Valorization of citrus lemon wastes through biorefinery approach: An industrial symbiosis

The present article deals with the processing of Assam lemon (AL), which is rare and under-explored variety and is abundantly available in North-East India. Studies on valorization of Assam lemon waste (ALW) into various value-added products are limited. During pre-processing of ALW a 4.19 ± 0.11% (v/w) essential oil and 12.67 ± 0.46% (w/w) pectin were recovered. Thereafter, the treated biomass was subjected to partial simultaneous saccharification and co-fermentation (PSSCF) for ethanol production. The maximum ethanol yield was obtained as 12.16 ± 0.15% (v/v) when solid loading, temperature, time and pentose to hexose utilizing strains ratio were kept as 30% (w/v), 35 °C, 24 h and 0.5, respectively. Model was found to be significant having R2 and R2(adj.) of 99.93 and 99.86, respectively. Fermented biomass showed a drastic reduction in crystallinity index (19.49%) along with a major change in FTIR peaks, which corroborates the improved bioconversion process. The overall process efficiency was found to be 69.17%. © 2021 Elsevier Ltd