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  • Author or Editor: Bhimanagouda Patil x
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Field studies were conducted for 2 years, at three sites in the Lower Rio Grande Valley of Texas, to evaluate the effects of location, rootstock, and irrigation on sheepnosing (elongation of the apex) of `Rio Red' grapefruit (Citrus paradisi Macf.). Based on the ratio of equatorial to polar diameter, grapefruit budded on sour orange (Citrus aurantium L.) rootstock grown at Weslaco had a significantly higher percentage of sheepnosed fruits (63%) than did fruit grown at Mission (57%), while the grove at Bayview produced a negligible percentage of sheepnosed fruit (4%). In a second study, `Rio Red' trees grown on `Carrizo' rootstock [C. sinensis (L.) Osbeck × Poncirus trifoliata (L.) Raf.] produced a significantly higher percentage of sheepnosed fruit (59%) than did those on `Swingle' (C. paradisi × P. trifoliata) (48%). In a third experiment, trees irrigated by microjet had a significantly higher percentage of sheepnosed fruit (53%) than did those that were flood-irrigated (43%). Although sheepnosed fruit had significantly greater peel thickness and a lower juice content, fruit quality was better than that of normal fruit because of a higher soluble solids: titratable acidity ratio. In 1999, the significant irrigation and rootstock effects were less than that due to growing location. Effects of location, rootstock and irrigation varied between years. The interaction between factors and years was mainly due to a lack of low amount of sheepnosing in 1998.

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Two-year field studies at three sites in the Lower Rio Grande Valley of Texas were conducted to evaluate the effects of location, rootstock, and irrigation on sheepnosing of `Rio Red' grapefruit (Citrus paradisi Macf.,) on sour orange (Citrus aurantium L.) rootstock. Based on the equatorial/polar diameter ratio, grapefruit grown in Weslaco had significantly higher percentage of sheepnosed fruits (62.66) than fruit grown in Mission (57.32), while Bayview had a negligible percentage of sheepnosed fruit (4.07). In a second study, `Rio Red' grapefruit grown on Carrizo [C. sinensis (L.) Osbeck × Poncirus trifoliate (L.) Raf.] had significantly higher percentage of sheepnosed fruit (59.46), compared to `Rio Red' grown on Swingle (C. paradisi × P. trifoliata) (47.83). In a third experiment, grapefruit with microjet irrigation had a significantly higher percentage of sheepnosed fruit (53.40), compared to flood irrigation (42.68). Although sheepnosed fruit had significantly greater peel thickness and a lower juice content, fruit quality was better because of higher soluble solids: titratable acidity ratio compared to normal shaped fruits. While significant, the irrigation and rootstock appear have a minor effect on sheepnosing less than growing location.

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Accumulating epidemiological evidences indicate that citrus phytochemicals have prevented chronic diseases such cancer and heart diseases. To enhance nutraceutical levels, field experiments were conducted using `Ruby Red' grapefruit on Carrizo citrange rootstock to evaluate the effects of variable fertilizer rates on nutraceutical contents. The trees received annual nitrogen rates from 0 to 280 kg·ha-1 (using a 1 N: 0.25 P: 1 K blend) under optimal irrigation schedule. Subsamples of fruit were analyzed for nutraceutical levels. HPLC analysis showed that naringin concentrations of the fruit collected from the trees treated with different levels of nitrogen differ significantly, and naringin levels decreased with increased nitrogen levels. Fruit from the control treatment had 1316 mg·mL-1 of naringin compared to the fruit collected from 280 kg N/ha per year trees (1056 mg·mL -1). A similar trend was observed with tasteless flavonoid naringenin rutinoside (narirutin). Total vitamin C [ascorbic acid (AA) plus dehydroascorbic acid (DHAA)] content from the fruit collected decreased with the nitrogen levels increased. These results demonstrate that increased fertilizer rates have an influence on the nutraceutical levels; therefore, there is a potential for further investigations on fine tuning the preharvest production programs to improve the nutritional value of the fruit.

