The temperature dependent functionality of Brettanomyces bruxellensis strains in wort fermentations

In recent years, Brettanomyces bruxellensis has found increasing application in brewery fermentations. Indeed, B. bruxellensis contributes to the flavour profile of many Belgian beers, typically during secondary or spontaneous fermentation. In North America, the yeast is used in primary fermentation to produce beers with ‘Brett’ characteristics with ‘fruity’ and/or ‘funky’ sensory profiles associated with the production of volatile esters and phenols. However, little is understood about the factors that influence flavour metabolite production or fermentation rate in this yeast. Here, the impact of temperature is reported on fermentation efficiency, flavour metabolite production and carbon utilisation of one commonly used and eight poorly characterised B. bruxellensis strains during wort fermentation. A high degree of strain and temperature‐dependent variability was found in fermentation efficiency and metabolite production amongst B. bruxellensis strains. Further, fermentation efficiency and carbon utilisation were temperature dependent, while ester production increased at higher temperature and phenol production was strain and temperature independent. These results indicate significant strain and temperature dependent variation, suggesting the potential application of strain variability as a tool to achieve product diversity in B. bruxellensis primary fermentations. © 2019 The Institute of Brewing & Distilling     

Mousy off-flavour production in grape juice and wine by Dekkera and Brettanomyces yeasts

The ability of four known species of Dekkera and Brettanomyces yeasts to produce mousy off-flavour in grape juice and wine was investigated for the first time. Using a sensory assessment technique the twelve type strains of Dekkera and Brettanomyces , representing four species, were found to grow and to be capable of producing mousy off-flavour in a grape juice medium; however, differences between strains were apparent. Four strains representing the two species of Dekkera (D. bruxellensis and D. anomala ) known to be associated with the spoilage of wine and other fermented beverages were further investigated for mousy off-flavour production in a red and white wine supplemented with nutrients. D. anomala and only one of the three D. bruxellensis strains tested grew in both wines and generally produced a moderate level of off-flavour, whereas the remaining two strains of D. bruxellensis , despite slowly losing viability (10- to 100-fold) over the 52–55 day period, produced detectable off-flavour. This work demonstrates the general ability of Dekkera and Brettanomyces yeasts to produce mousy off-flavour and confirms the importance of these yeasts for off-flavour production in grape juice and wine.     

对葡萄酒酒香酵母属不良风味抑制的研究进展

酒香酵母属是葡萄酒中固有的一种微生物,影响葡萄酒的品质.它在葡萄酒酿制的整个过程中代谢产生一种以4-乙基苯酚和4-乙基愈创木酚为典型的风味特征的一类不良风味,这些不良风味的存在降低了葡萄酒的品质,从而对葡萄酒工业造成严重的经济损失.本文对酒香酵母属的生理特征和葡萄酒易受其感染的原因进行综述以及对不良风味的抑制方法进行分类综述,以期国内葡萄酒工业对酒香酵母属不良风味的抑制有所借鉴.     

微波辅助提取葡萄皮渣中白藜芦醇的工艺研究

目的优化葡萄皮渣中白藜芦醇的微波辅助提取工艺。方法通过单因素试验,选择微波时间、料液比以及微波功率为自变量,白藜芦醇提取率为考察指标,采用正交试验设计分析研究各自变量对多糖提取率的影响。经极差与方差分析,从而获得最适的提取工艺条件。结果在微波提取时间70 s、料液比1:20(m:V)、微波作用功率为600 W的条件下获得白藜芦醇提取率为0.284%,相比有机溶剂乙醇提取法的提取率增加了42%。结论本研究可为葡萄皮渣的再利用与开发提供参考。     

酿酒葡萄皮渣中多酚物质提取的研究

以酿酒后分离的葡萄皮渣为原料,对其多酚类物质的提取条件进行了研究。在单因素试验的基础上,以乙醇体积分数、料液比、浸提时间、浸提温度为影响因素,以葡萄皮多酚得率为评价指标,进行4因素3水平正交试验,确定出的最佳浸提条件为浸提剂为体积分数70%的乙醇,浸提温度80 ℃,浸提时间40 min,按1∶7（g∶mL）的料液比,浸提次数为3次,在此条件下,葡萄皮渣中多酚提取量为30.03 mg/g。     

