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介绍了国内外关于酵母提前絮凝的研究进展及导致酵母提前凝的因素和酵母提前絮凝的假说机理,归纳了酵母絮凝的检测方法,提出了预防酵母提前絮凝的措施及酵母提前絮凝的研究方向。 相似文献
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Yue‐Ling Shang Xiao‐Min Li Guo‐Lin Cai Jian Lu Jian Chen 《Journal of the Institute of Brewing》2014,120(3):220-224
In the present study, small‐scale fermentations of seven malts from different maltsters in China were used to monitor their premature yeast flocculation (PYF) potential. Husk exchange was applied between PYF negative malt (PYF‐) and PYF positive malt (PYF+) to investigate the PYF factors potentially present in the husk. The results showed that PYF factors were present in both malt husk and the non‐husk part. The two factors showed various ratios among different PYF+ malts, and either of them could induce PYF if it reached the threshold. Moreover, the major antimicrobial substances damaging the yeast cells were in the non‐husk part. Copyright © 2014 The Institute of Brewing & Distilling 相似文献
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酵母提前絮凝是啤酒企业时有发生的现象,因其复杂的影响因素至今对酵母提前絮凝的发生机理及提前絮凝因子的本质没有明确的证实,也因此给整个啤酒酿造产业链造成了极大的困扰。近年来,随着环境污染及各种恶劣天气的出现,导致啤酒酵母提前絮凝发生相对增多,对麦芽企业及啤酒企业造成一定经济和名誉损失。作者综述了啤酒酵母提前絮凝的国内外最新研究进展,包括机理假说、提前絮凝因子的来源、形成机制及控制研究,以期对啤酒产业链提供有效解决酵母提前絮凝的思路和方法。 相似文献
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John Londesborough 《Journal of the Institute of Brewing》2011,117(4):475-487
Flocculation is prerequisite for bulk sedimentation of yeast during brewery fermentation. Although single yeast cells gradually sediment in green beer, this sedimentation rate is too slow without formation of large yeast flocs. The present review concerns the major determinants of yeast flocculation and sedimentation in brewery fermentations. Flocculation characteristics of yeast are strongly strain‐dependent and largely defined by which FLO genes are functional in each strain. In addition to the genetic background, several environmental factors affect flocculation. These can be, somewhat arbitrarily, classified as physiological factors, such as the calcium availability, pH, temperature and ethanol and oxygen concentrations in the medium or physical factors, such as cell surface hydrophobicity, cell surface charge and the presence of appropriate hydrodynamic conditions for the formation of large flocs. Once yeast flocs are formed, their size, shape and density and the properties of the surrounding medium affect the rate at which the flocs sediment. Higher gravity worts usually result in green beers with higher viscosity and density, which both retard sedimentation. Moreover, environmental factors during yeast handling before fermentation, e.g., propagation, storage and cropping, influence the flocculation potential of yeast in subsequent fermentation. Premature yeast flocculation (PYF) and the role of PYF factors are discussed. In conclusion, some potential options available to adjust yeast flocculation are described. 相似文献
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Joseph C. Lake R. Alex Speers Tom A. Gill Anna‐Jean M. Reid Douglas S. Singer 《Journal of the Institute of Brewing》2009,115(4):296-299
Premature yeast flocculation (PYF) is a poorly understood condition leading to attenuation of fermentation and poor alcohol yields. The yeast in suspension in fermenting worts prepared from either normal or premature flocculating malts was continually measured during the small 15 mL fermentation test recently developed in the Dalhousie laboratories. A simple inexpensive monitoring system was constructed from a laser level, photometric cell and data logger. This system allowed non‐destructive data collection of absorbance data (over 700 data points per fermentation) at ?650 nm. A non‐linear modeling technique was applied to the data, and yielded two best‐fitting logistic models. The model parameters were quantitatively compared to determine if statistical differences between PYF and normal wort were apparent. A student's t test of the logistic parameters indicated a significant difference (p > 0.025) between control and PYF worts for the increase in absorbance at the beginning of the fermentation. A significant difference (p > 0.0001) in the inflection time of absorbance down‐curve between the control and PYF wort was also noted. 相似文献
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Yue‐Ling Shang Xiao‐Min Li Guo‐Lin Cai Jian Lu 《Journal of the Institute of Brewing》2015,121(1):49-54
Premature yeast flocculation (PYF) is a universal phenomenon and has caused serious problems in the brewing industry. For brewing quality control, it is of great value to investigate the PYF factors that induce this destructive phenomenon. In the present study, two barley malts (PYF+ and PYF?), made from the same barley cultivar by one maltster in China, were selected for PYF factor investigations. The results showed that considerably higher amounts of the bound ferulic acid (FA), rather than arabinoxylan (AX), existed in the PYF+ wort compared with the PYF? wort. To better understand the role of these polysaccharides in PYF+ and PYF? wort, they were fractional precipitated with graded ethanol concentrations. The AX and FA contents in each fraction, as well as the molecular weight profiles and monosaccharide composition, were determined. Furthermore, the PYF?inducing activities of each fraction were measured using a small‐scale fermentation. It was found that the 40% ethanol‐precipitated fraction of both the PYF+ and PYF? wort, and the 60% fraction from the PYF+ wort, could induce the severe PYF phenomenon when added to the PYF? wort. These fractions were proposed to contain PYF factors of suitable molecular weight and a sufficient amount of the polysaccharides. In addition, it was found that the bound FA in arabinoxylan behaved as an important PYF factor in barley malt. The results of this work may contribute to the further study of the PYF mechanism. Copyright © 2015 The Institute of Brewing & Distilling 相似文献
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