36B-13

A. R. BONILLA¹, E. Thompson², C. Velazquez², and R. Lopez². (1) CITA, Univ. de Costa Rica, Ciudad Universitaria Rodrigo Facio, San Pedro, Mtes Oca, San Jose, 2060, Costa Rica, (2) CITA, Univ. de Costa Rica, San Jose, Costa Rica

Rising oil prices are motivating many nations to seek reliable energy alternatives. A surplus of bananas in international markets may be an important resource for the production of ethanol. The study objective was to evaluate banana pulp treatments to increase concentration of fermentable sugars. Pulp from fully ripened bananas (Musa AAA, Cavendish variety, Gran naine cultivar) was used throughout the study. The treatments evaluated were blanching and addition of a commercial pectolytic preparation before and after sterilization. Viscosity and suspended soluble solids (SS) were measured. Conditions adequate for the pectolytic treatment were also evaluated. Once the liquefaction parameters were established, the addition of a mixture of amylase and amyloglucosidase enzymes was assessed. The treated pulp (22% total sugar) was fermented by Saccharomyces cerevisiae (1.5 g inoculum/kg media). A 22 % sucrose solution was used to compare the banana fermentation. Nutrient salts were added to both media. Treatments and fermentations were run five and three times respectively. Pulp recovery was 66% without blanching and 50.7% after blanching (p < 0.05). Sterilization before enzymatic treatment reduced viscosity (5470 cP) and lowered SS (56.9%) more than adding enzyme first (3530 cP and 43.5% SS) (p<0.05). Highest viscosity reduction (64.5 cP) and lowest SS (45.5%) were obtained with 200 mL/kg of enzymatic preparation and 120 min reaction time (p<0.05). The addition of amylase and amyloglucosidase increased glucose concentration from 5.22 % to 5.86% (p<0.05). Ethanol productivity was higher from banana pulp than the sucrose solution, 7.09 vs. 4.76 g ethanol/kg-h (p<0.05). Higher yeast populations were reached at the stationary phase using banana pulp instead of sugar solution (4.0 x 108 vs. 2.0 x 108 UFC/mL) (p<0.001). Ethanol yield from the pulp was 7,0%. Enzymatic-treated unblanched banana pulp appears to be a promising source for ethanol production.

Session 36B, Biotechnology: General
8:30 AM - 12:00 PM, Monday AM Room Hall I-2

2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana