Integrated Biorefinery Strategy for Valorization of Pineapple Processing Waste into High-Value Products

The present study aims to recover value-added products from fresh pineapple processing wastes in an integrated biorefinery. Bromelain, a therapeutic protease, was extracted from pineapple by-products via an aqueous, low-temperature process. Bromelain-free biomass was rich in insoluble fibre and was further fractionated into hemicellulose, cellulose and lignin. The highest content of active bromelain was obtained from pineapple core waste of the different varieties namely, Smooth Cayenne (~ 1.9 ± 0.05 CDU/mg), Giant Kew (1.6 ± 0.05 CDU/mg) and MD2 (1.5 ± 0.1 CDU/mg). The activity of extracted bromelain was close to commercial stem bromelain (2.2 ± 0.1 CDU/mg, % purity of 95–96%). The fractionation of fibrous residue (97.2 ± 0.5 g/100 g of dry mass) was optimised, and maximum yield of hemicellulose (97.5 ± 0.2%) was obtained with 5% (w/v) alkali at the end of 1.5 h. The hemicellulose and cellulose-rich residues were further valorised into xylooligosaccharides (26.1 ± 0.4 g/100 g of hemicellulose) and glucose (85.3 ± 1.7 g/100 g of cellulose-rich residue), respectively. From one ton of fresh pineapple processing waste, ~ 1 kg bromelain, ~ 24 kg xylooligosaccharides, ~ 88 kg glucose and ~ 68 kg residual hemicellulose could be obtained. The proposed biorefinery concept not only addresses the environmental issues but also creates an opportunity to generate wealth in the form of products required for food and pharmaceutical industries from processing waste. As demand for more natural products is rising and consumers choice are prompted by healthy foods, conversion of pineapple waste into above mentioned valuable products creates a niche in food and therapeutics industry. Schematic for extraction of bromelain coupled with co-production of xylooligosaccharides and glucose from pineapple waste.