it susceptible to skinning injury and not ideal for highly mechanized harvest. A critical adjunct to breeding is to understand the genetics behind wound healing. Lignification and increased sugar at the wound site have been shown to be correlated with
Jollanda Effendy, Don R. La Bonte, and Niranjan Baisakh
Alba J. Collart, Stephen L. Meyers, and Jason K. Ward
commercial production is concentrated in North Carolina, California, Mississippi, Louisiana, and Texas, skinning injury remains one of the greatest concerns to sweetpotato producers nationally (M.W. Shankle, unpublished data). Sweetpotato skin is relatively
D.R. La Bonte and M.E. Wright
O.L. Lau and R. Yastremski
`Golden Delicious' apples (Malus domestics Borkh.) were subjected to either 0C controlled-atmosphere (CA) storage or to a postharvest coating of 1.0% to 2.5% Nutri-Save (NS; a polysaccharide derived from shellfish) plus air storage. NS-coated apples were greener and firmer and had higher titratable acidity (TA) and more shrivelled and injured fruit than the control after storage in air at 0C for 5 to 6 months and ripening in air at 20C for 7 days. Poststorage washing increased skin injury, and low relative humidity during ripening increased shriveling of NS fruit. NS applications led to an accumulation of CO2 and C2H4 and a small reduction of O2 in the fruit core cavities. The use of 1.5% O2 + 1.5% CO2 in the storage atmosphere was more effective than NS plus air storage in maintaining flesh firmness (FF) and TA without increasing fruit shrivel or skin injury. NS treatments maintained FF and a green skin in fruit ripened in air at 20C for 2 or 4 weeks following harvest, but some shrivel was evident by 4 weeks. Better retention of skin greenness was the only benefit derived from a poststorage NS treatment of CA-stored fruit during the shelf-life test.
`Newtown' apples (Malus domestics Borkh.) treated weekly with urea at 10 g·liter-l or Ca(NO3)2 at 7.5 g·liter-1 for 5 consecutive weeks from late August were greener at harvest and during storage than comparable control fruit. A postharvest dip in Nutri-Save, a polymeric coating, was better for retention of skin greenness than a dip in diphenylamine and both gave greener apples than control (nondipped) fruit. Fruit treated with Ca(NO3)2 displayed lesions that were larger and more numerous than typical bitter pit in the control fruit.
Maria Eloisa G. Quintana and Robert E. Paull
`Solo' papaya (Carica papaya L.) fruit removed at different points from a commercial packing house showed that skin injury due to mechanical damage increased as fruit moved through the handling system. The occurrence of “green islands” -areas of skin that remain green and sunken when the fruit was fully ripe-apparently were induced by mechanical injury. Skin injury was seen in fruit samples in contact with the sides of field bins, but not in fruit taken from the center of the bins. Bruise-free fruit at different stages of ripeness (5% to 50% yellow) were dropped from heights of 0 to 100 cm onto a smooth steel plate to simulate drops and injury incurred during commercial handling. No skin injury occurred, although riper fruit showed internal injury when dropped from higher than 75 cm. Fruit (10% to 15% yellow) dropped onto sandpaper from a height of 10 cm had skin injury symptoms similar to those seen on fruit from the commercial handling system. These results suggest that abrasion and puncture injury were more important than impact injury for papaya fruit. Heating fruit at 48C for ≈6 hours or until fruit core temperature (FCT) reached 47.5C aggravated the severity of skin injury. Delays in the application of heat treatment from dropping did not reduce the severity of skin injury significantly, except for fruit heated 24 hours after dropping. Waxing fruit alleviated the severity of skin injury, whether applied before or after the heat treatment. Skin injury to papaya was caused by abrasion and puncture damage-not impact-and increased during postharvest handling of the fruit. The injury was associated mainly with fruit hitting the walls of wooden bins-bin liners may reduce this injury.
