Chemical Expression Model Of Sensory Charharacteristic Of Apple Juice

In this paper, the sensory characteristics of apple juice, such as the appearance, flavor, and taste were analysised by quantitative description analysis. And the main chemical substance which affected the sensory characteristics of apple juice including volatile components, organic acids, sugar was measured. Finally the chemical expression models of sensory characteristic of apple juice were established by using principal component Analysis,partial least squares regression and Stepwise regression analysis. The conclusion is as follows:(1)The parameters of the sensory score were estimated by introducing the model using the maximum likelihood estimate that effectively removed sensory data outliers and laid the foundation of the relationship model between sensory characteristics and chemical substances(2)The results of the quantitative description analysis of apple juice by themultiple comparisons obtained, in the seventeen sensory characteristics of nine different varieties of apple juice, in addition to the sweet flavor and raw green taste, the remaining of sensory characteristics were significant or highly significant on 95% level, indicating that different varieties of apple juice were quite different senses. Also, using principal component analysis can effectively distinguish different varieties of sensory properties of apple juice.(3)The simple correlation analysis about apple juice between sensory characteristics and chemical indicators indicated that,①the sugar to acid ratio was the main chemical indicators that affected the flavor characteristics of apple juice,②pH, total acid and sugar acid ratio was the main chemical indicators that affected the taste of apple juice.(4)The quantitative aroma of apple juice samples by GC-MS detection was 63 species including 28 kinds of esters, 22 species of alcohols, 9 kinds of aldehydes and ketones and 7 species of acids 14 species of volatile components were commonded in nine varieties of apple juice, respectively,ethyl acetate, butyl acetate, 2-methylbutyl acetate, hexyl acetate, phenylethyl-acetate,2-methyl-1-propanol,1-butanol,2-methyl-1-butanol,1-hexanol, 2-hexene-1-alcohol, 6-methyl-5-heptene-2-alcohol, butyraldehyde,hexanal,caproic acid.The highest content of apple juice aroma substance is ethyl acetate, 1-butanol, 2-methyl-1-butanol,hexanol, 2-octanone.ethyl acetate, 1-butanol, 2-methyl-1-butanol, hexanol.(5)Relationships between flavor attributes and the volatile composition of apple juice were determined by principle component analysis (PCA) and partial least squares regression (PLSR).Results showed that①ethyl acetate, ethyl butyrate, 2-octanone, 2-hexene-1-alcohol, butyl acetate and linalool oxide were the volatile compounds that contributing the odour of the apple juice.②methyl butyrate, 2-methyl-1-propanol, hexanal, 2-methylbutyl acetate had a major impact on the flavor characteristics of apple juice③methyl butyrate and ethyl butyrate were major compounds that affecting apple flavor and fruit flavor of apple juice.④butyl acetate, 2-hexene-1-Ethyl alcohol affect were the main substances that affecting the beany flavor and the grass flavor of apple juice.⑤The chemical substance that main distinction between sour and the sweet is ethyl acetate, 2-octanone,linalool oxide and 2-methyl-1-propanol.(6)Doing stepwise regression analysis that the chemical substances in apple juice were regarded as the independent variables, the sensory taste scores were regarded as the dependent variable, the linear regression models were predicted, In addition to the astringency of the predictive linear regression model was Poor, the other models were better forecast accuracy. Percentage errors of prediction were less than 5%.