Antioxidant changes and sensory properties of carrot puree processed with and without periderm tissue

Carrot purees were thermally processed with and without the periderm tissue after a long and short blanch time, with and without vacuum deaeration treatments. Samples were stored at an elevated temperature (40 degrees C for 4 weeks) to determine physicochemical changes affecting antioxidant activity (AOX), as measured by the coupled oxidation of beta-carotene and linoleic acid assay, and overall quality characteristics. Differences in AOX between treatments before thermal processing and during storage were associated with increased levels of phenolic acids and the subsequent development of numerous compounds thought to be oxidation products of phenolic acids. Samples processed with periderm tissue contained higher levels of phenolic acids, total carotenoids, and sugars than samples processed without periderm tissue. Strained carrot color was adversely affected by a long blanch time compared to a short blanch in treatments with and without periderm tissue, indicating improved color with reduced preprocessing heating. Sensory analyses by a quantitative descriptive analysis panel indicated increased musty/moldy and terpene flavors in samples processed with periderm tissue that were seemingly related to elevated levels of phenolic acids and volatile terpenoids. Terpenoid levels were reduced with deaeration steps prior to thermal processing. Processing carrots without removal of periderm tissue has proven to be a viable option when short blanch times and deaeration steps are employed.