Effect of Low-Phytate Barley on Malt Quality, Including Mineral Loss, during Fermentation

Abstract

The recent development of low-phytate barley offers the possibility of improving fermentation efficiency and reducing the need for mineral supplementation in the brewhouse. Three barley lines have been developed with ≈50, 25, and 5% of normal phytate. The lines have a Harrington background, which increases the probability of producing barley with good malting quality from the lines. Samples of Harrington and the three lines were malted and tested for quality, including zinc and magnesium usage during fermentation. Effects of zinc supplementation at mashing-in and kettle-full also were investigated. The low-phytate lines all had adequate malt quality and were similar to Harrington. The 5% of normal phytate wort (not supplemented) had significantly higher levels of zinc and magnesium than the other three samples. Worts from the 50 and 25% of normal phytate lines also had significantly higher levels of magnesium than the Harrington wort. The 5% of normal phytate worts, both the control and mash-supplemented, used significantly more zinc during fermentation than all other worts. The mash-supplemented wort from the 50% of normal phytate malt also used significantly more zinc during fermentation than the 25% of normal phytate or Harrington worts. There were no significant differences in zinc usage among the worts supplemented at kettle-full. The low-phytate trait showed an insignificant tendency to improve fermentation, as measured by apparent attenuation limit, supporting further testing of low-phytate malts with pilot-scale brewing facilities and higher gravity worts in which minerals more likely would be limiting.