Changes in the oxidative state and nutrimental composition of orange residue (Citrus sinensis L.) dehydrated and ensiled at different times

ABSTRACT The aim was to evaluate the changes in oxidative state and chemical composition of orange residues dehydrated and ensiled at different times. Residues of fresh oranges after juice extraction were ground and divided into three parts, the first analyzed while fresh, the second dehydrated and the third ensiled in 7 plastic mini-silos and opened at 7, 14, 21, 28, 35, 42 and 49 days. Dry matter, crude protein, neutral detergent fiber, acid detergent fiber, pH, lactic acid, antioxidant capacity, phenols and flavonoids were measured. It was found that stabilization of lactic acid production occurred on day 28 of ensiling. The loss of dry matter and the increase of crude protein occurred from the 7th day to present later no changes; the process of fermentation during ensilage modified the antioxidant compounds, highlighting the increase (P<0.05) in the concentration of gallic, chlorogenic, vanillic, p-hydroxybenzoic and coumaric acids; the antioxidant capacity increased until reaching its maximum value on the 35th day of ensilage. Regarding dehydration, protocatechuic acid increased, while the other phenolic acids tended to disappear. It is concluded that the dehydration and ensilage of orange residues are dynamic processes that imply changes in the concentration of nutrients and antioxidants.