Study of the influence of endopolyga-lacturonase Kluyveromyces marxianus yeast species on the processes of clarification and quality of brandy wine materials and distillates

В работе представлены результаты исследований влияния эндополигалактуроназы дрожжей рода Kluyveromyces marxianus на процессы отделения и осветления сусла, а также качество коньячных виноматериалов и дистиллятов. Проблемой виноделия является высокое содержание полисахаридов в виноградной ягоде, что снижает выход сусла, затрудняет процессы его осветления, способствует окислению и обогащению нежелательными компонентами, ухудшающими качество готового продукта. Использование ферментных препаратов пектолитического действия в коньячном производстве ограничено из-за риска увеличения содержания метанола, который образуется при действии на пектины винограда пектинэстеразы. Перспективным направлением является использование в коньячном производстве эндополигалактуроназы, продуцируемой дрожжами вида Kluyveromyces marxianus . Установлено, что обработка сусла и мезги опытным ферментным препаратом, полученном при культивировании штамма дрожжей вида Kluyveromyces marxianus , способствует увеличению выхода сусла, снижению содержания взвесей и объема образующегося осадка при осветлении сусла, повышению его качества. Показано, что физико-химический состав виноматериалов и дистиллятов, полученных из обработанного сусла, практически не изменяется. Массовая концентрация метанола в опытных коньячных виноматериалах и дистиллятах не превышала уровня контрольных образцов. Установлена эффективность использования препарата в коньячном производстве с целью повышения выхода и качества сусла. The article presents the results of study on the influence of endopolygalacturonase yeast species Kluyveromyces marxianus on the processes of separation and clarification of must, as well as the quality of brandy wine materials and distillates. The problem of winemaking is the high content of polysaccharides in grape berries, which reduces the yield of must, complicates the process of clarification, contributes to the oxidation and enrichment with undesirable components degrading the quality of the finished product. Use of pectolytic enzymes in brandy production is limited due to the risk of increase in the content of methanol, appearing when pectin esterase acts on grape pectins. Use of endopoligalacturonase rendered by the yeast species Kluyveromyces marxianus is a promising direction in brandy production. It was found that treatment of the must and pulp with experimental enzyme preparation obtained by culturing a yeast strain of the species Kluyveromyces marxianus contributes to an increase in the yield of the must and a decrease in the content of suspensions and volume of the sediment formed in the process of must clarification, and quality improving. It was shown that the physicochemical composition of wine materials and distillates obtained from the treated must remained permanent. Mass concentration of methanol in the experimental brandy wine materials and distillates did not exceed the level of control samples. The effectiveness of use of the preparation in brandy production was established in order to increase the product yield and quality of the must.

The Effects of 1-Methylcyclopropene in the Regulation of Antioxidative System and Softening of Mango Fruit during Storage

The function of 1-methylcyclopropene (1-MCP) in the regulation of quality and antioxidative system of mango fruit was investigated during storage at ambient temperature. Changes in fruit quality, colour, ethylene production, respiration rate, fruit softening enzyme activities, and antioxidative enzyme activities were studied in this study. The results demonstrated that 1-MCP was beneficial for maintaining quality. 1-MCP treatment retarded the decline of firmness, weight, total soluble solid, and titratable acidity, which served as significant parameters for assessing fruit quality in the process of storage. Compared with the fruit of the control group, the treatment with 1-MCP dramatically delayed the colour change of both the pulp and peel and suppressed climacteric peaks of ethylene generation and respiration speed. The significant inducement of peroxidase, catalase, and superoxide dismutase activities were followed by 1-MCP treatment. The fruit treated with 1-MCP displayed significantly inhibited activation of enzymes on the cell wall, i.e., pectin esterase (PE), endo-1,4-β-d-glucanase (EGase), exopolygalacturonase (exo-PG), and endopolygalacturonase (endo-PG), during storage. The results suggested that 1-MCP imposed underlying impact on the maintenance of the softening and extension of postharvest life of mango fruit.

Activity Changes of Several Enzymes during Pepper (Piper nigrum L.) Decortication by Fermentation Using Bacillus subtilis CICC10076 and Natural Water Retting

The activity changes of pectinases, xylanase and cellulase during pepper (Piper nigrum L.) decortication by fermentation using Bacillus subtilis CICC10076 and natural water retting were investigated. The results showed that the activities of all the enzymes remained at much lower levels in the natural retting water than those in the fermentation broth of Bacillus subtilis CICC10076. The activities of xylanase and cellulase in both the retting water and fermentation broth remained at very low levels, which suggested that xylanase and cellulase play little role in pepper decortication. For Bacillus subtilis CICC10076, pectin esterase activities reached the peak at 36h, pectin lyase activities peaked at 12h and 54h, respectively. Polygalacturonase activities peaked at 12h first and increased rapidly again from 54h. It suggested that pectinases were the major enzymes for pepper decortication.