| Summary: | 碩士 === 國立臺灣大學 === 動物科學技術學研究所 === 97 === Whey is a byproduct of cheese manufacture resulting from the coagulation. Bioactive peptides derived from whey protein are widely investigated and their amino acid sequences have been identified. Fermentation by microorganisms and enzymatic hydrolysis with digestive enzymes and protease result in their release. Thus, the objective of this study was to investigate the effects of different hydrolytic reactions (alcalase, neatrase, pepsin, Lb. kefiranofaciens M1 (M1)) on in vitro biological properties, such as antihypertensive, antioxidative and immunomodulatory reaction of whey protein.
Immunomodulatory results demonstrated that whey protein hydrolysates (WPHs) from alcalase could significantly induce the production of TNF-α and IL-12 in murine macrophage cell line (RAW 264.7) and murine splenocytes. Further evaluating the effects of the WPHs obtained from combination of alcalase hydrolysis and Lb. kefiranofaciens M1 fermentation on cytokine production displayed that the secretion of cytokines induced by WPHs from Lb. kefiranofaciens M1 and combination group significantly higher than WPHs from alcalase only and whey control on both cells. In addition, Th2-polarized splenocytes revealed that milk whey fermented by Lb. kefiranofaciens M1 had IL-12 inducing and IL-4 repressing activities. These results suggest that the whey protein hydrolysates from Lb. kefiranofaciens M1 may be able to direct the Th1/Th2 balance toward Th1. The putative immunomodulin in the whey protein hydrolysates from Lb. kefiranofaciens M1 might be peptidoglycans in Lb. kefiranofaciens M1. Antioxidant results indicated that WPHs obtained from neutrase in fresh whey exhibited the highest DPPH radical-scavenging activity compared with other treatments. In addition, evaluation of chelating ion ability showed that WPHs hydrolyzed by pepsin had the highest ability of Cu2+ chelation. In angiotensin I-converting enzyme (ACE) inhibitory activity, WPHs obtained from neutrase in WPC exhibited the highest ACE inhibitory activity. Further purification by microfiltration and size exclusion chromatography, one peptide with molecular mass 262.37 Da showed the highest ACE inhibitory activity. The sequence of this peptide will be determined in the near future.
In conclusion, we successfully manufactured whey protein hydrolysates which contain antihypertention, antioxidation and immunomodulation properties by different hydrolytic reactions. In the future, the animal tests will be conducted to verify the in vitro biological effects of whey protein hydrolysates and the purified biological peptides of whey protein will be further identified to boost the biological effects.
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