ARS | Publication request: Nutrient composition and flavonoid content of orange fermentation residues

Submitted to: Subtropical Technology Conference Proceedings
Publication Type: Abstract
Publication Acceptance Date: October 1, 2008
Publication Date: October 16, 2008
Citation: Widmer, W.W. 2008. Nutrient composition and flavonoid content of orange fermentation residues. Subtropical Technology Conference Proceedings. 59:16.

Technical Abstract: Drying the waste (CPW) from citrus juice processing into citrus pulp pellets (CPP) for use as a cattlefeed is currently profitable with the record prices seen during the last season. However, prices could well return to the marginal values they have been for many years and concerns regarding volatile organic emissions produced during CPP production remain. Just one third of the residual peel oil that is present in citrus waste is recovered during CPP production with most being vented to the atmosphere during the drying process. Improvements in limonene recovery and development of alternative value added co-products obtained from CPW can add stability and value to the citrus crop. With the new process developed to recover 85% of the limonene contained in citrus waste and utilize all the fermentable sugars for ethanol production, the residue left after fermentation and distillation still contain half the solids originally present in CPW. These need to be utilized and the composition of the residue was evaluated for flavanoid and nutrient content for comparison with CPP currently utilized as cattlefeed. Proximate analysis of the distillation residues revealed small differences with commercial CPP. The distillation residues contained about 70% more ash and 40% more protein than commercial CPP. The polymethoxylated flavones were left intact and evenly distributed between the supernatant and insoluble solids portions of the residue. The flavanone glycosides narirutin and hesperidin underwent some hydrolysis, but greater than 80% remained in the glycoside form and approximately 80% of the hesperidin was present as a precipitate in the insoluble residue.