The Upcycling of Waste Frying Oil for Sophorolipid Production and the Effect on Its Productivity

Abstract

Waste frying oil (WFO) is a degraded oil from repeated exposure to high temperatures during cooking. Many research studies about recycling WFO are highly promoted to reduce its negative impact on the environment, with one of them focused on the production of a naturally-derived eco-friendly biosurfactant, sophorolipid (SL). SL has many advantages for the environment and people, but its production cost is high. Using WFO as a SL substrate for production may lead to cost reduction as it is less expensive than fresh oil. However, its physical characteristics are different from fresh oil and its effect on SL productivity (g/day) has not been investigated. This research focused on the effect of acid value (AV), peroxide value (PV) and carbonyl value (CV) of WFO on SL productivity. It was confirmed that the produced SL concentrations of 106.7~113.0g/L for six kinds of WFOs did not differ significantly from that of 111.1g/L for fresh oil with CV< 0.01. However, WFO required longer culture period (9 days) to reach the same SL concentration when higher degradation oil was used, compared to that of fresh oil (6 days).

graphical abstract