Non-enzymatic Browning Reaction Involoving 5-HMF

Appearance,taste,texture and nutritional value are four considered factors when people choose foods.The color of food is the most direct reflection of the appearance of food.It may also have different degrees of influence on the texture and even the nutritional value of food.5-HMF is not only a dehydration decomposition product of glucose or fructose under acidic conditions but also a common intermediate product of Maillard reaction,Caramelization,and Ascorbic acid oxidative decomposition reaction.5-HMF inevitably reacts with the ingredients presenting in the food itself or the produced intermediates in food processing,especially the heating process,which leads to the production of colored substances.We conclude that this process may be one of the important causes of browning of foods.Therefore,this paper selects representative components of foods?vitamin B1,Lysine,Alliin?to react with 5-HMF,and studies the changes in color and key influencing factors?time,temperature,material ratio,metal ion concentration,pH,light?.Besides,product was separated,purificated,and identificated,in order to clarify the role and effects of 5-HMF in food processing.?1?Non-enzymatic browning caused by Vitamin B1 and 5-HMF reactionThe interaction between Vita min B1 and 5-HMF was studied and the browning reaction was observed.According to research the influences of different reaction conditions on the browning reaction,it was found that pH and temperature were important factors affecting the browning of the reaction system:When the pH was less than 10,the browning was not obvious,and when it was greater than 10,the browning was very significant;The browning reaction was relatively sensitive under 90?,and browning was stronger than other temperatures.The yellow product was isolated and purified by TLC?methanol:dichloromethane=1:9?and HPLC,and was identified as Dihydroxymethyl furfural by means of ¹³C-NMR,¹H-NMR,UPLC-MS-MS and other means.The course of the reaction was also inferred under the catalysis of Vitamin B1.Besides,three byproducts were initially identified by UPLC-MS-MS?2?Non-enzymatic browning caused by Lysine and 5-HMF reactionThe influence of different reaction conditions on the reaction of Lysine and 5-HMF was studied.It was found that the reaction time,pH of the system,and metal ions were the key elements of browning:after 15 minutes of reaction at 160?,the solution turned dark brown.When the pH of the system exceeds the isoelectric point of Lysine,the browning reaction of the system was stronger;the reaction was more sensitive to metal ions,and the browning reaction was significantly accelerated when Fe²⁺or Cu²⁺was present.The reaction product was analyzed by UPLC-MS-MS,and was identified as an i mine formed by the condensation of an a mine and a reactive carbonyl group.It was preli minarily assumed to form through the pathway to generate Schiff base in the Maillard reaction?3?Non-enzymatic browning caused by the reaction of Alliin with 5-HMFIt was found that the browning reaction was not strong,after the interaction between Alliin and 5-HMFin aqueous solution.Although temperature,system pH,and metal ions have an effect on the browning reaction,they are not significant;however,they are slightly sensitive to Lysine for natural illu mination.The structural analysis of the reaction product was carried out by UPLC-MS-MS,which shows the product was a Schiff base adduct of Alliin and 5-HMF.In addition,it was inferred from the reaction energy that the substance may accelerate the decomposition of Alliin itself,tending to generate more pyruvic acid and avoiding the production of more colored substances.In short,the browning reaction occurred between 5-HMF and these three representative substances.However,the degree of browning is different:the browning of Lysine and 5-HMF is the strongest,followed by Vitamin B1 and 5-HMF,and the weakest was Alliin and 5-HMF.The roles played by the three substances are also not exactly the same:Vita min B1 only acts as a catalyst in the reaction,while Lysine and Alliin are directly involved in the reaction.Although the reaction system of Lysine and Alliin formed adducts of Schiff base,the former promotes the formation of browning substances and the latter promotes their own decomposition.Different reaction systems and different browning mechanisms will provide different solutions and strategies for non-enzymatic browning based on 5-HMF.