Evaluation of Changes in the Microbial Profile, Physico-Chemical and Nutritional Attributes During the Bioconversion of Soursop (Annona muricata) Must to Wine

Abstract

Low alcoholic wines of amiable qualities were produced from soursop (Annona muricata). The fermentation process was for a period of 7 days at 26 ± 2⁰ C and soursop wines coded I, II, III and IV were produced. The microbial counts were taken during the fermentation process using Nutrient agar and Malt Extract agar respectively. Changes in the physicochemical and nutritional properties (pH, temperature, specific gravity, alcohol content, titratable acidity, sugar content, carbohydrate content, soluble protein, ash content and fat content) during the control/spontaneous and modified fermentation processes of the soursop must were also monitored. The mean bacterial counts ranged from 0.1×10⁴ cfu/ml to 1.7×10⁴ cfu/ml respectively. The mean fungal counts varied from 0.1×10⁴ cfu/ml to 0.6×10⁴ cfu/ml respectively. The differences in the microbial counts were insignificant (P>0.05). Microbial isolates identified included; Bacillus megaterium, B. subtilis, B. coagulans, Streptococcus sp., Staphylococcus sp., Alcaligenes sp. and B. polymixa, Saccharomyces cerevisiae, Trichoderma sp. and Penicillium sp. Wine IV had the lowest total organoleptic attributes while wine I had the highest total organoleptic attributes. This study revealed that low alcoholic wine with appreciable characteristics and acceptability can be produced from ripe soursop fruit.

Keywords: Soursop, bacterial counts, fungal counts, must, organoleptic

Nig J. Biotech. Vol. 25 (2013) 1-11