The abundance and low fat content of Pacific whiting support Its use for the production of surimi. The degradation of muscle proteins by myxosporidian secreted proteinase(s) has been associated with its soft texture. High residual activity is retained through the washing process used in the production of surimi and precludes the formation of a strong heat-set gel by surimi sols. Physical, chemical and SDS-PAGE analysis defined the reinforced oxidation of free sulfhydryl groups on myofibrillar proteins to disulfide bonds by potassium bromate. SDS-PAGE demonstrated myosin degradation during heat-setting and the protection of myosin from protelnase attack by bromate. A level of 0.075% bromate Inactivated 89.87% of the total proteinase activity in sols. It was assumed that cysteine proteinases were Inactivated and residual activity was associated with proteinases with a serine active site. Major iraprovement in gel coheslveness and elasticity was observed at bromate levels [less than or equal to] 0.075% with only a slight improvement at higher levels. Maximum hardness was observed at 0.150% with no (P>0.050) increase at higher levels. Brittleness was improved (P>0.050) by bromate levels [greater than or equal to] 0.100%; no maximum degree of brittleness was observed within the range ([less than or equal to] 0.250%) of concentrations investigated. An optimum folding test grade of AA was achieved by a minimum of 0.150% Potassium bromate improved gelling characteristics of sols of Pacific whiting surimi through proteinase inactivation and reinforced disulfide formation during heat-setting. Improvement in cohesiveness and elasticity was primarily a function of proteinase inactivation. Maximum hardness and brittleness required additional oxidative capacity which was not fully required for an optimum folding test grade. / Graduation date: 1989

Varying concentrations of the food preservatives nisin and lysozyme were adsorbed onto glass surfaces chemically modified to exhibit different degrees of hydrophobicity. The antimicrobial activity of the adsorbed preservatives was evaluated by documenting the ability of Listeria monocytogenes to adhere and grow on the glass surfaces. A bioluminescence protocol was developed to effectively enumerate bacterial cells adhered to glass. Lysozyme adsorption onto glass surfaces was monitored by labeling with ¹²⁵I. Results indicated that synergy was present for 0.9/0.1 molecular ratio of nisin/lysozyme. Synergistic effect was increasing gradually with the increase of nisin in the ratios tested. This trend was observed on both surface types. However, the magnitude of synergy was more pronounced on hydrophobic surfaces than on hydrophilic ones. Results from protein radiolabeling showed that lysozyme was adsorbed with higher mass to hydrophilic surfaces than to hydrophobic ones. / Graduation date: 1999

The effects of various pressure treatments (OK, 30K, 60K, 75K psig) and packing medium (water or cocktail sauce) on shucked oysters were investigated. The pH, moisture content, microbiological tests (including aerobic plate count (APC) and anaerobic plate count (ANPC)), enzyme assays (i.e. α-amylase, β-amylase, lipase and peroxidase activities) were conducted to determine the quality of pressure treated oysters during a 6 week shelf-life study. The moisture content in water-packed oysters under OK, 30K, 60K and 75K psig pressure treatments was slightly increased during storage, while that in cocktail sauce-packed samples was significantly lower than in water-packed samples. Addition of cocktail sauce lowered the pH in oysters, which effectively inhibited the microbial growth, but altered the appearance. The microbial shelf-life of water-packed oysters with pressure treatment of 60K and 75K psig was extended several weeks compared with the controls while 30K psig had less of an effect. Pressure treatments did not inhibit enzyme activities in oysters, however, the addition of cocktail sauce was significant in inhibiting the enzyme activities in this study. / Graduation date: 2000

Pasteurization radiation offers a new means of extending the refrigerated storage life of foods. This procedure avoids many of the undesirable changes which result when sterilization radiation is used and still eliminates most of the spoilage organisms. Shrimp was treated with 5 ppm chlortetracycline and subjected to pasteurization levels of gamma radiation and stored at 38°F. The levels of irradiation used were 0.5 and 0.75 megarad. These levels were based on the flavor threshold of irradiation intensity. The quality of the stored irradiated shrimp was determined by subjective evaluation, chemical analyses and microbiological examinations. The storage life of the shrimp irradiated at 0.5 megarad was extended to 5 weeks, compared with 1 week for the unirradiated samples held at the same temperature. Throughout the ten week storage period, the samples which received doses of 0.5 megarad and CTC and those which received 0.75 megarad with and without CTC remained in good condition. / Graduation date: 1963

