ISHS Acta Horticulturae 527: International Symposium on Growth and Development of Fruit Crops
MEASUREMENT OF GAS EXCHANGE CHARACTERISTICS OF WAXES APPLIED TO CITRUS FRUIT |
| Authors: | Peter D. Petracek, H. Dou, J. Mourer, C. Davis |
| Keywords: | Citrus paradisi Macf., gas exchange, postharvest handling, coatings |
| DOI: | 10.17660/ActaHortic.2000.527.8 |
| Abstract:
Citrus fruit destined for the fresh market are coated with water-based waxes to improve shine and reduce water loss. Waxing restricts gas exchange through the peel, however, and thus reduces internal O2 levels and increases internal CO2 and organic volatiles levels. Low O2 levels not only may stimulate anaerobic respiration and the production of compounds that impart off-flavors, but may also cause a peel disorder that severely reduces marketability. Consequently, the influence of formulation on gas permeability may become a factor in developing waxes for citrus fruit. Three approaches for assessing gas exchange characteristics of applied waxes were examined in these studies. In the first approach, internal gas levels of non-coated and coated fruit were measured by sampling the internal core of the fruit with a syringe. This approach provided a simple method for evaluating the in situ influence of wax formulation on internal gas levels. In a second approach, whole fruit gas exchange was calculated from measured respiration rates and steady state internal gas levels. This approach permitted the determination of O2 exchange characteristics of non-coated or coated intact fruit. In the third approach, gas transport coefficients were determined by measuring gas exchange through wax coated nickel grids in a flow through system. This approach allows the direct determination of gas flow characteristics (permeability, diffusion, and partition coefficients) of applied waxes. | |
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