Effect of storage parameters on folate and carotenoid retention and other quality characteristics in fresh-cut spinach

Spinach is a popular green leafy vegetable that is a significant source of folate and carotenoids. This research focused on optimizing the folate assay for spinach and investigated the effects of temperature, controlled atmosphere, and simulated injury to leaf tissue on the retention of folate and carotenoids and other quality attributes of fresh cut spinach.; The microbiological method for determination of folate in was improved by enhancing the recovery of L. rhamnosus using a microaerophilic enrichment procedure. Optimum pH values for release of bound folate in spinach samples treated with alpha-amylase or protease were 3.0 and 4.0, respectively. alpha-amylase had no significant effect on measured folate, however, addition of protease at pH 4.0 for 8 h significantly increased measured folate. A dual enzyme treatment (protease and conjugase) is sufficient to determine folate content in spinach.; The effect of storage temperature (4, 10 and 20°C) on retention of folate, carotenoids, and other quality characteristics in packaged fresh spinach were determined. Based on visual color and appearance, spinach was unacceptable after 8, 6, and 4 d at 4, 10, and 20°C, respectively. Color differences (DeltaE), chlorophyll degradation, fresh weight loss, and microbial populations increased at all storage temperatures and occurred more rapidly at higher temperatures. Peroxidase activity increased but was not significantly (p > 0.05) affected by storage temperature. Lipoxygenase activity was unaffected by storage time or temperature. Substantial losses of folate and carotenoids occurred at each storage temperature. Only 53% of folate in packaged spinach was retained after 8, 6, and 4 d at 4, 10, and 20°C, respectively. Carotenoid losses increased with temperature with only 54, 61, and 44%, respectively, of initial detected levels remaining. Folate and carotenoid retention, and quality changes were for packaged samples were similar to air-exposed samples.; The effect of oxygen concentration (4, 6, 8 and 21%) on retention of folate, carotenoids, and other quality characteristics in fresh spinach was determined. Based on visual appearance, spinach at all oxygen concentrations remained acceptable for up to 12 d at 4°C and 98% RH. Color differences (DeltaE), chlorophyll degradation (except 4% O2), and microbial populations increased at all oxygen concentrations. Fresh weight, peroxidase and lipoxygenase activities were unaffected by oxygen concentration or storage time. (Abstract shortened by UMI.)...