Determinação do Perfil Químico por GC-MS e HPLC-DAD de uma Nova Cerveja Fermentada por Grãos de Kefir e sua comparação à Cerveja Convencional.

Abstract

Beer is one of the oldest and most widely consumed beverages in the world, It has a complex chemical composition characterized by amino acids, carbohydrates, minerals, and vitamins. The beverage also contributes to prevent a number of health-related problems, in addition to the constant search for innovations in the brewing industry. When combined with the nutritional and medicinal benefits of Kefir, the beverage has anti-inflammatory and anti-ulcerogenic activities. Based on this, the present work sought to analyze the chemical profile of a new beer fermented by Kefir grains by GC-MS and HPLC-DAD and make the comparison with conventional beer. For the study, three hind of beer samples were produced, one conventional, one fermented with Kefir grains at room temperature and another at controlled temperature, in order to verify the chemical composition of each one. The beers with Kefir had lower alcohol content than the conventional Barley Wine, being respectively 7.3% and 8.9%. The extraction of the compounds was done by HS-SPME, which proved to be very promising because it is a simple and sensitive technique that does not use solvents. Thirteen compounds were identified in the Kefir, being acetoin and acetic acid the most abundant. Similarly, 18 compounds were found in the beer, being ethanol, ethyl acetate, isopentyl alcohol and isopentyl acetate the most abundant. However, the conventional beer presented 4 fewer compounds compared to those with Kefir, showing that the probiotic beers have a richer chemical profile. By extraction of the fractions by SPE, it was found that the beers had hydrophilic compounds, highlighting the style of beer adopted, and the presence of phenolic compounds such as flavonoids, including rutin and quercetin. It was verified that despite the difference in the yeast used, the chromatographic profiles were very similar, i.e., even changing the form of fermentation the same product, beer, was obtained. Finally, by means of statistical analysis, PCA, HCA and PLS-DA, it was found that the beers fermented with Kefir grains had greater similarity between them than with conventional beer.