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Jennifer L. Baeten, Thomas C. Koch and Irwin L. Goldman

Carrot has been bred for increased levels of pro-vitamin E α-tocopherol. This vitamin is lipid soluble. Carrot root has been shown to have measurable levels of lipid, but it is not certain if the lipid level is correlated to α-tocopherol levels. The HPLC method is needed to quantify levels of α-tocopherol. Measuring lipids may be less time consuming in a breeding program. We developed a method for extracting lipids from carrot tissue based on the Soxhlet extraction method. The Soxhlet extraction uses a non-polar ether solvent to pull lipids out of freeze-dried tissue. A collection of carrot accessions ranging in α-tocopherol concentration 0.04–0.18 ppm and carotenoid concentration 10.63–1673.76 ppm were used in this investigation. Root tissue was freeze-dried and lipid levels were measured in an experiment with two replications. The mean lipid level of root tissue was 0.05 g fat/g tissue. The range was 0–1.1 g fat/g tissue. Phenotypic correlations were performed among lipid, α-tocopherol, and β-carotene concentrations in these samples. Twenty-four samples were tested for lipid levels (12 high and 12 low). From these results, percent lipid of the root was determined. Correlations were made between the lipid data and α-tocopherol data of the given samples.

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Marilyn Rivera-Hernández, Linda Wessel-Beaver and José X. Chaparro

Squash and pumpkins (Cucurbita sp.) are important contributors of beta-carotene to the diet. Consumers of tropical pumpkin and butternut squash (both C. moschata Duchesne) prefer a deep orange mesocarp color. Color intensity is related to carotene content. Among the five domesticated Cucurbita species, C. moschata and C. argyrosperma Huber have a close relationship. In crosses between these two species, fertile F1 plants can be easily obtained when using C. argyrosperma as the female parent. This research studied the relationship between and within C. moschata and C. argyrosperma by sequencing three genes in the carotenoid biosynthesis pathway and generating gene trees. Genotypes used in the study differed in flesh color from very pale yellow to dark orange. In some cases, haplotypes were associated with a particular mesocarp color. Further study of these types of associations may improve our understanding of color development in Cucurbita. The frequency of single nucleotide polymorphisms (SNPs) in the sequenced fragments was low. There were more SNPs and more heterozygotes among C. moschata accessions than among C. argyrosperma accessions. Haplotypes of the outgroups (C. ficifolia C.D. Bouché and C. maxima Duchesne) were always distinct from C. moschata and C. argyrosperma. These later species had both distinct haplotypes and shared haplotypes. Haplotypes shared among species tended to be maintained in the same branch of the phylogenetic tree, suggesting either gene flow between the species or a common ancestral gene. Both explanations suggest a close genetic and evolutionary relationship between C. moschata and C. argyrosperma.

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Catherine Nicolle, Gérard Simon, Edmond Rock, Pierre Amouroux and Christian Rémésy

Carrot (Daucus carota L.) is ranked among vegetables as the most consumed and the best provitamin A provider. Moreover, carrot also contains vitamins, phenolic compounds, and other antioxidant micronutrients. The influence of carrot genetic background on the content of several micronutrients was investigated. Carotenoids and vitamins (C and E) were analyzed by HPLC in 20 varieties of carrot, and antioxidant activity of carrots was investigated with colorimetric methods (ORAC and Folin-Ciocalteu). There were large differences among cultivars in carotenoid content (0.32 to 17 mg/100 g of fresh weight). In yellow and purple carrots, lutein represents nearly half of the total carotenoids. By contrast, in orange carrots, β-carotene represents the major carotenoid (65%). The concentration of vitamin E ranged from 191 to 703 μg/100 g of fresh weight, whereas the concentration in ascorbic acid ranged from 1.4 to 5.8 mg/100 g. For all these components, dark-orange carrots exhibited the highest values. Significant differences among these 20 varieties were also recorded for mineral and total phenolic compound concentrations. Purple and dark-orange carrots could be preferred to usual carrot varieties to benefit from their specific micronutrients (anthocyanins, carotenoids, or vitamin E). ORAC is a complex reflection of phytomicronutrients but is not tightly linked to vitamin C levels, as shown for white carrots, which are rich in this vitamin.

