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Beiquan Mou

There is increasing medical evidence for the health benefits derived from dietary intake of carotenoid antioxidants, such as β-carotene and lutein. Enhancing the nutritional levels of vegetables would improve the nutrient intake without requiring an increase in consumption. A breeding program to improve the nutritional quality of lettuce (Lactuca sativa L.) must start with an assessment of the existing genetic variation. To assess the genetic variability in carotenoid contents, 52 genotypes including crisphead, leaf, romaine, butterhead, primitive, Latin, and stem lettuces, and wild species were planted in the field in Salinas, Calif., in the Summer and Fall of 2003 with four replications. Duplicate samples from each plot were analyzed for chlorophyll (a and b), β-carotene, and lutein concentrations by high-performance liquid chromatography (HPLC). Wild accessions (L. serriola L., L. saligna L., L. virosa L., and primitive form) had higher β-carotene and lutein concentrations than cultivated lettuces, mainly due to the lower moisture content of wild lettuces. Among major types of cultivated lettuce, carotenoid concentration followed the order of: green leaf or romaine > red leaf > butterhead > crisphead. There was significant genetic variation in carotenoid concentration within each of these lettuce types. Crisphead lettuce accumulated more lutein than β-carotene, while other lettuce types had more β-carotene than lutein. Carotenoid concentration was higher in summer than in the fall, but was not affected by the position of the plant on the raised bed. Beta-carotene and lutein concentrations were highly correlated, suggesting that their levels could be enhanced simultaneously. Beta-carotene and lutein concentrations were both highly correlated with chlorophyll a, chlorophyll b, and total chlorophyll concentrations, suggesting that carotenoid content could be selected indirectly through chlorophyll or color measurement. These results suggest that genetic improvement of carotenoid levels in lettuce is feasible.

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Alexandra B. Napier, Kevin M. Crosby, and Soon O. Park

Muskmelons (Cucumis melo L.) play an important role in the American diet. Ranked as one of the top 10 most-consumed fruits by the USDA, cantaloupe melons have the highest amount of beta-carotene of all the ranked fruits. Beta-carotene, also called pro-Vitamin A, is an essential nutrient required for eye health, and may have the potential, as an antioxidant to reduce the risks associated with cancer, heart disease, and other illnesses. Breeding melons with increased levels of beta-carotene will benefit consumer health. Research has found phytonutrients are most bioavailable when consumed in their fresh form, rather than as vitamin supplements. The high level of beta-carotene found in some melons has a genotypic component, which may be exploited to breed melons high in beta-carotene. Molecular markers and marker-assisted selection (MAS) can be used to increase the efficacy of the breeding process, while lowering breeding costs. An F2 population was created using `Sunrise', the female parent, containing no beta-carotene crossed with `TAM Uvalde', a high beta-carotene variety. A field population consisting of 115 F2 individuals and a greenhouse population containing 90 F2 individuals were grown. The resulting fruit were screened phenotypically and ranked according to beta-carotene content. Chisquare values fit the previously reported model of a single dominant gene for presence of beta-carotene (orange-flesh) vs. absence (green or white flesh). A continuous distribution of beta-carotene concentrations from high to low suggested quantitative inheritance for this trait. Two eight-plant DNA bulks composed of either high or low beta-carotene F2 individuals were screened for polymorphic molecular markers using the amplified fragment-length polymorphism technique.

