Aproveitamento de resíduos do processamento de café para produção de carotenoides por leveduras e bactérias

Abstract

Coffee is one of the most important agricultural products in world trade. During its processing a large amount of residues are created, the deposition of which causes serious environmental problems. The bark and coffee pulp are the main by-products but only a small part of it can be reused. One alternative is to use them as a carbon source in fermentation processes for obtaining value-added products, such as microbial pigments. Carotenoids comprise a group of natural pigments widely distributed in nature with wide variety of structures and functions. They are responsible for yellow, orange and red in a variety of plants, animals and microorganisms. The study aimed to select a microorganism able to use the pulp and coffee husk extract as a carbon source for the production of carotenoids, determine the best method of recovery and extraction of these intracellular pigments and optimize production. Moreover, the study tries to evaluate the antioxidant and antimicrobial potential. Finally, to assess the β- carotene content present in the carotenoids extracts. Rhodotorula mucilaginosa CCMA 0156 strain was selected. The three tested extraction methods (acetone: methanol (7: 3 v / v) acetone: petroleum ether (1: 1 v / v) ethyl acetate: petroleum ether (1: 1 v / v)) were efficient in the recovery of carotenoids. Optimization of carotenoid production was achieved by experimental design technique. Maximum concentration of specific carotenoids (361.29±36.0 µg g-1) was obtained in pulp extract (6.68 %) medium containing 2 g l−1 glucose, 10.04 g l−1 peptone, 3 g l-1 yeast extract. Specific carotenoids (296.58±13.2) in husk extract (8.36 %) medium containing 6.36 g l−1 glucose and 3.68 g l−1 peptone. Carotenoids produced exhibited antioxidant and antimicrobial activities against pathogenic bacteria: Salmonella cholerasus, Escherichia coli, Staphylococcus aureus and Listeria monocytogenes and toxigenic fungi: Aspergillus flavus, A. parasiticus, A. carbonarius and A. ochaceus. β-carotene represented 13 and 20% of the total carotenoids produced in coffee pulp extract and husk extract, respectively.