High-gravity brewing and distilling-past experiences and future prospects

G. G. Stewart

    Research output: Contribution to journalArticle

    23 Citations (Scopus)

    Abstract

    High-gravity brewing employs wort (15-20°P original gravity) at a higher than normal concentration, and to obtain sales-gravity beer, dilution with water (usually carbon filtered and deoxygenated) is required at a later stage in processing. Using this method, increased production demands can be met without significant expansion of brewing, fermenting, and storage facilities. Scotch whisky production, particularly grain whisky, also is increasingly employing high-gravity techniques (18-21°P wort) during a continuous fermentation procedure. The principal advantage to this procedure is the more efficient use of existing processes. The disadvantages of high-gravity brewing include decreased beer foam stability, a variety of stress effects on yeast, and problems with beer flavor matching compared with sales-gravity brewed beers. The stress effects of high-gravity wort also include enlargement of the yeast vacuole and changes in the topography of the yeast cell surface. Hydrodynamic stress effects on yeast are also a problem, particularly when employing centrifugation at the end of fermentation to crop yeast for recycling into a subsequent fermentation. Finally, difficulties encountered in both brewing and distilling include the inability of yeast to completely utilize the largest fermentable wort sugar-maltotriose. This is particularly the case during grain whisky production by continuous fermentation under high-gravity wort conditions. © 2010 American Society of Brewing Chemists, Inc.

    Original languageEnglish
    Pages (from-to)1-9
    Number of pages9
    JournalJournal of the American Society of Brewing Chemists
    Volume68
    Issue number1
    DOIs
    Publication statusPublished - 2010

    Keywords

    • Beer foam
    • Centrifugation
    • Esters
    • Flow cytometry
    • Grain whisky
    • High-gravity brewing

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