no. 39 and MPO include electrostatic charge, hydrogen bonds, and covalent bonds. The antioxidative peptide produced in this research may exert antioxidant activity in vivo due to its potential inhibition effect on MPO.

Effect of Trypsin on Antioxidant Activity and Gel-Rheology of Flaxseed Protein

Enzymatic hydrolysis of flaxseed protein (FP) was carried out using trypsin in order to obtain flaxseed protein hydrolysates possessing better antioxidative property and modified rheological properties. The antioxidative properties of hydrolysates were much higher than the unhydrolyzed flaxseed protein. The hydrolysis also significantly reduced the hydrodynamic diameter of the magnitude of zeta potential of the dispersions. The gelling point of the hydrolysates occurred earlier than the unhydrolyzed sample while the duration of hydrolysis (30–120 min) did not affect gelling point of the hydrolysates. Considerable decrease in the gel strength and the frequency dependence of gel strength were observed in gels produced using hydrolyzed flaxseed protein. The above findings indicate that hydrolysates possessing high degree of antioxidative properties. The gels produces from these hydrolysates will have fast gelling property and will produce gels with reasonable strength. Thus, flaxseed protein hydrolysates obtained from trypsin hydrolysis can be used in applications that require proteins with higher antioxidative properties but softer texture.

Optimization of Enzymatic Hydrolysis for Protein from Black Bean by Response Surface Methodology

Taking the degree of hydrolysis (DH) as the index, the optimal hydrolysis process for the protein from black bean was explored by response surface methodology (RSM) to prepare polypeptides. Four proteases were used to hydrolyze the black bean protein and determine the DH of black bean protein. The results indicated that the optimal reaction systems were as follows: The black bean protein solution was treated with the alkaline protease hydrolysis firstly and then the trypsin hydrolysis was used in order to improve the DH. The DH of protein was increased to 35.64% and the yield of peptides production was higher than using only alcalase.