Evaluation of antioxidant peptides generated from Jiuzao (residue after Baijiu distillation) protein hydrolysates and their effect of enhancing healthy value of Chinese Baijiu

Abstract

BACKGROUND: Jiuzao is the residue after Bajiu distillation which is usually used as forage for livestock. However, it is not fully utilized yet considering the content of protein remained. The present study aimed to isolate antioxidant peptides from Jiuzao protein hydrolysates, then add these peptides into Baijiu product to enhance the healthy value of Baiju. Meanwhile environmental pollution caused by massive Jiuzao can be mitigated indirectly. RESULTS: Four peptides Ala-Tyr-Ile(Leu) (AYI(L)) andAsp-Arg-Glu-Ile(Leu) (DREI(L)) were identified from Jiuzao protein hydrolysates, the extraction contents of AYI + AYL and DREI + DREL were 896.10 and 110.51 mg kg −1 Jiuzao, respectively. On the one hand, antioxidant activities of these peptides were investigated. For in vitro antioxidant assays, AYI, AYL and DREI exhibited strong capacities in oxygen radical absorbance capacity (ORAC) assay. Furthermore, three levels of four peptides were assessed by 2,2'-azobis(2-methylpropanimidamidine) (AAPH)-induced HepG2 cells model. The results showed that these peptides exerted a degree of antioxidant activities in cells. Meanwhile, selected peptides concentrations according to cell assays remined at effective doses after in vitro digestion. On the other hand, the influence of these four peptides on the characteristic aroma compounds in Baijiu was studied. Most characteristic aroma compounds releases were increased with the addition of peptides.CONCLUSION: In the study, antioxidant activities of peptides were evaluated, the feasibility of utilizing Jiuzao protein hydrolysates to obtain beneficial peptides was also proved. Healthy effect of Baijiu or other food can be increased by adding these functional substances. The findings might contribute to food application and Baijiu industries.

Assessment of in vivo antioxidant activity of a tripeptide Ala‐Tyr‐Ile fromJiuzao(a by‐product of baijiu distillation) protein hydrolysates and its stability in baijiu

“…In order to measure whether AYI can exist stably in baijiu, three different concentrations (10, 50, and 100 mg/L in consistent with in vivo antioxidant assay) of AYI were added into baijiu (Shandong, China). The content changes after 1, 7, 14, and 21 days were determined by HPLC using our previous method (Jiang et al., 2020). To establish the calibration curve, a series of working standard solutions of AYI (1, 2, 5, 10, 20, 50, 100, and 200 mg/L) were prepared and analyzed by the same method mentioned above.…”

“…A tripeptide Ala‐Tyr‐Ile (AYI) (Figure 1a) was isolated from Jiuzao protein hydrolysates in our previous study and was proved with antioxidant capacity in vitro by AAPH‐induced oxidative stress HepG2 cell model (Jiang et al., 2020). Considering the limitations and differences of in vitro assays compared with internal condition and no relevant study reports the in vivo antioxidant activity of AYI.…”

“…Jiuzao is a by‐product of baijiu production. Considering its composition, there is a content of protein that has not been used by now (Jiang et al., 2020). Therefore, it is a proper choice to explore antioxidant peptides remained in Jiuzao protein hydrolysates to enhance baijiu function.…”

Current Trends of Bioactive Peptides—New Sources and Therapeutic Effect

“…The antioxidant properties of peptides are most often expressed as free radical scavenging (DPPH • , ABTS +• , or OH • ) and metal ion chelation (Fe 2+ and Cu 2+ ) activity, inhibition of lipid peroxidation, reducing power, and their influence on the activity of enzymes involved in the oxidation–reduction process (e.g., SOD, CAT, PPO, and GSH-Px) [ 100 ]. Recently, the activity of antioxidant peptides has been studied in different cell lines such as HepG2 (hepatocarcinoma), Caco 2 (intestinal cells), HUVeCS (human umbilical vein endothelial cells), and Chang liver cells [ 84 , 101 ].…”

“…Recently, the activity of antioxidant peptides has been studied in different cell lines such as HepG2 (hepatocarcinoma), Caco 2 (intestinal cells), HUVeCS (human umbilical vein endothelial cells), and Chang liver cells [ 84 , 101 ]. Several models e.g., AAPH-, H 2 O 2 -treated HepG2, H 2 O 2 -treated Caco 2, and H 2 O 2 -treated SH-SY5Y/HUVeCS cells have been used to investigate the cellular antioxidant activity of peptides [ 93 , 100 ]. Eight peptides with the highest antioxidant activity were selected from hazelnut meal hydrolysates by Shang et al [ 93 ].…”