. Commercial cooling of fruits and vegetables. Fruit; Fruit; Vegetables. PER CENT MARKETABLE FRUIT lOOr 50 60 TEMP- °F Fig. 3. General effect of temperature on the market life of fresh fruits and vegetables. Some commodities (for example, those showing chilling sensitivity) exhibit special characteristics which may cause important variations from this curve. tion begins. With highly perishable commodi- ties, a few hours' delay before starting cooling can cause damage which cannot be overcome by subsequent good handling practices. Cooling of strawberries, for example, should commence within 2 h
. Commercial cooling of fruits and vegetables. Fruit; Fruit; Vegetables. PER CENT MARKETABLE FRUIT lOOr 50 60 TEMP- °F Fig. 3. General effect of temperature on the market life of fresh fruits and vegetables. Some commodities (for example, those showing chilling sensitivity) exhibit special characteristics which may cause important variations from this curve. tion begins. With highly perishable commodi- ties, a few hours' delay before starting cooling can cause damage which cannot be overcome by subsequent good handling practices. Cooling of strawberries, for example, should commence within 2 hours of harvest. The longer the delay beyond this time, the greater the deterioration of the fruit (fig. 4). Temperatures favorable for maximum growth and development of rot organisms often coincide with field temperatures encountered during fruit and vegetable harvest. Without rapid handling and cooling, therefore, rot organisms may quickly consume the produce. The inhibiting effect of low temperatures on these organisms varies with the organism involved. Certain rot organisms will continue to grow, although slowly, below 32°F while others become com- pletely inactive at somewhat higher tempera- tures. One major cause of loss in many fresh fruits, the Rhizopus rot organism, will not grow at temperatures below 40°F. Thus, the presence of Rhizopus rot indicates a history of tempera- tures above 40°F. Ethylene physiology of fruits and vegetables Ethylene gas (C2H4) is produced by most if not all plant materials, and may have important beneficial or detrimental effects on fruits and vegetables during postharvest handling. The compound induces ripening in fruits and senes- cence (loss of green color, shedding of leaves, etc.) in other plant tissues. For the gas to exert an effect a certain threshold concentration must accumulate in the internal atmosphere of the 'issues, and produce temperature must be above a minimum level. Neither threshold concentra- tion nor minimum tempera
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