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The effect of potassium bromate on the gel-forming ability of Pacific whiting (Merluccius productus) surimiAguilar, Ramon Pacheco 03 March 1989 (has links)
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
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Antimicrobial activity of nisin and hen lysozymeJaczynski, Jacek 16 November 1998 (has links)
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
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Effect of high hydrostatic pressure (HHP) on the bacterial count and quality of shucked oystersShiu, Shu-Er 16 July 1999 (has links)
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
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Radiation pasteurization of raw and chlortetracycline-treated shrimpAwad, Ahmed Ali 28 January 1963 (has links)
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
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How Do We Keep Conservation Alive When Kids Have Less and Less Contact with Nature?Payan, Rafael January 2012 (has links)
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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EFFECT OF CONTROLLED GAS ATMOSPHERE PACKAGING UPON THE STORAGE QUALITY OF PRECOOKED BEEF SLICES.Carr, Timothy Perry. January 1985 (has links)
No description available.
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Molecular genetic analysis of preservative resistance in Zygosaccharomyces bailiiMollapour, Mehdi January 2001 (has links)
No description available.
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Basidiomycota in forest reserves and plantation forests in Peninsular MalaysiaUjang, Salmiah January 1997 (has links)
No description available.
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Effect of a competitive microflora on Salmonella recovery from freeze-thawingAllen, Rachel Louise January 1999 (has links)
No description available.
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Long-term changes to food web structures and mercury biomagnification in three large, inland North American lakesPoulopoulos, John 31 January 2013 (has links)
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
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