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Open access

E. Chalutz, Mina Schiffmann-Nadel, J. Waks, and F. S. Lattar

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

T. A. Wheaton and Ivan Stewart

Abstract

Substantial improvement in the external color of harvested citrus fruit was achieved by holding at optimum temperature and ethylene concentration. Under specific conditions, marked improvement in orange and red pigmentation occurred. Initial color development was most rapid at 30°C but carotenoid accumulation ceased after a few days. Best color was obtained with fruit held at 15-25°C for longer periods of time. Optimal ethylene concentration decreased as temperature decreased. At the lowest temperature, high ethylene concentration inhibited color development.

Full access

Steven Pao, Peter D. Petracek, and G. Eldon Brown

Peeling and storage characteristics of citrus fruit infused with water or enzyme solution were compared. Fruit were vacuum- or pressure-infused with water or water-containing pectinase. The enzyme treatment did not affect peeling times of white or red grapefruit, oranges, or tangelos. Pressure and vacuum infusion methods produced similar results. Grapefruit and oranges infused with water had significantly less juice leakage and were firmer than fruit infused with enzyme. Microbial levels and respiration rates and ethylene emanation during storage were the same for enzyme- and water-treated fruit.

Open access

M. F. Oberbacher and G. Eldon Brown

Abstract

Growth of fungi from the surface of excised peel taken from Florida citrus fruit interfered with controlled studies on pigment changes of the flavedo. Control of these fungi was not achieved even though whole fruits were dipped in various concentrations of sodium hypochlorite before removing discs of peel for incubation in culture on a defined medium (5). Normally, the presence of fungal growth was evident on all discs of excised peel after 3 to 5 days incubation at 30°C. Development of a technique to control these fungi was necessary to allow longer incubation of discs to observe pigment changes.

Free access

Jacqueline K. Burns

Oxygen uptake and glycosidase activities were examined in normal and granulated juice vesicles of several citrus fruit. Oxygen uptake was low in normal juice vesicles isolated from freshly harvested `Lee' tangelos [Citrus reticulate Blanco cv. Clementine × (Citrus paradisi Macf. cv. Duncan × Citrus reticulate Blanco cv. Dancy)] and stored `Dancy' tangerine (C. reticulate Blanco) and `Marsh' grapefruit (Citrus paradisi Macf.) (35.7, 17.9, and 11.6 μl O2/hr per g fresh weight, respectively), but was 2- to 3-fold higher in granulated juice vesicles. As severity of granulation increased in grape. fruit, O2 uptake increased. Oxygen uptake in normal and disordered juice vesicles of all citrus fruit examined was reduced to nondetectable levels with 0.1 mM KCN and was insensitive to salicylhydroxamic acid. α - and β -galactosidase and α- and β -glucosidase activities were present in extracts of normal grapefruit juice vesicles (123, 214, 51, and 25 nmol·hr-1·g-1 fresh weight, respectively) and was 2- to 3-fold higher in extracts of granulated tissue. α- and β -mannosidase activities, nondetectable in normal juice vesicle extracts, were present in extracts from granulated tissue. The results suggest that increased metabolic activity occurs in granulated juice vesicles and the energy produced may be used to support cell wall synthesis and modification. Increases in O2 uptake and glycosidase activities correlate well with observed symptoms of section-drying in citrus.

Free access

Huating Dou* and Gary A. Coates

Influence of 1-MCP application in citrus fruit juice color and vitamin C concentration was determined for `Fallglo' tangerines, `Valencia' oranges, and white `Marsh' grapefruit. MCP was applied at 500 μL·L-1 for `Fallglo', and 1000 μL·L-1 for `Valencia' oranges and `Marsh' grapefruit at 75 °F for 7 hours in a container of 3' × 3' × 3.5' dimension. After three months storage at 40 °F and 93% relative humidity, vitamin C concentration in juice (mg/100 mL) was higher in MCP treated than non-treated `Valencia' oranges (37.1 vs. 30.6) and `Fallglo' tangerines (26.9 vs. 24.0). No difference was found in vitamin C concentration from `Marsh' grapefruit juice either treated (27.9) or non-treated (28.7) with MCP. Forty percent of vitamin C concentration was lost from one month after packing to the third month in storage for white `Marsh' grapefruit. Vitamin C loss was much slower for tangerines in comparison to grapefruit in postharvest. Juice color was not influenced by the MCP application for `Valencia' oranges while Hue and Chroma were improved in treated fruits for `Fallglo' tangerines and `Marsh' grapefruit compared to non-treated fruits. Applying MCP before degreening reduced vitamin C degradation 6 weeks after packing but not at 12 weeks for `Fallglo' tangerines. However, fruit color was improved at 6 and 12 weeks of storage. These results are important for postharvest quality management of citrus fruit and juice.

