Browsing by Author "Leon Boyd, Committee Member"

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Characterization of Naturally Occurring Fruity Fermented Off-flavor in Peanuts Using Descriptive Sensory, Consumer, and Instrumental Analyses
(2008-08-24) Greene, Jeffrey Lynnette; Roger McFeeters, Committee Member; Leon Boyd, Committee Member; MaryAnne Drake, Committee Co-Chair; Timothy H. Sanders, Committee Chair
Marine Harpacticoid Copepod Culture for the Production of Long Chain Highly Unsaturated Fatty Acids and Carotenoid Pigments
(2006-02-15) Rhodes, Adelaide; Donna Wolcott, Committee Member; Leon Boyd, Committee Member; Peter Ferket, Committee Co-Chair; Sam Mozley, Committee Co-Chair
Nitokra lacustris Shmankevich, an epibenthic, coastal harpacticoid copepod species, is shown to provide several advantages for use as a live feed in the aquaculture of marine fish. This study addresses culture methods, population growth rate prediction, fatty acid composition and carotenoid content of N. lacustris. The highly consistent growth rate and the high proportion of highly unsaturated fatty acids (HUFA) and astaxanthin indicate that this species also has potential as a fish oil replacement in the animal feeds industry. Nitokra lacustris was chosen as the test organism because of its small size, short generation time, high reproductive rates, and potential to contain substantial concentrations of long-chain HUFA and ketocarotenoid pigments. The ability of harpacticoid copepods to synthesize HUFA and ketocartenoids may be related to the highly variable coastal habitats of theses species. HUFA and carotenoids are important in energy storage and protection from cell membrane degradation for many marine plants and animals. Nitokra lacustris contains a high amount of the essential fatty acids DHA and EPA as well as the essential carotenoid pigment astaxanthin, when compared to other live feeds (rotifers and Artemia). N. lacustris is also able to convert HUFA and astaxanthin from a diet that is deficient in these nutrients. The ability of N. lacustris to bioconvert essential fatty acids and carotenoid pigments without the addition of fish oil represents a potential new source of HUFA and astaxanthin for the animal feeds industry as well as for human health supplements
Thermal Processing of Sour Cream using Continuous Flow Microwave Heating - Feasibility Study
(2007-07-26) Settle, David William; Josip Simunovic, Committee Member; Jonathan C. Allen, Committee Member; Leon Boyd, Committee Member; Arthur P. Hansen, Committee Chair
The purpose of this research was to develop a sour cream that could withstand the effect of UHT continuous microwave processing. The major benefit to the manufacturer of the UHT processing would be extended shelf-life, especially in conjunction with asceptic packaging. This would result in less spoilage, thus increased profits. This becomes increasingly important as sour cream increases in popularity and is sold and marketed at greater distances from the point of processing One major problem with UHT processing of acidic dairy products is that high temperatures cause milk proteins to aggregate, especially at pH's around the pI (isoelectric point) of casein. Fouling (or burn-on) of the heat-exchanger tube walls is another factor that excludes the use of UHT processing to sterilize sour cream. The proper formulation of sour cream with the use of stabilizers such as starch and gelatin can also minimize aggregation, reduce syneresis, and increase the viscosity of the final products. The addition of gelatin is often used in sour cream formulations as it increases water binding, whey retention, and adds to mouthfeel, and gives the final product sheen-like appearance. In order to characterize the performance and functionality of sour cream under continuous flow microwave thermal processing conditions, seven sour cream formulations with different gelatin and starch content were produced and processed. Yield stress and viscosity tests were performed and compared to rheological tests performed on commercial brands to determine if they were within the upper and lower commercially accepted limits. Viscosities were dynamically measured with the Stresstech. Dielectric properties of the sour cream samples were also analyzed. Dielectric measurements were taken at 5#176; C intervals. Microwave processing was performed using a 5 kw microwave system. Processing was performed at an output power of 3 kilowatts at 915 MHz at flow rate of 4 liters per minute to determine dielectric properties and estimate the need for formulation adjustments. Rheological analysis of the seven NCSU sour cream formulations showed no correlations between stabilizer levels and yield stress or viscosity. Measurement of time and temperature data showed that variations were present and that processing conditions had an influence on the rheological behavior of the sour creams. Because of this, a single formulation could not be determined as optimal. All seven formulations were more viscous than the commercial brands tested but had lower yield stresses. Also, none of the seven formulations had visual casein aggregation. Rheological analysis of the seven formulations indicated that UHT continuous microwave processing was feasible using any of the formulations. This new process will allow sour cream to be ascetically packaged which had never been done. Aseptic packaging would allow manufactures to increase profit margins by reducing spoilage and eliminate refrigeration costs.