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  • Author or Editor: Robert E. Paull x
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Moringa (Moringa oleifera), also known as the pot herb drumstick or horseradish leaves, requires irradiation treatment for insect disinfestation before shipping to the west coast of the United States from Hawai’i. This irradiation treatment as well as packing and air shipment leads to leaflet abscission. To minimize this abscission, the shipper had been including frozen gel packs in the shipping carton. However, these packs are heavy and lead to chilling injury on the leaflets and the development of mold on the leaves adjacent to the gel pack. Holding and shipping the product at 12 °C negated the need for the frozen gel packs. Inclusion of a sachet of 1-methylcyclopropene in the carton significantly reduced leaflet abscission. Further reduction was obtained by the inclusion of an ethylene absorption sachet, thus helping to maintain the overall product quality and marketability.

Open Access

Abstract

Compositional changes of longan [Euphoria longan (Lour.) Stend] and rambutan (Nephelium lappaceum L.) collected in two seasons were measured during storage at two temperatures. Seasonal variation reflected both preharvest conditions and maturity at harvest. Total sugars and titratable acidity of longan aril showed little change after harvest at 4° and 22°C. Sucrose of rambutan aril increased from 51 mg·g−1 to 76 mg·g−1 when fruit were stored at 12°, and no change occurred when stored at 22°. Titratable acidity, 20.8 meq·g−1 at harvest in rambutan aril, first declined and then increased at both storage regimes. Succinic acid was found in rambutan aril only at harvest and declined rapidly to an undetectable level. No malic acid was detected in rambutan. A high level of citric acid (≈175 meq·g1) was maintained during storage. The organic acids in longan aril were succinic, malic, and citric acids, present in a ratio of 10:5:1. Ascorbic acid content declined in aril tissue of both longan and rambutan during storage. Total phenols showed little change in either fruit during storage. Except for the changes noted, there were only minor compositional changes in longan fruit stored for 35 days at 4° and rambutan stored for 20 days at 12°.

Open Access

Abstract

Waxing the fruit and crown of fresh pineapple [Ananas comosus (L.) Merr.] with a 20% v/v paraffin-polyethylene: water mixture reduced the incidence and severity of internal browning caused by chilling injury to 15% and 31%, respectively, of the unwaxed control. Symptom incidence in waxed fruit was not affected by fruit maturity at harvest. Increasing wax:water emulsion concentration up to 50% v/v further decreased symptom incidence and severity with the greater suppression occurring with less than 20% v/v. Crown leaves were extremely susceptible to chilling injury; they turned grey and became desiccated following 8°C storage. Waxing did not affect these symptoms. Waxing assisted in retaining fruit shell appearance and reduced the rate of shell degreening by 60%. The major changes in internal browning and fruit external appearance occurred during holding at room temperature following 8° storage. Varying wax composition with polyethylene and pH had no significant effect on fruit characteristics.

Open Access

Taro [Colocasia esculenta (L.) Schott] corms from 57 vegetatively propagated cultivars were evaluated for yield, physical and chemical characteristics, and either microwaved, microwaved and ground into poi, or fried. Poi color ranged from purple to orange or yellow and the dry matter content from 18.3 to 48%. The taste panel preferred poi made from a number of other cultivars than that made from the most common cultivar `Lehua Maoli' used in Hawaii, and a darker bluish-red poi was preferred. Corm total soluble solids were positively correlated to corm specific gravity and dry matter, and to the taste preference of microwaved corm and poi. The fried cultivars varied widely in yield and corm color varied from cream to white. Additionally, some cultivars did not have purple vascular bundles, and others were acrid after frying. Chip oil content was negatively correlated to corm weight, dry weight, and chip yield. The `Bin Liang' cultivar was judged the best overall in fried chip taste. Considerable variation in corm yield and quality characteristics existed in this widely cultivated vegetatively propagated tropical crop.

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Ripe yellow papaya fruit in the markets frequently show green sunken areas called “green islands” (GI). This disorder seems to be caused by mechanical injury in a commercial postharvest handling system. Fruit at different stages of ripeness (5 to 50% yellow) were dropped from different heights (0 to 100 cm) onto a smooth steel plate to try to create GI. The injury sustained was not the same as GI seen in fruit from the handling system. Fruit (10 to 15% yellow) dropped on different grades of sandpaper (220 mesh to 36 mesh) from a height of 10 cm had injury symptoms similar to those seen on fruit from the handling system. These results suggest that abrasion damage was more important than impact damage in papaya fruit. Heating fruit at 48°C for -6 hours or until fruit core temperature (FCT) reached 47.5°C aggravated the severity of GI. Delaying the time of heating from the time of dropping did not significantly lower the severity of GI, except for fruit heated 24 hours after dropping. Waxing fruit alleviated the severity of GI. The results indicate that avoidance of abrasive surfaces such as the plywood walls of field bins is the best approach to avoiding the unsightly GI blemishes on papaya peel.