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John Stommel, Judith A. Abbott, Robert A. Saftner, and Mary J. Camp

Consumer acceptance of fresh and processed tomato (Lycopersicon esculentum Mill.) products is influenced by product appearance, flavor, aroma, and textural properties. Color is a key component that influences a consumer's initial perception of quality. Beta-carotene and lycopene are the principal carotenoids in tomato fruit that impart color. Analytical and sensory analyses of fruit quality constituents were conducted to assess real and perceived differences in fruit quality between orange-pigmented, high-beta-carotene cherry tomato genotypes and conventional lycopene-rich, red-pigmented cherry tomato cultivars. Thirteen sensory attributes were evaluated by untrained consumers under red-masking light conditions where differences in fruit color could not be discerned and then under white light. Panelists preferred the appearance of the red-pigmented cultivars when viewed under white light, but scored many of the other fruit-quality attributes of red- and orange-pigmented genotypes similarly whether they could discern the color or not. Irrespective of light conditions, significant genotype effects were noted for fruit appearance, sweetness, acidity/sourness, bitterness, tomato-like flavor, unpleasant aftertaste, firmness in fingers, juiciness, skin toughness, chewiness, bursting energy, and overall eating quality. Attributes whose scores differed between white and red-masking lights were intensities of tomato aroma, tomato-like flavor, sweetness, bursting energy, juiciness, and overall eating quality. The results demonstrated a color bias favoring red-pigmented fruit and highlight the influence that color has on perception of tomato fruit quality, particularly on tomato-like flavor, juiciness, and overall eating quality. Interactions between fruit chemical constituents likely influenced perceptions of quality. High-beta-carotene genotypes contained higher levels of sugars and soluble solids and equal or higher titratable acidity than the red-pigmented cultivars. Total volatile levels did not differ among genotypes; however, several individual volatiles were significantly higher in high-beta-carotene genotypes.

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Gene E. Lester, John L. Jifon, and Gordon Rogers

Muskmelonfruit[Cucumis melo L. (Retiulatus Goup)] sugar content is related to potassium (K)-mediated phloem loading and unloading of sucrose into the fruit. During fruit growth and maturation, soil fertility is often inadequate (due to poor root uptake) to satisfy the demand for K. Potassium uptake also competes with the uptake of Ca and Mg, two essential minerals needed for melon fruit membrane structure, function and postharvest shelf-life. Supplemental foliar-applied K could alleviate this problem especially during the critical fruit growth/maturation period. We conducted experiments to determine the effects of timing of supplemental foliar K applications on fruit quality and health attributes of orange-flesh muskmelon `Cruiser'. Plants were grown in a greenhouse and fertilized with a regular soil-applied N–P–K fertilizer throughout the study. Entire plants, including the fruit were sprayed with a solution of a novel glycine amino acid-complexed potassium (Potassium Metalosate, 24% K), diluted to 4.0 mL·L-1, 3 to 5 d after anthesis (fruit set) and up to 3 to 5 d prior to abscission (full-slip). Three sets of plants were either sprayed weekly, or bi-weekly or not sprayed (control). Fruit from plants receiving supplemental foliar K matured on average 2 days earlier, and had significantly higher fruit K concentrations, soluble solids, total sugars, ascorbic acid (vitamin C), beta-carotene, and were firmer than fruit from control plants. In general, there were few differences in fruit quality aspects between bi-weekly or weekly treatments. The data demonstrate that fruit quality and marketability as well as some of the developmentally induced K deficiency effects can be alleviated through foliar nutrition.

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Gene E. Lester, John L. Jifon, and Gordon Rogers

