Pullulan production by Aureobasidium pullulans MTCC 1991 from apple pomace and its characterization

Apple pomace, a by-product of the apple juice processing industry, is significant agro-based waste in the Union Territory of Jammu & Kashmir, India. A considerable amount of apple is processed for juice production, resulting in a surplus of apple pomace, which is generally underutilized. This study utilized apple pomace as a substrate matrix for producing pullulan by applying Aureobasidium pullulans MTCC 1991. Solid-state fermentation was done at a lab scale in Erlenmeyer flasks to produce this exopolysaccharide. The suitable conditions for solid-state fermentation of apple pomace were: a solid-liquid ratio of 1:4, inoculum volume of 3 mL, pH 6 and incubation time of 14 days. A yield of 42 mg/g dw was obtained in the control sample without adding any other nutrients or chemicals. The addition of yeast extract at a concentration of 1% (w/w) and sucrose (5% w/w) significantly (p < 0.05) increased the yield to 62 mg/g dw and 75 mg/g dw, respectively. The purified pullulan had similar characteristics to that of standard pullulan, as confirmed by ATR-FTIR, H NMR and TLC techniques. Pullulan production from apple pomace can be a better way to utilize this by-product from the apple juice industry. It will be a cost-effective technique for pullulan production as an inexpensive substrate and an environmentally friendly approach are also used.