Production of Gluten-Free Craft Beers of High Antioxidant and Sensory Quality.

Usually, gluten-free "beers" are produced by replacing cereals containing gluten with substitutes that do not contain it or, alternatively, through enzymatic, precipitation, and/or clarification steps. The research was aimed at increasing the concentration of antioxidant compounds and improving the sensory quality of gluten-free craft beers produced from gluten-containing raw materials according to a patented brewing method that represented the starting point of the research. The experiments were organized to evaluate the effects of original combinations of four brewing procedures (Strong, Light, Very Light, Ultra-Light-differing from each other by grains/water ratio, hops/water ratio, protein rest, and boiling time), three yeast strains (M21, K97, S33), and a possible dry hopping. The beer gluten contents ranged from <5 to 13.90 mg/L. The maximum total phenolic content (200 mg/L) was detected in beers produced by combining the Light procedure, inoculation with M21 strain, and dry hopping. The highest overall sensory quality scores (4.0) were assigned to the beers obtained through the Light and Ultra-Light procedures, fermented by M21 and S33 strains, and dry hopped. Dry hopping was the main factor capable of differentiating the beers, increasing antioxidant content and improving perlage, foam characteristics, the intensity of many olfactory and gustatory characteristics, and the overall sensory quality. The brewing procedure affected all the physico-chemical indices and most sensory characteristics, except for color, citrous and spicy flavors, sweetness, effervescence, and body. The use of different yeasts did not impart significant differences for most of the variables considered.