Phenolic autoxidation is responsible for color degradation in processed carrot puree

Strained carrots were thermally processed with reduced oxygen pretreatments and exposed to elevated storage temperatures to accelerate physicochemical changes (40 degrees C for 4 weeks). Strained carrot pretreatments prior to processing included a nitrogen sparge (N(2)), blanch/frozen with nitrogen sparge (BFN(2)), oxygen sparge (O(2)), and a control (C) that received no pretreatment. Changes in color, total soluble phenolics, total carotenoids, phenolic acid molecular weight, sugars, and pH were monitored during storage. Greater losses of color, total soluble phenolics, and total carotenoids occurred in control and O(2)-sparged samples as compared to N(2)-sparged and BFN(2) samples. Molecular weight of phenolic acids was lower in nitrogen-sparged samples than control and oxygen-sparged samples. Phenolic polymerization due to autoxidation was responsible for color loss in processed strained carrots. Processing treatments that reduce residual oxygen may result in better color retention after processing and during storage. Determining the mechanism(s) and magnitude of these reactions are important for devising strategies to prevent quality loss in strained carrots.