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- Author or Editor: Kate A. Nishijima x
Chilling injury symptoms were reduced when `Sharwil' avocados (Persea americana Mill.) were held at 37 to 38C for 17 to 18 hours and then air-cooled at 20C for 4 hours before storage at 1.1C for ≥14 days. In contrast, nonheated fruit developed severe surface discoloration and pitting. Chilling injury symptoms were reduced further when the heated fruit were stored in perforated polyethylene bags during 1.1C storage. No treatment equaled or surpassed the quality of fruit in nontreated controls.
Longan (Dimocarpus longan) fruit production and global exports are rapidly expanding. Consumer acceptance of this high value crop requires that fruit arrive in excellent condition. Pericarp browning and fungal diseases are the main postharvest problems for longans. Research was conducted to establish optimum storage temperatures and packaging systems to retain fruit quality of ‘Biew Kiew’ longans. Average respiration rates for longans stored at 20 °C (61.6 mg CO2/kg/h) were about twice the rate as those stored at 10 °C (32.7 mg CO2/kg/h) and triple the rate for those stored at 5 °C (21.1 mg CO2/kg/h). Ethylene rates were below 0.4 μg·kg−1·h−1. Fruit quality and shelf life were greatest when stored at 10 °C. Longans held at 20 °C were unmarketable after 10 d, and fruit stored at 5 °C exhibited chilling injury (CI). After storage at 10 °C, longans packaged in microperforated (MP) bags, clamshell (CL) containers, or Peakfresh® film (PF) had the highest visual quality ratings, lowest disease incidences, and longest shelf life when compared with fruit in Lifespan® film (LS) or fiberboard boxes. The most promising packages (MP, CL, PF) were evaluated further under constant 10 °C or simulated shipping (SS) conditions with fluctuating temperatures (22 °C/10 °C/22 °C). Longans in CL containers had the highest visual quality and lowest disease incidence when stored at 10 °C, but there were no differences among package treatments under SS conditions. Also, sensory ratings were greatest for fruit packed in CL or PF when stored at 10 °C but all sensory scores decreased under SS temperatures. When longans were stored under fluctuating temperatures, aril texture and flavor ratings were highest for CL packages. CL, PF, and MP are suitable packages for longans stored under optimal temperatures. However, for longans stored under SS conditions, sensory quality was highest when packaged in CL containers.
A reduced heat shock period for `Sharwil' avocado (Persea americana Mill.) before quarantine cold treatment is described. The shortened heat pretreatment period of 8 to 12 hours, rather than the originally recommended 18 hours at 38C, is effective in reducing chilling injury symptoms when the pulp is at ≤2.2C during 16 days of storage. The reduced durations and the range of pretreatment hours affords packinghouses greater efficiency and more flexibility and will reduce handling costs relative to the longer exposure.
Viable larvae of the Oriental fruit fly (Dacus dorsalis Hendel) were found in Carica papaya L. ‘Kapoho’ fruit after hot water double-dip quarantine treatment in Hawaii. Two types of blossom end defects, navel and definite pinhole, were responsible for the failure of the quarantine treatment. These defects resulted from abnormal placental growth near the blossom end of fruit. Defective fruit also had higher incidences of internal infection by Cladosporium sp. and Fusarium spp. A survey conducted in the Puna district of the island of Hawaii showed that the incidence of trees bearing defective fruit ranged from 5.3% to 31%.
Thermal death kinetics, decimal reduction times (D-values), and rate constants, k, at 43 to 49 °C were determined for spore or cell suspensions of Colletotrichum gloeosporiodes (Penz.) Penz. & Sacc. in Penz., Guignardia psidii Ullasa & Rawl, Guignardia sp. Viala & Ravaz., and Enterobacter cloacae (Jordan) Hormaeche & Edwards. D-values for Monilinia fructicola (Wint.) Honey, Rhizopus stolonifer (Ehr.: Fr.) Vuill., and Stemphylium lycopersici (Enjoji) Yamamoto were calculated and extrapolated from published reports. We compared the relative heat resistances of the various postharvest pathogens to their expected survival during quarantine heat treatments and found that Guignardia, Rhizopus, and E. cloacae could be expected to survive quarantine heat treatments.
Papaya (Carica papaya L.) cultivars and breeding lines were evaluated for resistance to Enterobacter cloacae (Jordan) Hormaeche & Edwards, the bacterial causal agent of internal yellowing disease (IY), using a range of concentrations of the bacterium. Linear regression analysis was performed and IY incidence was positively correlated with increasing inoculum concentrations for susceptible cultivars Kapoho Solo and Laie Gold but not for resistant cultivars or lines. It was determined that the inoculum concentration of 9 to 10 Log10 colony-forming units per milliliter (cfu/mL) was able to reliably differentiate resistant and susceptible papaya germplasm. Red-fleshed cultivars SunUp and Sunrise were the most resistant papaya groups evaluated at this dose concentration. Yellow-fleshed cultivars, Kapoho Solo and Laie Gold, were susceptible to E. cloacae. ‘Rainbow’, an F1 hybrid between ‘SunUp’ and ‘Kapoho Solo’ that is yellow-fleshed, was moderately resistant to E. cloacae, exhibiting limited symptoms of the disease. Yellow-fleshed I-Rb F5/F6, an advanced inbred line derived from ‘Rainbow’, is resistant and offers the potential of improving resistance of yellow-fleshed commercial cultivars. A colorimeter was used to objectively measure internal flesh color and distinguish between infected and non-infected tissue in red- and yellow-fleshed papayas using L*C*H* color space analysis. Symptomatic tissue (72.4 and 79.0°) had higher hue angle means than non-symptomatic tissue (62.8 and 75.0°) for all cultivars or lines in red- and yellow-fleshed papayas, respectively. Yellow (“Y”) hue color also distinguished infected tissue from non-infected tissue. Symptomatic tissue that had Y hue color resulted in 79 to 81° hue angle means among red- or yellow-fleshed papayas. Our results demonstrated the usefulness of colorimetry to help detect infected papaya tissue. In surveys of naturally infected papaya, high populations (8.57 × 107 cfu/g) of E. cloacae were recovered in infected fruit of ‘Kapoho Solo’ and represent a food safety concern for fresh and processed papaya. In isolations from inoculated fruits, we observed decreases of ≈1 to 2 Log10 cfu/g in final bacterial populations when high-dose range inoculum concentrations (9 to 12 Log10 cfu/mL) were used. This dose range may represent a saturation range for E. cloacae inoculation.