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Antioxidant activity is widely used as a parameter to characterize different plant materials for potential health benefits. This activity is related with compounds capable of protecting a biological system against the harmful effect of reactions that can cause excessive oxidation, involving reactive oxygen and nitrogen species (RONS). There has been growing interest in the beneficial health effects of consuming fruits and vegetables. Mainly, the presence of lycopene, ascorbic acid, and phenolic antioxidants is believed to have the protective mechanism. The free radical-scavenging activities of grapefruit extract of `Rio Red', `Marsh White', and commercial juice were extracted with different solvents, such as hexane, ethyl acetate, and chloroform. The dried extracts were screened for their radical scavenging activity using the α,α -diphenyl-β-picrylhydrazyl (DPPH) method. The ethyl acetate extracts of commercial juice and `Marsh White' were found to possess more radical scavenging activity compared with the other two extracts. However, chloroform extracts of `Rio Red' grapefruit were the most active, which may be ascribed to the presence of more lycopene. Furthermore, the antioxidant capacity of `Rio Red' and `Marsh White' extracts was assayed through the phosphomolybdenum method and expressed as equivalent to ascorbic acid (μmol·g-1 of the extract). The order of antioxidant capacity for `Rio Red' extracts was found to be hexane > chloroform > ethyl acetate, while the order for `Marsh White' was chloroform > hexane > ethyl acetate. The results indicate that the extent of antioxidant activity of the extract is in accordance with the amount of lycopene/phenolics present in that extract; commercial juice and `Rio Red' may provide a good source of antioxidants.

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Twenty-four genotypes of `Walla Walla' sweet onion (Allium cepa L.) grown in two locations were evaluated for several characteristics associated with bulb flavor and storage losses. The range of pyruvic acid content in bulbs stored (at 5C and 65–75% RH) for 0, 2, and 4 months were 3.4–7.54, 3.48–18.81, and 3.92–12.61 (μmol·g–1), respectively, among different genotypes. Bulb quality of several genotypes decreased during storage, as indicated by lower total sugar concentration (fructose, glucose, and sucrose) and greater pungency. At 5C after 4 months of storage, the range of marketable bulbs (percent by weight) was 31% to 89% among genotypes; however, at 15C, only two genotypes survived with 60% marketable bulbs. Pungency and sweetness changed independently during storage. Pyruvic acid was not correlated (r = 0.038) with the percentage of marketable bulbs remaining after 4 months of storage. In comparison with the short-day sweet onions (`Vidalia' and `Texas Grano 1015Y), `Walla Walla' sweet onions showed two-fold higher sugar: pungency ratio among genotypes.

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Sweet onions have gained global importance because of their mild flavor and tear-free properties. A field investigation with seventeen Walla Walla Sweet onion entries grown at the IAREC of Washington State Univ. were evaluated in 1994 and 1995. The flavor and quality characteristics such as pyruvic acid and total sugar (fructose, glucose, and sucrose) concentrations were analyzed by spectroscopy and HPLC respectively. The pyruvic acid concentration in bulbs stored (5 °C and 65% to 75 % relative humidity) for 0, 2, and 4 months increased as the storage time increased. During 1994 and 1995 the pyruvic acid ranges during storage were 4.8 to 7.9 and 2.9 to 9.6 mmols·g–1, respectively. Total sugar concentration in 1994 decreased as the storage period increased, while in 1995 the trend was reversed. There was a higher concentration of sucrose in 1995. In general, Walla Walla onions showed a higher sugar: pyruvic acid ratio among different entries compared to short-day (Vidalia and Texas Grano 1015Y) onions.

