Effects of brewing procedures and oenological yeasts on chemical composition, antioxidant activity, and sensory properties of emmer-based craft beers

Emmer is among the most ancient domesticated grains. In craft brewing, emmer is used in an adjunct, due to its tannic astringency and typical nutty aroma. The aim of this study was to evaluate the effects on the quality of emmer-based craft beers exerted by the employment of two novel brewing procedures (BP1 and BP2) and four oenological Saccharomyces cerevisiae starter strains, namely 17,290, 14,061, 9502, and 9518. The two technological approaches differed for water conductivity (570 and 440 mu S/cm), protein rest (30 and 10 min), boiling step (90 and 55 min), and Irish moss addition (only in BP1). The highest total phenolic concentrations were detected in the beers fermented by 17,290 and 14,061 strains. The beers fermented by 14,061 showed the highest contents of volatile esters, alcohols, and terpenes (the latter if produced according to BP1). The beers produced according to BP2 had the highest concentrations of volatile acids, norisoprenoids, hydrocarbons, and phenols with significant effects of the utilized starter strain. The highest overall sensory score (similar to 4.5) was assigned to BP2-9502 beers and it was positively correlated with color, pH, foam amount and persistence, olfactory finesse, body/fullness, and negatively correlated with CO2, titratable and volatile acidity, saltiness, and sourness.