酿酒葡萄皮渣红外干燥研究

对酿酒葡萄皮渣进行红外干燥研究,以期优化葡萄皮渣的干燥工艺,也为其它物料的红外处理干燥提供理论基础。实验对自然晒干、连续红外干燥、间歇红外干燥以及红外对流两步干燥进行研究,对每种干燥方法的干燥特征、灭菌效果以及干燥质量进行比较分析,并且对不同干燥处理的葡萄籽的超微结构进行观察。结果表明,连续红外干燥的干燥速率最高;除自然晒干和IR9min-CD55℃外,所有干燥方法均具有较好的灭菌效果;皮渣的总多酚和原花青素在所有干燥过程中都有一定损失,连续红外干燥对总多酚和原花青素具有较好的保护作用;红外干燥的葡萄籽的组织之间出现较多的孔隙,而自然晒干和对流干燥的葡萄籽组织间没有或有少量的孔隙。综上,连续红外干燥适合酿酒葡萄皮渣的干燥处理,具有高干燥品质。      

Production of white wine by Saccharomyces cerevisiae immobilized on grape pomace

White wine was produced with Saccharomyces cerevisiae cells immobilized on grape pomace, by natural adsorption. The support, the main solid waste from the wine industry, consisted of the skins, seeds and stems. Immobilization was tested using different media, namely complex culture medium, raw grape must and diluted grape must. Grape pomace was revealed to be an appropriate support for yeast cell immobilization. Moreover, grape must was shown to be the most suitable medium as immobilized cells became adapted to the conditions in the subsequent alcoholic fermentation in the wine‐making process. The wines produced, either with immobilized cells or with free cells, were subjected to chemical analysis by HPLC (ethanol, glycerol, sugars and organic acids) and by gas chromatography (major and minor volatile compounds); additionally, colour (CIELab) and sensory analysis were performed. The use of immobilized systems to conduct alcoholic fermentation in white wine production proved to be a more rapid and a more efficient process, especially when large amounts of SO₂ were present in the must. Furthermore, the final wines obtained with immobilized cells demonstrated improved sensory properties related to the larger amounts of ethanol and volatile compounds produced. The more intense colour of these wines could be a drawback, which could be hindered by the reutilization of the biocatalyst in successive fermentations. Copyright © 2012 The Institute of Brewing & Distilling     

Diversity in Spoilage Yeast Dekkera/Brettanomyces bruxellensis Isolated from French Red Wine. Assessment During Fermentation of Synthetic Wine Medium

Yeast Brettanomyces bruxellensis is a contaminant found worldwide and is responsible for red wine spoilage due to the development of animal and phenolic off‐odours. During this study, 24 Brettanomyces bruxellenis isolates were obtained from red wine samples from two French wineries and these were discriminated as 23 strains. Nine strains coming from 2 wineries and 4 vintages were cultivated in synthetic wine medium for 1500 hours and they gave nine different behaviours. Four main growth patterns (with different growth steps and durations) and three main different sugar consumption profiles were obtained. Glucose and fructose were not limiting substrates for all strains. The production level of 4‐ethylphenol was found to vary from strain to strain (from 0.350 to 2.773 mg L^?1) and was independent of the biomass concentration. Some strains presented a coupled‐to‐growth production of volatile phenols, others did not. This study showed that different strains of Brettanomyces bruxellensis behaved differently, one from another, under the given conditions taking into consideration several aspects. The results thus demonstrate a large intraspecific diversity.     

Antibacterial activities and total phenolic contents of grape pomace extracts

The aim of this study was to determine the total phenolic contents and antibacterial effects of grape pomace extracts (cultivars Emir and Kalecik karasi) against 14 bacteria, and the effects of the extracts on the growth and survival of two of the bacteria during storage. The total phenolic contents of grape pomace of Emir and Kalecik karasi cultivars extracted with acetone/water/acetic acid (90:9.5:0.5) were 68.77 and 96.25 mg GAE g^?1, respectively. The agar well diffusion method was used to test the antibacterial activity of the extracts at 1, 2.5, 5, 10 and 20% (w/v) concentrations in methanol on spoilage and pathogenic bacteria including Aeromonas hydrophila, Bacillus cereus, Enterobacter aerogenes, Enterococcus faecalis, Escherichia coli, Escherichia coli O157:H7. Mycobacterium smegmatis, Proteus vulgaris, Pseudomonas aeruginosa, Pseudomonas fluorescens, Salmonella enteritidis, Salmonella typhimurium, Staphylococcus aureus and Yersinia enterocolitica. All the bacteria tested were inhibited by extract concentrations of 2.5, 5, 10 and 20%, except for Y enterocolitica which was not inhibited by the 2.5% concentration. However, pomace extracts at 1% concentration had no antibacterial activity against some of the bacteria. According to the agar well diffusion method, E coli O157:H7 was the most sensitive of the bacteria. Generally, using the serial dilution method, while the extracts at 0.5% concentration had bacteriostatic activities on E coli O157:H7 and S aureus, the extracts appeared to have bactericidal effects at 1 and 2.5% concentrations. In accordance with this method, S aureus was more sensitive than E coli O157:H7 to the extracts. Copyright © 2004 Society of Chemical Industry     

