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  • Author or Editor: J.K. Collins x
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The effects of retail-display packaging on strawberry fruit quality were studied using freshly harvested `Cardinal' strawberries. Fruit free from blemishes and disease were placed into plastic vented boxes, covered with vented plastic lids or plastic wrap, and placed at 1 and 5C overnight One-half of the treatments were removed from coolers, held at 25C for eight hours, returned to the coolers and evaluated over a 15-day storage period. The plastic overwrap greatly decreased weight loss during 15 days of storage; carbon dioxide reached 0.8 and 2% per mg fresh weight at 1 and 5C, respectively. Type of cover did not affect overall appearance or disease ratings. Exposure of fruit to 25C for eight hours led to no loss of overall quality. Storage of fruit at 50C led to greater disease incidence and loss of quality. The respiration rate of fruit warmed at 25C reached equilibrium after six hours, regardless of initial storage temperature. Fruit in vented dome-lid boxes had more weight loss than plastic-wrapped boxes at both temperatures.

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The red flesh of watermelon contains lycopene, a pigment with antioxidant properties that help prevent certain types of cancers. This experiment was done to determine cultivar variation in lycopene content, and the effectiveness of colorimetric measurements for predicting lycopene content. Ten ripe melons per cultivar of hybrid, open-pollinated, and triploid types were selected from field plantings at Lane, Okla. Melons were cut transversely and color measured with a colorimeter at three heart and three locule sites, in a counterclockwise rotation starting at the ground spot. For lycopene content, a 100-g sample of heart tissue was removed, extracted with a hexane-acetone-ethanol mixture, and lycopene concentration measured spectrophotometrically at 503 nm. Lycopene content varied among cultivars, from 33.96 μg·g–1 in `Crimson Sweet' to 66.15 μg·g–1 in `Crimson Trio'. Chroma and “a” colorimeter values were highly correlated with lycopene content (P < 0.001). Linear and quadratic regression of lycopene against colorimeter values yielded an R 2 of 0.55. Results indicate that, like tomatoes, watermelon cultivars vary widely in lycopene content. Colorimeter readings did not adequately predict lycopene values.

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Application of modified-atmosphere storage (MA) (high carbon dioxide and/or low oxygen) extends the shelf life of several fruits. This study was done to determine the effects of MA on quality and flavor of blackberries. `Navaho' and `Arapaho' blackberries were harvested in 1998 and 1999, precooled overnight at 2 °C, and placed in 0.5-L treatment jars. Treatments of 15% CO2/10% O2 or of air (0.03% CO2/21% O2) were applied at 2 °C for 3, 7, or 14 days. After treatment application, jars were held at 2 °C for an additional 11, 7, or 0 days, respectively. Seven and 14 days of application of CO2 reduced the incidence of decayed and leaky berries by 10% to 20% for both `Arapaho' and `Navaho', but firm berries decreased 10% after 14 days of treatment. Titratable acidity was slightly lower, and pH higher, in control fruit but soluble solids content was not affected by treatment. Anthocyanin content was not affected by treatment in `Arapaho' berries but was lower in `Navaho' berries after 7 and 14 days of treatment. Samples taken for taste tests after 3 and 7 days of treatment had no off-odors or off-flavors. `Arapaho' and `Navaho' blackberries benefitted from high CO2 storage, with a minimum of 7 days of treatment application needed to increase marketable berries by 10%.

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Okra develops chilling injury after 4 to 5 days at 2C or 8 days at 5C. Intermittent warming has prevented or delayed chilling injury in warm season crops. The purpose of this experiment was to find a way to prevent or delay chilling injury in okra. Field grown `Annie Oakley', `Blondy', and `Clemson Spineless' okra pods were held constantly at 2, 5, or 10C or placed at 2C or 5C for 2 days followed by 2 days at 10C (2-10 and 5-10, respectively) then returned to their original temperature. After 8 days of storage, all boxes were placed at 20C for 1 day; color was measured with a colorimeter, and pods were rated subjectively for chilling injury. `Annie Oakley' and `Clemson Spineless' pods held at 2C were olive-green to brown; okra held at 2-10 was green and still marketable. Less chilling injury occurred to pods held at 5 and 5-10 compared to those at 2C. Pods held at 2-10, 5, or 5-10 had injury after 8 to 10 days of storage compared to 5 days at 2C. Although chilling injury could not be completely prevented in okra by intermittent warming, shelf life could be lengthened by cooling pods at 2C for no more than 2 days to eliminate field heat and reduce weight loss, followed by storage at a higher temperature.

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Okra pods are highly perishable due to a high respiration rate and chilling sensitivity. The purpose of this experiment was to evaluate okra cultivar response to package and storage temperature. Freshly harvested `Annie Oakley', `Blondy', `Burgundy', `Clemson Spineless' and `Emerald' okra pods were placed in plastic boxes and shrink-wrap bags. Pods were evaluated for weight loss, chilling injury and electrolyte leakage during 8 days of storage at 12.5 and 3°C. Weight loss was similar for all cultivars at both temperatures, but it was much less when pods were stored in bags compared to boxes. Percent electrolyte leakage was similar for all cultivars before storage. `Blondy' displayed the most severe chilling injury after 8 days of storage at 3C while `Emerald' had few symptoms of chilling injury. After 8 days of storage, all cultivars except `Emerald' had increased electrolyte leakage. These results indicate that okra pods have increased membrane permeability with chilling injury, and the degree of chilling injury may differ with cultivar.