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Fall onions, grown for their long shelf life, have become popular both in domestic and export market. Sixty cultivars of onion from 14 major seed companies were grown in Quincy, Wash., and were analyzed for their flavor, quality, and anticarcinogenic flavonol, quercetin. The highest quercetin concentration (in mg·kg–1 fresh weight) was observed in the red onion `Feugo' (495.6) followed by `Tango' (396.8), while the least amount was in the yellow onion `Pinnacle'(152.5). The pyruvic acid content varied from 1.5 to 18.7 mmol·g–1 and total sugar (glucose, fructose, and sucrose) levels ranged from 9.4 to 36.9 mg·g–1 fresh weight among different cultivars. The ratio of sugar:pyruvic acid showed marked variation (1.6 to 64.00) among different cultivars. The variation in oligosacharides were ≈60-fold over all cultivars. The maximum degree of polymerization (DP) observed was DP8. We conclude that there is a potential for developing a mild onion for longer shelf life and better health properties. Yield at harvest and storage performance based on rot also was evaluated during storage.

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Representative varieties and genotypes of different colored onions were compared to determine the extent of differences in the distribution of quercetin and quercetin glycosides. The dry skins, outer rings, and inner rings were separated and extracted with ethanol to obtain quercetin glycosides that were then hydrolyzed to free quercetin, or aglycone. Free quercetin was used as the standard for quantification by reverse phase high performance liquid chromatography (HPLC).

Significant difference (P=0.05) in total quercetin content was observed between dry skin and inner rings (edible parts). A decrease in total quercetin content was observed from the dry skin to inner rings. The highest total quercetin content was observed in the dry skins of Red bone variety (30.74 g/kg dry weight) while Contessa variety contain the least amount (0.082 g/kg dry weight). Total quercetin content in outer scales (1-2 scales) in Kadavan variety is the highest (481 mg/kg fresh weight); however, trace amounts are observed in Contessa. Inner rings (5-6 and 7-10 scales) contain less amount of total quercetin in all the varieties.

Outer scales of all the varieties except 1015Y and Contessa contain moderate amount (2.5-16 mg/kg fresh weight) of free quercetin. Kadavan contain the highest amount of free quercetin (20.64 g/kg dry weight).

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The anti carcinogenic flavonol, aglycone, or free quercetin and quercetin glycoside content of seventeen onion varieties and 22 genotypes (Asgrow seed co.) and also 37 breeding lines (Texas A&M University) were analyzed by high performance liquid chromatography (HPLC). Quercetin glycosides were hydrolyzed into aglycones.

Total quercetin content in yellow and red onions varied from 80.34 to 286.4 mg/kg fresh weight in different varieties. Marked variation in total quercetin content between Texas A&M breeding lines (56-202 mg/kg fresh weight) and Asgrow breeding lines (54-287 mg/kg fresh weight) was observed. White onions contain trace amount of total quercetin. Free quercetin in Texas A&M breeding line 20272-G was 12.4 mg/kg fresh weight; however, other varieties and breeding lines contain negligible amount of free quercetin. It was concluded that the `designer' onion varieties with high quercetin content for health consciousness can be produced.

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Open column chromatography is an effective and common technique for the separation and purification of chemical constituents. Limonoids are found in significant quantities in citrus fruits. Citrus limonoids have documented anti-cancer activity in several types of cancer, such as breast, colon, skin, and neuroblastoma in animal models and in vitro cell culture studies. Furthermore, limonoids have shown anti-inflammatory properties and inhibitory effects on bone resorption. In addition to many potential health benefits, limonoids have also shown antifungal and insect anti-feedant properties. To meet the large demand of limonoids for bioactivity studies, defatted grapefruit seeds were extracted using acetone and concentrated under vacuum. The dried extract was loaded onto a silica gel column and eluted with mixtures of dichloromethane and ethyl acetate with increasing polarity to obtain three compounds. The purity of the compounds (1–3) have been analyzed by HPLC and the structures have been identified by using NMR spectra and mass spectra as nomilin, limonin, and deacetylnomilin, in respective order of elution. The results will be presented in greater detail on the poster. This project is based upon work supported by the USDA-CSREES under Agreement USDA IFAFS #2001 52102 02294 and USDA #2005-34402-14401 “Designing Foods for Health” through the Vegetable & Fruit Improvement Center.

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