利用葡萄渣黑曲霉固态发酵产果胶酶的研究

对黑曲霉（Aspergillus niger）BB-6利用葡萄渣固态发酵产果胶酶的发酵条件进行研究。结果表明,在基础发酵培养基中添加葡萄糖4%、硫酸铵0.6%,含水量60%,培养温度30 ℃条件下培养72 h,果胶酶酶活达12.226 U/g。     

Detection of pectinmethylesterase activity in presence of methanol during grape pomace storage

Methanol is an unwanted component in the production of spirit beverages. Its presence in grape pomace stored until distillation greatly affects the composition of the final product, which requires redistillation, modifying the aromatic characteristics of the distillate. Consequently, reduction of methanol, by controlling its formation during pomace storage, can increase the quality of grappa. The aim of this work was to monitor pectinmethylesterase activity during grape pomace storage, in order to identify its presence related to methanol release. The enzyme activity was detected during various storage times by spectrophotometric and electrophoretic methods. Results show that yeasts do not contribute to PME production. Moreover, by using paranitrophenyl acetate, a specific substrate for esterase, also as PME substrate, we demonstrate the presence of several enzymes hydrolysing ester bonds.     

Effect of grape pomace extracts obtained from different grape varieties on microbial quality of beef patty

Grape pomace extracts were obtained from 5 different grape varieties grown in Turkey. The extracts were concentrated to obtain crude extracts; and incorporated into beef patties at 0% (Control), 1%, 2%, 5%, and 10% concentrations to test their antimicrobial effects in different storage periods (first, 12, 24, and 48 h). The numbers of microorganism were generally decreased by the extract concentration during the storage period. All the microorganisms tested were inhibited by the extract concentration of 10% in all the storage periods. Furthermore, the foodborne pathogens including Enterobacteriaceae and coliform bacteria, and the spoilage microorganisms including yeasts and moulds and lipolytic bacteria were also inhibited by 5% of Emir, Gamay, and Kalecik Karasi varieties in beef patties. Considering the results, the extracts of grape pomaces might be a good choice in the microbial shelf life extension of the food products as well as inhibiting the food pathogens as the case of beef patties. PRACTICAL APPLICATION: Grape pomace consists of seeds, skins, and stems, and an important by-product that is well known to be the rich source of phenolic compounds, both flavonoids and non-flavonoids. These substances have considerable beneficial effects on human health. The use of natural antimicrobial compounds, like plant extracts of herbs and spices for the preservation of foods has been very popular issue because of their antimicrobial activity. Therefore, grape pomace should be added into some food formulations to benefit from their protective effects. In this respect, this study reports the effect of addition of grape pomace extracts obtained from different grape varieties on microbial quality of beef patty. The results obtained in this study may be useful for food industry, which has recently tended to use natural antimicrobial sources in place of synthetic preservatives to prevent microbial spoilage.     

Effects of time of grape pomace fermentation and distillation cuts on the chemical composition of grape marcs

 The effects of fermentation time and distillation cuts on the composition of distillates in terms of ethanal, 1,1-diethoxyethane, methanol, 1-butanol, 2-butanol, 1-propanol, 2-methyl-1-propanol, 2-methyl-1-butanol, 3-methyl-1-butanol, ethyl acetate, ethyl 2-hydroxypropanoate, 3-methylbutyl acetate, hexyl acetate, 2-phenylethyl acetate, hexanol, trans-2-hexenol, trans-3-hexenol, cis-3-hexenol, 2-phenylethanol, ethyl butyrate, ethyl hexanoate, ethyl octanoate, ethyl decanoate, ethyl dodecanoate, 2-methylpropanoic acid, 3-methylbutanoic acid, hexanoic acid, octanoic acid, decanoic acid, and dodecanoic acid were assessed through data generated according to a factorial design using analysis of variance and principal component analysis. Four times of storage of pomace obtained following winemaking of two grape varieties of white Verde wine (Alvarinho and Loureiro) and three distillation cuts were considered; volatile compounds in the 24 samples generated were analyzed directly, and indirectly after extraction and concentration, by capillary gas chromatography. The results generated have suggested clear differences (P<0.05) between distillate cuts obtained throughout fermentation times for each grape variety. The major differences between the different distillate fractions analyzed were accounted for by the contents of diethyl butanoate, ethyl 2-hydroxypropanoate, and the sum of 3-methylbutanoic and 2-methylpropanoic acids for Loureiro, whereas the main differences were accounted for by the contents of diethyl butanoate and the sum of the carboxylic acids for Alvarinho. Received: 23 January 1998 / Revised version: 5 June 1998     

