The biochemical and organoleptic changes that took place in raw whole Pacific shrimp and in the cooked meat during eight days of iced storage were investigated. A steady increase of both microbial numbers on the raw shrimp and pH in the raw shrimp and cooked meat was observed. The levels of total and non-protein nitrogen and total carotenoid pigment decreased during the storage period. Tyrosine levels showed a. decrease in the raw shrimp, but a progressive increase in the cooked meat was observed. Although proteolytic and polyphenolase activity in the raw shrimp decreased during storage, the losses in nitrogenous components was probably related to a combination of the autolytic degradation of the shrimp coupled with the washing action of melting ice. Trimethylamine oxide levels were shown to decrease in raw shrimp daring storage due to the washing action of melting ice and its reduction to dimethylamine and formaldehyde and in lower amounts, to trimethylamine. The latter, probably is the result of bacterial activity, while the former is due to the action of enzyme systems in the shrimp. Levels of dimethylamine and formaldehyde increased in a parallel manner during the storage period. Trimethylamine levels also increased, but at a much slower rate. Organoleptic quality as shown by taste panel evaluations progressively declined during the storage period. Dimethylamine and formaldehyde levels appeared to be more sensitive indices of cooked shrimp quality than microbial numbers, pH and trimethylamine levels. / Graduation date: 1973

Graduation date: 1948

Certain compounds having the "carbonyl enediol" structure ( Formula omitted) , and also sodium chloride, were studied for use in glazes for frozen whole dressed fish. Incorporation of these compounds caused, in general, formation of thicker, glazes on the fish than did water alone and the glazes so formed were relatively non-cracking. The cyclic compounds, reductinic acid (in concentration 0.6475% or 0.00568M), and 1-ascorbic acid (1.0% or 0.00568M), afforded satisfactory protection against oxidative rancidity for periods of the order of 5 to 6 months. On the other hand, the acyclic compounds, reductone (0.5% or 0.00568M), diammonium dihydroxymaleate (0.518% or 0.00568M), dihydroxy maleic acid (0.84% or 0.00568M), gave comparatively poor protection. Sodium chloride (2.0%) gave about the same protection as water alone. The antioxidants probably protect the fish against oxidative rancidity by rendering atmospheric oxygen unavailable to the indigenous fats. / Science, Faculty of / Zoology, Department of / Graduate

The thesis deals with the use of a dilatometer in studying some of the physico-chemical phenomena occurring in fresh fish flesh when subjected to freezing at temperatures ranging from 0° C to -30° C. Two different kinds of fish flesh, marine lingcod (Ophiodon elongatus) and fresh water rainbow trout (Salmo gairdnerii) were used for comparison. True freezing point determinations of samples of fresh flesh cut from the above species of fish were made and found to be the same, viz, -1.5°C (29.1°F.). The percentage of water removed as ice at varying temperatures below the initial freezing point were calculated by necessary adjustments of experimentally determined values. A permanent net decrease in volume accompanying freezing and thawing of the samples of flesh was observed and measured. This change in volume is probably due to the denaturation of the protine, and was found to be 0.075%. The coefficient of cubical expansion (∝) of anhydrous fish muscle was measured for the first time and found to have the average value of 0.000118 over a temperature range from -30°C. to +20°C. / Science, Faculty of / Zoology, Department of / Graduate

No description available.

