No description available.

In the form of a potable spirit, an extract of grapefruit skin has been found to develop an attractive opalescence when diluted to below about 38 % ethanol (v/v). This phenomenon is analogous to the pastis effect, called louching, common in many drinks popular in some countries bordering the Mediterranean. The main objective of this research was to develop spirit liquor with commercial potential from grapefruit skin, largely a waste commercial product, as the dominant if not exclusive ingredient other than alcohol and water. This would require making extracts by distillation of undried skins, which would develop a dense opalescence significantly below 40 % v/v ethanol, the common alcoholic strength of spirits as sold in New Zealand. The product concept was thus a clear liquid which when poured over ice for example, would yield a cool opalescent drink with a characteristic grapefruit flavour. In the case of citrus, the chemical basis of louching is the greater solubility of citrus skin terpenes, principally limonene, in ethanol than in water. The louch point is synonymous with the chemical expression critical micelle concentration, detected here by light scattering at the arbitrary wavelength of 450 nm. Early results with an obvious opalescence showed that the alcohol concentration at which the terpenes ceased to be soluble in the grapefruit distillate was about 38 % (v/v). This point was similar to that for pastis (Pernod brand), where the principle louchable ingredient is anethole. However, the light scattering was much greater for pastis. Thus, a grapefruit spirit sold at 40 % ethanol with the louching intensity of pastis should require increasing the solubility of limonene in solutions with a lower ethanol concentration. This in turn should allow higher concentrations of limonene in true solution in 40 % ethanol, theoretically resulting in a more intense louch in the final drink. Thus, a broad range of hydrocolloids and surfactants was tested in an attempt to increase the solubility of limonene in lower ethanol concentrations. None of hydrocolloids or surfactants lowered the louch point of a standard limonene concentration in ethanol/water. The informal flavour assessment showed that the spirit flavour from grapefruit zest alone lacked intensity. It was then thought that better flavour might be obtained by using the whole grapefruit (zest, pith, and juice) rather than zest alone. The additional of pith or pith plus juice caused no significant change in the louch point or light scattering. However, the final flavour was informally judged to be more intense than that derived from zest alone. The problem still remained that the light scattering of grapefruit distillate was never as high as that achieved by pastis, even though it was found (by gas chromatography) that the concentration of limonene (w/w) in the grapefruit spirit was at least as high as that of anethole in pastis. The cause was due to the fact that as a louched compound, anethole was a solid with a flat crystal structure because the melting point (21.4C) is well above that of a cool drink (Handbook of Chemistry and Physics, 1947). By contrast, limonene remains a liquid even in an iced drink because its melting point is far below 0C. Flat crystals would obviously scatter light far more than would a micelle containing a liquid, in this case limonene. Although such a grapefruit distillate did not louch as well as pastis, it could still have market potential on the basis that it would be made from the distinctive New Zealand cultivar of grapefruit. Thus a formal sensory assessment was conducted, using a focus group. The grapefruit distillates at 40 % ethanol were perceived by most panellists as refreshing, clean, fruity, and citrusy in aroma, but somewhat deficient in grapefruit flavour, and there was a common perception of strong chemical finish. At this stage of development a commercial proposition cannot be sensibly made.

No description available.

The sensitivity of Arizona-grown grapefruit to chilling temperatures varied throughout the harvest period studied. This sensitivity was high in October, decreased in November and December, then increased in February. In April and May there was another decrease in sensitivity to chilling temperatures. Coating fruit with vegetable oils or fats successfully delayed the development of chilling injury and reduced the degree of injury, however, vegetable oils applied as water emulsions were even more effective in preventing chilling injury to 'Redblush' grapefruit extending the period of marketability more than 100 days. Postharvest application of CaCl₂ and certain plant growth regulators significantly increased the resistance of 'Marsh' grapefruit to chilling injury, but less so than oil emulsions. Scanning electron microscope photomicrographs of 'Marsh' grapefruit peels showed that severe chilling injury was a depressed area of collapsed cell, just beneath the epidermis layer. As the severity of chilling injury increased, non-collapsed cells gradually increased in size. Cell walls were irregularly shaped; thin in some areas and thick in others. Oil glands in depressed areas were not ruptured during cold storage. Hence release of toxic materials through rupturing of oil glands is not a factor in chilling injury. Compared to non-injured tissue, injured tissue from the same fruits had significantly lower water and osmotic potentials, and low, near zero, turgor pressures. There was a significant negative correlation (r = -0.5; p < 0.05) between the water potentials of the peels and the percentage of 'Marsh' grapefruit with severe chilling injury during storage at 2.8C. Ion leakage tended to increase during cold storage, and when the fruit were transferred to room temperature. Internal conductivities declined sharply during cold storage and then increased very strongly during periods at room temperature.

No description available.

