Utilization of food waste for bioethanol production in a circular bioeconomy approach

In this pioneering study, we explored the utilization of ten different types of food waste, categorized into three distinct groups, to produce bioethanol and the utilization of by-products from bioprocesses being utilized for incorporation into animal feed. In this study, suspensions of food waste (5% w.v-1) underwent gelatinization (G) or gelatinization combined with ultrasonic treatment (G + S), followed by hydrolysis using alpha-amylase, amyloglucosidase, pectinase, and cellulase enzymes. Subsequently, the waste was categorized into blends: EAS (potatoes), BNCP (processed foods), and ABP (fruits). The blends underwent hydrolysis using enzymatic kits and separate hydrolysis and fermentation (SHF), with and without supplementation with algal biomass as a source of micronutrients. The final composition of hydrolyzed waste was evaluated to determine its suitability for addition to animal feed. Potatoes and processed foods exhibited the highest hydrolysis efficiencies (HE), achieving maximum hydrolysis with amylolytic enzymes. The EAS and BNCP blends achieved HE levels exceeding 80%. The highest concentrations of bioethanol were attained in processes that incorporated supplementation of the EAS mixture with Spirulina platensis, achieving an 85.54% fermentative efficiency and yielding 0.33 g ethanol.(g glucose)-1. This result showed no difference compared to the supplementation of ABP and PNCP. The hydrolyzed waste demonstrated high levels of carbohydrates and proteins, rendering it a viable alternative for incorporation as an ingredient in animal feed. Therefore, alongside bioethanol production, there exists an opportunity to derive a by-product from this process, in alignment with biorefinery principles and promoting the bioeconomy.