| As a large condiment,soy sauce is favored by people all over the world.Its flavor characteristics are an important indicator of the quality of soy sauce.Carbohydrates in soy sauce have an important influence on the color and taste of soy sauce.The development of caramel like compounds is closely related to the carbohydrates metabolism.Nowadays,there are many studies on the sugars of soy sauce,however,the effect of carbohydrate metabolism on the flavor of soy sauce was not fully studied.This article studied the effects of sugar addition on the physical and chemical indicators of koji,the aroma and volatile compounds,taste and non-volatile compounds in the fermentation process of soy sauce.Finally,soy sauce models were established to study the formation mechanism of caramel-like compounds during the fermentation process of soy sauce.This study aims to provide theoretical basis for the flavor quality regulation of high-salt liquid fermentation soy sauce.The main research contents are as follows:(1)The contents of reducing sugar,soluble sugar,total sugar,carbohydrates and their contents in the process of koji,and high-salt liquid fermentation soy sauce were measured.It was found that the content of reducing sugar in koji,increased first and then decreased,and the content of soluble sugar and total sugar was found gradually decreased;total sugar and reducing sugar content in soy sauce increased first and then decreased;HPLC was used to detect 9 varieties of carbohydrates in koji,koji(44h)and soy sauce respectively.During the fermentation process,the contents of ribose,maltose and raffinose in soy sauce were significantly increased.The content of arabinose,mixture(xylose,galactose,mannose),glucose,and lactose increased first and then decreased(p<0.05),and the contents of glucose and mixture(xylose,galactose,mannose)were increased.Among them,glucose and mixtures(xylose,galactose,mannose)have the highest content and consumption efficiency.(2)Aroma sensory evaluation of different sugar addition(xylose and glucose)of soy sauce,qualitative and quantitative analysis of volatile compounds,and calculation of key aroma activity values(OAV values)revealed that the effect of sugar addition on soy sauce flavor was significant.The results of the study showed that the addition of xylose can enhance the caramel and smoky aroma of soy sauce,and the addition of glucose can enhance the maltand potato aroma of soy sauce.LLE-GC/MS was used to measure the soy sauces in different sugar groups.It was found that the addition of sugar sources can significantly improve the acids,ketones,heterocyclic compounds,furan(ones),alcohols,phenols,aldehydes,and sulfur compounds(p<0.05).The OAV values of 14 aroma active compounds in soy sauce were found to increase the OAV value of key aroma compounds in soy sauce significantly(p<0.05).The highest OAV value was 3-methylbutanal,followed by HEMF and 2-methylbutanal.The OAV values of 3-methylbutanal and 2-methylbutanal in the added glucose group were significantly higher than those of xylose.In the group,the OAV value of HEMF was significantly lower than that of the xylose group(p<0.05).This result has a strong malt flavor in the glucose group soy sauce in the aroma sensory analysis,and is clearly consistent with the caramel aroma in the xylose group soy sauce.(3)The sensory analysis,basic indicators and microbial number of different sugar addition on soy sauce.It was found that the addition of sugar can significantly increase the content of non-volatile substances in soy sauce and significantly affect the taste(p<0.05).The addition of xylose can significantly improve the salty taste of soy sauce.The addition of glucose can significantly improve the umami taste,sourness and sweetness of soy sauce.With the progress of fermentation on different sugar group soy sauce,the content of reducing sugar increases first and then decreases.Adding xylose can significantly increase the deep matter content in soy sauce and the number of moulds and yeasts in the moromi.The addition of glucose can significantly increase the content of total nitrogen,total acid,amino acid nitrogen and free amino acid in soy sauce,and the number of lactic acid bacteria and the total number of bacterial colonies in the moromi(p<0.05).(4)The mechanism of carbohydrates metabolism in soy sauce flavor quality was clarified by examining the aroma sensory of the validated model soy sauce,basic indicators(reducing sugar,amino acid nitrogen,dark matter,and yeasts amount)and the relative content of caramel aroma compounds.The results showed that the addition of yeasts and heat treatment of soy sauce can make the caramel aroma in the sauce more intense;in the soy sauce system,most of the production of HDMF originates from the Maillard reaction,and a large part of HEMF is composed of yeast,produced using Maillard reaction intermediates. |
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