An unsettling trend is gaining momentum - many Americans may be losing their interest in the `natural world'. According to research undertaken by Patricia Zaradic, an Environmental Leadership Program fellow in Bryn Mawr, and Oliver Pergams of the University of Illinois at Chicago, "nature just isn't as entertaining as it used to be." Studies of Americans' recreational habits show a nearly 25 percent per capita decline in camping, fishing, hunting and visits to state and national parks since the mid-1980s (Gambino 2008). Like "climate change," some suggest that the downward trend in outdoor recreation by Americans is a manifestation of fiction rather than fact. But the trend is unmistakable: A smaller percentage of people in the United States and elsewhere are participating in outdoor recreation (Smith 2008). Pergams and Zaradic show a trend in human behavior that ultimately may be far more foreboding for the environment than declining tropical forest cover or increasing greenhouse gas emissions - widespread declines in nature-based recreation (Kareiva 2008). The question that has yet to be answered is to what degree this trend will have in influencing our society's future and in how we will value - or devalue - our natural environment. Will future generations that grow up and live in a world estranged from the natural environment want to protect it? America's 200-year conservation tradition may be at risk. Two dominant factors influenced the environmental philosophies of notable historic American conservationists. One was their direct and repeated interaction with the natural world beginning at a very early age; the other was an environment-focused family tradition. These same factors influenced the environmental ethos of today's conservationists, land managers and environmental educators. It is impossible to determine if these factors will be of equal significance one hundred years from now. However, we can predict with reasonable certainty based on the recent historic record, motivators identified by current environmentalists, and the results of independent surveys of adolescent subjects reported in this study that, at least for now and for the foreseeable future, if implemented in combination with others variables, these will favorably influence the conservation ethic of our youngest citizens.

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Numerous anthropogenic disturbances have occurred in large lakes over recent decades. These may alter concentrations of the biomagnifying contaminant mercury (Hg) in fish, but long-term impacts of disturbances on Hg trophodynamics are poorly understood. Elemental analyses of archived museum ichthyology specimens could be used to study historical, pre-disturbance fish food webs, but there is uncertainty about effects of chemical preservatives on the results of such analyses. In this thesis, long-term preservation effects were studied, and archived fish were used to reconstruct historical food webs and Hg trophodynamic patterns in three large North American lakes, Nipigon, Simcoe and Champlain. After 24 months of formalin/ethanol preservation, fish muscle delta-15N and delta-13C had average changes of +0.4 ‰ and -0.9 ‰, respectively. Shifts in mean Hg concentration was +5 % after 12 months. A suite of 26 other elements analyzed over 24 months showed consistent responses to preservation, usually involving an increase in concentration immediately following preservation. In the second phase of the thesis, stable isotope and Hg analyses were performed on archived and modern fish from the study lakes, dating to the 1920s-60s and 2006-7, respectively. Trophic relationships were often relatively stable over time, but stable isotope metrics revealed a decrease in Lake Nipigon delta-15N range and less pelagic feeding among Lake Simcoe pumpkinseed and yellow perch. In Lake Champlain, the re-introduction of lake trout in recent decades did not have a major effect on overall food web dimensions. Significant Hg biomagnification factors were found in 1920s and 2006-7 Lake Nipigon (which were not statistically distinguishable from each other) and 2006 Lake Champlain. These biomagnification factors ranged from 0.09 to 0.17, which is within the range found in other studies globally. Archived fish and government monitoring records indicated that fish Hg concentrations decreased in Lakes Simcoe and Champlain since historical periods, but remained similar or increased in Lake Nipigon. This thesis confirms the utility of archived fish for elemental analyses. It highlights the risks of Hg contamination and food web change that may be faced by remote lakes, and it provides evidence for relatively stable Hg biomagnification rates in large lakes. / Thesis (Ph.D, Biology) -- Queen's University, 2013-01-30 15:43:33.438