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  • Author or Editor: R. W. Buescher x
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The effects of ethephon concentration, maturity, and length of storage before treatment on red color development were determined in harvested rin tomatoes. Red color development was greater in fruits treated with 1% ethephon than in fruits treated with higher or lower concentrations. Ethephon-induced color was greater in fruits treated 42 days from anthesis than in fruits treated at 35, 49, 56, and 63 days. Less red color developed as time in storage before treatment increased. It is suggested that ethephon (ethylene) directs red color formation in rin fruits if it is applied prior to the onset of predetermined pathways which result in the expression of the yellow color.

Open Access
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Abstract

Hardcore in sweet potato roots (Ipomoea batatas (L.) Lam) is induced by chilling and subsequent exposure to nonchilling temperatures prior to cooking. The defect is detected only after cooking and could adversely affect consumer acceptance and utilization. Of seven cultivars tested, ‘Red Jewel’ and ‘Jewel’ were the least susceptible to hardcore, while ‘Georgia Jet’ and ‘Jasper’ were the most susceptible. Cured roots were more susceptible than those freshly harvested in all cultivars except ‘Centennial’. Exposure to ethylene during the post-chilling induction period did not reduce the incidence of hardcore but significantly reduced its severity.

Open Access
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Abstract

Organic acid and sugar levels were determined quantitatively by gas-liquid chromatography in tomatoes (Lycopersicon esculentum Mill.) stored up to 21 days at 2°C and subsequently ripened at 20°. The concentration of malic acid in the pericarp declined during chilling, but citric acid accumulated. Citric acid was considerably higher after ripening of fruit chilled for 21 days than in non-chilled fruit. Sucrose and fructose levels declined during storage while the concentration of glucose remained fairly constant. Both glucose and fructose levels were lower in fruit ripened after 4 and 21 days of low temperature storage than in non-chilled fruit.

Open Access
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Abstract

Turning tomatoes (Lycopersicon esculentum Mill.) were held at 20°C and exposed to ambient, 5, 10, 20, 40 and 60% CO2 with 21 ± 1% O2. C2H4 evolution was rapidly reduced when fruits were exposed to CO2. In 5, 10 and 20% CO2, C2H4 evolution continued to decline with increasing duration of exposure but after 4 days in 40 and 60% CO2, C2H4 evolution increased probably because of injury. Maximum retardation of color development occurred while exposed to between 10 and 20% CO2. After removal of CO2, color development advanced rapidly and after 4 days in air, color of fruits that had been exposed to 5 and 10% CO2 was indistinguishable from that of fruit held continually in air. Color of fruits exposed to 20, 40, and 60% CO2 never reached color of fruits held only in air, in addition, exposure to these concentrations reduced subsequent salability due to enhanced mold growth, uneven ripening, and watersoaking. Intermittent exposures to 20% CO2 and air caused rapid fluctuation of C2H4 evolution and retarded color development. CO2 was not effective in inhibiting wound induced C2H4 evolution.

Open Access
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Abstract

Postharvest exposure of snap beans to elevated CO2 (40%), but not reduced O2 (2.5%), enhanced softening when the pods were subsequently heated. Softening and solubilization of pectic substances induced by CO2 were related to lowered hydrogen ion concentrations, which were caused by the depletion of malic acid. In contrast, high CO2 stimulated succinic acid accumulation but did not alter citric acid levels. Blanching and boiling reduced the content of both succinic and malic acids in pods. Transelimination was effective in depolymerizing and solubilizing pectic substances in snap bean pods. The shift in pH induced by CO2 increased the transelimination reaction and thus increased pod softening.

Open Access

Abstract

Electrolyte leakage from tissue discs and internal conductivity of intact fruit of peach (Prunus persica (L.) Batsch) were determined during storage at 1°C and after transferring to 21°. Both methods produced similar results, however, the method used for measuring internal conductivity was rapid, nondestructive, and seemed to be more sensitive. Electrolyte leakage remained fairly constant while internal conductivity tended to decline during 5 weeks of chilling. Electrolyte leakage and internal conductivity increased when fruits were transferred to 21°. At 21° fruits which had been chilled for 2 weeks had enhanced leakage while conductivity was enhanced in fruits chilled for 1 and 2 weeks. In fruits transferred to 21° after 3 or more weeks of chilling, leakage and internal conductance declined and woolliness was concomitantly detected. The binding of free ions appears to be closely associated with woolliness in peaches.

Open Access

Abstract

Snap beans (Phaseolus vulgaris L.), when broken during harvesting and handling, develop a brown discoloration on the broken ends which is not removed by processing and is detrimental to the appearance and processed grade. Broken-end discoloration (BED) was controlled when samples were treated before storage with 7500 to 10,000 ppm SO2 for 30 seconds or when samples were stored in controlled atmospheres containing 20 or 30% CO2 for 24 hours. Processed quality attributes of color, flavor, texture, and sloughing were not affected by these treatments. Oxygen levels of 5% or less also controlled BED but caused off-flavors in the canned product. Elevated CO2 levels were not injurious to snap bean quality as long as O2 was maintained at 10% or higher.

Open Access

Abstract

Pectinesterase (PE), polygalacturonase (PG), and cellulase (Cx form) activities and softening of 4 physiological maturities were compared in normal and rin tomatoes (Lycopersicon esculentum Mil cv. Rutgers). PG, PE, and Cx-cellulase activities increased during ripening of normal fruits. In rin fruits, PG activity was not detected, PE activity remained relatively constant, and Cxcellulase activity increased during ripening. The lack of softening in rin fruits appears to be associated with the lack of PG activity.

Open Access

Abstract

Ripening is a dramatic event in the development of many fleshy fruits. Tomato ripening involves a number of chemical and physical changes which convert the fruit from a relatively inedible state to one of optimal quality (2, 19). These changes appear to be highly synchronized, as evidenced by the fact that respiratory patterns, rate of ethylene production, carotene development, and flavor and textural changes normally associated with the ripening process, occur in close succession during the relatively short period in which the fruit ripens (2, 22). The association of these changes with seed maturation supports the popular view that ripening is of adaptive significance in seed dispersal by rendering fruit attractive to animals responsible for dispersal.

Open Access

Abstract

Brown-end discoloration (BED) of broken snap beans (Phaseolus vulgaris L.) occurs whenever pods are held for several hours before processing. Increases in phenylalanine ammonia lyase (PAL), catecholase, and peroxidase activities as well as total phenolic content coincided with the development of BED. The intensity of BED and catecholase activity declined with increasing incubation temperatures (40 to 70°C). Perosidase activity did not decline until after 60° and PAL activity was stable through 70°. We therefore believe that catecholase oxidation of phenolic substances are directly associated with BED of snap beans.

Open Access