No abstract

Raising the temperature from 16°C to 20°C or 25°C for prolonged periods during steeping or germination reduces HWE and TSN and slows down wort separation in laboratory mashes. When the higher temperatures are applied only during the last steep or the first two days of germination the initial rate of modification is accelerated, as is the development of a-amylase and endopeptidase. After four or five days germination the levels of enzyme activity are substantially lower than in the control malt. However, some barleys give malts with acceptable standard analyses after 4 rather than 5 days of germination.

A method has been developed for assessing the homogeneity of a sample of malt using the Friabilimeter. Material retained by the Friabilimeter sieve is further fractionated using a sieve with slits 2*2mm wide by 23mm long, as recommended by the EBC for assessing corn size. Material composed of unmodified grains and large pieces of endosperm is collected from the sieve and weighed. This gives a rapid and reproducible estimate of the proportion of unmodified material in the sample. The technique readily detects small quantities of unmodified grain added to a sample of malt. Staining half corns with Calcofluor gives similar scores for homogeneity but with poorer reproducibility and the technique is much slower. Staining with methylene blue gives much lower figures for homogeneity and is also slower and less reproducible than the Friabilimeter method.

Steeping barley at 30°C instead of 16°C can reduce malting time by 24 hours. The malts produced have normal analytical values but the mashes filter slowly and the malts would be expected to give poor wort separation in a brewery. These run-off problems probably result mainly from starchprotein interactions.

Blue aleurones in barley are associated with elevated levels of polyphenolic materials such as anthocyanins and anthocyanidins. A rapid method has been developed for assessing the anthocyanin content of barleys, malts and worts. Malts were prepared from a range of barleys, some of which had intensely blue aleurones, while others were only slightly blue or showed no visible pigmentation. The malting quality of barley was not affected by aleurone colour and ales and lagers of sound flavour as well as acceptable analytical parameters were brewed from malts having pronounced blue aleurones. In some cases sweet worts prepared from blue aleurone malts had a slight pinkish tinge, but this disappeared during wort boiling, and beer colours were normal. Levels of anthocyanins in barley correlated with those in malt and in wort. However, the concentration of anthocyanins was unrelated to the amount of anthocyanogens ortotal polyphenols. High anthocyanin levels in either barley or beer had no deleterious effects on beer flavour or the rate of haze development.