Dados do Trabalho

Título

AGROINDUSTRIAL WASTES FROM BRAZILIAN CENTRAL PLAIN (CERRADO): NUTRIENT CONTENT, FERMENTATION POTENTIAL AND SCALE-UP KINETICS

Introdução

The trade of fruits from Brazilian Central Plain (CERRADO), has significantly grown during the last few years, not only because of the consumption of fresh fruits but also the industrial production of derivatives such as ice-creams, fermented drinks and desserts. This generates an expressive amount of wastes like peels, seeds, shells and bagasse, which are commonly discarded despite their rich nutrient content and their potential use as substrate in biotechnological processes. This work compares carbohydrate content as well as yeast growth and ethanol yield during fermentation of seeds from Eugenia dysenterica (cagaita), Hancornia speciosa (mangaba), Syzygium cumini (jamelão), Annona crassiflora (araticum) and shells from Dipteryx alata (baru) and Caryocar brasiliensis (pequi).

Material e Métodos

Previous fermentation experiments were performed cultivating the strain S-05 of the yeast Saccharomyces cerevisiae in Erlenmeyer flasks with 100 mL culture broth containing 9% of each waste sample shaked at 50 rpm during 72 hours in triplicate repetitions. Carbohydrate concentration was determined by spectrophotometric analysis (Dubois), cell growth was evaluated by direct counting in Neubauer chamber and ethanol production was determined out of weight difference after CO2 release (Santos et al.). Kinetic profiles were obtained from cell growth, carbohydrate consumption and ethanol production data, collected in regular time intervals of 6 hours during fermentation process in a stirred tank reactor with a total volume of 5 litres.

Resultados e Discussão

The carbohydrate concentrations ranged between 300 mg per mL (baru shells) and 35.6 mg per mL (mangaba seeds), while maximal cell growth values varied from 75 million cells per mL (pequi shells) to 14 million cells per mL (araticum seeds). The higher ethanol yields were obtained from fermented pequi shells (9.14%) while the lower ones were from mangaba seeds (2.0%). Specific growth rates were similar in all studied samples, being 0.153 h-1 during exponential growth fase and 0.062 h-1 during the stationery growth fase.

Conclusão

These results evidence the potential of all studied wastes as substrates for bioethanol production and their suitability for scale-up procedures. These residues could be considered as sustainable biofuel sources that should contribute to reduce waste volumes during manufacture of industrial derivatives from those fruits.