Open access

S. Ben-Yehoshu, B. Shapiro, and R. Moran

Abstract

The marked extension of life of citrus fruit by individual seal-packaging has attracted both basic and commercial interest (5). Delayed physiological deterioration by seal packaging was related to the alleviation of water stress of the harvested fruit (10). A risk from this technique is the possibility that decay might be enhanced by the water-saturated atmosphere of the sealed fruit (5). Although most reports do not describe any marked effect on decay, several noted that the percent decay of ‘Shamouti’ and ‘Valencia’ oranges was lightly increased by seal-packaging (5). This increase could be a function of time, since the storage life of sealed fruit is longer than that of nonsealed fruit (5, 20). Sealing of citrus fruit increased stem-end rot in general and Alternaria rot in particular (5). However, this type of decay usually requires 8 weeks for incubation, longer than fruit are usually kept in sealed packages. The major pathogen causing decay of citrus is still the green mold Penicillium digitatum Sacc. (20).

Free access

Gary Thompson, Russel Tronstad, and Michael Kilby

During the last two decades, per capita consumption of fresh fruit has increased markedly. Although many believe that this increase has been caused by a heightened concern in health and diet, economic analyses indicates that changes in retail prices and increasing per capita incomes adequately explain the increased consumption of fresh fruit. Also, with more single households and women entering the labor force, the convenience factor of focal preparation has likely caused an increase in the consumption of fresh fruit. Substantial substitution between fresh fruit products has occurred: grapes and strawberries have increasingly substituted for citrus fruit, particularly grapefruit. These results suggest that relative prices for fresh fruits, increasing disposable income, and the changing demographic composition of households have prompted observed increases in the per capita consumption of fresh fruit.

Free access

Kurt D. Nolte, Gregory W. Erdos, and Karen E. Koch

Localization of sucrose synthasa (SS), an enzyme Previously shown to be highly active in transport tissues of citrus fruit, was further defined via immunohistochemical analysis of stage II calamondin fruit. Using the indirect immunogold technique, 8 μm sections were first reacted with rabbit anti-SS polyclonal serum followed by incubation with 5 nm gold conjugated goat-anti-rabbit IgG. Little immunolabel was observed in the majority of peel tissues, however an abundant immunoreaction was evident in parenchyma cells directly adjacent to the segment epidermis surrounding juice sacs. Antibody was not associated with this epidermnl layer. Similarly, in juice vesicle stalks (JVS) the internal parenchyma cells showed significant SS localization compared to minimal immunoreaction in the epidermal layers of the JVS. Although the antigen did not appear to be specifically localized within the vascular bundles, an extensive distribution of the enzyme was associated with the parenchymatous cells immediately adjacent to vascular strands.

Free access

Kwan Jeong Song, Ed Echeverria, and Hyoung S. Lee

The distribution of sugars (sucrose, glucose, and fructose) and related enzymes between the stem and the blossom halves of `Valencia' oranges [Citrus sinensis (L.) Osbeck] was determined at three stages of fruit development. The blossom half contained significantly higher concentrations of sugars during later stages of development and maturation (12% and 20%, respectively). Neither the enzyme marker for sucrose synthesis [sucrose-phosphate synthase (SPS)] nor enzymes of CO2 fixation (NADP-malic enzyme, PEP carboxylase, and PEP carboxykinase) were significantly different between the halves. Sucrose synthase (SS), the enzymatic marker for sink strength, had significantly higher activity in the blossom half during later stages of fruit development when rapid sugar accumulation takes place. These data suggest that differential distribution of sugars between the stem and the blossom halves of citrus fruit is, in part, the result of differential sink strength.