Acetic Acid as Value-added Product from Pesticide-free Banana and Pineapple Peels

Abstract

Wastes from banana and pineapple peels pose increasing disposal and pollution problems as they represent a large fraction of the fruit. One mitigating measure to address this concern is the conversion of these wastes into high-value products. This study explored the potential of producing acetic acid from banana and pineapple peels through fermentation. Physicochemical characterization showed an initial sugar content of 12.60% for banana peel and 11.61% for pineapple peel, thus indicating their potential for conversion to acetic acid. Further, the pesticide residue analysis in the peels revealed that organochlorines, organophosphorus, and pyrethroids are way below the maximum residue limit (MRL) values set by the Bureau of Philippine Standards (BPS), Joint FAO/WHO Codex Alimentarius Commission (CAC), and the European Commission (EC) Regulation No. 396/2005, which enhanced their suitability as raw material for use in fermentation. Processing the peels to achieve various sugar concentrations of 15% (15°Brix), 20% (20°Brix), and 25% (25°Brix), and the subsequent addition of Saccharomyces cerevisiae allowed the peels to undergo anaerobic fermentation to produce ethanol. The maximum amount of ethanol obtained at a temperature of 26.7 °C and pH of 3.63 was 10.81% v/v (Day 10) from banana peels and 10.60% v/v (Day 10) from pineapple peels at 27 °C and pH of 3.27, both from 20% (20°Brix) sugar concentration. Aerobic fermentation of the extract with Acetobacter aceti converted ethanol to acetic acid. The maximum amount of acetic acid produced, which was from 20% sugar solution at 27.4 °C and pH of 3.59, was 4.56% for banana peels after 16 d while that of pineapple was obtained after 18 d of fermentation at 28 °C and pH of 3.34. For both banana and pineapple peels, no significant differences in the amount of acetic acid produced from three different sugar concentration were observed. The acetic acid produced from banana and pineapple peels can be explored further for potential industrial applications