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P. Perkins-Veazie and J.K. Collins

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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P. Perkins-Veazie and J.K. Collins

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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P. Perkins-Veazie and J. K. Collins

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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P. Perkins-Veazie and J.K. Collins

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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P. Perkins-Veazle and J.K. Collins

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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P. Perkins-Veazie and J.K. Collins

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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P. Perkins-Veazie and J.K. Collins

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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P. Perkins-Veazie, J.K. Collins, M. Siddiq and K. Dolan

Most watermelon in the U.S. is consumed fresh. Development of value-added products from watermelon is desirable for new market niches, and provides alternative markets for fruit that are cosmetically undesirable for the fresh market. The objective of this experiment was to determine if different processing techniques changed the lycopene and quality aspects of juices and concentrates. Watermelon flesh was macerated, followed by holding at room temperature (no heat) or heating to 50 °C. Macerate was then placed in a hydraulic press to obtain juice. Adding heat to macerate increased juice yield by 1% to 2% and increased lycopene content by 1 to 2 mg·kg–1. The residual pomace (waste from juicing) also contained lycopene, about 110% of that found in the juice, or 10% from the original macerate. In a second experiment, juice was subjected to pasteurization, which caused a slight loss of lycopene and beta-carotene compared to the unpasteurized juice. In a third study, juice was concentrated to 42 °Brix using either 40 or 50 °C heat treatments, followed by pasteurization. Heating juice to 50 °C concentrated the lycopene by 17% compared to heating to 40 °C. Pasteurization increased the lycopene content of the 40 °C concentrate by 10% but not of the 50 °C concentrate. In summary, the addition of heat at various steps during processing and pastuerization of watermelon concentrated but did not degrade lycopene. Additionally, the residual pomace created from juice manufacturing is a concentrated source of carotenoids and may have potential use as a value added nutraceutical product.

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P. Perkins-Veazie, J.K. Collins and J.R. Clark

Fruit at three stages of ripeness were harvested from four erect blackberry (Rubus spp.) cultivars, `Navaho', `Choctaw', `Cheyenne', and `Shawnee', for 2 years to evaluate fresh-market shelf life during 7 days of storage at 2C, 95% relative humidity. Ethylene production was highest from dull black fruit and varied widely among cultivars, ranging from 7.3 to 51.1 pmol·kg–1·s–1 for `Navaho' and `Choctaw' fruit, respectively. Weight loss ranged from 0.8% (`Shawnee') to 3.3% (`Navaho') after storage. Mottled (50% black) fruit of all cultivars were higher in fruit firmness and titratable acidity and had lower soluble solids and anthocyanin concentrations than fruit at other stages of maturity. Cultivars did not differ in total anthocyanin concentration, but dull black fruit had a higher anthocyanin concentration than shiny black fruit. Dull black `Choctaw', `Shawnee', and `Cheyenne' fruit were softer and had more leakage and decay than shiny black fruit. Both shiny and dull black `Navaho' fruit had less leakage than fruit of other cultivars. All cultivars at the shiny black stage were considered marketable after 7 days at 2C because fruit were firm with little decay or leakage. However, red discoloration appeared more frequently on shiny black than on dull black fruit. Mottled fruit of erect cultivars should not be harvested, while shiny black fruit of `Cheyenne', `Shawnee', and `Choctaw' might be suited for regional markets. Either shiny black or dull black `Navaho' fruit could be shipped to distant markets.

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P. Perkins-Veazie, J.K. Collins and J.R. Clark

Blackberry fruit often exhibit an unattractive discoloration following harvest and storage. This redness appears at random on the berry and has been associated with sunburn or high temperature damage, or with fruit harvested less than fully ripe. We began a study to separate and identify causes of red drupe. Black (fully ripe) berries, free of sunburn, of six blackberry cultivars were harvested in the morning and subjected to conditioning treatments of 20 hours at 2 or at 20°C, followed by 7 days storage at 2°C. Strong cultivar differences and effects of conditioning treatment were found. `Navaho', `Arapaho' and `Chester' had little or no red drupe, regardless of conditioning treatment. As much as 50% of `Shawnee' and `Choctaw' berries exhibited red drupe, with more appearing in fruit conditioned at 2°C. Development of red drupe in berries conditioned at 2°C was quadratically related to total anthocyanin and juice pH, while that of fruit conditioned at 20°C was quadratically related to percent titratable acidity. The red drupe disorder in blackberries is exacerbated by low temperature storage and may be due to decreased cellular pH and subsequent anthocyanin glycosylation in individual drupelets.