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Guy J. Hallman

`Arkin' carambolas (Averrhoa carambola L.) were subjected to the fruit fly quarantine treatments of hot water immersion at 43.3 to 43.6C for 55 or 70 rein, 46.0 to 46.3C for 35 or 45 rein, or 49.0 to 49.3C for 25 or 35 rein, or vapor heat at 43.3 to 43.6C for 90 to 120 rein, 46.0 to 46.3C for 60 or 90 rein, or 49.0 to 49.3C for 45 or 60 min. Marketability, color, weight loss, internal appearance, flavor, total acids, and soluble solids content were determined. The 49.0 to 49.3C treatments resulted in excessive damage to the carambolas 2 to 4 days after treatment. There were no statistically significant differences in the variables measured among the other treatments and control; however, heat-treated carambolas appeared duller in color than control fruits. Overall, fruit treated at 46.0 to 46.3C lost significantly more weight than that treated at 43.3 to 43.6C.

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Guy J. Hallman

Canistel [Pouteria campechiana (HBK.) Baehni] fruit were subjected to cold storage and hot-water immersion treatments known to kill immature Caribbean fruit flies [Anastrepha suspensa (Loew)] in other fruit. Cold storage at 1 or 3C for 17 days did not cause appreciable loss in canistel quality compared with fruit stored at the normal 10C. Unripe canistels immersed in water at 46C for 90 min or at 48C for 65 min, however, developed dark blotches on the peel and a 2- to 3-mm-thick layer under the peel that did not soften. Canistels were infested with Caribbean fruit flies and subjected to 1 or 3C storage for up to 14 days. The resulting lethality data were fitted to three probability density functions (PDF) to estimate the number of days required to achieve quarantine security (99.9968% dead). The normal and Gompertz PDFs gave some reasonable estimates, while the logistic PDF gave low estimates. At 1C, 14 days would be needed to achieve quarantine security, while at 3C a minimum of 15 days would be required. These estimates must be tested to determine if they are valid after a large amount of Caribbean fruit fly immatures is subjected to the treatments.

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Raymond G. McGuire and Guy J. Hallman

Harvested, mature-green guava (Psidium guajava L.) fruit were coated with cellulose- or carnauba-based emulsions to compare the effect on fruit ripening and quality of ripened fruit. Coatings containing 2% or 4% hydroxypropylcellulose significantly slowed softening an average of 35% or 45%, respectively, compared to uncoated fruit (a delay of 1 to 2 days in September and 4 to 5 days by January). A 5% carnauba formulation slowed softening by 10% to 30% and was most effective at reducing weight loss. Neither of the cellulose- nor the carnauba-based coatings affected the decay susceptibility of softened fruit, but coated fruit did not develop as much color, had a lower soluble solids concentration, and were more prone to surface blackening in storage than uncoated fruit.

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Maria E. Monzon, Bill Biasi, Elizabeth J. Mitcham, Shaojin Wang, Juming Tang and Guy J. Hallman

The external and internal quality of ‘Fuyu’ persimmon fruit (Diospyros kaki L.) was evaluated after heating with radiofrequency (RF) energy to 48, 50, or 52 °C, holding at the target temperatures for durations ranging from 0.5 to 18 minutes, hydrocooling, and ripening at 20 °C for 12 days. These treatment conditions were identified for control of third instar Mexican fruit fly larvae (Anastrepha ludens). The treatments had no commercially significant effect on firmness, soluble solids content, titratable acidity, or weight loss of the fruit. RF-treated persimmon fruit attained a deeper orange–red skin color than control fruit. There was a greater incidence of slight to moderate flesh browning in fruit heated to 50 and 52 °C as compared with 48 °C. Calyx browning increased slightly in all RF-treated fruit and was the highest in the longer treatments at each temperature. Heating persimmon fruit with RF to 48 °C and then holding for 6 or 12 minutes showed the least damage, and the latter treatment was longer than should be required for a quarantine treatment against the third instar Mexican fruit fly. Holding persimmons for 6.6 minutes at 48 °C should provide control of the Mexican fruit fly and maintain fruit quality. Confirmation tests with infested fruit should be conducted.