Abstract: 【Objective】To obtain the desired flavor quality and antioxidant activity Maillard reaction products (MRPs) from enzymatic hydrolysate of chicken bone extract, the effects of controlled Maillard reaction parameters on those qualities were studied in this paper.【Method】Enzymatic hydrolysate of the chicken bone extract was sequentially added with 0.5% (w/w) xylose, cysteine hydrochloride, and thiamin to adjust pH values at  pH 5, pH 7, and pH 9 with 6 mol·L^-1 NaOH, respectively, then reacted for 90 min in the Maillard reaction kettle at 95℃, 105℃, 115℃, respectively. Indicators including UV absorption rate, browning rate, reducing power, ABTS+ radical scavenging activity were measured by UV-visible spectrophotometer. The MW distribution of peptides of different controlled reaction conditions were analyzed by gel permeation chromatography (GPC) with HPLC. Changes of flavor were observed by electronic nose and electronic tongue. The acceptability of MRPs flavor was determined by sensory evaluation. Changes of plasmid DNA damage protective effect of MRPs were analyzed by agarose gel electrophoresis. Correlation analysis between indexes of MRPs was also performed to establish possible linkages between controlled reaction condition and different parameters of MRPs in this study.【Result】The content of intermediate product increased with pH value. The higher the pH value was, the faster the primary reaction rate of Maillard was, while the degree of browning increased with temperature rose. The content of peptides of 1 000-200 Da in all the reaction systems accounted for more than 50% of the total peptides content, and was significantly correlated with sensory evaluation score (r=0.772, P<0.05). The contents of peptides of >3 000 Da, 3 000-1 000 Da, and <200 Da were highly positive correlated with each other (P<0.01), and were all highly negatively correlated with the peptides of 1 000-200 Da (P<0.01). Principal component analysis (PCA) on the flavor of each MRPs indicated that the temperature could significantly change the composition of volatile flavor of MRPs, while different pH value mainly caused the differences in taste of MRPs. Sensory evaluation score of each MRPs decreased with the increasing of pH, the score of the MRPs which prepared at pH 5 and 105℃ increased by 57.32% compared to the initial sample, and was the highest. Reducing power and ABTS+ scavenging capacity of the MRPs with pH 5 were significantly higher than that of pH 7 and 9, while DNA damage protection effect of MRPs was significantly positively correlated with ABTS + scavenging capacity (r=0.689, P<0.05). Correlation analysis results showed that sensory evaluation scorewas highly negatively correlated with UV absorption rate, browning rate and content of peptides with MW <200 Da (P<0.01), while UV absorption rate was highly negatively correlated with reducing power (P<0.01). 【Conclusion】In the Maillard reaction system of enzymatic hydrolysate of chicken bone extract, pH and the reaction temperature significantly affect the quality characteristics of MRPs. In the range of this experiment, MRPs with controlled reaction conditions of pH 5 and 105^oC was better than the other groups on the flavor quality, color and comprehensive antioxidant activities.

Key words: enzymatic hydrolysate of chicken bone extract, pH, temperature, controlled Maillard reaction, flavor quality, antioxidant activity