A Comparative Study On Maillard Reaction Characteristics Of Common Mono-and Oligosaccharides In Dairy Products

Dairy products are rich in sugars and proteins,making them highly nutritious,but also making them highly susceptible to Maillard reactions during processing and storage.In recent years,prebiotics such as galactooligosaccharides and fructooligosaccharides etc have been widely used in dairy products,further improving the nutritional properties.However,studies have reported that the reductive carbonyl groups and unique structures contained by galactooligosaccharides and fructooligosaccharides accelerate the occurrence of Maillard reactions in dairy.The Maillard reaction characteristics of various types of mono-and oligosaccharides in dairy products remain unclear.Therefore,in this study,we used no added sugars as control and added lactose（Lac）,fructose（Fru）,galactose（Gal）,galactooligosaccharides（GOS）and fructooligosaccharides（FOS）,which are commonly found in dairy products,respectively,as substrate,to construct Maillard reaction simulation systems with whey protein isolate（WPI）,casein phosphopeptide（CPP）,lysine（Lys）,arginine（Arg）by monitoring the differences in the variation of Maillard reaction indexes among the systems at 30℃,studying the characteristics of Maillard reaction for five mono-and oligosaccharides.First,the changes of p H and color difference in the simulated reaction system were monitored and verified by thermodynamic and kinetic binding.Results of p H changes after 30 days of storage: Fru>Gal>Lac>FOS>GOS in WPI system;Gal>Fru>Lac>GOS>FOS in CPP system;Fru>Gal>Lac>GOS>FOS in Arg system;Gal>Lac>GOS>FOS>Fru in Lys system.Change of △E: Fru>Gal>GOS>Lac>FOS in WPI system;Gal>Fru>Lac>GOS>FOS in CPP system;GOS>Fru>Lac>Gal>FOS in Arg system;Gal>Fru>GOS>Lac>FOS Lys system.Next,the products of different stages of the Maillard reaction were measured separately.Initial product accumulation was compared by determination of 294 nm UV absorbance,intermediate product accumulation was compared by 360 nm UV absorbance and 5-hydroxymethylfurfural content,and terminal product accumulation was compared by 420 nm UV absorbance and fluorescent Advanced glycation end products（AGEs）content.After 30 days of storage,for all stages of the reaction products accumulated,WPI,CPP as well as Arg systems were generally monosaccharides > oligosaccharides.Whereas in monosaccharides Gal > Fru and distinct differences between oligosaccharides.The Lys system differed greatly from the other systems,but conformed to the rule of Gal > GOS,Fru > FOS.Finally,a comparative study of the extent of Maillard reaction,based on the determination of the fast index and amino group loss,revealed the following: After 30 days of storage,the FAST index order in WPI system is FOS>GOS>Lac>Fru>Gal,in contrast to CPP system sequence.The results of the amino loss assay :Gal>Fru>GOS>Lac>FOS in both WPI and CPP syetem.Fru>Gal>GOS>Lac>FOS in Arg system,Gal>Lac>GOS>Fru>FOS in Lys system.