Food processing by-products as sources of hydrophilic carbon and nitrogen for sophorolipid production

Abstract

Valorization of unavoidable food supply chain waste via biotechnology would be beneficial to the implementation of circular economics and may help increase market competitiveness of the final product via reduced feedstock costs. The suitability of post-milling wheat feed, potato processing scraps and sugar-beet pulps to act as the sole source of hydrophilic carbon (glucose), nitrogen and micronutrients for sophorolipid production using Starmerella bombicola was assessed. While all three feedstocks were viable for sophorolipid production, potato scraps were the most promising feedstock, with product titers of 60.5 and 77.8 g/L from batch and fed-batch bioreactor fermentations, respectively. The viability of potato hydrolysate as a feeding media was also demonstrated, with a three-fold increase in productivity of fed-batch over batch fermentation. This bodes well for future use of potato hydrolysate in more sophisticated fermentation schemes involving continuous feeding and in-situ separation. To holistically evaluate the viability of the potato waste as fermentation feedstock, supply chain modeling was conducted using the UK as a case study. The modeling identified ideal locations for industrial scale fermentation of the potato waste, such as North-West England, East Midlands and Central Scotland. The scale of the facility was shown to greatly alter the complexity of the supply chain, leading to significant changes in environmental and fiscal costs. Practical processing considerations and the implication on process techno-economics are also discussed. The insights provided will be useful for future development of sustainable feedstock for industrial sophorolipid production and industrial biotechnology in general.