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N. S. AFFRIFAH, M. S. Chinnan, and R. D. Phillips. Dept. of Food Science & Technology, Univ. of Georgia, 1109 Experiment St., Melton Bldg., Griffin, GA 30223-1797 In spite of the varied heat treatments applied to control the hard-to-cook defect, few studies have been directed at the enzymatic pathways proposed as being responsible for the defect. Current literature supports the role of phytase in the development of the defect through the formation of insoluble pectates. However, no attempts have been made to explore phytase inactivation as a strategy for preventing the hard-to-cook defect. The effectiveness of different pre-treatments in maintaining the storage stability of cowpeas was investigated. Factors were initial moisture content (13, 20%), steaming temperature (100, 121°C), and steaming time (2, 4, 6 min). Steamed cowpeas were dried at 60°C and stored at 4°C or 42° C/80% RH for 9 wk. Samples analyses were conducted before and after storage for cooked texture, phytase activity, phytate content, water absorption, electrolyte leakage, and pectin loss. The cooked texture following treatment was comparable to the control; before storage, peak force values for treated samples were between 504-639N and 616N for the control. Only steaming at 121° C for 4 or 6 min effectively prevented hardening during storage. Steaming reduced the phytase activity of cowpeas to 53to 64% of original activity; however, storage resulted in a significant increase in activity. Phytase activity was not correlated with cooked texture. Steaming and storage significantly decreased water absorption from 91.28% to 75.68 to 88.02% after 24h soaking. A decrease in phytate content and increases in electrolyte leakage and pectin loss were also recorded. Although the treatments resulted in better cooked texture, the improved storage stability of the treated cowpeas occurred through a pathway different from that typically associated with the hard-to-cook defect. This was evidenced by the lack of correlation between the cooked texture and the measured physiochemical indices.
Session 32, Food Chemistry: Component interactions and processing effects
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |