Reduced Phytate Barley Malt to Improve Fermentation Efficiency

Brewery fermentations require continuous yeast growth to efficiently convert fermentable sugars to ethanol. Yeast growth is dependent on an adequate supply of nutrients, including minerals. Minerals are generally assured in the brewery with addition of nutrient supplements but reduced phytate barley malts could reduce the need for supplements. The present study used bulked segregant analysis to determine effects of the reduced phytate trait in barley on field performance, barley quality, malting quality and brewing performance. Two bulks from a doubled haploid population, along with a series of normal and reduced phytate controls, were grown at 3 to 5 western Canadian sites in 2006, 2007 and 2008. The normal and reduced phytate barley bulks had similar yields, but the reduced phytate barley had significantly lower test weight. Rates of endosperm modification were similar between the two phytate types, although, reduced phytate malt was significantly more friable. Malt extract and α-amylase levels were significantly lower in the reduced phytate bulk. Zinc and magnesium levels were significantly higher in reduced phytate worts and these worts produced better yeast growth as indicated by greater amino acid use during fermentation. Brewing performance tended to be better with reduced phytate worts, but not consistently so, likely due to the lower levels of malt extract and alpha-amylase. Results supported the incorporation of the reduced phytate trait into malting barley varieties, but with attention to breeding for improved test weight and levels of alpha-amylase.