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Mark Lefsrud, Dean Kopsell, Carl Sams, Jim Wills and A.J. Both

Determination of carotenoid concentrations in plant tissue requires dried samples for analysis ( Kopsell et al., 2004 ; Tai and Chen, 2000 ). However, the plant growth environment can have a significant impact on the water content of the

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Cynthia L. Barden and William J. Bramlage

Antioxidants are believed to protect against the oxidation of α-farnesene to conjugated trienes in apple (Malus domestica, Borkh.) peel, thus providing resistance against superficial scald development. We conducted three experiments in which apples were a) harvested weekly, during which they were exposed to increasing hours at <10C during ripening; b) induced to ripen with no hours at <10C by applying ethephon; and c) enclosed in paper bags as they ripened. Inducing ripening with ethephon increased total water-soluble reducing compounds and percentage inhibition of lipid oxidation of peel extracts, increased concentrations of α-tocopherol, carotenoids, and ascorbic acid in peel, but only slightly reduced scald. Delayed harvests increased all of these antioxidants except ascorbic acid and greatly reduced scald development. Bagging fruit before ripening decreased α-tocopherol, carotenoid, and ascorbic acid concentrations, decreased total water-soluble reducing compounds, and increased scald development. We conclude that changes in these antioxidants probably are affected more by ripening and light intensity than by low temperature before harvest. Chemical name used: (2-chloroethyl)phosphonic acid (ethephon).

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Carl M. Jones and James R. Myers

Continued and mounting evidence of the health benefits provided by carotenoid and anthocyanin pigments has increased public interest in dietary sources of these important phytonutrients. Tomatoes (Lycopersicon esculentum) are the primary dietary contributor of lycopene and an important source of beta-carotene. A collection of tomatoes containing the genes hp-1, dg, ogc, Ip, B and Af that are known to affect carotenoid and anthocyanin levels have been analyzed using HPLC. Levels of lycopene, beta-carotene, phytoene, and phytofluene have been determined in these accessions. Accession LA 3005, containing the dg gene, had the highest lycopene levels of the accessions analyzed (14 mg/100 g fresh wt.). A rapid HPLC method for quantitation of carotenoid levels from tomato fruit has been developed. “Heirloom” black and purple tomatoes have also been included in the accessions analyzed and have carotenoid levels comparable to cultivated red tomatoes. Anthocyanin presence has been confirmed only in the accessions LA 1996 (Af) and in some fruit of segregating plants from LA 3668 (Abg). Total monomeric anthocyanin content of LA 1996 as measured by the pH differential method is estimated to be 5.6 mg/100 g in the outer pericarp tissues and 18.6 mg/100 g in the skin tissue.

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Kil Sun Yoo*, Julio Loaiza, Kevin Crosby, Leonard Pike and Steve King

About 40 watermelon samples with various flesh colors (red, pink, orange, and yellow) were tested for their carotene, sugar, and ascorbic acid contents. Carotenoids were separated and purified by using a preparative HPLC system and identified by comparing the spectra with standard compounds by using a diode array detector. Sugar and ascorbic acid contents were measured by HPLC methods. Red and pink colored watermelon contained lycopene as the major carotenoid, with a wide range of variation (5 to 51 μg·g-1). Beta-carotene was the second major carotenoid and was less than 6 μg·g-1. There were also lutein and violazanthin in less than 1.5 μg·g-1 range. Yellow and orange flesh watermelons contained a complex mixture of carotenes. Prolycopene, lycopene, or beta-carotene was the major component, depending on the variety, and the contents were less than 24, 3, and 9 μg·g-1, respectively. There were also minor carotenoids, such as violaxanthin, lutein, neurosporene, zea-carotene with a 0 to 3.5 μg·g-1 range. Neurosporene, zea-carotene, and prolycopene were not found in the red watermelons. There was great variation in total sugar content, range being from 22 to 102 mg-1, while the °Brix was from 4.0 to 15.5. Sucrose, glucose, and fructose were the main sugars in the watermelon and their composition were grouped as sucrose-dominant or fructose-dominant groups. Some varieties with very low levels of sucrose were generally low in the total sugar content. Watermelon contained fairly low levels of ascorbic acid, less than 58 μg·g-1 and some varieties had nearly no ascorbic acid. Estimation of total carotenoid in the yellow watermelons by measuring absorbency at 435, 485, or 503 nm was tested and 435 nm showed the highest correlation coefficient (r 2 =0.845).

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Tyann Blessington, Douglas C. Scheuring and J. Creighton Miller Jr.

