ISHS Acta Horticulturae 318: II International Symposium on Specialty and Exotic Vegetable Crops
POSTHARVEST RESPIRATION, MOISTURE LOSS, SENSORY ANALYSIS AND COMPOSITIONAL CHANGES IN JICAMA (PACHYRRHIZUS EROSUS) ROOTS |
| Authors: | K. A. Bergsma, J. K. Brecht |
| Keywords: | Carbohydrates, chilling injury, curing, dry matter, films, waxes, yam bean |
| Abstract:
Respiration rates of jicama roots were very low, initially ranging from 5 ml CO2·kg-1·hr-1 at 5°C to just under 30 ml CO2·kg-1·hr-1 at 20°C. Respiration rate declined to 10 ml CO2·kg-1·hr-1 during 13 days at 20°C, but rose slightly at 10°C during the same period while remaining constant at 5° and 15°C. Dry matter of individual roots ranged from 9.5 to 12.5% and differed little from initial levels after 19 days of storage. Initial soluble solids content (SSC) was about 6% on a fresh weight basis and increased at all temperatures up to 19 days of storage. Total soluble sugars (TSS) were about 45% of the initial dry weight and increased during the first 7 days of storage at all temperatures, however TSS subsequently declined at 20°C between 7 and 19 days while continuing to increase at 5°, 10° and 15°C. TSS correlated well with soluble solids measurements. Starch content was about 22% of the initial dry weight and decreased during the first 7 days of storage at all temperatures. Starch content continued to decrease between 7 and 19 days of storage at 5°, 10° and 15°C, but increased at 20°C during the same time period. The rate of fresh weight loss was nearly linear for up to 17 days at all storage temperatures, but was greater at 15° and 20°C than at 5° and 10°C. Some roots lost as much as 35% of their initial fresh weight during 17 days at 20°C. Chilling injury symptoms occurred following 7 days at 1°, 5° and 10°C with an additional 2 days at 20°C to allow symptoms to develop, but were not evident during up to 49 days at 15°C. Jicama roots stored for 8 days at 15°, 25° or 30°C and 100% relative humidity did not show any evidence of periderm formation when compared to control roots held at 20°C and ambient humidity or when compared to initial samples. Paraffin wax was the most effective treatment in reducing moisture loss but resulted in the highest losses due to decay; roots coated with carnauba wax lost nearly as much moisture as the control. Wrapping with PVC film reduced moisture loss by nearly 50% compared to the control without any losses | |
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