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Small fruit are rich in several types of phytochemicals, vitamins, and minerals. These compounds have health functional properties that may protect humans from cardiovascular disease and certain cancers. Several of these phytochemicals, such as dietary fiber, anthocyanins, and polyphenolics, also contribute to small fruit quality. Other components contribute to appearance and taste. Nonvolatile organic acids contribute to the perceived sourness of small fruit and changes in levels can alter visual color by affecting cellular pH and anthocyanin structure. The soluble sugars glucose, fructose, and sucrose contribute directly to the perceived sweetness of the fruit and provide carbohydrates for other metabolic functions such as phenolic and ascorbic acid synthesis.

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Okra stored at 3C in 12.7-pm high-density polyethylene (HDPE) bags developed less chilling injury than fruit stored in plastic boxes. Okra held in HDPE bags at 12.5C for 8 days had more decay and reduced overall appearance than fruit held in plastic boxes. `Emerald Green' okra lost more weight in storage than the other four cultivars regardless of temperature or storage duration, while `Blondy' had the most decay. `Annie Oakley' and `Clemson Spineless' had better shelf life than the other cultivars.

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Watermelons contain the carotenoids b-carotene, phytofluene, lycopene, and lutein. These carotenoids play an important role in plant oxidative protection and may serve to protect humans against oxidative assaults. Of the carotenoids, lycopene is the predominant pigment in red-fleshed melons (30-130 μg·g-1), b-carotene is present in small amounts (1-14 μg·g-1), and other carotenoids are present in minute amounts (1-3 μg·g-1). Seventy varieties were screened for lycopene content using scanning colorimetry, spectrophotometry, and HPLC techniques, and grouped as low, medium, high, or very high in lycopene. Pink-fleshed heirloom varieties such as Sweet Princess and Black Diamond contained low amounts of lycopene (<40 μg·g-1). A number of seeded and seedless varieties had medium amounts of lycopene (40-60 μg·g-1). Varieties in the high category (60-80 μg·g-1) were primarily seedless types, although `Dixie Lee', an open-pollinated, seeded variety had 69 μg·g-1, indicating that high lycopene content is not restricted to hybrid or seedless melon germplasm. Six selections were found to be very high in lycopene (>80 μg·g-1), including the minimelon Hazera 6008 (Extazy). Total carotenoids and carotenoid profiles were determined by HPLC for 23 varieties in 2003. Both seeded and seedless type melons had varieties high in bcarotene, lycopene, and total carotenoids. These results indicate that commercial watermelon varieties have a wide range in lycopene and b-carotene content, and that most commercially important varieties are high in lycopene and total carotenoids, providing important sources of phytonutrients to the human diet.

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The red flesh of watermelon contains the fat-soluble carotenoid pigment lycopene. A high level of lycopene in human blood serum has been correlated with a reduced incidence of several cancers. This experiment was done to determine the variation in lycopene content among watermelon cultivars and ripeness stages. Ten melons per cultivar of hybrid, open-pollinated, and triploid (seedless) types were selected from field plantings at Lane, Okla. Additionally, 20-melon, quarterly shipments of hybrid or triploid types were used from commercial growers. Melons were cut transversely and a 100-g sample of heart tissue was removed from the center, frozen at –80 °C, extracted with a hexane–acetone–ethanol mixture and pigment quantified at 503 nm. Unripe melons (about 3 to 5 days from fully ripe) had 18% less lycopene than ripe melons. The average lycopene content of all ripe melons sampled (open-pollinated, hybrid, triploid) was 47.82 μg/g (n = 247 melons), while that of ripe hybrid and triploid melons was 54.76 μg/g (n = 209 melons). Lycopene content of ripe melons varied among cultivars, from as little as 33.96 μg/g in `Crimson Sweet' to as much as 75.72 μg/g in `Scarlet Trio'. These results indicate that fresh watermelon has a naturally high level of lycopene and that potential for enhanced lycopene content is already present in the germplasm of commercial cultivars.

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In the United States, as much as 10% of the watermelon sold is as a minimally processed product. These products are prepared at the retail level as cubed flesh in plastic food containers or as halved slices wrapped in plastic film. The shelf life of these products at different temperatures is not known. In this study, `Allsweet' and `Jubilee' ripe watermelons were washed, wiped with a 5% bleach solution, and cut into transverse slices using surface-sterilized knives. Halves of these slices were sprayed with distilled water (pH 7.0) or with Natureseal plus 5% ascorbic acid (pH 4.5), wrapped with plastic film (0.05-mm thickness), and stored at 2 and 5 °C for 4 to 6 days. Weight loss of wrapped slices was 0.1 % at 2 and 5 °C after 4 days of storage and 0.5% of slices sprayed with Natureseal. Watermelon flesh became slimy after 3 and 5 days of storage at 5 and 2 °C, respectively, especially in slices treated with Natureseal. Fruit rinds developed brown stains and became very soft. In a separate study, watermelon slices (flesh and rind) placed in jars at 10 °C lost the characteristic watermelon odor after 2 days and a more pumpkin-like odor developed. Respiration after 1 day at 10 °C was 6 to 8 mL CO2/kg-h and increased after 5 days of storage to 13 and 25 mL CO2/kg-h for `Allsweet' and `Jubilee', respectively. Ethylene production was 0.04 to 0.06 μL/kg-h after 1 day of storage, increasing to 0.55 μL/kg-h after 5 days of storage. Results indicate that cut watermelon should be held at temperatures of 2 °C or less for no more than 3 days.

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