M.S. Hernandez, H.E. Arjona, O. MartÌnez, M.S. Hernandez, and J.P. Fernandez-Trujillo
Araza (Eugenia stipitata Mc Vaugh) is a plant from the Myrtaceae family originated from Amazonia. The postharvest behavior of its promissory fruit has been sparingly studied. Weight loss, softening, decay, and chilling injury (skin scald) at temperatures below 10-12 °C limits its shelf-life to less than 10 days. The application of calcium pretreatments slightly improved flesh firmness after 7 days at 20 °C and resulted in skin injury, particularly at concentrations higher than 4% (w/v). A warming treatment of 6, 12 or 18 h at 20 °C was applied to fruit after 6 d storage at 10 °C. Treated fruit had less scald, suppressed decay, and ripened normally after a total of 2 weeks of storage and a shelf life of 3 days.
M. Ahmedullah, M. E Patterson, and G. Apel
Table grapes cvs. Flame Seedless, Black Monukka and Canadice and blueberries cvs. Bluecrop and Northland were exposed to chlorine dioxide (C102) gas under laboratory conditions. Chlorine dioxide was generated chemically. Grapes were fumigated in a plexiglass chamber with C102 for 30 minutes, packed in TKV lugs with Botrytis inoculum planted among the clusters and stored at 0° C for 8 weeks. Blueberries were consumer packed with 5, 10, and 15 gr. Absorb (C102 generator) in Tyvex sachets, enclosed in pillow-pak bags and stored at 0° C for 75 days and at 20 or 30° C for 16 days.
At periodical intervals, moisture loss, decay and quality parameters were evaluated. Chlorine dioxide caused bleaching and skin injury around the capstem on blueberries but not on grapes. Decay was reduced with C102 treatment but moisture loss increased in blueberries. We could store grapes for two weeks without fungal growth. Storage for longer periods necessitated treatment with higher concentrations of C102 which were not generated under our laboratory conditions.
Christopher B. Watkins and Kenneth J. Silsby
Occasional occurrence of a superficial skin injury associated with CA storage can cause severe commercial loss in the `Empire' cultivar in the northeast. To develop industry strategies to prevent losses due to the disorder, we have examined a number of factors related to its occurrence. 1) Fruit from six orchards were stored with 2% or 5% CO2 (with 2% O2) at 0.5 or 3°C for 6 or 9 months. Orchard variation in susceptibility was high. Preharvest factors such as maturity or mineral levels in the fruit did not account for these differences. Incidence of the disorder was much higher at 5% than at 2% CO2. However, temperature did not affect the extent of injury. 2) Exposure of fruit stored at 2% CO2/2% O2 to 5% CO2 at 4-week intervals from harvest until 20 weeks indicated that fruit were most susceptible to injury between 0 and 8 weeks. 3) A postharvest treatment with diphenylamine (DPA) prevented occurrence of the disorder, ethanol reduced it, but ascorbic acid had little effect. 4) Fruit were held at storage temperatures for up to 10 days before exposure to either 2% or 5% CO2. Injury was highest in fruit exposed one day after harvest and negligible when exposed after 10 days. Collectively the results indicate that rapid CA can aggravate the disorder if care is not taken to maintain low CO2 concentrations in the storage atmosphere but that use of DPA for control of superficial scald will prevent its occurrence.
Tolerance of apples to low levels (0.5%) of O2 was cultivar-dependent. `Spartan' (SP), `Delicious' (RD), and `Golden Delicious' (GD) apples (Malus domestica Borkh.) held for 7 months in 1.0% O2 (with 1.5% CO2) at 0.5C, plus ≈2 months in air at 0C and 7 days in air at 20C, were similar to those held in 1.5% O2. However, incidence of skin injury in fruit held in 0.5% O2 was very high in SP (purple-brown discoloration), low in RD (purple-brown discoloration), but only negligible in GD (lesions). Skin discoloration in SP and RD developed rapidly in air at 20C. Holding in 0.5% O2 improved retention of flesh firmness and juice acidity in GD and, under certain conditions, reduced scald in RD and SP, delayed yellowing in GD, but increased flesh breakdown in SP, flesh browning and alcohol flavor in SP and RD, and core browning in RD.