Produção de vinagre como estratégia de aproveitamento tecnológico da amora-preta: avaliação do processo submerso e do processo lento

Abstract

Blackberry (Rubus sp) is part of the so-called berries, presenting remarkable nutritional features, such as high content of mineral salts, vitamins and bioactive compounds with biological activity. Such compounds may aid in the prevention of cardiovascular diseases, cancer, diabetic retinopathy, fibrocystic and eye diseases, among others. Nevertheless, blackberry presents a fragile structure and a high respiratory activity, resulting in reduced shelf-life. In this way, it is important, from a technological viewpoint, to develop new products derived from blackberry which preserve the fruit original nutritional quality and bioactive compounds. Thus, the present work aimed at the technological utilization of blackberry for developing vinegar by means of the submerged and the slow processes with successive cycles of acetification. Initially, an alcoholic fermented product was obtained in stirred tank bioreactor. Subsequently, acetic fermented products were obtained either in a grapia (Brazilian ash) vinegar barrel or in a bench bioreactor. In the alcoholic fermentation, an industrial strain of Saccharomyces cerevisiae r.f. bayanus was used. In the acetic fermentation, wild strain of acetic acid bacteria isolated from colonial vinegar from Pato Branco city was used. The alcoholic fermentation presented yield of 0.39 g/g, volumetric productivity of 1.77 g/Lh and efficiency of 75.5%, besides high polyphenol contents (983.35 mg GAE/100g and 1702.52 mg GAE/100g). In the successive acetification cycles performed in grapia barrel, average production of 51.6 g acetic acid/L, yield of 72.2% (as acetic acid) and volumetric productivity of 0.4 g/Lh were observed. On the other hand, the acidification performed in bench bioreactor presented lower values of average production (42.26 g acetic acid/L) and yield (70.2%). High polyphenols and anthocyanins content along with high antioxidant activity were observed in the vinegars obtained by both production processes. Vinegars produced from blackberry can be considered gourmet vinegars with high functional potential. The transformation of blackberry into vinegar might be a strategy of value addition to the production chain, contributing for spreading this culture in Brazil.