104C-6 |
Effect of storage temperature on vitamin content and other quality attributes of commercially packaged spinach |
S. PANDRANGI and L. F. LaBorde. Dept. of Food Science, Pennsylvania State Univ., 111 Borland Lab., University Park, PA 16802-2504 Among green vegetables, spinach is a rich source of carotenoids and folate. Harvested spinach is packed in ice and transported over long distances to processing facilities where it is washed and packaged for shipment to the retail stores. Since temperature abuse is likely to occur during this period, studies are needed to determine the stability of these vitamins as affected by temperature. Objectives were to determine the effect of storage temperature on folate and carotenoids stability and to monitor fresh weight, dry weight, microbial counts and enzymatic activity. Pre-packaged spinach (cv. Unipack 151) obtained from a fresh-cut processor was placed in temperature-controlled chambers at 4, 10, or 20oC. Spinach leaves exposed to air served as controls. Folate was measured using a microbiological assay and carotenoids were determined by HPLC. Fresh and dry weight, aerobic and psychrotrophic bacterial populations, and peroxidase and lipoxygenase activities were monitored. Based on visual appearance, spinach was unacceptable after 8, 6, and 4 days at 4, 10, and 20oC, respectively. At all temperatures, gas compositions inside the packages were similar to air indicating rapid diffusion of respired gases through packaging film. There was approximately 50% loss of folate in spinach in packages and controls at all temperatures. Significant losses (10-80%)of neoxanthin, violaxanthin, lutein, chlorophyll a, b and trans beta carotene were also observed. Fresh weight decreased by 40% during storage. Aerobic microbial populations at each temperature increased from (4.5 to 6.0-logs) at day 0 to a maximum of 7-logs with psychrotrophic populations following a similar trend. Peroxidase activity increased significantly at 4 and 10oC but did not change at 20oC. Lipoxygenase was unaffected by temperature. Significant losses of folate and carotenoids occur even when spinach is stored at 4oC. Therefore reported values for folate and carotenoids may not reflect actual levels in fresh-cut spinach.
Session 104C, Fruit & Vegetable Products: Vegetables (Processed)
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