The role of starch digestion in the brewing of gluten-free beers

Celiac disease affects an estimated 1% of the global population, and symptoms are triggered by the consumption of gluten in sensitized individuals. Other gluten sensitivities exist but are poorly characterized or often under-diagnosed, leading a number of people to pursue a gluten-free or gluten-reduced diet even in the absence of a diagnosis. Gluten is a complex suite of proteins from the prolamin fraction of storage proteins in barley, wheat, and rye, meaning that foods or beverages that are produced from these cereals will also contain gluten. Beer is one such beverage that is traditionally produced from malted barley and is thus incompatible with a gluten-free lifestyle. The simplest option to produce a gluten-free beer would seem to be to use alternative, gluten-free, grains such as millet, sorghum, teff, rice, corn or other starchy materials. However, barley has thousands of years of development as a brewing agent behind it and these alternative ingredients cannot be incorporated into the brewing process without substantial alterations. Particularly, these ingredients generally have much lower endogenous starch degrading activity and much higher starch gelatinization temperatures as compared to barley which makes generating sufficient fermentable sugars for yeast fermentation a challenge. In this review we will further elucidate these challenges as well as the solutions that are being developed to bring beer to the gluten-free masses.