Free access

Abstract

The effect of waxes and plastic shrink wraps on weight loss from papaya (Carica papaya L.) fruit during ripening was determined. Loss of ≈8% of initial weight from mature-green papaya produced “rubbery”, low-gloss, unsalable fruit. The rate of weight loss from ripening papaya was ≈0.1% initial weight/day per mbar. The highest rate of weight loss occurred via the stem scar (nearly 3500 mg·cm−2·day−1) while 4.4 mg·cm−2·day−1 was lost through the skin. The major mode of weight loss was the skin because of its larger surface area. The stomata did not appear to function in ripening fruit. The skin's resistance to water movement increased at the start of ripening, then declined with no apparent change in the rate of total water loss. Part of the decline in resistance was associated with the disruption of the cuticle with latex, especially after the 50% ripe stage. These results suggest that the major site of resistance to weight loss changed late in ripening. Fruit waxing reduced weight loss by 14% to 40%, while plastic shrink wraps reduced loss by ≈90%. The loss of water was the major component of weight loss. Some waxes and one wrap delayed ripening by 1 to 2 days at ambient temperatures, after storage for up to 2 weeks at 10C. Occasionally, off-flavors occurred in waxed and wrapped fruit when the fruit cavity CO2 level exceeded ≈7% at the full-ripe stage.

Open Access

`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.

Free access

Abstract

Papaya (Carica papaya L.), a climacteric fruit, became progressively less susceptible to chilling injury as it ripened. Symptoms of chilling injury included skin scald, hard areas in the pulp around the vascular bundles, and water soaking of tissue. Mature green fruit were most sensitive to chilling and began showing injury after 10 days of storage at 2°C. Chilling injury symptoms began to occur after 20 days at 7.5°. Fruit that showed 60% yellowing could be kept at 2° for 17 days without developing injury. Preconditioning papaya fruit for 4 days at 12.5° before storage for 12 or 14 days at 20° reduced chilling sensitivity. The decrease in chilling sensitivity with preconditioning was associated with partial fruit ripening. Waxing and wrapping papaya with polyethylene reduced chilling injury, but the fruit had an off-flavor. Controlled atmospheres of low oxygen (1.5% to 5%) with or without high C 02 (2% or 10%) delayed ripening, but did not reduce chilling injury symptom development. Calcium treatment led to increased chilling injury of papaya fruit. Delaying storage until the fruit ripened decreased chilling susceptibility and increased storage life at chilling temperatures. Shipping 60% yellow fruit at 2° could provide a procedure for achieving fruit fly disinfestation. Differences in cultivar response to chilling injury were noted.

Open Access

Slips are side-shoots or fruit with large crowns that grow from buds on the pineapple (Ananas comosus L.) peduncle. The slips are widely used for pineapple vegetative propagation when crowns are left attached to the fruit that is marketed. There is a difference between the two most popular low-acid pineapple hybrids grown worldwide. The ‘Pineapple Research Institute 73-50’ (CO-2, MD-1) slips develop few roots when planted compared with ‘Pineapple Research Institute 73-114’ (MD2). The slow rooting of 73-50 leads to slow field establishment and can extend the crop cycle. Our objective was to determine the cause of this reduced rooting and evaluate treatments to increase the rooting rate. Rooting trials in moist, coarse vermiculite showed that larger slips and green slips with red hues also had a greater number of roots compared with smaller slips and green or yellow slips. Delaying harvesting of the slips after the fruit were harvested also resulted in a greater number of roots. Treatments including components frequently used for rooting cuttings did not significantly increase root numbers. An exception was a tendency for slips treated with potassium nitrate to have greater rooting during some tests. We present data that support the conclusion that the poor root development is associated with the mechanical impedance of the root from the tightly affixed basal leaf bracts. Removal of the lower ten bracts can lead to greater root numbers. When the slip with the bracts removed was tightly wrapped in plastic wrap and masking tape, rooting was reduced. The sizing and selection of slips that are green with a red hue and collected as late as possible after fruit harvest had the best rooting response.

Open Access

Sugar peas (Pisum sativum var. saccharatum cv. Manoa Sugar) were stored for 14 or 21 days under controlled atmospheres (CA) of 21% or 2.4% O2, plus 0%, 2.6%, or 4.7% CO2 at 10 or 1C. Changes in appearance, weight, and in the concentrations of chlorophyll, total soluble sugars, insoluble solids, and soluble protein were evaluated before and after storage. After 14 days of storage at 10C there were minor changes in all indicators of quality under the various storage conditions, but the appearance of sugar peas was better under CA than under 21% O2. When quality was evaluated after 21 days, however, storage under CA at 10C was not as beneficial as storage in 21% O2, at 1C. Holding peas in 2.4% O2, for up to 3 weeks at l0C, a higher than recommended storage temperature, maintained better quality than 21% O2. Increasing the CO, concentration from 0% to 2.6% or 4.7% had no adverse effects on quality and had a beneficial effect in some treatments. Compared with storage in 21% O2, the appearance of the peas was better, the concentrations of chlorophyll and soluble sugar were maintained at higher levels, and the insoluble solids were decreased in all atmospheres with 2.4% O2. Appearance and concentrations of chlorophyll, soluble sugars, and proteins were maintained at 1C regardless of treatments.

Free access