Identification Of The Nutty Flavor Of Cheddar Cheeses And The Synergetic Effect Of Flavor

Cheddar cheese is a is a kind of hard cheese favored by Chinese consumers for its mild and nutty aroma.At present,although the research on nutty aroma compounds in Cheddar cheese has made some progress,the research on nutty aroma compounds of Cheddar cheese based on Chinese taste preference is still rarely reported.Therefore,this study analyzed the nutty aroma compounds of Cheddar cheese according to the taste preferences of Chinese people,determined the threshold and optimal concentration range of compounds in the cheese matrix,and studied the interaction between compounds.In order to enhance the nutty flavor of cheese,the adjunct culture with high yield of 3-methylbutanal was screened and applied to the production of Cheddar cheese to explore the effect of strains on the flavor of cheese,so as to provide a theoretical basis for the development of nutty-flavored cheese products that can cater to Chinese consumers' preference.In this study,nine samples of top-selling Cheddar cheeses in the Chinese market were selected,and the descriptive analysis was carried out.According to the score of nutty flavor,the cheese was classified into three grades: high,medium and low.Fortynine volatile flavor compounds were identified by GC-MS via headspace-solid-phase microextraction,and 14 odor-active compounds were identified by GC-O.Partial least squares regression(PLSR)was applied to analyze the correlation between cheese sensory attributes and odor active compounds,and it was found that 3-methylbutanal,2-methylbutanal,and benzaldehyde had a good correlation with “nutty” and “umami”aromas.Combined with the results of the aroma addition experiment,it was found that3-methylbutanal,2-methylbutanal,and benzaldehyde can bring a nutty flavor to cheese within a suitable concentration range.The threshold,optimal concentration and synergistic effect of nutty flavor compounds in the cheese matrix were determined.The thresholds for 3-methylbutanal,2-methylbutanal,2-methylpropanal,and benzaldehyde in the cheese matrix were150.31,175.39,150.66,and 500.21?g/kg,respectively.The optimal concentration ranges of these aldehydes were determined as 150–300,175–325,150–350,and 500–1500 ?g/kg,respectively.Threshold method,Feller's additive model,and ?-?diagrams were used to study the aroma synergy between the four compounds.Based on the results of the threshold method and Feller's model,five binary mixtures were found to have synergistic effects,and only the pair of 2-methylpropanal and benzaldehyde was determined to have a masking effect.In addition,the synergistic olfactory effects between the four ternary mixtures and the quaternary mixture of these aldehydes were also assessed using Feller's model.In a ?-? plot analysis,synergism was usually observed when these odor pairs were at their threshold levels.Taking 3-methylbutanal,the main compound of nutty flavor,as the research object,multiple strains of Lactococcus lactis were screened according to the ability of producing 3-methylbutanal,KADC enzyme activity,KADH enzyme activity,salt and acid tolerance,acidifying ability,and autolysis degree.Although 408 strain was identified as the strain with the highest capacity of producing 3-methylbutanal,YN2-1strain was identified as the most suitable adjunct culture.The two strains were added as adjunct culture in the production of Cheddar cheese,and were matured together with cheddar cheese without adjunct culture.After 90 days of maturation,Cheddar cheese supplemented with YN2-1 had stronger nutty flavor,broth flavor and overall flavor,and higher content of nutty flavor compounds 3-methylbutanal and benzaldehyde,compared with the other groups.In summary,the experimental results demonstrate the feasibility of adding adjunct culture to enhance the nutty flavor of Cheddar cheese.