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- Author or Editor: F. Gordon Mitchell x
Abstract
The multibillion-dollar United States fresh fruit and vegetable industries are under threat because of actual or potential quarantines that may be imposed within hours or days if any one of many insect pests are introduced (40; P.V. Vail, personal communication). California, Florida, Texas, and Hawaii are particularly vulnerable because their climates are favorable for fruit fly species, and important shares of their produce enter into interstate and international trade. The 1980-82 California infestation by the Mediterranean fruit fly, Ceratitis capitata (Wied.), was eradicated. The Caribbean fruit fly, Anastrepha suspensa (Loew), is currently being fought in Florida and the Mexican fruit fly, Anastrepha ludens (Loew), poses a problem in Texas. In Hawaii, 3 fruit flies are endemic. They are the Oriental fruit fly, Dacus dorsalis (Hend.), the melon fly, Dacus cucurhitae (Coq.), as well as the Mediterranean fruit fly. The Queensland fruit fly, Strumeta tryoni (Froggatt), is endemic in parts of Australia and threatens to become much more widely distributed.
`High-temperature controlled-atmosphere (high CO2/low O2) conditioning was investigated as a possible treatment to delay the incidence of internal breakdown of peaches and nectarines (Prunus persica L. Batsch) during subsequent cold storage. Maintaining an atmosphere of 5% to 15% CO2 added to air or to 1% to 5% O2 while conditioning peaches for 2 days at 20C partially prevented fruit ripening (compared to fruit conditioned in air), as measured by flesh softening and loss of green pigment, while no off-flavors were detected. Conditioning of peaches at 20C for 4 days in air or in air + 20% CO2 was detrimental to fruit quality, as indicated by flesh softening or detection of off-flavors.
Storage at 0C of `O'Henry' and `Fairtime' peaches and `Red Jim' and `September Grand' nectarines (Prunus persica L. Batsch) resulted in significantly longer postharvest life than did storage at 5C, due to differences in the development of internal breakdown (IB) symptoms. Conditioning at 20C for 2 days before storage at 0 or 5C generally prolonged the storage life of fruit of these cultivars. The use of elevated CO2 during conditioning helped maintain fruit firmness. Addition of 5% CO2 to air gave the best results in maintaining fruit firmness and freedom from IB symptoms for up to 6 weeks. Reducing the O2 content kept flesh firmness high after storage but did not delay the appearance of IB. Conditioning at 30C using various atmospheres was less effective than conditioning at 20C.
The susceptibility to chilling injury (CI) or internal breakdown (IB) was evaluated in the most currently planted yellow- and white-flesh peach [Prunus persica (L.) Batsch] and nectarine [Prunus persica var. nectarine (L.) Batsch] and plum [Prunus salicina Lindel] cultivars from different breeding sources and fruit types. Cultivars were segregated into three categories (Cat. A, B, and C) according to their susceptibility to CI or IB symptoms (mealiness and flesh browning) when exposed to 0 °C or 5 °C storage temperatures. Cultivars in Cat. A did not develop any symptoms of CI after 5 weeks of storage at either temperature. Cultivars in Cat. B developed symptoms only when stored at 5 °C within 5 weeks of storage. Cultivars were classified in Cat. C when fruit developed CI symptoms at both storage temperatures within 5 weeks of storage. Most of the yellow- and white-flesh peach cultivars developed IB symptoms when stored at both storage temperatures (Cat. C). Most of the new nectarine cultivar introductions did not develop CI symptoms when stored at 0 °C or 5 °C after 5 weeks (Cat. A). Three out of six plum cultivars tested had CI symptoms within 5 weeks storage at 0 °C. However, all of the plum cultivars tested developed CI symptoms when stored at 5 °C (Cat. B). The importance of proper temperature management during postharvest handling was demonstrated.
Good quality of fresh `Mission' figs (Ficus carica L.) was maintained for up to 4 weeks when kept at 0, 2.2, or 5C in atmospheres enriched with 15% or 20% CO2. The visible benefits of exposure to high CO2 levels were reduction of decay incidence and maintenance of bright external appearance. Ethylene production was lower, and fruit softening (as measured with a deformation tester) was slower in the high-CO2-stored figs than in those kept in air. Ethanol content of the CO2-treated fruit increased slightly during the first 3 weeks and moderately during the 4th week, while acetaldehyde concentration increased during the first week, then decreased. The results may be applicable to the transport and storage of fresh `Mission' figs, as high CO2 extended their postharvest life, especially near 0C.
Abstract
The tolerance of peaches [Prunus persica (L) Batsch ‘Suncrest’] to different heat treatments, utilizing hot water and hot air at 38°, 40°, 42°, and 43°C was evaluated. Following treatment, and after 5 days at 20° (simulated marketing conditions), following 10 days at 0° (simulated holding and transit conditions), surface browning was the major symptom of heat injury. Significant injury occurred to fruit from all the treatments at 43°. However, some treatments, i.e., water dipped (40 min at 38°) + either 24 or 30 hr at 38° in air; and water dipped (40 min at 40°) + either 12 or 24 hr at 40° in air were tolerated by the peaches.
Abstract
The tolerance of avocado (Persea americana Mill. cv. Fuerte) to different heat treatments, using hot air at 43°C, was evaluated. The heat-treated avocados did not soften or ripen normally and exhibited severe surface browning after a 14-day simulated transit period at 7° followed by a 4-day simulated marketing period at 20°. Heat treatments also increased rate of weight loss, susceptibility to vibration injury, and loss of fresh avocado flavor.
Optimum controlled atmosphere (CA) storage conditions were evaluated over a two year period for California-grown `Hass' avocado (Persea americana). Fruit harvests corresponded to early, middle and late season commercial harvests. Various temperatures and CA conditions were tested. The results indicate that the storage life of `Hass' can be extended from 3 to 4 weeks in 5C air, to 9 weeks in 5C CA if they are held in 2% oxygen and 2 to 5% carbon dioxide. Loss of quality as determined by chilling injury expression and flesh softening was greatly reduced in these conditions. Fruit maturity influenced the response to CA storage. Late season fruit had greater loss of quality in storage than earlier fruit. In 2% oxygen and 2.5% carbon dioxide, continuous exposure to ethylene levels as low as 0.1 ppm significantly increased quality loss. Delays in cooling and CA atmosphere establishment of up to three days after harvest did not effect quality.
Abstract
Development of gray mold rot, caused by Botrytis cinerea Pers. ex Fr., in strawberry fruits during expedited cross-country truck transport and marketing periods of ca. 7 days at 5°C resulted mostly from preharvest infections. Postharvest infections occurred occasionally when healthy fruits were appressed against the lesion of a diseased fruit. Under the same conditions, postharvest conidial inoculations failed to produce visible lesions unless massive inoculum was used. Improved quality control at harvest, prompt cooling, and reduction of transit temperatures appeared to offer opportunities for disease reduction.
Abstract
Kiwifruit from 3 growing locations were harvested at 4 maturity levels. Weight, length, width, flesh color, flesh firmness, harvest soluble solids, titratable acidity, respiration, and ethylene production were measured at harvest, and subsequent storage behavior and sensory quality of the fruit were evaluated. The results indicate that a combination of initial soluble solids content at harvest, and flesh firmness, similar to the maturity index for pear, seems promising as a maturity index for kiwifruit.