Valorisation of orange peel: supplement in fermentation media for ethanol production and source of limonene

The usage of the citrus wastes for strategic valorization is a concept for the production of various commercial products. Wastes from citrus fruits have a considerate amount of sugar and limonene. In the present work, partially removed limonene from hydrolysed orange peel was used for supplementation as carbon source in minimal media for the production of ethanol. A novel yeast strain, Saccharomyces cerevisiae strain BT1 (MK373758) was isolated from Toddy, obtained from Borassus flabellifer (toddy palm), Bhatan, Mumbai. This strain was used in the formulated fermentation media for the production of bioethanol. Optimization of critical parameters was done for pH, temperature and time of fermentation vs production of bioethanol. The Brix, pH, sugar content and ethanol content were measured during the fermentation process. The ethanol content was estimated by dichromate method and high performance liquid chromatography (HPLC) and the yield obtained was 0.95%. In addition, limonene was also extracted from hydrolysed orange peel and estimated by gas chromatography-flame ionization detection (GC-FID) and was found to be 0.4% (v/v). The two valuable products, bioethanol, and d -limonene, obtained from orange peel waste, promises its valorisation at a larger scale. Graphical abstract