Boston University. University Professors Program Senior theses. / PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / 2031-01-02

Thesis (Ph.D.)--Murdoch University, 2002. / Thesis submitted to the Division of Social Sciences, Humanities and Education. Bibliography: leaves 335-355.

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The performance of four immunochemical test kits in detecting aflatoxin contamination in cottonseed under non-laboratory conditions was evaluated. Naturally contaminated cottonseed was analyzed at cotton gins, ammoniation plants, cotton oil processing plants, a dairy farm and at the University of Arizona. Evaluation was based on the ability to determine aflatoxin concentrations as more or less than 20 ppb when analyzed on-site and in the laboratory using a common extract. Comparison of results from both locations showed excellent agreement (Afla-20 Cup 86 ± 6%, (n = 188); Agri-Screen I, 75 ± 9%, (n = 56); Agri-Screen II, 93 ± 5%, (n = 106); Agri-Chek, 93 ± 4%, (n = 156) and Aflatest-10, 90 ± 4%, (n = 178)). Overall agreement between on-site and laboratory results was 88%. Comparison of kit results to those of TLC demonstrated a low potential for obtaining false negative values. From these results the kits can reliably be used to screen cottonseed for aflatoxin contamination under non-laboratory conditions.

A dynamic model of fresh beef packaged under modified atmospheres has been developed. This model links the change in meat color with the permeation of gases (O₂, CO₂, N₂) through the packaging film. Its viability is demonstrated with experimental data using muscle semimembranosus with which it was shown that color change of the meat surface and the change of headspace gas concentration were well described by the model. Moreover, the model parameters were obtained independently of the model itself through the literature. A major result of the model showed that surface color is independent of oxygen concentration above 5%. Moreover, under aseptic conditions and ambient atmosphere concentrations, shelf-life of muscle semimembranosus was shown to be 11 days with this value possibly being a minimum.

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Oxidation products of unsaturated fatty acids in foods cause rancid flavor and limit the storage stability of food products. Even though many synthetic antioxidants are used, increasing interest has been directed towards the utilization of normal food constituents having antioxidative properties. / In aqueous lysine-sucrose model systems, the effects of reaction time, pH and molar ratio were studied on the formation of non-enzymatic browning reaction (NBR) products. The extent of sucrose hydrolysis was measured and the antioxidant effect of NBR products on linoleic acid emulsions was examined. Nuclear magnetic resonance (NMR) spectra were obtained at various stages of browning. / Sucrose produced NMR products with lysine in an aqueous system at 100(DEGREES)C. The C-13 NMR spectra indicated that the NBR started when sucrose and lysine were dissolved in water. The C-13 NMR spectra also showed that heating did not have an effect on the gross composition of polymeric species. The absorbance at 480 nm of 0.75 M lysine-sucrose solution heated up to 6 hours increased with reaction times. The pH values of heated lysine-sucrose solution gradually decreased with reaction time. When 0.75 M sucrose or lysine solution was heated separately up to 6 hours, there were no changes in absorbance in pH. In the pH range of 3.52 - 6.35, higher absorbance was obtained from heated lysine-sucrose solution at acidic pH levels than at neutral pH levels. / As the concentration of lysine and sucrose solution was increased, the absorbance increased. At longer reaction times or acidic pH levels, enhanced hydrolysis of sucrose to reducing sugars resulted in more NBR products. NBR products obtained at a longer reaction time, an acidic pH, and higher concentration of reactants showed a darker brown color and were effective in preventing the formation of peroxides. The oxygen uptake of linoleic acid emulsion having NBR products was smaller than that of linoleic acid emulsion without NBR products. Based on these results, it was concluded that sucrose may act as an antioxidant in processed foods containing both amino acids and lipids. / Source: Dissertation Abstracts International, Volume: 48-02, Section: B, page: 0312. / Thesis (Ph.D.)--The Florida State University, 1987.