| In this paper,Better reusing raw materials and excellent fermentation agent,the bitter substances and debittering test of whey from xinjiang were conducted.Mixed fermentation of whey products were prepared,the fermentation process was optimized,the changes of amino acids and flavor substances contained therein were analyzed,and the quality of the products was evaluated.The main findings are as follows:(1)Gel separation and MALDI-TOF-MS were used to separate and identify the whey bitter peptides.The trypsin hydrolyzed milk bitter peptides was selected and the parameters of the hydrolysis were optimized.The results showed that the content of hydrophobic amino acids in whey bitter peptides was higher,and the bitter peptides had an average hydrophobicity of Q> 5.86 kJ / mol.According to Ney’s Q principle and sensory evaluation,it was shown that the isolated whey bitter peptides had bitter taste.The results showed that there were 14 peptides by MALDI-TOF-MS in the whey bitter peptides:9 kinds of peptides with bitter were tasted,including EELVLTVLLDYRRCYL hydrophobicity,and the value of the film is 14.57 kJ/mol,the FLPV hydrophobicity 9.30 kJ/mol,and the RWELLVLLLL hydrophobicity 8.33 kJ / mol.The results show that the bitterness of whey was mainly caused by hydrophobic amino acid.The bitter test of optimized combination of trypsin enzymolysis showed:The hydrolysis addition was 0.32%,the hydrolysis temperature was 44.50℃,the hydrolysis time was 1.60 h,the reaction pH was 8.22,and the experiment was carried out under the optimized conditions.The bitterness value was 1.16 and the degree of hydrolysis was 61.18%.(2)12 strains of yeast and 9 lactic acid bacteria were obtained by separation and purification of traditional identification method,18 S rDNA and 16 S rDNA molecular identification.The excellent fermentative agents Y12,Y14 and L8 were obtained by tolerance test and fermentation performance in whey.(3)MINITAB software were used to optimize the fermentation conditions of the original flavor whey wine and the whey vinegar.The original flavor whey wine optimum fermentation conditions were as follows:the inoculation amount of Y14 was 6%,the inoculation amount of Y12 wa 6%,the inoculation amount of L8 was 1%,the fermentation time was 136 h,the fermentation temperature was 30℃,the initial sugar content was 20%,and the alcohol was 7.61%vol of the original flavor of sake.The whey vinegar optimum fermentation conditions were as follows: the inoculation amount of L9 was 11%,the initial alcohol was 7%vol,the fermentation time was 248 h,and the fermentation temperature was 35℃,and the total acid content was 6.54 g/L.(4)The Amino acid analyzer and HS-SPME-GC-MS technique was used to analyze the amino acids and volatile flavor substances of the original flavor whey wine and whey vinegar.The results showed that the total amino acids were 0.29% and the functional amino acids 0.05%.35 different flavors were found in the original flavor whey wine,including 52.65% of 7 kinds of alcohol flavor components,33% of 17 kinds of ester flavor components,2.17% of 3 kinds of acid flavor components,0.71% of 2 kinds of aldehyde flavor compounds,0.79% of 3 kinds of ketone flavor compounds and 2.25% of 4 kinds of hydrocarbon flavor components.The amino acids in the original flavor whey wine were determined.Determination of amino acid in whey vinegar samples showed: 17 kinds of amino acids were detected.the total amino acids were 0.46%,and 4 kinds of functional amino acids were 0.078%.The whey vinegar contains 25 different flavors,including 7.4% of 4 kinds of acid flavor components,57.03% of 13 kinds of ester flavor components,0.42% of one kind of aldehyde flavor component,29.1% of 2 kinds of alcohol flavor components,Ketone flavor ingredients 1.48% and 0.39% of 2 kinds of hydrocarbon flavor compounds.Mixed strains of fermented whey products were nutritious,unique flavor,can be very good to give the body the necessary nutrients. |
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