Shrimp waste samples were extracted with a variety of organic solvents. Each fraction was measured for antioxidant activity by determining the rate of oxidation of β-carotene-linoleic acid in an emulsion system. An ethanol extract exhibited the highest antioxidant activity. Purification of the most active fraction was accomplished by thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). Antioxidant activity was not significantly effected by heating at 100°C for 4 hr or 30 days storage at 4°C. Purified antioxidant samples were further analyzed by several spectroscopy methods such as Fourier transformed-infrared spectroscopy (FT-IR), mass spectrometry and nuclear magnetic resonance (NMR). The antioxidant was characterized as an ortho-disubstituted benzene. The content of antioxidant in shrimp waste was estimated to be 1.80 ppm. Antioxidant from shrimp waste was extracted and partially purified by silica gel glass column chromatography. Two species of rockfish (Sebastolobus alascanus, Sebastes ruberriumus) were treated with crude antioxidant solution respectively, while rockfish fillets (Sebastes alutus) were treated with different concentrations of antioxidant solutions from the column chromatography. Higher a* values were found in rockfish samples treated with antioxidants compared to the control without antioxidant during iced storage. Furthermore, rockfish fillets treated with 0.20%, and 0.50% (w/v) antioxidant had lower 2-thiobarbituric acid (TBA) values compared to the control group of rockfish fillets (Sebastes alutus). Crude extract (0.50% w/w), and purified antioxidant (0.10%, 0.20%, and 0.50% w/w) from shrimp waste were applied to sablefish mince and evaluated for their effectiveness to inhibit oxidative and hydrolytic rancidity of mince samples. Treatments with crude extract (0.5%), partially purified antioxidant (0.2%, 0.5%) had a significantly lower TBA, and peroxide value (PV) compared to the control group during refrigerated (4°C) and frozen storage (-20°C). The results from free fatty acid values suggested that antioxidant from shrimp waste had no effect on hydrolytic rancidity in sablefish mince. / Graduation date: 1995

No description available.

Graduation date: 1998

A growing interest in sustainable development has made efficient utilisation of starting materials and, if they occur, by-products become increasingly important. Vast amounts of by-products are generated by the forestry and food industry. Incineration for energy production is one way to make use of these by-products but some of them contain compounds that would have an increased value if they were extracted, so called “high value species”. The by-products are often very complex, so reliable methods for analysis of the high value species are required in the development of processes to utilise them. A wide range of compounds can be analysed using chromatographic separation coupled to mass spectrometry, making it a powerful tool in the evaluation of methods for extracting high value species from industry by-products. This thesis is based on four studies of potential high value species. In the first study, methods were developed to differentiate isobaric flavonoids and then use this knowledge to determine the identity of the flavonoids in three different plant extracts. In the second study, three different methods to extract betulin from birch bark were evaluated regarding extracted amount and purity of betulin. One of the methods was then investigated in industrial scale using a model approach. In the third study, the flavonoid contents of lovage were determined and other major extracted compounds were investigated by high performance liquid chromatography coupled to electrospray ionisation mass spectrometry. Gas chromatography and supercritical fluid chromatography were used to obtain complementary information about major components. In the fourth study, high resolution mass spectrometry utilising two different types of fragmentation was used with the purpose of overcoming the shortcomings of the methods developed in the first study. The results indicated that it would be possible to develop methods compatible with chromatographic separation for differentiating different types of isobaric substituents. The ability of performing sequential fragmentation was used to investigate some isobaric aglycones by creating spectral trees, and unique pathways were found for each of them.

Proximate analysis of the commercial shrimp meat waste samples indicated the presence of 94.6% protein and 4.2% fat on a dry basis. The HPLC analysis revealed the presence of 17 amino acids (proline most abundant) and 7 sugars (ribose being the most abundant). The changes in the concentration of the amino acids and sugars after heat treatment, are explained based on their interaction through the Maillard reaction and by the thermal hydrolysis of proteins and polysaccharides present in tissue. Carotenoid pigments ($ beta$-carotene, canthaxanthin, astacene, and astaxanthin monopalmitate) were extracted and separated by thick layer chromatography. Their structures were identified tentatively by thick layer chromatography (TLC) and subsequently confirmed by Fourier transformed infrared (FT-IR) spectroscopy. Lipids were separated and categorized into glycerides, sterols, and phospholipids by thin layer chromatography while flavor-active components were extracted by different organic solvents into acidic, basic, and neutral fractions and their sensory properties determined. The flavor profile of the raw and cooked shrimp meat waste revealed the presence of 59 compounds in raw shrimp compared to 44 in cooked. The components identified were of different functional groups, including fatty acid esters, long chain alcohols, aldehydes, ketanes and hydrocarbons. Many fractions provided desirable aroma (nutty, fruity, floral, green woody, meaty) indicating the presence of important flavor compounds in the commercial shrimp waste. / Model studies were carried out under different experimental conditions (water content, pH), to observe the influence of these parameters on the formation of Maillard reaction products. Furthermore, a comparative study between direct injection of the aqueous solutions and its organic extracts was conducted. The direct injection of aqueous solutions revealed the presence of many water soluble components that were not detected by organic solvent extraction such as droserone and 3,9-diazatricyclo$ lbrack7.3.0.0 sp{*}.3 sp{*}.7 sp{ *} rbrack$-dodecan-2,8-dione while maltoxazine and acetanilide are example of compounds identified only in the dichloromethane extracts. Results also demonstrated that monosaccharides affected the yield of the compounds produced whereas the amino acids influenced the sensory properties of these models. Fructose and ribose were found to be the most reactive sugars in their respective categories. Thiazoles were found to be more water soluble whereas $ beta$-carbolines were more abundant in the organic extracts. The influence of water content was investigated in model systems containing fructose or glucose. It was found that water free systems decreased the yield of pyrazines and thiazoles while the formation of pyrrole and pyridine derivatives increased under dry heating conditions. The formation of Maillard reaction products were studied under different pH conditions in order to assess the effect of pH on the formation of heterocyclic compounds. Pyrazine and furan derivatives were the most affected by pH and alanine was found to be a better nitrogen source than lysine in the formation of pyrazines under different pH conditions. Finally, based on energy minimization studies using MM2 force field, a plausible mechanism was proposed for the formation of maltol in Maillard model systems.

Thesis (M.S.)--University of Hawaii at Manoa, 2006. / Includes bibliographical references (leaves 69-72). / vii, 89 leaves, bound ill. 29 cm

No description available.

No description available.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Vita. / Digitized by Kansas Correctional Industries