发酵法活化葡萄皮渣膳食纤维工艺的研究

以葡萄酒厂的副产物-葡萄皮渣为原料,采用嗜热链球菌和保加利亚乳杆菌混合发酵技术活化其中的膳食纤维,提高了葡萄皮渣中可溶性膳食纤维的含量。经正交试验得到乳酸菌发酵活化葡萄皮渣膳食纤维的最佳反应条件为：液料比10：1（v／w）,菌种比1：1（v／v）,发酵温度42℃,发酵时间12h,接种量10％,产品SDF含量为19．54％（干基）,较原料中SDF提高3．6倍。     

Role of oxygen on acetic acid production by Brettanomyces/Dekkera in winemaking

Since the large occurrence of Brettanomyces yeasts in strict anaerobiosis environments (sparkling wines) has been found without an increase in acetic acid content, we evaluated the influence of the oxygen concentration on acetic acid production. Results showed that the oxygen concentration exerted a strong influence on both growth and acetic acid production by Brettanomyces yeasts in winemaking. Full aerobiosis lead to a large production of acetic acid causing a block of metabolic activity. Semi-aerobiosis resulted in the best condition for alcoholic fermentation (Custers effect) combined with acetic acid production. In anaerobic condition Brettanomyces yeasts did not result in high acetic acid production and a pure, even if slow, alcoholic fermentation occurred. The absence of an increase in acetic acid in wines, does not exclude the active presence of Brettanomyces yeast since the characteristic ‘high acetic producer’ in Brettanomyces yeast is linked to the presence of oxygen. ©1997 SCI     

Biotransformation of hop derived compounds by Brettanomyces yeast strains

Several hop derived compounds in wort are known to be converted by yeast during fermentation, influencing the overall perception of the beer. A deeper understanding of such metabolic processes during fermentation is needed to achieve better control of the outcome. Here, the interaction between hop derived compounds and the yeast genera Brettanomyces was studied. Several Brettanomyces strains with different genomic backgrounds were selected, focusing on two traits: beta-glucosidase activity and nitrate assimilation. The role of three beta-glucosidases present in Brettanomyces bruxellensis and Brettanomyces anomalus and their impact on the final monoterpene alcohol profile was analysed. The beta-glucosidase activity was highly strain dependent, with B. anomalus CRL-49 exhibiting the highest conversion. Such activity could not be related to the release of aglycones from hops during fermentation, as a substantial part of such activity was intracellular. Nevertheless, the reduction of geraniol to β-citronellol was remarkably efficient for all Brettanomyces strains during fermentation, and it is suggested that two oxidoreductases BbHye2 and BbHye3 may have an influence. Moreover, the transfer of nitrate from hops to wort and its further assimilation by Brettanomyces species was analysed. The amount of nitrate in wort proved to be linearly proportional to the contact time of the hops with the wort. The level of nitrate assimilation by yeast was shown to be dependent on the nitrate assimilation cluster (YNR, YNI, YNT). Hence, the desired yeast strains may be selected according to the genetic make-up. © 2020 The Authors. Journal of the Institute of Brewing published by John Wiley & Sons Ltd on behalf of The Institute of Brewing & Distilling     

Investigation of using possibility of grape pomace in wafer sheet for wheat flour substitution

In this study, grape pomace (GP), a by-product consisting of grape skins and seeds rich in dietary fibres and polyphenols, was used in wafer sheets at different concentrations [5.00 (GP5), 10.0 (GP10), and 15.0 g 100 g⁻¹ (GP15)] for the partial replacement of wheat flour (WF) and improve the functionality of wafer sheets. The GP inclusion at concentrations higher than 5.00 g 100 g⁻¹ significantly affected the texture of sheets as well as the flow behaviour of batters, resulting in softer sheets and more viscous batters (P < 0.05). Moisture contents did not significantly change after GP addition (P > 0.05). After the addition of GP, the L* values decreased and the a* values increased, making the wafers darker (P < 0.05). Moreover, under simulated in vitro digestion conditions, the bioaccessibility of total phenolic compounds in saliva, gastric juice, and intestinal juice was significantly higher than control even at the lowest GP concentration (P < 0.05). Regarding sensory properties, only smoothness and crispness were significantly affected by GP addition, and samples were found to be crisper with higher concentrations of GP. In conclusion, it is possible to partially replace the WF in wafers with GP at a concentration of 5.00 g 100 g⁻¹ to develop a product with higher functionality and nutrient content.