Suitability of the miniature fermentability method to monitor industrial fermentations

A. J. Macintosh, J. Adler, E. Eck, R.A. Speers

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    Abstract

    Malt barley breeders and maltsters often strive to improve the quality of their product by improving fermentability. Small-scale assays are often used to assess the fermentability of wort produced from malt under standardized mashing techniques. However, anecdotal reports suggest that these assays have poor correlation with industrial fermentations in addition to inconsistency between assays. There are several factors that are likely to contribute to this behavior such as pitching rate, mashing regime, fermentation temperature, barley modification, and batch size. This study aimed to isolate and examine the effect of fermentor size on wort fermentability through the use of miniature-scale (15 mL) assays fermented in parallel to industrial sized operations. These miniature fermentations were conducted at identical temperatures to their industrial scale counterparts and used oxygenated wort mashed and pitched by local craft breweries. Wort density was measured throughout the fermentations using a portable densitometer while the turbidity was assessed via spectrophotometer at 600 nm. It was found that fermentation vessel size had a significant effect on the apparent degree of fermentation; however, observed disparities were consistent between the assay and fermentor dimensions. For example, a difference in final density of 1.1 +/- 0.2 degrees P was observed between the final density of a 19.6 hL craft brewery and the miniature fermentation assay over three consecutive experiments. However, when the wort from an 8.5 hL brewpub was tested using this lab assay, no significant differences in final attenuation were found (P > 0.05). The shear generated through consumption of sugar and subsequent production of carbon dioxide was theoretically determined for each fermentation. A reduced shear generated within the shorter (miniature scale) fermentors likely influenced the yeast floc distributions and subsequent final density.

    Original languageEnglish
    Pages (from-to)205-211
    Number of pages7
    JournalJournal of the American Society of Brewing Chemists
    Volume70
    Issue number3
    DOIs
    Publication statusPublished - 2012

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