Muskmelon [Cucumis melo L. (Reticulatus Group)] fruit sugar content is directly related to potassium (K)-mediated phloem transport of sucrose into the fruit. However, during fruit growth and maturation, soil fertilization alone is often inadequate (due to poor root uptake and competitive uptake inhibition from calcium and magnesium) to satisfy the numerous K-dependent processes, such as photosynthesis, phloem transport, and fruit growth. Experiments were conducted during Spring 2003 and 2004 to determine if supplemental foliar K applications during the fruit growth and maturation period would alleviate this apparent inadequate K availability in orange-flesh muskmelon `Cruiser'. Plants were grown in a greenhouse and fertilized throughout the study with a soil-applied N-P-K fertilizer. Flowers were hand pollinated and only one fruit per plant was allowed to develop. Starting at 3 to 5 days after fruit set, and up to 3 to 5 days prior to fruit maturity (full slip), entire plants, including the fruit, were sprayed with a glycine amino acid-complexed potassium (potassium metalosate, 24% K) solution, diluted to 4.0 mL·L-1. Three sets of plants were sprayed either weekly (once per week), biweekly (once every 2 weeks) or not sprayed (control). Fruit from plants receiving supplemental foliar K matured on average 2 days earlier than those from control plants. In general, there were no differences in fruit maturity or quality aspects between the weekly and biweekly treatments except for fruit sugar and beta-carotene concentrations, which were significantly higher in the weekly compared to the biweekly or control treatments. Supplemental foliar K applications also resulted in significantly firmer fruit with higher K, soluble solids, total sugars, ascorbic acid (vitamin C) and beta-carotene concentrations than fruit from control plants. These results demonstrate that carefully timed foliar K nutrition can alleviate the developmentally induced K deficiency effects on fruit quality and marketability.

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Fekadu Gurmu, Shimelis Hussein, and Mark Laing

(ISTRC) Symp., 9–15 Nov. 2007, Arusha. ISTRC, Arusha, Tanzania van Jaarsveld, P.J. Faber, M. Tanumihardjo, S.A. Nestel, P. Lombard, C.J. Benadé, A.J.S. 2005 Beta carotene–rich orange-fleshed sweet potato improves the vitamin A status of primary school

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Gene Lester

This article examines the nutritional quality and human health benefits of melons, specifically, muskmelon or cantaloupe (Cucumis melo L. var. reticulatus Naud.) and honeydew melon (Cucumis melo L. var. inodorus Naud.) types. Melons are naturally low in fat and sodium, have no cholesterol, and provide many essential nutrients such as potassium, in addition to being a rich source of beta-carotene and vitamin C. Although melons are an excellent source of some nutrients, they are low in others, like vitamin E, folic acid, iron, and calcium. Since the U.S. diet is already high in fat and protein content, melons should be included in everyone's diet, along with five to eight servings per day of a variety of other fruit and vegetables, to ensure adequate nutrition, promote individual health, and reduce one's risk of cancer and certain other chronic diseases.

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Kevin M. Crosby, Daniel Leskovar, John L. Jifon, and Joseph Masabni

standard refractometer (Atago, Japan), whereas beta-carotene was measured by the spectrophotometric method of Sadler et al. (1990) , with slight modifications. Yields were higher at Uvalde for all cultivars due to larger fruit sizes and less disease

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Chen Jiang, Penelope Perkins-Veazie, Guoying Ma, and Christopher Gunter

The consumption of fresh muskmelons (Cucumis melo reticulatus L.) has been linked to severe illness outbreaks due to contamination with bacterial pathogens. Antimicrobial essential oils (EOs) were incorporated into wash water sprays and evaluated as potential agents for postharvest disinfection of ‘Athena’ muskmelons. Freshly harvested fruits were sprayed with 0.5% EOs from cinnamon leaf, thyme, or clove bud emulsified in a whey protein emulsion (WP) as potential washing disinfectants, together with deionized water, water with 200 µL·L−1 free chlorine (pH 7, free turbidity), or oil-free WP as controls. Melons were treated, stored at 4 °C and then evaluated weekly for weight loss, rind color, mesocarp firmness and the compositional quality traits soluble solids content (SSC), pH, β-carotene content, and total ascorbic acid (AsA) for up to 21 days. Essential oil–treated melons were not different from controls in fruit quality and composition with the exception of fruits treated with thyme oil, which were statistically lower in SSC (0.8 °Brix) than those treated with water or cinnamon oil treatment. Internal carbon dioxide was statistically higher (≈0.1% higher in value, equal to a 25% increase) in muskmelons receiving whey protein–based treatments after storage for at least 7 days. Overall, our results suggest that EOs as disinfectants have little effect on quality or composition of muskmelon fruit.