G. M. WALKER (1), M. Moench (1), G. Palomba (1), J. Ianieri (1), F. Clark (2), K. Duncan (2), P. Iannetta (3); (1) Abertay University, Dundee, Scotland; (2) Inveralmond Brewery, Perth, Scotland; (3) James Hutton Institute, Dundee, Scotland
Raw Materials I
Friday, June 6 - 4:00 p.m.-5:45 p.m.
Level 4, Grand Ballroom
Faba beans (Vicia faba L.) are legumes rich in starch, protein, and minerals and can be cultivated without nitrogen fertilizers (as they are diazotrophic, or N-fixing). There are very few reports of the use of non-cereal starches as adjuncts in brewing, but legumes such as faba have great potential in this context. Currently, faba beans can be fractionated into protein- and starch-rich components. The former are exploited as important additives to salmon feed, and we have evaluated faba bean starch concentrate for use as a novel carbohydrate adjunct for brewing. Experimental infusion mashings were conducted using whole faba beans and bean starch concentrate, together with malted barley, in simulated ale brewing trials at laboratory and pilot-brewery scales. Results have shown there was no significant differences between the faba bean starch concentrate and whole faba bean flour regarding the sugars released by hydrolysis following mashing. Total sugars released by both these adjuncts were 67 g/L and 69 g/L, respectively, and favorable levels of glucose, maltose, and maltotriose from faba starch hydrolysis were found by HPLC analysis. Nevertheless, FAN (free amino nitrogen) may be expected to be higher in wort prepared from whole bean flour compared with the starch concentrate, and this may influence yeast fermentation performance. Experimental fermentations and brewing trials were performed using malt wort prepared with varying proportions of faba adjuncts. Two different fermentation methods (traditional ale brewing and simultaneous saccharification and fermentation [SSF]) and two different enzymatic combinations (using commercial endo-amylase and exo-1,4-alpha-D-glucosidase) have also been tested. It was found that a malt mash supplemented by 40% faba starch concentrate (at 10% solids), obtained following the two enzymatic treatments, produced beers with 3.09 and 3.23% ABV, respectively. This indicates a possible synergistic effect of malt enzymes and exogenous commercial enzymes. Subsequent pilot brewing trials using faba adjuncts (25% faba starch) have resulted in beer with 5.0% ABV possessing good sensory characteristics and defined as a very acceptable mildly hopped summer ale. This presentation will discuss additional findings from experimental research and brewing trials using faba beans and faba starch concentrates as novel carbohydrate adjuncts. Typically, cereal adjuncts such as wheat, maize, and rice are often used to reduce brewing production costs and to vary the final beverage characteristics. However, given global food insecurity and the cost of cereal grains, legume grains, in particular faba bean starch concentrates, may become attractive for farmers, brewers, and distillers in the future.
Graeme Walker graduated with a B.S. degree in brewing and biochemistry in 1975 and completed his Ph.D. degree in yeast physiology in 1978, both from Heriot-Watt University, Edinburgh. He was awarded a D.S. degree from Abertay University in 2004. His professional career has included the following: Royal Society/NATO postdoctoral fellow at the Carlsberg Foundation, Copenhagen; lecturer (biochemistry) at Otago University, New Zealand; lecturer (biotechnology) at Dublin City University; visiting researcher at Case Western Reserve University in Cleveland, OH; senior lecturer (microbiology) at Dundee Institute of Technology; and reader (biotechnology) at Abertay University, Dundee. He is currently professor of zymology at Abertay, where he directs a yeast research group investigating growth, metabolism, and stress in industrial yeasts. He is an active member of the Institute of Brewing & Distilling and American Society of Brewing Chemists. Graeme has published more than 200 articles in journals, books, and conference proceedings and has also authored textbooks, including Yeast Physiology and Biotechnology (J. Wiley, 1998). He acts in a consulting capacity for international brewing and biotechnology companies.