Browsing by Author "Leon C. Boyd, Committee Member"

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Beta-lactoglobulin Complexed Vitamins A and D in Skim Milk: Shelf Life and Bioavailability
(2003-11-18) Liu, Ying; Jonathan C. Allen, Committee Chair; George L. Catignani, Committee Member; Leon C. Boyd, Committee Member; sarah_ash@ncsu.edu, Committee Member
As reduced fat dairy products became popular in the U.S., the reduction of vitamins A and D in these products rendered a nutritional concern. Beta-lactoglobulin has been reported capable of binding fat-soluble vitamins. In order to justify the potential of beta-lactoglobulin as a stable and protective carrier for the vitamins, stability and bioavailability of beta-lactoglobulin complexed vitamins A and D in skim milk were investigated in this study. The first objective of this research was to observe the stability of vitamin A palmitate and vitamin D₃ in fortified skim milk during storage. The fortifiers included regular oil-based vitamins, Roche dry vitamins, and spray-dried and freeze-dried protein-based vitamins. Milk was stored in different packaging materials including glass test tubes, plastic bottles, and paperboard cartons. The effect of High Temperature Short Time (HTST) and Ultra High Temperature (UHT) pasteurizations on shelf life was also studied. Vitamin A palmitate and vitamin D₃ were extracted by organic solvents and assayed by High Performance Liquid Chromatography (HPLC). Results showed that vitamin D₃ was relatively stable in all milks during the 4 weeks of shelf life. Vitamin A concentrations remained stable in most HTST milk except for those fortified with Roche dry vitamin A. A significant decrease in retinyl palmitate was detected in UHT protein-based vitamin-fortified skim milk. The second objective was to test the ability of different forms of fortified skim milk to boost vitamin levels in vitamin-depleted rats. Serum, liver and bone tissues were assayed for both vitamins and calcium. Data indicated that oil-based vitamin A-fortified skim milk was as efficient as positive AIN-93G pelleted rodent diet in raising the vitamin A levels in the tissues and protein-based vitamin D₃ fortified skim milk most effectively boosted the serum 25-OH D level. In conclusion, beta-lactoglobulin complexed vitamin A palmitate is not an appropriate fortifier for UHT skim milk while beta-lactoglobulin complexed vitamin D₃ is a more stable and effective fortifier than the regular oil-based fortifier.
Calcium Chloride and Vitamin D Fortified Beverages: Bioavailability in Wistar Rats
(2008-12-05) Lovett, Mallorye Deloris; Gabriel Keith Harris, Committee Member; Brenda P. Alston-Mills, Committee Member; Jonathan C. Allen, Committee Chair; Leon C. Boyd, Committee Member
Calcium and vitamin D deficiency is now recognized as an epidemic in the United States. Calcium and vitamin D play a critical role in the prevention of metabolic diseases including osteoporosis, osteomalacia, and rickets. Epidemiological research indicates that average intake of these nutrients is well below the RDA. Dairy products continue to be the main source of calcium intake. The major source of vitamin D is from sensible sun exposure. Greater intake of calcium and vitamin D has been correlated to a reduction in fractures, prevention of osteoporosis, and increased bone mass. The objective of this study was to test effects of a water-soluble form of vitamin D and calcium chloride as fortifiers for an aqueous sports drink solution with a rat bioavailability assay. A water-soluble vitamin D fortifying ingredient was prepared as a spray-dried complex with bovine beta-lactoglobulin. Vitamin D content of the complex was assessed by HPLC. Flavored beverages were formulated with various ratios of calcium and vitamin D in a 4x4 factorial design. Female Wistar rats were housed under incandescent lighting and randomly divided into the treatment and control groups. After a 4-week depletion phase, rats were given specialized drink formulations and low calcium, vitamin D-deficient diet for an additional six weeks. Blood and femur bones were removed for further analysis. Serum vitamin D was measured by ELISA. Results demonstrate that fortified drink solutions could be accurately formulated to contain calcium chloride at 0, 1, 2 and 2.5 g Ca/L with palatability to rats. The vitamin D content of the drinks was formulated to be 0, 10, 20, and 40 µg/L. Serum vitamin D was significantly greater (p< .0001) in rats receiving the vitamin D-fortified drinks. Water-soluble vitamin-D can be used to fortify aqueous products with this fat-soluble vitamin to help facilitate the uptake of calcium. Regular consumption of flavored sports drink fortified with calcium and vitamin D may significantly increase dietary calcium and vitamin D intake.
Effects of Frozen Storage and Harvest Time on the Textural and Sensory Properties of Rabbiteye Blueberries (Vaccinium virgatum Aiton)
(2010-04-30) Swift, Jennifer Elizabeth; Gina E. Fernandez, Committee Member; Leon C. Boyd, Committee Member; Shyamalrau P. Tallury, Committee Member; James R. Ballington, Committee Chair
Rabbiteye blueberries (V. virgatum Aiton), while praised for small stem scars, improved firmness over highbush cultivars, ease of mechanical harvesting, and superior keeping quality in storage, have also been reported to be have tougher skins after extended frozen. Growers and processors alike fear that significant increases in blueberry skin toughness following extended frozen storage could lead to a decrease in demand for the species. Furthermore, industry representative have been of the opinion that later harvests produce the toughest berries. The objectives of this study were to objectively determine by mechanical textural analysis if there is a change in the toughness of rabbiteye blueberry skins over time when frozen, and also if later harvests resulted in fruit with tougher skins before, and especially after frozen storage. In addition, the objective data were compared to sensory panel data to determine whether consumers could detect any changes in firmness and/or toughness, and if they found them to be unpalatable. In the first year four rabbiteye cultivars; Premier, Tifblue, Powderblue, and Ira, one highbush cultivar; Beaufort, and one rabbiteye - highbush hybrid variety NC 3465 were picked, individually quick frozen (IQF) and stored at -14ï‚° F for a total of 13 months. A second harvest of Premier, Powderblue and Tifblue were picked two weeks after the first, frozen and stored in the same manner. In the second year, cultivars Powderblue, Tifblue, Premier, and Beaufort were picked again, as well as Brightwell, another rabbiteye cultivar. Three harvests were picked of Powderblue, Tifblue, Beaufort and Brightwell, and two harvests of Premier were collected. All harvests and cultivars were simultaneously tested every three months by puncture and compression tests on a TA-XT Plus Texture Analyzer to measure skin toughness and berry firmness. Large, untrained sensory panels of approximately 75 persons each evaluated skin firmness and firmness liking every three months. Also in the second year, small samples from each harvest were separated at six months and stored for an additional seven months at 6ï‚° F to evaluate toughness at temperatures closer to consumer freezers. Results over two years did not reflect increased toughness over time, except in the small test for treatments at 6ï‚°F, which confirmed past research, and indicated a storage temperature threshold at which toughness increased significantly. In both years, most cultivars tested as being much firmer and as having tougher skins while fresh than after freezing. Results did not indicate later harvests result in increased toughness among rabbiteye cultivars. Mechanical textural analysis and sensory results both indicate cultivar effect to be much more significant than time. Furthermore, year-to-year differences due to environmental conditions, location and ripeness all had impact. In both years, Beaufort was found to have the least tough skins both by mechanical testing and sensory panels. In the first year, Powderblue had significantly tougher skins than all other cultivars, and in the second year, Brightwell was the toughest by a significant margin, whereas Powderblue was average in skin toughness.