Improvements in the characterisation and quality of vigour in malting barley

Malting conditions during steeping and germination must be optimised if suitably modified malt is to be produced quickly and efficiently. The 'germination profile' which comprises a measurement of germinative energy (percentage germination, GE) over 3 d and calculations of germination index (mean germination time, GI) and germination homogeneity (uniformity of germination, GH), were shown to provide an informative means of characterising the overall vigour and potential germination performance of barley grain under various conditions. These conditions included incubation temperatures of 10°C, 20°C and 30°C in petri-dishes and a range of volumes of water, from 0.5 ml to 2.5 ml, added to the incubation vessel (Erlenmeyer flasks). At 20°C, GI was 5.71, higher than at 10°C or 30°C for intact grains, and 9.17 for partially de-husked grains. With 1.0 ml of water, GE was 98.5%, GI 5.00 and GH 53%. More water (2.5 ml) reduced GE to 43.5%, but GI for the grain increased to 6.62. Priming experiments were performed where barley grains were pre-treated by hydrating in water for up to 30 h, then dried back, prior to germination testing. Priming for 20 h was the optimum time required to improve vigour compared to the control. This treatment resulted in a GI of 9.3 (maximum 10) compared to a value of 5.8 for the control and a GH of 74%, compared to 43.8% for the untreated control grains. The priming treatments did not significantly alter the germinative energy values of the samples but these were already high for the control. It is concluded that malting barley quality control should include measurement of a 'germination profile' as a simple means of presenting and analysing the complex data obtained from measurements of germination made over 3 days.