Avaliação da composição biotiva e aromática de cerveja artesanal elaborada com adição de casca de beterraba (Beta vulgaris)

Abstract

Beer is the most consumed alcoholic beverage in the world, and the craft beer sector is highlighted due to the diversity of styles and raw materials that can enhance the functional and antioxidant characteristics of the product. In this sense, the search for differentiation and reduction of production costs made breweries look for new sources of carbohydrates that give the product different sensory characteristics, longer shelf life for containing bioactive compounds. In this way, the present study elaborated a Belgian blond ale style craft beer with the addition of different percentages of beet husk (Beta vulgaris), an adjunct rich in fermentable sugars, minerals and antioxidant compounds, being a promising alternative for use in craft breweries seeking confer aromatic complexity and increase the bioactive properties of the beverage, as well as its application has low cost, as it is a residue of food production. The objective of this work was to elaborate and analyze the influence of beetroot skins on the formation of phenolic compounds, volatile profile and antioxidant capacity of beer supplemented with beetroot skins. Musts supplemented with beet husks were prepared using 4 treatments, including a control, B1 (100g/L), B2 (150g/L) and B3 (200g/L), calculated according to the volume of the must. Fermentations were carried out for 11 days at 18°C, aged at 3°C for 15 days and bottled (7 g sucrose per bottle) at 20°C for 15 days. The beers were evaluated by HPLC (ethanol, glycerol, organic acids and phenolic compounds), GC-MS (volatile compounds) and antioxidant activity. The results corroborate that the addition of the adjunct to the wort increased the complexity of the beer's volatile profile, the phenolic composition and antioxidant activity. The adjunct-supplemented beers were influenced with respect to ethanol production. Beer B2 (61.6 g/L) and beer B3 (60.3 g/L) significantly increased the ethanol content (p < 0.05). Sample B1 (54.5 g/L) contained an ethanol concentration lower than P (56.5 g/L, control), but showed no significant difference (p<0.05). On the other hand, sample B1 showed the greatest significance (p<0.05) of glycerol formation (4.0 g/L) among all samples evaluated. Sample B2 generated a lower concentration of glycerol (3.2 g/L) (p<0.05). Although sample B3 was supplemented with a greater amount of adjunct (200 g/L), it had a similar glycerol concentration (3.5 g/L) to the control (P). Must supplementation with beet husks influenced the formation of organic acids, when compared to sample P (7.1 g/L), which contains the lowest content of organic acids, samples B1 (9.4 g/L), B2 (8.2 g/L) and B3 (8.5 g/L) showed a significant increase (p < 0.05) of organic acids. Fifty-seven volatile compounds were identified by GC-MS in all wort formulations, most abundant in beers added with beet husk, including some important esters for aromatic characterization of beers, isoamyl acetate, ethyl decanoate, 2-methyl- 1-butanol, ÿ-phenethyl acetate was more abundant in the control beer. Other groups of volatile compounds such as terpenes, hydrocarbons, phenols and sulfur compounds were more abundant in beers added with the adjunct. The supplementation of beet husks in beers had a positive impact on antioxidant activity, evaluated by the DPPH and ABTS methods and on the content of phenolic compounds. When the ABTS+• method was applied, the highest antioxidant activity was observed in sample B3 (24.50 mmol TEAC/L). However, in the DPPH method, samples B2 (12.25 mmol TEAC/L) and B3 (12.30 mmol TEAC/L) presented the highest antioxidant activity. Nineteen phenolic compounds from the group of flavonoids, tannins, benzoic acids, cinnamic acids and stilbenes were identified (Fig. 4B). Sample B3 had the highest significant content of flavonoids and stilbenes (p < 0.05). In contrast, a higher content of tannin and cinnamic acids identified in sample P (p < 0.05). In addition, sample P (control) had the lowest concentration of syringic acid, coumaric and caffeic acid; however, when the wort was supplemented with adjunct, the content of these compounds increased significantly. The results of this study suggest that the addition of beet husks resulted in an increase in the concentration of ethanol and organic acids and aromas of the beers, as well as reduced the formation of glycerol. Supplementation of the adjunct increased the antioxidant activity and phenolic composition, enhancing the bioactive characteristics of the beverage. Thus, the use of the adjunct demonstrated its potential to enrich the volatile and phenolic composition of beers, serving as a promising alternative for application as an adjunct in craft beers.