Using Purple Amerindian Yam (cará roxo, Dioscorea trifida L.) as brewing adjunct: technical and sensorial analysis

Abstract

Purple Amerindian Yam (PAY, Dioscorea trifida L.) is an important component of traditional people dietary in Brazilian central amazon rainforest. It is mainly produced by family farmers, using ecologically friendly ways of cultivation. Face to the new Brazilian legislation about brewing adjuncts, its technical viability for use as brewing adjunct was evaluated, besides a sensorial analysis of the resulting beers by trained consumers. Were produced 4 different beers: control group (only barley malt), PAY15, PAY30 and PAY45, using 15%, 30% and 45% of PAY in substitution of barley malt respectively. Along mashing phase, sugar concentration was affected only in PAY45, while soluble protein increased in all assays using adjunct. The kinetic of fermentation was not affected in any assay. In the final products, not significant differences were observed for pH and sugars and proteins concentration. Alcoholic concentration was signiticantly decreased only by the PAY45 assay. EBC scale values increased in assays using PAY, due its purple color. Flavors and aroma's perceptions for hops and ferment were not affected, being the only significant organoleptic difference observed to malt's flavor in PAY45 assay. These results indicate the viability of PAY as brewing adjunct, viable to substitute until 30% of barley malt.