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  • Author or Editor: Charles R. Barmore x
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Abstract

Chlorophyllase activity in rind tissue of calamondin (Citrus microcarpa Bunge) increased 195% following a 10 ppm ethylene treatment at 30°C for 24 hours with a concomitant decrease in chlorophyll. A 6 to 12 hour treatment with ethylene was required before detecting increased chlorophyllase activity. Cycloheximide applied immediately prior to the ethylene treatment reduced ethylene stimulated chlorophyllase activity by 60% and reduced chlorophyll degradation markedly, indicating that ethylene stimulated the synthesis or activation of chlorophyllase.

Open Access

Abstract

Pectinesterase (PE) activity was determined in avocado fruit (Persea americana Mill) at various times during controlled atmosphere storage (CA) and subsequent softening. A reduction in the initial softening time as related to storage temperature or ethylene accumulation in the CA unit was associated with a decrease in the PE activity of firm fruit at time of removal from storage. It is suggested that PE activity in fruit could be used to monitor a change in softening time during CA storage.

Open Access

Abstract

A diluting and dispensing system is described for providing concentrations of ethylene as low as 0.1 ppm to a number of different chambers in a continuous flow system for treatment of plant tissue. Several concentrations can be provided simultaneously. The system eliminates the need for routine recharging of the ethylene reservoir.

Open Access

Abstract

Using leaf expiants of Citrus madurensis Lour. cv. ‘Calamondin’, it was demonstrated that many chemicals will accelerate the abscission processes at concentrations of 10−2 to 10−1M. Representative of classes of chemicals tested were mineral acids, bases, and salts; organic acids and salts; non-ionic organic compounds. Several observations were made: Low (< 3) or high (> 13) pH will accelerate the abscission processes; cations and anions do differ in the capacity to accelerate the abscission processes but those that were most effective were active in the concentration range of 10−2 to 10−1M; inorganic PO4 −3 was as effective on abscission as the organic anions tested; acceleration of abscission by these various agents at 10−2M was accomplished without visible tissue damage.

Open Access

Abstract

Studies with enzymatically isolated cuticles revealed that the abaxial cuticle was the primary site of ethylene diffusion from the leaf. With fruits, the flavedo and cuticle of the rind were found to offer considerable resistance to ethylene diffusion. The albedo was quite permeable. Measurement at various positions on the fruit show that the point of stem attachment was apparently the path of least resistance for ethylene diffusion from the fruit cavity.

Open Access

Abstract

Preharvest development of external red color of ‘Irwin’ and ‘Keitt’ mango (Mangifera indica L.) was enhanced with an application of the antitranspirant poly-l-p-menthen-8-9 diyl (Vapor Gard) prior to commercial fruit maturity. Both the percentage of fruit surface area showing red color and intensity of the red color was increased. Red color development in storage at 21°C was not affected by Vapor Gard. This effect was specific for the anthocyanin pigment(s). Colorimetric measurements in both yellow and green areas indicated that Vapor Gard did not affect disappearance of chlorophyll and development of yellow color at time of or following harvest.

Open Access

Chopped `Salinas' crisphead lettuce (Lactuca sativa L.) was packaged in four types of polymeric films and stored at 1 or 5C for 14 days. Discoloration and off-flavors developed in lettuce stored in the two films in which the naturally produced CO2 rose above 20%. In the two films (oriented low-density polyethylene) with O2 transmission rates higher than 3000 ml·m-2· day-1·atm-1 at 22C, CO2 remained below 20%, O2 was between ≈ 2% and 15%, and the lettuce was acceptable after 14 days of storage at either 1 or 5C. Appearance and flavor were affected more by temperature than by length of storage.

Free access