Research On Bitterness Of Litchi Wine And The Optimization Of Bitterness Control Technology

the bitterness of litchi wine was a prominent problem affecting the quality of litchi wine.Determined key ingredients and controlled its contents effectively,which had a significance to improve the quality of litchi wine.To identify the key ingredients which affected bitterness of litchi wine,litchi wine as the experimental material was clarified to study the relationship between bitterness and bitter ingredients in litchi wine before and after clarification,determined the key ingredients and found out the effective methods to control bitterness,provided a theoretical basis to solve and control the bitterness of litchi wine effectively.The main contents and results of the study were as follows: 1 The relationship between the bitterness and related ingredients in litchi wineReference to the production process,litchi wines were clarified to access the wines with significant differences in bitterness(P<0.05),bitterness and related ingredients were detected and compared to explore the relationship between the bitterness and related ingredients in litchi wine.The results showed that there were no significant differences in the contents of fructoids,aldehydes,esters and acids in the two kinds of litchi wine with different bitterness,indicated that there were not directly relation to bitterness and those substances;there were differences in the contents of Amino acids in the two kinds of litchi wine with different bitterness,but the contents of Amino acids were much lower than the amino acid taste threshold((29)200mg/L),there were not directly relation to bitterness and Amino acids;there were significant differences in the contents of phenolic compounds in the two kinds of litchi wine with different bitterness and its low taste threshold,phenolic compounds had an important effect on the bitter taste of litchi wine.2 Determined and verified the key ingredient affecting the bitternessIn order to determine the key ingredient of phenolic compounds which affected the bitterness in litchi wine,phenols were detested from different wine with different bitterness,the effect of phenols on the bitterness in litchi wine were verified by means of proof.The results showed that the contents of catechins and epicatechin were significantly different in wines with different bitterness,while the content of chlorogenic acid,rutin and gallic acid in wine were lower,and the difference was not significant,initially thought that catechins and epicatechin were key ingredients of bitterness in litchi wine.It had been proved that the addition of catechins and epicatechin can restore bitterness,which had a direct effect on bitterness,and its contents were positively correlated with bitterness.Again,It was determined that catechins and epicatechin were the key ingredients of bitterness in litchi wine.3 Optimization of Bitterness control technology in litchi wineThe phenolic content as an indicator to screen the clarifier and optimize the clarification process.The results showed that polyvinylpyrrolidone(PVPP),bentonite,gelatin and casein could adsorb phenolic compounds in litchi wine,among them,PVPP had the best adsorption effect on phenolic compounds better than bentonite and gelatin,the treatment time was best at 24 ~ 72h;L9(34)orthogonal experiment was used to optimize the clarification process,the results showed that PVPP and treatment time had a great influence on phenolic compounds,but influence of bentonite was small,the optimum clarification process which PVPP 800 mg / L,bentonite 200 mg / L,treatment time 72 h could effectively reduce the phenolic content.reduced the bitterness and improved the quality of litchi wine.