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  • Author or Editor: P. Perkins-Veazie x
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Small fruit share several general characteristics. A significant source of starch is missing in strawberry, blueberry, cranberry, raspberry, blackberry, and grapes; thus, sugars accumulated at time of harvest represent the maximum amount of sweetness available. Total non-volatile acids decrease or stay the same, depending on the fruit. Immature small fruit are astringent, due to the presence of a variety of phenolic compounds that are diluted, metabolized, or immobilized in mature fruit. Ripeness can be determined by obvious changes in color, coinciding with or prior to fruit softening. Berry color is governed by the loss of chlorophyll and the accumulation of water soluble flavanoids and anthocyanins, rather than through accumulation of fat-soluble carotenoids. Environmental changes, especially temperature and rainfall, affect sugars, acidity, and color while storage conditions are more likely to affect color and acidity.

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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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The effectiveness of microorganisms applied in production of vegetable transplants has had mixed results. Bell pepper (Capsicum annuum L.) transplants were grown in a greenhouse using organic methods and the organic-certified potting mix was inoculated, or not, with beneficial bacteria or arbuscular mycorrhizal (AM) fungi, or both. Other transplants were grown in the same greenhouse with a conventional potting mix, which was not inoculated. Transplants were established in the field at various planting dates in a Bernow or Stigler soil and grown using conventional or organic methods. Pod yield and nutrient contents were determined. Yields of organically grown plants were similar to those of conventionally grown plants when both were grown on the Bernow soil. When grown on both soil types, yield was higher for the Bernow than for the Stigler soil. Treatment had little effect on pod mineral content. Chlorophylls, total carotenoid, and vitamin C contents of pods from plants grown on the Stigler soil were generally lower than those from plants grown on the Bernow soil. Average pod fresh weight for plants developed from seedlings inoculated with beneficial bacteria or AM fungi was greater than that from plants developed from conventionally grown seedlings. Inoculation did not improve fresh pod weights over that from plants developed from organically grown, but not inoculated, seedlings. Amending potting mix with the microorganisms tested did not provide extraordinary benefit or detriment for use in production of bell pepper.

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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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Firmness of blackberries greatly determines shelf life for fresh market. Firmness in blackberries appears to be due to a combination of skin toughness and internal receptacle to permit large sample size measurements. Subjective rating of fruit require consistent evaluation by raters over harvest dates and years, and is subject to fatigue error. The FirmTech2 firmness tester was developed to provide rapid compression measurements and has been successfully used in determining the firmness of cherries and blueberries. Blackberries from a large number of clones ranging in firmness from rock-hard to squishy were measured with the FirmTech2 using a deformation range of 25 to 100 g. Additionally, blackberries were placed in storage at 2, 5, and 2/20 °C to monitor effects of storage temperature on blackberry firmness. Berries were subjectively rated and then placed on the Firmtech for measurements. A comparison of firmness readings for fruit only in the “1” (firm) category was made. Differences found among fruit readings agreed with observed differences in field subjective ratings. Stored fruit that had become soft and mushy could not be statistically differentiated from firmer fruit in quantitative readings. In conclusion, the Firmtech2 allowed rapid evaluation of breeding lines before storage.

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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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