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.

No description available.

No description available.

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.

The effects of nitrogen and potassium fertilization on tomato flavor were studied. Field-grown Walter c.v. tomatoes were treated with three levels of nitrogen and potassium. Soluble solids, pH, titratable acidity (TA), volatile flavor compounds, and sensory evaluation of overall flavor were studied. / Taste panel tests indicated that the lower fertilization level (100 lb/A N- 150 lb/A K) yielded tomatoes with a more desirable flavor. Tomatoes grown at the two higher levels of fertilization (200 lb/A N-300 lb/A K; 300 lb/A N-450 lb/A K) did not differ in flavor. Soluble solids and TA were found to increase with increasing levels of N and K. There was a modest trend toward lower pH values in tomatoes grown at lower fertilization levels. Although no qualitative differences were observed among volatiles from the three treatments, several compounds were found to change quantitatively with treatment. MS and GC enrichment were used to tentatively identify these volatiles. Hexenal, 2-hexanone, 2,4-hexadienal, benzaldehyde, phenylacetaldehyde, beta-ionone and 6-methyl-5-hepten-2-one were found to increase with increasing levels of N and K fertilization. Farnesol isomers appeared maximally in treatment II and eugenol decreased with increasing fertilization. / This study indicates that tomatoes treated with high levels of N and K do not exhibit desirable flavor despite an increase in both TA and soluble solids. This may be due to the intrusion of undesirable flavors from volatiles whose production is increased under conditions of high N and K fertilization. / Source: Dissertation Abstracts International, Volume: 43-10, Section: B, page: 3182. / Thesis (Ph.D.)--The Florida State University, 1982.

Source: Dissertation Abstracts International, Volume: 40-07, Section: B, page: 3077. / Thesis (Ph.D.)--The Florida State University, 1979.

The present study was designed to achieve three goals: (1) to investigate some physical properties of the crude antimicrobial substance (lactobulgarican) produced by Lactobacillus bulgaricus, (2) to test the effect of several types of sugar present in the growth medium of L. bulgaricus on production of lactobulgarican, and (3) to purify and characterize the pure lactobulgarican. / Lactobulgarican was located extracellularly and was more active toward gram-negative than -positive organisms. It had an optimum pH of 4.0. It was reversibly inactivated at pH range of 5.0-12.0 but irreversibly inactivated at pH 1.0. At the optimum pH, lactobulgarican was highly thermostable. It was also stable to refrigerated storage up to 18 days. / Carbohydrate-free formula, with a given type of sugar added, was used to test the effect of sugar on lactobulgarican production. Among the sugars tested, glucose produced the lowest pH value and the largest inhibition zone under a short incubation period, i.e., 48-hours. Under a long incubation period, i.e., 96-hours, both glucose and lactose, at the same concentration, produced comparable results. A ninety-six hour incubation period was the best one among those tested. Fructose and sucrose were not fermented by L. bulgaricus, and did not produce any inhibition zones. / Reversed phase HPLC column was used to purify lactobulgarican. Lactobulgarican did not contain lactic acid or hydrogen peroxide. The UV spectrum of lactobulgarican produced two broad peaks at 198 and 274 nm. Negative and positive chemical ionization mass spectra produced peaks at m/e 181, 180, 163 and 179, 91, 88, 57, respectively. The biuret test for lactobulgarican was negative. Results from the UV and mass spectra indicated the possible presence of a hexose and a phenol-containing compound, possibly phenylalanine. The molecular weight of lactobulgarican was (LESSTHEQ) 507. / Source: Dissertation Abstracts International, Volume: 46-01, Section: B, page: 0012. / Thesis (Ph.D.)--The Florida State University, 1984.

Walnuts contained about 16.66% protein and 66.90% lipids. Linoleic (61.21%) and linolenic (13.81%) acids accounted for up to 75% of the total fatty acids in walnut lipids. The majority of walnut proteins were soluble in 0.1 M NaOH with a minimum solubility at pH 4. Albumins, globulins, prolamins, and glutelins respectively accounted for 6.81, 17.57, 5.33, and 70.11% of the total protein. Both protein solubility and electrophoretic analyses revealed glutelins to be the major walnut proteins. The total protein contained at least seven major polypeptides with estimated molecular weight range 19,590-21,830 and 33,340-37,150. Lysine was the first limiting essential amino acid in total proteins, globulins, and glutelins. Leucine and methionine plus cysteine were the limiting amino acids, respectively, for prolamins and albumins. Hydrophobic and acidic amino acids dominated the amino acid composition in all protein fractions. Minimum extractability of nitrogen at 0.5-1 M TCA represented the nonprotein nitrogen compounds in defatted walnuts. The nonprotein nitrogen values in walnuts ranged from 6.24 to 6.50% of the total nitrogen. Native or heat denatured walnut glutelins were easily hydrolyzed in vitro by the common digestive proteases. The tannin content of inshell and shelled walnuts was in the range of 889-1095 and 574.4-667.2 mg catechin equiv./100 g walnut, respectively. After three weeks of storage, walnut assayable tannins were reduced by about 20%. Blanched walnuts (BW) retained about 2% of assayable tannins, had a buttery-sweet taste, and rated less astringent then unblanched walnuts (UW). The astringency scores and tannin content of BW were correlated (r = 0.9249). / Source: Dissertation Abstracts International, Volume: 57-03, Section: B, page: 1526. / Major Professor: Shridhar K. Sathe. / Thesis (Ph.D.)--The Florida State University, 1996.

Source: Dissertation Abstracts International, Volume: 37-07, Section: B, page: 3331. / Thesis (Ph.D.)--The Florida State University, 1976.