| Maillard reaction widely present in food processing is popular with producing attractive color, aroma and taste. However, formation of browning compounds is sometimes limited to the application in food as flavor enhancers. Therefore, it is necessary to control the color formation during Maillard reaction. In this study, light-colored Maillard reaction product (MRP) was prepared through the influencing factors of color formation in soybean peptide-xylose system. Sensory properties, molecular weight distribution (MWD), antioxidant activity of MRPs and their relationship were also investigated. Furthermore, a novel method to producing light-colored MRPs with meaty aroma, mouthfulness and antioxidant activity was proposed based on mechanism of inhibiting color formation. The main content and results are as follows:Effect of few substances such as phenols, vitamins and sulfur-containing compounds on color formation was investigated in lysine-xylose model Maillard reaction system as the index of A420, L*, a*, b*,ΔE and C*. Rutin has not remarkable effect on color formation inhibition. L- ascorbic acid, riboflavin, thiamine, tea polyphenol and NaCl was effective in some extent. L-cysteine had significant effect on color formation inhibition.Through research, the influencing factors of flavor and color in soybean peptide-xylose Maillard reaction system, five light-colored MRPs with harmonious flavor was prepared. The MWD of MRPs determined using gel filter liquild chromatograph presented siginificant difference. Comparing with PX, the fraction content below 500 Da MRPs was noticeably increased. The fraction content of 500-1000Da MRPs was significantly decreased. The fraction content between 1000-5000 Da MRPs was also decreased. The fraction content above 5000Da MRPs was sharply decreased. The result of the volatile compounds of MRPs analyzed by SPME-GC-MS showed that the content of nitrogen-containing compounds was increased in PXCC, while distinctly decreased in other MRPs compared with PX. Furans content was increased in PXCC, PXCR and PXC while decreased in PXCB and PXCN. Ketones content in PXCB and PXCR was significantly increased, while that of other MRPs was not siginificantly different. Aldehydes content was remarkably increased in PXC and PXCN, decreased in PXCB and PXCC, but no changes in PXCR. Esters content was decreased in all MRPs except for that of PXC. Alcohols content in PXCC was much higher than that of PX, while that of PXCN and PXCR were much lower. Sulfur-containing compounds in five MRPs were much greater than in PX. Acids content in PXCB, PXCC and PXCR were much higher than in PX. Five MRPs has different sensory characteristics. Mouthfulness and sweetness of five MRPs were the poorest than in PX. Meaty, continuity, umami and overall acceptance were better than in PX. Overall acceptance, mouthfulnedss and continuity of PXC was the best in five MRPs. Umami of PXCC was the best. Saltiness of PXCN was the best. PXCB had prominent burnt and meaty. Five MRPs showed high antioxidant activity by DPPH scavenging activity, inhibiting lipid peroxidation activity, reducing power and chelating activity. Therefore, it might be applicable to special food according to their sensory characteristics.Analyzing the correlation of sensory characteristics, volatile compounds, MWD and antioxidant activity by PLSR, meaty and sulfur-containing compounds showed highly positive correlation. Nitrogen- containing compounds, furans, aldehydes, esters, content of above 5000 Da MRPs and between 1000-5000 Da MRPs fractions were siginificantly positive with overall acceptability. The fraction between 1000-5000 Da MRPs, mouthfulness and continuity presented highly positive correlation. Nitrogen-containing compounds, furans, aldehydes, esters, alcohols of the MRPs fraction below 1000 Da were positively correlated to chelating activity and DPPH scavenging activity. Nitrogen-containing compounds, esters, alcohols, sulfur-containing compounds and content of below 1000 Da MRPs were positively correlated to reducing power. Furans, aldehydes, esters of the fraction above 5000 Da MRPs were positively correlated to inhibiting lipid peroxidation activity. However, sulfur-containing compounds, acids of the fraction below 1000 Da MRPs were negatively correlated to inhibiting lipid peroxidation activity.Kinetics of color development on cysteine was investigated. The result indicated that A420, L*, a* followed the zero-order kinetics. b* andΔE followed exponential kinetics by non-linear fitness. Changes of xylose content followed second-order kinetics. Moreover, xylose content was extremely correlated with A420,b*.The color-inhibiting mechanism of cysteine in soybean peptide-xylose system was further investigated. Cysteine reacted with Amadori compounds formed by condensation and rearrangement between anion compounds and reducing sugar, which effectively interrupted further deoxydization and cyclization of Amadori compounds. Thus, the brown compounds formation was inhibited. Based on reaction mechanism of cysteine and Amadori compounds, a novel method to prepare light-colored MRPs by controlling color formation was proposed, namely, two stages gradient temperature-elevating Maillard reaction. The MRP-60 with light color was prepared by initially heated at 80 oC for 60 min, after added cysteine, raising temperature to 120 oC immediately and held for 110 min. Volatile compounds, MWD, sensory characteristics and antioxidant activity of MRP-60 and PXC were also compared. MWD of MRP-60 was not significant with PXC. Furthermore, MRP-60 has better overall acceptance and antioxidant activity. Therefore, it can be useful for industries in production of light-colored MRPs with attractive taste, aroma and antioxidant activity.
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