Microsprinkler irrigation offers excellent flexibility for site-specific management of water and nitrogen inputs for citrus orchards in the southwestern United States. Escalating water costs, declining water availability, and increasing regulation of nitrogen (N) fertilizer use are causing growers to adopt practices to improve water and N use efficiency. A three-year field experiment was initiated in the spring of 1996 on six-year-old pink grapefruit trees at the University of Arizona Citrus Agricultural Center. The objectives of this experiment are to i) evaluate the effects of fertigation frequency and fluid N application rate on the yield and fruit quality of microsprinkler irrigated grapefruit, and ii) develop best management guidelines for fluid N application frequency and rate for microsprinkler irrigated citrus. Treatments include a factorial combination of two N rates (recommended and 2 the recommended rate) and three fertigation frequencies (weekly, monthly, and tri-monthly). Minimal treatment effects were observed during the first season due to the influence of previous management practices. During the second season, fertilized trees yielded greater than the control trees. There was no significant difference between N rates, but fruit yield was generally higher with monthly or weekly fertigation. Leaf tissue samples collected during the second and third growing seasons showed increasing leaf N with increasing fertigation frequency at the high N rate.

No description available.

Thesis (Ph. D.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains xvii, 122 p. : ill. Includes abstract. Includes bibliographical references (p. 46-53).

Atherosclerotic cardiovascular diseases (CVD) are the leading cause of death and often develop due to obesity-induced complications including hyperlipidemia, elevated blood pressure (BP), inflammation, and oxidative stress. Epidemiological, animal model, and cell culture studies indicate that citrus, and grapefruit specifically, exert cardiovascular health benefits, likely due to the high flavonoid content in citrus fruits. Grapefruit and/or isolated grapefruit flavonoids elicit cardiovascular benefits via improvements in lipid metabolism and endothelial reactivity, and by antioxidant and anti-inflammatory actions. The aim of this work was to determine the role of six-week daily consumption of grapefruit on weight, lipid, and BP control as well as inflammatory and oxidative stress markers in overweight/obese adults. Further, we sought to evaluate the acute, postprandial effects of grapefruit consumption on metabolic, inflammatory, and oxidative stress markers in response to a high fat, high calorie (HFHC) double meal challenge. Participants were randomized to either a grapefruit group (n=42) in which they consumed 1.5 grapefruit/day for six weeks or to a control condition (n=32). Ten participants who completed the feeding trial also participated in the postprandial study. On two test days participants consumed a HFHC meal for breakfast and again for lunch. A ruby red grapefruit was consumed with breakfast on the first test day. Blood samples were collected at baseline and for the subsequent eight hours on each day. In the feeding trial, grapefruit consumption resulted in reductions in waist circumference (p<0.001), systolic BP (p=0.03), total cholesterol (p=0.001), and LDL-cholesterol (p=0.021) compared to baseline values. F2-isoprostanes and hsCRP values were nonsignificantly lower in the grapefruit vs. control arm following the intervention (p=0.063 and p=0.073, respectively). In the postprandial evaluation, insulin concentrations were significantly higher 30 minutes (p=0.007) and 2 hours (p=0.025) post HFHC + grapefruit meal consumption vs. HFHC alone. HFHC + grapefruit intake resulted in lower IL-6 concentrations after two hours (p=0.017) and lower F2-isoprostanes after 5 hours (p=0.0125). These findings suggest that regular grapefruit consumption may reduce CVD risk by targeting many of the risk factors and pathogenic factors involved in endothelial dysfunction. However, this dietary change alone is unlikely to result in significant CVD risk reduction.

Cyclosporine forms the cornerstone of therapy to prevent rejection after organ transplantation. However, the clinical use of the drug is compromised by a narrow therapeutic window and a wide inter- and intra-individual variation in metabolism. Cyclosporine is metabolised by the CYP3A4 isoenzymes in both the liver and intestine, while it has been reported that the metabolism of the drug can be inhibited by certain furocoumarin derivatives in grapefruit juice. Methoxsalen (8-methoxypsoralen) is a furocoumarin and a potent inhibitor of the cytochrome P450 system in both the liver and intestine. The study was conducted to investigate the possibility whether methoxsalen may inhibit the metabolism of cyclosporine and thereby increase the bioavailability of the drug. The interaction is of clinical relevance since both drugs are used in the treatment of psoriases. The study, conducted in 12 healthy male volunteers, was a three-way comparative bioavailability study with a wash out period of one week between treatments. The patients received 40 mg methoxsalen, 200 mg cyclosporine or a combination of the two on three separate occasions. Blood samples of 10 ml were collected by venupuncture at the following times: 0, 0.5, 1, 1.5, 2, 2.5, 3.4, 5,6, 8, 12 and 24 hours after drug administration. Methoxsalen was analysed by a high pressure liquid chromatograph method (HPLC) with UV detection (LOQ = 10 ng/ml), while cyclosporine was analysed using a fluorescence polarisation immunoassay (FPIA) technique. There was a statistical significant difference in AUCo-00 and Cmax ' for cyclosporine when methoxsalen was added to the drug regimen. When the methoxsalen levels were compared with those in the presence of cyclosporine, the levels were lower, although the difference was not statistical significant. We conclude that methoxsalen increase the levels of cyclosporine by inhibiting the P450 system enzymes in the liver and intestine. However, the absorption of methoxsalen is highly variable in the same individual which needs to be considered before this interaction can be regarded as being of any clinical relevance. / Thesis (M.Sc.(Pharmacology))--North-West University, Potchefstroom Campus, 2004.