Research On Brewing Technology And Fermentation Kinetic Models Of Mead (Low-Quality Honey Brewed Liquor)

In this study, the honey we used was low quality. EC1118was used in this study as active wine dry yeasts. Response surface methodology (RSM) was employed to optimize the fermentation conditions of mead. Based on the optimization of mead production, fermentation kinetic of mead was studied. In order to achieve high-quality mead with an extended period of peak taste and aroma, simultaneous microwave and ultrasound technology was applied to mead forced ageing process. The conclusions were developed as follows:1. Study on fermentation of brewing yeasts for meadFour active dry yeasts, namely EC1118, Angel Yeast, DV10, D254, were studied. The gas producing, flavor producing and ethanol production ability were determined to compare their differences. These yeasts were also evaluated in terms of their fermentation performance under ethanol, sulphur dioxide and acidity. The results obtained in this work show that EC1118are appropriate for mead production. This strain exhibited powerful gas producing, good flavor and better fermentation capabilities.2. Optimization of fermentation conditions of meadEC1118was used in this study as active wine dry yeasts. The main aim of the present work was to optimize mead production using Response Surface Methodology. The effects of pH, diammonium phosphate concentration and temperature on mead quality, concerning the final ethanol, was studied. The results showed that regression equation fit well with experimental data and the optimum extraction conditions determined in order to maximize the combined responses were pH value of5.1, diammonium phosphate concentration of1.2g/L, temperature of27?. The mead produced under these conditions had the following characteristics:ethanol concentration of10.6%, good flavor.3. Fermentation kinetic models of meadBased on the optimization of mead production, the variation of the essential substances in the process of mead fermentation was investigated. In addition, the fermentation kinetics of mead was studied by determining the change in the concentration of yeast, alcohol and total sugar content in this paper. Based on Logistic equation and Luedeking equation, the kinetics models of cell growth, alcohol production and substrate consumption were set up. The fit values of the three models were0.994,0.984,0.996, respectively. The model was found to be capable of reflecting all batch culture phases to a certain degree of accuracy, giving the models:X (t)=1.44exp(0.02t)/{1-0.2[1-exp(0.02t)]}, P(t)=2.74exp(0.02t)/{1-0.2[1-exp(0.02t)]}-2.74, S(t)=216.26-37.51exp(0.02t)/{10.2[lexp(0.02t)]}-5.41n(0.8+0.2exp(0.02t)), and the parameter value:Xo, ?m,?, Yx/s, Yp/s, S (0):1.44,0.02,1.90,0.14,0.10and178.75respectively.In this study, mead fermentation kinetics were studied, and provided a reference value for the industrial production of mead.4. Synergistic effect of simultaneous microwave and ultrasound on the maturation of mead In this study, the results of using simultaneous microwave and ultrasound technology as a fermentation activator to improve the quality of meads were evaluated. This study, the effect of final temperature, microwave power and simultaneous microwave and ultrasound processing time on the physical and chemical indicators of mead were investigated. It was found that simultaneous microwave and ultrasound treatment was effective to accelerate the aging process, where the ester compounds were significantly increased. According to the results, the regression equation fit well with experimental data and the optimal condition was obtained with a final temperature of69?, microwave power of337W and simultaneous microwave and ultrasound processing time of3. At these conditions, ester yield as1.495g/L.The GC/MS were used to analysis the quality of mead pretreatment with simultaneous microwave and ultrasound. For the pretreatment with simultaneous microwave and ultrasound,94aroma compounds,accounting for73.71%of all aromatic substances, were identified, including32esters accounting for17.57%,18alcohols accounting for16.49%,8acids accounting for6.30%,26aldehydes and ketones accounting for15.45%. For the mead without processing,85aroma compounds.accounting for78.80%of all aromatic substances,were identified, including16esters accounting for11.82%,24alcohols accounting for24.38%,6acids accounting for4.25%,29aldehydes and ketones accounting for15.39%. The result showed that the aging process made the aroma components more complex, ester content increased. So, the pretreatment with simultaneous microwave and ultrasound improving the further aging process.