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  • Author or Editor: E. Chalutz x
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Abstract

An inexpensive method for accurate control and measurement of fresh air introduction into experimental storage rooms is described.

Open Access
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Abstract

We discuss criteria for the design of cold storage facilities for use in research. Factors considered are: determination of the desired accuracy of temperature and relative humidity control, methods of air circulation and fresh air introduction.

Open Access

Abstract

With the expected ban on ethylene dibromide fumigation, cold exposure remains the only quarantine treatment for citrus fruit against the Mediterranean fruit fly. Following a cold treatment, ‘Marsh’ grapefruit (Citrus paradisi Macf.) developed chilling injury (Cl), mostly in the form of slight peel pitting on 3% to 10% of the fruit depending on the season and on other factors. There was no difference in the incidence of Cl between fruit treated at 0°C for 10 days or at 2.2° for 16 days as regulations require. The cold treatment also enhanced decay development during long-term storage of the fruit at 11°. Mold rots developed on Cl peel pitting, and their incidence increased from 1.7% to 3.5% during a storage period of 12 weeks. The presence of the fungicide Thiabendazole (TBZ) in the wax coating of the fruit reduced the incidence of Cl by more than 50%. Delayed cooling, i.e., keeping the freshly harvested packed fruit for 6 days at 17°C prior to initiation of cold treatment, reduced the incidence of Cl by the same extent. By combining a TBZ treatment with delayed cooling, the susceptibility of grapefruit to Cl can be reduced, and cold treatment can be practiced with a low risk of Cl and subsequent decay development.

Open Access

Abstract

Incorporation of thiabendazole (TBZ) in the wax coating applied to grapefruit significantly reduced the amount of low temp pitting which developed during prolonged storage at 8 and 12°C.

Open Access

Abstract

Postharvest treatments with thiabendazole (TBZ) and benomyl reduced the incidence of chilling injury (Cl) in grapefruit (Citrus paradisi, MacFadyen) as expressed by peel pitting. The effect persisted during prolonged storage at 2, 5 and 8°C. Thiabendazole was more effective than benomyl. The effectiveness of both TBZ and benomyl in water suspension increased when followed by waxing, but the greatest reduction in Cl was obtained with the chemicals incorporated in the wax coating. The effect of TBZ was enhanced by increasing concentration and residues, while the effect of benomyl did not change with concentration. Both chemicals were effective in reducing rots during cold storage. There was a marked increase in the incidence of rots during shelf-life. These rots, primarily of the mold type—Penicillium digitatum Sacc. and P. italicum Wehmer, developed mostly in pits induced by the low storage temperatures.

Open Access

Abstract

Changes in air composition of the citrus storage atmosphere and of the internal atmosphere of the fruit as affected by the ventilation rate were studied using 1 grapefruit and 2 orange cultivars. These changes were examined in relation to fruit weight loss, ethanol content of the juice, and rot development during storage periods of up to 5 months. Rates of ventilation affected the CO2 concentrations more than the O2 levels of both the external and internal atmospheres of the fruit. In small-scale tests, ventilation rates as low as 10%·hr−1 of the empty volume of the storage space did not cause major changes in the gas composition, nor did they effect fruit quality adversely. In commercial tests, however, an increased rate of ventilation (70% to 100%·hr−1) was needed to reach similar results. On the basis of this information we recommend reducing the ventilation rate in commercial citrus storage rooms from 150% or 200%·hr−1, the rate now commonly employed, to 100%·hr−1. This reduced ventilation rate will help lower costs of refrigeration, while maintaining good fruit quality.

Open Access

Abstract

Precooling at -2°C for 6 - 24 hrs prior to simulated ventilated shipment reduced weight loss of citrus fruit. Weight loss from the fruit was reduced as cooling rate increased. The difference in weight loss between precooled and control fruit was maintained during simulated shipment and after storage. Precooling the fruit to temp below 0°C could adversely affect its quality and should be avoided.

Open Access

Abstract

Peel injury in 3 citrus fruit cultivars fumigated with ethylene dibromide (EDB) was due to the persistence of resudue of the fumigant in the fruit peel. Initial resudues after fumigation were proportional to the concn and time of exposure. The desorption rate during aeration increased with temp. Incidence of peel injuries was highest in fruit stored at low temp or wrapped in polyethylene bags, probably due to prolonged action of EDB residues on the peel.

Storage of fumigated fruit in an atmosphere containing an increased concn of CO2 delayed the appearance of damage. Susceptibility was greatest in ‘Marsh’ grapefruits, followed by ‘Shamouti’ and ‘Valencia’ oranges.

Open Access

Jewel sweetpotato storage roots previously treated with ultraviolet (UV–C) light and then stored for 30 days before artificial inoculation with Fusarium solani showed increased resistance to Fusarium root rot; as indicated by reduced lesion size, the rate of decay development of rotted tissues. There was a hormetic relationship between the incidence of Fusarium root rot and UV–C doses. The optimum dose of UV which reduced Fusarium root rot was 3.6× 104 ergs/mm2. Exposure of sweetpotato to UV–C doses promoted phenylalanine ammonia–lyase (PAL)4 production with the maximum PAL activity occurring at 3.6×104 ergs/mm2. Crude extracts from UV–C treated sweetpotatoes reduced germination, germ tube elongation and growth of F. solani when compared to untreated extracts.

Free access

Low doses of ultraviolet light (254nm UV–C) irradiation reduced postharvest rots of pome, stone and citrus fruits. Brown rot (Monilinia fructicola) of `Elberta' and `Loring' peaches was significantly reduced by UV–C. Alternaria rot (Alternaria spp.) and bitter rot (Colletotrichum spp.) the principal storage rots of `Golden Delicious apples showed significant reduction following UV–C treatment. Further application of UV–C was effective in controlling green mold rot (Penicillium digitatum) of `Dancy' Tangerines and `Marsh Seedless' grapefruits, stem end rot (Alternaria citri), as well as sour rot (Geotrichum candidum) of `Dancy' tangerines after irradiation.

Free access