Preparation Of Peptide Derived-maillard Reaction Intermediates By Simultaneous Dehydration-reaction

Maillard reaction intermediates(MRIs)are intermediate products which arise from Maillard reaction involving carbonyl-group compounds and amine-group compounds.Compared with Maillard reaction substrates,Maillard reaction intermediates exhibit higher reactivity during thermal processing,and can continue the Maillard reaction to quickly produce fresh flavors.Compared with Maillard reaction products(MRPs),this kind of non-volatile intermediates has more stable physical and chemical properties at room temperature,which is favorable for storage and does not have the flaw of quick loss of flavor.Therefore,MRIs can be developed as stable flavor precursors to achieve controlled formation of fresh flavor during thermal processing.Peptides are abundant in food and hydrolytic products.Not only can peptides directly enhance the taste characteristic of food,but also they can participate in Maillard reaction as amino donors to produce rich aroma compounds.So,peptides possess the double advantages of enhancement of taste and formation of characteristic aroma.Therefore,using peptides as reaction precursors to prepare MRIs have both great theoretical value and practical application significance for developing new flavor-controlled products.The enzymatic technology was used to hydrolyze corn protein to prepare peptides of Maillard reaction precursor.Setting the degree of hydrolysis(DH)and protein extraction rate indexes,the hydrolysis process for preparing corn peptide was determined as follows: the concentration of protamex protease ?(1500 U/g),hydrolysis time of protamex protease ?(4 h),aminopeptidase concentration(240 U/g),hydrolysis time of aminopeptidase(3 h),water/substance ratio(1:10,w/w).The main products were small molecule peptides under the above enzymatic hydrolysis conditions.And the enzymatic hydrolysates were used to establish the corn peptides-xylose(CP-Xyl)system.According to the principle of the interaction between cysteine and MRIs that the browning can be inhibited via a two-stage temperature rising process,the preparation conditions of MRIs derived from CP-Xyl were determined as follows: The add amount of xylose was 30% of the corn peptide content,the initial pH of the mixture was adjusted to 7.4,the reaction temperature was 80°C,and the reaction time was 70 min.Since the yield of the Peptide-derived MRIs obtained by atmospheric thermal reaction was low in aqueous peptide-reducing sugar system,research was further focused on the effect of key parameters on the intermediates(peptide derived-ARP)yield through the model system of glutathione-xylose(GSH-Xyl).The yield of peptide derived-ARP significantly increased through the method of simultaneous dehydration-reaction(SDR).To elucidate mechanism of SDR to improve peptide derived-ARP yield and the the state change of peptide derived-ARP in the preparation process,the key compounds indicating the degradation process of peptide derived-ARP,3-deoxyxylosone(3-DX)and 1-deoxyxylosone(1-DX),were prepared.Then 3-DX and 1-DX were purified and characterized after reacting with o-phenylenediamine to form a stable derivative.To reveal the effect of SDR temperature on the formation and degradation of peptide derived-ARP,the kinetic model of Maillard reaction was established to fit the changes in the concentrations of the compounds from the GSH-Xyl system during SDR.Based on the result of reaction kinetics analysis,the mechanism and characteristics of peptide derived-ARP formation and degradation under SDR were clarified.Peptide derived-ARP formation and degradation rate was highly dependent on temperature and the latter was more sensitive to temperature.By regulating the reaction conditions of temperature and pH,the ratio of peptide derived-ARP formation rate constant to its degradation rate constant could be controlled to achieve an efficient preparation of peptide derived-ARP from GSH-Xyl Maillard reaction system through SDR,and the yield of peptide-derived ARP increased from 8.44% to 67.98%.The SDR method was further applied to prepare MRIs from CP-Xyl system.Based on a significant positive relationship between concentration changes of peptide derived-ARP and 1-DX,under the preparation conditions of adding xylose of 30% of corn peptide content,initial pH 7.4,and reaction temperature 80°C,the mixture of CP-Xyl system was carried out for 30 min by SDR.By the addition of the same amount of CP-Xyl,MRIs,and MRPs into biscuits,the volatile flavor compounds of the samples were analyzed during baking process by gas chromatographytandem mass spectrometry(GC/MS).It was noted that the samples added MRIs formed a large number of aldehydes,furans,and pyrazines at the fastest rate and these volatile flavor compounds are typical baking scent for enriching the characteristic aroma of baked biscuits.By the addition of different amount of CP-Xyl MRIs to biscuits,it was found that the addition proportion of 0.3% had the best sensory attributes effect on biscuits through the measurement of color difference and sensory evaluation.