Influence of gluten-free adjuncts on beer colloidal stability

Abstract

This work deals with issues related to the colloidal stability of craft beers. It is generally known that haze in beer is directly related to the formation of complexes resulting from the interaction of haze active polyphenols and protein fractions [1–18]. How some variables in the malting process and formulation can contribute to the colloidal stability of the final beer have been considered. Micro malting tests on four glutenfree cereals/pseudocereals (millet, amaranth, buckwheat and quinoa) were carried out in order to identify the optimal conditions for obtaining malts suitable for brewing. Quality of malts was checked analysing diastatic power, beta glucans content and Kolbach Index. The gluten-free malts were under-modified if compared to traditional malts, but potentially suitable as adjuncts (especially buckwheat). Nine beers with different formulations were produced in the laboratory using the malts obtained from the micro malting tests. The evaluation of beer stability was carried out analyzing indices validated by European Brewery Convention (sensitive proteins and cold turbidity) and two unconventional methods (gluten analysis and antioxidant activity). Moreover, three beers (the reference obtained with 100% malted barley, the other two with the buckwheat malts) were subjected to CE analyses (Capillary Electrophoresis) in order to define their protein content. According to the results the use of gluten-free adjuncts, besides relevant process conditions (i.e. alkalinized first steeping water in the malting process), can lead to more stable final products with a gluten content less than 100 mg/L and so potentially suitable by coeliacs according to EU regulation 828/2014.