44C-18 |
Phenolic synthesis in maroon carrots treated with ethylene and methyl jasmonate stored at different temperatures |
J. B. HEREDIA, J. G. Loaiza, and L. Cisneros-Zevallos. Department of Horticultural Sciences, Texas A&M University, Horticulture & Forest Science Bldg., Room 202, College Station, TX 77843-2133 Ethylene and methyl jasmonate are known to induce accumulation of some phenolic compounds in plant tissues. Carotenes and phenolics, such as isocoumarins and anthocyanins, influence flavor and color in carrots. It is also known, that the presence of these phenolic compounds may protect crop products from oxidative deterioration and also increase the health and nutritional properties for human diets. This research was done to determine if physiological stresses such as application of ethylene, methyl jasmonate and storage temperature induce phenolic compound synthesis and/or accumulation in maroon carrots. Maroon carrots were treated with air (control), 1000-ppm ethylene, and methyl jasmonate (headspace vapors). Treated carrots were stored at 0, 10 and 20°C and alternating temperature conditions (being transferred back and forth from 0°C to 20°C). Total carotenes, phenolics, anthocyanins and isocoumarins were evaluated using spectrophotometric methods. Titratable acidity, total soluble solids and pH were also evaluated as quality parameters. Ethylene induced accumulation of carotenes (25% at 0°C), and caused an increase in isocoumarins (154-280%) at all studied temperatures. The combination of ethylene treatment and alternating temperature resulted in the highest isocoumarin accumulation (280%). Methyl jasmonate showed an increase in carotenes (30%), anthocyanins (6%) and acidity (68%) only at the alternating temperature conditions, but did not induce isocoumarin accumulation at any temperature. In all treatments, total phenolics increased in relation to initial day (27-57%). Total soluble solids, titratable acidity and pH seems to be altered by temperature effects. Results suggest that treatments of ethylene, methyl jasmonate and temperature induced the accumulation of phytochemicals such as isocoumarins, carotenes and phenolics with different effects in maroon carrots. Manipulation of stress conditions show a potential to induce the accumulation of compounds that could improve food value by conferring functional properties.
Session 44C, Fruit & Vegetable Products: Chemistry
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