Towards a Valorization of Corn Bioethanol Side Streams: Chemical Characterization of Post Fermentation Corn Oil and Thin Stillage
2020
Gabriella Di Lena | Petra Ondrejíčková | Josè Sanchez del Pulgar | Veronika Cyprichová | Tomáš Ježovič | Massimo Lucarini | Ginevra Lombardi Boccia | Stefano Ferrari Nicoli | Paolo Gabrielli | Altero Aguzzi | Irene Casini | Roberto Caproni
First-generation biofuel biorefineries may be a starting point for the development of new value chains, as their by-products and side streams retain nutrients and valuable molecules that may be recovered and valorized for high-value applications. This study provides a chemical characterization of post-fermentation corn oil and thin stillage, side streams of dry-grind corn bioethanol production, in view of their valorization. An overall long-term study was conducted on the two co-products collected over 1 year from a bioethanol plant. Water content, acid value, sedimentation, mineral composition, and fatty acid profiles were analyzed on post-fermentation corn oil. Results highlighted that its acid value was high (19.72&ndash:24.29 mg KOH/g), indicating high levels of free fatty acids, but stable over the year due to standardized operating conditions. The fatty acid profile was that typical of corn oil, with a prevalence of linoleic (54&ndash:59% of total fatty acids) over oleic (23&ndash:27%) and palmitic (12&ndash:17%) acids. Macronutrients, fatty acid, and mineral profiles were investigated in thin stillage. Results revealed the acidic pH (4.05&ndash:4.68) and high dilution (90&ndash:93% water) of this side stream. The dry mass was composed of fats (19&ndash:30%), proteins (8.8&ndash:12.8%), ash (8.7&ndash:9.5%), and fiber (7.3&ndash:9.8%). The concomitant presence of a variegate complex of molecules of nutritional interest in corn bioethanol co-products, with several potential high-value market applications, make the perspective of their recovery a promising strategy to create new cross-sector interconnections according to circular economy principles.
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