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Impact of barley malt quality and wort composition on the occurrence of premature yeast flocculation.

机译：大麦麦芽质量和麦芽汁组成对过早酵母絮凝发生的影响。

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摘要

Premature yeast flocculation (PYF) is a sporadic phenomenon, which can have serious economic and production implications for both the brewer and maltster. PYF is characterized by the occurrence of poor or incomplete attenuation, early or premature flocculation and results in poor flavour development and aberrant fermentation profiles. Malt constituents are believed to cause PYF. Fermentations of wort, from control & PYF malts, were fermented and analyzed for wort constituents, yeast growth, attenuation and cell surface physical properties (hydrophobicity, zeta potential, Helm's flocculation, orthokinetic capture coefficient, zymolectin and mannose receptor densities). Differences were found in carbohydrate and FAN composition of the worts produced from both classes of malted barley. The PYF wort exhibited aberrant fermentation profiles after 60 h when modeled by a logistic equation.; Yeast was inoculated into two fermentations, prepared from two grades of malted barley, a high quality and a poor quality, suggested to induce the premature flocculation phenomenon. Wort composition was determined utilizing FPLC, GC and HPLC. Fermentations were examined to determine the effect of malt quality on cell surface physical properties, yeast growth, and attenuation during fermentation progression.; Differences in peptide and carbohydrate composition of worts produced from both classes of malted barley are discussed. In addition, the occurrence of premature yeast flocculation is characterized in terms of effect on fermentation progression and cell surface physical properties. Results suggest that while PYF malt impaired the metabolic activity of the yeast cells and there was little effect on cell surface physical properties.
机译：酵母过早絮凝（PYF）是一种零星现象，对啤酒酿造商和麦芽制造商都有严重的经济和生产意义。 PYF的特征是发生的衰减不佳或不完全，早期或过早的絮凝，并导致不良的风味形成和异常的发酵特性。麦芽成分被认为会引起PYF。对来自对照和PYF麦芽的麦芽汁发酵液进行发酵并分析麦芽汁成分，酵母生长，减毒和细胞表面物理特性（疏水性，ζ电位，Helm絮凝，原动力捕获系数，zymolectin和甘露糖受体密度）。两种麦芽大麦产生的麦芽汁中碳水化合物和FAN组成存在差异。当通过逻辑方程建模时，PYF麦芽汁在60小时后表现出异常的发酵特性。酵母被接种到两个发酵中，这两个发酵是由两种等级的发芽大麦制成的，优质和劣质，表明会诱发过早的絮凝现象。使用FPLC，GC和HPLC测定麦芽汁组成。检查发酵以确定麦芽质量对细胞表面物理特性，酵母生长和发酵过程中衰减的影响。讨论了从这两类麦芽大麦生产的麦芽汁中肽和碳水化合物组成的差异。另外，根据对发酵进程和细胞表面物理性质的影响来表征过早酵母絮凝的发生。结果表明，虽然PYF麦芽损害了酵母细胞的代谢活性，但对细胞表面物理特性的影响很小。

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  • 作者

    Wood, Dave.;

  • 作者单位

    Dalhousie University (Canada).;

  • 授予单位 Dalhousie University (Canada).;
  • 学科 Agriculture Food Science and Technology.
  • 学位 M.Sc.
  • 年度 2006
  • 页码 113 p.
  • 总页数 113
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 农产品收获、加工及贮藏;
  • 关键词

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