The presence or potential presence of internal feeding insects in tree fruits grown in the United States has caused the development and implementation of specific quarantine procedures to prevent the accidental introduction of these pests to areas
tephritid fruit flies and therefore subject to quarantine restrictions. Hot forced air treatments have been proposed for dragon fruit disinfestation with minimal reduction in quality ( Hoa et al., 2006 ); however, irradiation generally is more efficient and
Sweetpotato [Ipomoea batatas (L.) Lam.] roots of three Hawaii-grown cultivars (`Mokuau', `Okinawan', and `Yoshida') were treated with 0, 200, or 400 Gy x-ray irradiation and stored for 12 weeks at 15 °C. The storage quality of nonirradiated and irradiated roots was compared for weight loss, sprouting, firmness, color, postharvest decay, and carbohydrate concentrations. Nonirradiated roots lost 3 to 4% weight during storage, whereas roots treated with 400 Gy lost 4.7% to 8.6% weight. Sprouting was negligible for all treatments. Storage tended to increase root firmness, while irradiation tended to decrease firmness. When all cultivars were averaged, sweetpotatoes treated with 400 Gy and stored for 12 weeks had the lowest starch concentrations and highest total sugar concentrations. Glucose and fructose concentrations were not affected by irradiation, but these sugars increased during storage. Sucrose concentrations of roots irradiated with 400 Gy were double those of nontreated roots after 12 weeks storage. The purple-fleshed cultivars, `Mokuau' and `Okinawan', retained good quality following irradiation and storage, but firmness decreased somewhat for roots treated with 400 Gy. The `Okinawan' sweetpotato is the primary export cultivar from Hawaii. For the white-fleshed cultivar, `Yoshida', postharvest decay adversely impacted the internal color, firmness, and overall quality of roots treated with 400 Gy and stored for 12 weeks.
provitamin A than Cavendish-type bananas ( Wall, 2006 ). Dwarf Brazilian bananas are limited in mainland U.S. and international markets because of quarantine restrictions. The fruit can be exported at the mature green stage under a nonhost quarantine status
.7%, respectively, while for the control weight loss was 5.1%. Fig. 1. Cumulative weight loss of ‘Kent’ mango fruit treated with aqueous 1-methylcyclopropene (1-MCP) with or without quarantine hot water treatment (QHWT). Data are means ± se (n = 10, except for A
Heat treatments have been used to control diseases and insect infestation of fruit. The development of heat treatments have been the result of empirical experiments based on the efficacy on the insects coupled with parallel experiments on the phytotoxicity of host fruit. Such heat treatments while approved as quarantine treatments have occasionally produced fruit of poor quality. Thermal processing of foods, an established science, employs kinetics of enzyme inactivation, thermal death times evaluation of various time-temperature relationships to determine the adequacy of the heat process to ensure the safety of the product as well as minimize over-processing to preserve the products quality. There is a need to develop thermo-processing guidelines in the development of quarantine heat treatments and also to enhance product quality. We will report methods that we have developed to determine the thermal death kinetics of insects, fruit pathogens and kinetics for thermotolerance of the fruit.
Abstract
Exclusion of plant diseases and pests by quarantine procedures is an ancient and valuable practice. The word quarantine comes from the Latin word for 40, quadraginta, and the practice of holding a ship outside of port for 40 days if suspected of carrying disease. Carefully and rigorously applied quarantine methods have restricted the spread of plant diseases and insect pests numerous times. With increasing travel and trade, quarantine barriers are becoming increasingly difficult to maintain and we see new introductions of pests throughout the world. With the demand for exotic products, simple exclusion of potentially infested products is an unsatisfactory response to quarantine requirements. Methods are needed to protect domestic crops from foreign pests with minimal impact on commerce. An ideal quarantine system is highly reliable, harmless to the commodity and to the consumers of the commodity, and inexpensive to apply and administer. It is difficult to develop a system that meets these requirements, and various trade-offs are essential. Since the discovery and development of ethylene dibromide (EDB) and methyl bromide (MB) as general-purpose fumigants, the usual response to quarantine requirements has been an automatic resort to these fumigants. However, considering the potential hazards in the use of fumigants, we are taking a broader approach at our laboratory to the quarantine problems posed by the fruit flies; we hope to utilize infestation biology of the insects, the natural resistance of host plants, various field control measures, and a broader arsenal of alternative postharvest treatments to minimize the use of chemical fumigants.
Persimmon ( Diospyros kaki L.) fruit are host to various quarantined pests, including various fruit flies, lightbrown apple moth, and longtailed mealybug ( Dentener et al., 1996 ; Paull and Armstrong, 1994 ), which limit fruit export and
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.
The market quality and condition of grapefruit (Citrus paradisi Macf.) were compared after three heat treatments for quarantine control of Caribbean fruit flies [Anastrepha suspensa (Loew)]. Treatment by forced air at 48C for 3 hours was compared with immersions in water at either a constant 48C for 2 hours or with a gradual increase to 48C lasting 3 hours. The immersion at a constant 48C significantly increased weight loss and promoted injury and decay while reducing firmness and color intensity after 4 weeks of storage. By more slowly heating fruit in the gradient water immersion, weight, firmness, and natural color were retained, and injury was substantially reduced, but the incidence of decay remained high. No loss in quality resulted from treatment by forced hot air. These heat treatments had little effect on juice characteristics, although acidity was slightly reduced by each method of application. In taste tests, juice from fruit treated in water that was gradually raised to 48C was preferred over that of fruit treated at a constant 48C.