Preparation Of Proline Maillard Reaction Intermediate And Its Flavor Enhancement

Maillard reaction intermediates are important flavor precursors produced in Maillard reaction.Amadori rearrangement products(ARPs)are one of them.ARPs have no aroma,and its physicochemical properties are stable at room temperature.However,they have high thermal reactivity and are easy to continue the Maillard reaction during heating,quickly forming an ideal and fresh flavor,which can make up for the lack of easy loss of flavor of the complete Maillard reaction products.At the same time,it can give consumers a sense of pleasure and achievement in the cooking process,which has important application value.The Maillard reaction products of proline have bread and biscuit-like flavor and characteristic aroma of rice,which have great appeal in the fields of baked products,tobacco and coffee.In this thesis,proline and glucose were used as raw materials,a method suitable for industrial production--vacuum concentration-spray drying synergistic method was researched to prepare ARP.Furthermore,the flavor enhancement of ARP was researched by electronic tongue combined with gas chromatography-mass spectrometry(GC-MS).The specific research contents are as follows:Using glutathione as a browning indicator,the conditions for the formation of proline-glucose ARP in the water phase were determined by the gradient temperature-elevating Maillard reaction tracing method.The results showed that the time for proline-glucose ARP to form in large quantities at p H 7.4 and 90?was 100 min.ARP was purified by ion exchange chromatography,and its structure was identified by mass spectrometry and nuclear magnetic resonance spectroscopy.It was determined that it was N-(1-deoxy-D-fructose-1-yl)-proline,with a relative molecular mass of 277,and a molecular formula of C₁₁H₁₉O₇N with four main isomers.Thereafter,an HPLC method for the determination of proline-glucose ARP in aqueous phase was established with purified ARP as the standard.The effect of vacuum concentration-spray drying process parameters on the yield and color of intermediates was explored.The ARP conversion was improved from 3.63%to 69.15%through the method of vacuum concentration coupled with spray drying.Within a certain range,with the increase of solid content,flow rate and inlet air temperature,ARP yield first climbed up and then declined,and the color of the product showed a deepening trend with the raise of inlet flow rate and air temperature.Accordingly,the relationship among three process parameters,ARP yield and product color was clarified.Based on the conditions of industrial production,the optimal preparation parameters of proline-glucose ARP have been determined:the initial reaction solution was concentrated under reduced pressure at 90?to a 20%solid content,the inlet temperature of spray drying was 180?,and the flow rate was 500 m L/h,which provides a theoretical basis for the mass production of proline-glucose ARP.The flavor enhancement effect of proline-glucose Maillard intermediates was studied.The taste characteristics of spray-dried ARP products were analyzed by electronic tongue and sensory evaluation.The results showed that when the addition amount of ARP products was more than 0.4%,the salt content could be reduced by 20%without reducing the saltiness,and the umami taste was significantly enhanced.This discovery provides a basis for the application of ARP for reducing salt and increasing umami taste.Furthermore,the effects of intermediates on the secretion of aldosterone in saliva were studied.It was found that products with low and medium reaction degrees stimulated the secretion of aldosterone in oral cavity and increased its sensitivity to salt,while products with high reaction degree inhibited the secretion of aldosterone.The flavor-forming capacity of the intermediates of proline-glucose system was studied.Under simulated baking conditions,the flavor formation laws of the five systems including proline-glucose reaction substrate(Pro-Glu),pure ARP,mixture of ARP and proline(ARP Pro),Maillard reaction-spray dried products(MSPs),and Maillard reaction products(MRPs)were analyzed.Under the same amino group concentration and heating conditions,MSPs produced the most abundant flavor substances,32.2 times that of Pro-Glu,12.3 times that of pure ARP,7.3 times that of ARP-Pro,and 5.5 times that of MRPs.At the same time,MSPs formed the most typical baking aroma substances such as aldehydes,furans and pyrazines,indicating that MSPs can enrich the flavor profile of food and strengthen the characteristic aroma of baked products.The application effect of proline-glucose intermediates in baking system was investigated.Different proportions of MSPs were added to the baking Scone system,then the flavor profile,color and taste of scones were evaluated by electronic nose,color difference measurement and sensory evaluation,respectively.The results showed that when the addition amount of MSPs was 0.3%,the flavor enhancement effect and color enhancement effect of Scone were the best.By comparing the flavor loss of Scone with and without MSPs after storage under refrigerated conditions for different periods of time,it was found that adding MSPs could reduce the flavor loss during storage.