Aroma profile of a gluten-free barley malt beer crafted to remove gluten using a barley malt extract with high peptidase activity

Abstract

Gluten-free beer (GFB) was produced from gluten-containing barley malt wort by adding an enzyme-enriched malt extract to the wort, intended for patients with celiac disease. Nevertheless, the aroma profile of such beer is unknown. The results indicated that the treatment reduced 3-methylbutyl acetate, 2-methylbutyl acetate, ethyl hexanoate, 2-methylpropyl acetate, and ethyl butyrate when compared with the reference. Moreover, foam, free amino nitrogen, aging stability, and color deviated significantly in the GFB. Although the values were below the odor threshold, analysis of aging components indicated increased amounts of heating, including 2-furfural and aging indicators, including phenylacetaldehyde. GC-O/MS following a descriptive profile test revealed that the attribute honey significantly increased. Further the shift in aroma composition of the GFB, long-chain free fatty acids (LCFFA) were analyzed, as they have been previously described to negatively correlate with ester metabolism and may be increased because of the technology applied. LCFFA analysis in wort revealed a significant increase in hexadecanoic and linoleic acids caused by the procedure. To clarify the findings, conventional barley malt worts were spiked with hexadecanoic acid, linoleic acid, and a mixture of these acids. A significant decrease in all esters concomitant with a honey-like aroma was observed when linoleic acid was added, but the aging analysis revealed no difference. Through adjustment of ester content to the reference, the spiked beers were less rated honey. The results indicate that aging components are sensed higher in the absence of esters; thus, by reducing LCFFA concentrations of gluten-free wort, the aroma of GFB could be enhanced.