Potatoes are stored to ensure a continuous supply; however, losses due to shrinkage and sprouting can be large. It is believed that ionizing irradiation will become more prominent for sprout inhibition due to the increasingly higher operating costs of low-temperature storage and possible phase-out of chemical sprout inhibitors. The effects of storage and ionizing irradiation (gamma and electron beam) on antioxidant activity (AOA), phenolic content, and carotenoid content were analyzed using the potato cultivar Atlantic. Tubers were subjected to 0, 75, and 200 Gy γ-irradiation doses, stored at 20 °C, and analyzed after 0, 10, 20, 75, and 110 days. Tubers from another harvest were subjected to a surface dose of 0 or 200 Gy e-beam irradiation, stored at 20 °C, and analyzed after 0, 10, 20, 75, and 110 days. AOA was measured via the DPPH method; phenolic content via the Folin-Ciocalteau method and individual phenolics via HPLC; and carotenoid content via absorbance at 445 nm and individual carotenoids via HPLC. During early storage, higher doses resulted in higher AOA, while, during longer storage, lower doses produced greater AOA. Phenolic content increased in storage during the γ-irradiation study, but decreased in the e-beam study, partly due to increases in chlorogenic acid in the former and decreases in caffeic acid in the latter. The e-beam dose of 200 Gy resulted in significantly greater total phenolics than 0 Gy. Total carotenoids and lutein decreased with storage, but were not affected by irradiation. Storage exerted a much greater influence on AOA, phenolic content, and carotenoid content than either irradiation treatment.

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Mark G. Lefsrud, Dean A. Kopsell, David E. Kopsell and Joanne Curran-Celentano

Crop plants are adversely affected by a variety of environmental factors, with air temperature being one of the most influential. Plants have developed a number of methods in the adaptation to air temperature variations. However, there is limited research to determine what impact air temperature has on the production of secondary plant compounds, such as carotenoid pigments. Kale (Brassica oleracea L.) and spinach (Spinacia oleracea L.) have high concentrations of lutein and β-carotene carotenoids. The objectives of this study were to determine the effects of different growing air temperatures on plant biomass production and the accumulation of elemental nutrients, lutein, β-carotene, and chlorophyll pigments in the leaves of kale and spinach. Plants were grown in nutrient solutions in growth chambers at air temperatures of 15, 20, 25, and 30 °C for `Winterbor' kale and 10, 15, 20, and 25 °C for `Melody' spinach. Maximum tissue lutein and β-carotene concentration occurred at 30 °C for kale and 10 °C for spinach. Highest carotenoid accumulations were 16.1 and 11.2 mg/100 g fresh mass for lutein and 13.0 and 10.9 mg/100 g fresh mass for β-carotene for the kale and spinach, respectively. Lutein and β-carotene concentration increased linearly with increasing air temperatures for kale, but the same pigments showed a linear decrease in concentration for increasing air temperatures for spinach. Quantifying the effects of air temperature on carotenoid accumulation in kale and spinach, expressed on a fresh mass basis, is important for growers producing these crops for fresh markets.

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Joshua D. Williamson, Cameron P. Peace, Frederick A. Bliss, David T. Garner and Carlos H. Crisosto

The Y locus of peach [Prunus persica (L.) Batsch] controls whether a tree will produce fruit with white or yellow flesh. Flesh color has implications for consumer acceptance and nutritional quality, and improved cultivars of both flesh types are actively sought. This paper focuses on evidence that the flesh color locus also controls senescent leaf color (easily observed in the fall) and hypanthium color. In two progeny populations totaling 115 progeny plus their parents, the three traits co-segregated completely. Trees carrying the dominant allele for white flesh had yellow senescent leaves and yellow hypanthia, while homozygous recessive yellow-fleshed types exhibited orange senescent leaves and orange hypanthia. Senescent leaf color was also measured quantitatively, with major colorimetric differences observed between white-fleshed and yellow-fleshed progeny. Senescent leaf hue angle and reflected light wavelengths of 500 to 560 nm were the parameters most affected by the flesh color locus. Results were verified with 10 white-fleshed and 10 yellow-fleshed cultivars. The findings show that the Y locus in peach controls the type and concentration of carotenoids in multiple organs, including fruit, leaves, and flowers. The ability to discriminate between white and yellow flesh color using a simple visual method, applicable in plants not yet at reproductive maturity, is valuable to breeders wanting to save time, growing space, and money.