MEETING ABSTRACT

O-5
Malting and brewing with buck wheat. B. D. SCHEHL (1), H. H. Wijngaard (1), B. P. Nic Phiarais (1), E. K. Arendt (1). (1) Department of Food and Nutritional Sciences, National University of Ireland, University College Cork, Cork, Ireland.

Buckwheat is pseudo-cereal that is regarded safe for celiac sufferers and may replace other gluten containing cereals in a daily diet especially since it is regarded as highly nutritious grain. Buckwheat contains dietary fibre, resistant starch, D-chiro-inositol, fagopyritols (galactosyl derivatives of D-chiro-inositol), rutin (an anti-oxidant), and a high level of minerals and vitamins. The overall objectives of the study were: i) to develop a malting procedure for buckwheat by optimising the steeping, germination and kilning process; ii) to gain a fundamental understanding of changes taking place during the malting process; iii) to optimise the initial brewing steps, which should lead to the production of a gluten-free beer based on buckwheat. To optimize the malting procedure the controllable malting conditions steeping temperature, steeping time and germination time, as well as kilning time and temperature were optimized in a computer controlled pilot-scale malting machine. The buckwheat malt quality was determined by standard brewing methods as well as by HPLC, enzyme tests and rheological tools. Steeping time was optimized and was shortened in comparison to barley. Buckwheat achenes are smaller in size than barley kernels, and absorbed water more rapidly. The optimal steeping time ranged from 7 to 13 h. An optimal germination temperature of 15°C (= air-off 16.5°C) was determined. A higher germination temperatures led to a less controllable and vigorous germination; it also increased malting loss, due to longer rootlets. Hereafter, a germination time of 4–5 days was selected for buckwheat: the grains were modified to a maximum level, but nutrients had not yet been exhausted. Amylolytic activities of buckwheat and barley malted differed significantly. A maximum alpha-amylase activity of 63.07 units g(^–1) was determined in buckwheat malt, which was low in comparison to barley malt (147.4 units g(^–1)). A maximum total beta-amylase activity of 49.97 units g(^–1) was determined in buckwheat malt and 745.96 units g(^–1) in barley malt. The optimum kilning regime was as follows: 5 h at 40°C, 3 h at 50°C followed by 3 h at 60°C. Due to the differences between barley and buckwheat malt, the milling and mashing profile needed to be adjusted. The grist needed to be milled to a very small grist size and mashing procedure for 100% buckwheat malt: 15 min at 35°C; 15 min at 45°C; 40 min at 65°C; 30 min at 72°C; 10 min at 78°C. Overall, the malting and mashing process were optimized effectively. A low alcohol beer can be obtained by brewing with the adapted procedures. When a traditional lager is required, industrial enzymes need to be added and the fermentation process needs to be optimized.