Effect Of Brewing Technology On The Active Antioxidant Components Of Polyphenols Of Mead

Natural honey is rich in nutrients and functional ingredients, and its nutrition and health care function have been increasingly concerned. Mead is a low-alcohol beverage wine, with honey as the main raw material through dilution, fermentation, aging, clarification, and filtration. Currently researches on mead are more concentrated to improve the sensory quality, increase the alcohol content and so on, and the changing situation of the active components, such as antioxidant compounds, and the impact of production process on these components are rarely reported. In this paper, the effects of brewing technology on the antioxidant ingredients in mead were mainly studied, with the total phenolic and total flavonoid content as main indexes, to explore the influence of various factors during fermentation on the antioxidant ingredients in mead, and to provide a theoretical basis for the development of mead. The main results were as follow:(1) Effect of honey pretreatment on antioxidant components of mead: The honey solution was subjected to different treatments(pectinase and heating), and the control experiment was set at the same time. Results showed that the contents of total phenolic and total flavonoid of the control one were the highest, up to 128.18mg/L and 67.01mg/L respectively, and the aroma of wine and honey was both pure and pleasant, and the taste of mead was refreshing. With enzymatic hydrolysis and heat treatment of liquid honey, the contents of total phenolic and total flavonoid, and the sensory scores were lower than those of the control one, indicating that both antioxidant components and sensory quality were adversely affected by honey pretreatments.(2) Selection of Saccharomyces cerevisiae: Five active dry yeast, i.e. FX10, EC1118, BO213, KD, QA23, were used for single-strain and mixed-stains experiments, with the total phenolic and total flavonoid contents as the main research targets. Results showed that the single strain EC1118 was the best, followed by FX10 and BO213, and the total phenolic and total flavonoid contents of mead fermented by these three yeast were higher than those of the honey solution; mixed-strains test results showed that the total phenolic and total flavonoid contents of the 4 groups of mead fermented by mixed-strains were significantly higher than those of EC1118, of which the EC1118/BO213(1:1) was the best, with its sensory score higher than EC1118.(3) Effect of fermentation technology on the antioxidant components of mead and its process optimization: Initial sugar content of the honey solution were set to 16%, 19%, 22%, 25% and 28%. Results showed that, when the initial sugar content was 16%, the total phenolic and total flavonoid contents of mead increased most significantly, up to 56.6% and 55.4%, respectively. Overall, with the increase of initial concentration of sugar, the relative variation of total phenolics and total flavonoids between before and after fermentation decreased gradually, and the higher the initial sugar concentration was, the more difficult it was to complete fermentation, the deeper the mead color was, and the mead was also more turbid. Through single factor test and response surface design analysis, the influence of different factors on the active antioxidant components content of mead was studied, and the technical conditions of fermentation were optimized. Results showed that both inoculation amount and SO2 showed significant effect on the total phenolic content of mead, and zymosan Opti MUM insignificant; the optimal values were: inoculation amount 0.28g/L, SO2 127mg/L, zymosan Opti MUM 0.11g/L, with other conditions as initial sugar content 16%, initial p H3.3, fermenting accessory ingredient Fermaid K 0.3g/L, fermentation temperature 26℃, and the total phenolic content was up to 151.87mg/L, the relative error between which and the theoretical value was 0.45%.(4) Effect of distillation on the antioxidant components of mead: The honey fermentation liquors were distilled, to obtain three distilled liquors of different alcohol contents( 8.6%, 21.6%, and 42.8%vol). Results showed that compared with the fermented mead, total phenolic and flavonoid contents of the three distilled liquors were significantly decreased, indicating that distillation operation was not conducive to maintaining the functional composition of fermented mead.(5) Clarification of mead: Four clarifying agents, i.e. bentonite BIN, INOFINE V, PVPP, gelatin, were used to treat mead respectively, in order to study their influence on antioxidant components of mead. Results showed that clarifying agent could improve the clarity, but also led to the decline of the contents of antioxidant components of mead; among the four clarifying agents, gelatin was the best, and the total phenolic and flavonoid contents of mead losses were less, which decreased by 1.0% and 3.8% respectively.