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

Digitized by Kansas Correctional Industries

Freezing is one of the important technologies for preservation of foods. In this project, using surimi as a food model, thermophysical properties of frozen foods were evaluated and the freezing process was simulated using a finite element package. To measure temperature-dependent thermal conductivity, a line-source probe system was used. Effects of test conditions and sample history were investigated. Thermal conductivity of Alaska pollock (Theragra chalcogramma) surimi having 0, 4, 6, 8, and 12% cryoprotectant levels was measured in the range of -40 to 30 ° C. Other thermal properties were analyzed using differential scanning calorimetry (DSC) at the same cryoprotectant concentrations and in the same temperature range. Each dynamically corrected DSC thermogram was used to determine initial freezing point, unfreezable water (bound water), apparent specific heat, enthalpy and unfrozen water weight fraction. When water content of the sample is controlled, thermophysical properties of surimi have a relatively weak dependence upon cryoprotectant level in the unfrozen and fully frozen (-40° C) ranges. However, the initial freezing point and the properties just below this point were significantly affected. From measured data, the Schwartzberg thermal property models for frozen foods were investigated. The models agreed well with experimental data. However, possibility for further improvement is demonstrated by using DSC analysis. This research additionally demonstrated the great potential of DSC for measuring and modeling frozen food thermal properties. Using the derived property models, a commercial PC-based finite element package was used to simulate the process of freezing a food block in a plate freezer. The capability of the program to handle temperature-dependent thermal properties and time-dependent boundary conditions enabled a simulation which accounted for measured changes in thermal properties, ambient temperatures and overall heat transfer coefficient. Predicted temperature history agreed well with measured data. Sensitivities of important model parameters, which were varied within their experimental error range, were also investigated using a factorial experimental design method. The result showed that in decreasing order of influencing freezing time prediction, attention should be given to apparent specific heat, block thickness, overall heat transfer coefficient, ambient temperature, thermal conductivity, and density. / Graduation date: 1991

Formulation studies of value-added seafood nuggets were done using appropriate mixtures of surimi, kamaboko, broken shrimp, and shrimp broth made from shrimp processing waste. A total of 19 formulations were prepared and, on the basis of sensory analysis, two formulations (comprising of 75% surimi: 25% shrimp, and 100% surimi containing shrimp broth) were used throughout this study. / Initial storage trials of both raw and cooked battered and breaded value-added nuggets in air and under various modified atmospheres (MAP) showed that a microbiological shelf-life of 28 d was possible for cooked nuggets at 4 and 12$ sp circ$C packaged under various gas atmospheres, compared to $ sim$14 d for raw nuggets stored/packaged under similar conditions. / Growth of Listeria monocytogenes occurred in both raw and cooked nuggets at 4 and 12$ sp circ$C, irrespective of packaging conditions. However, growth of Clostridium botulinum type E was inhibited in both raw and cooked nuggets stored at 4, 12, and 25$ sp circ$C. While inhibition was suspected to be due to the decrease in pH of raw nuggets to $ sim$4.1-4.5, due to the growth of lactic acid bacteria (LAB), subsequent studies on cooked and sterilized nuggets showed that the anti-botulinum effect was due to heat resistant Bacillus species. Further challenge studies with C. botulinum type E in sterile nuggets (i.e., in the absence of LAB and Bacillus spp.) showed that toxin was produced after 14 and 28 d in nuggets stored in air, and in air with an Ageless SS oxygen absorbent at 25 and 12$ sp circ$C, respectively. Further studies have now confirmed that Bacillus isolates, specifically B. subtilis, inhibited the growth of C. botulinum type E.

The storage life at 43°F of ground dover sole fillets (Microstomas pacificus) was determined microbiologically after treatment with ionizing radiation and antimicrobial agents. Sodium benzoate, potassium sorbate and the sodium salts of the methyl and propyl esters of parahydroxybenzoic acid (MPB and PPB) all approximately doubled the refrigerated storage life of irradiated dover sole. The dose levels employed were 0.1, 0.3, and 0.5 Mrad. The concentration of the agents used in each case was 0.1 percent. The normal spoilage of dover sole is caused predominately by the outgrowth of pseudomonads. After irradiation, however, the spoilage is due to the outgrowth of Achromobacter and certain Gram positive organisms. The spoilage pattern was not changed by the antimicrobial agents tested except at the higher dose level (0.5 Mrad), at which the spoilage was caused by yeasts. The additives had no effect on the growth rate of the microorganisms of dover sole. They merely prolonged the length of microbial dormancy that followed radiation exposure. Possible mechanisms involved in the combined effect of antimicrobial agents and irradiation are discussed. / Graduation date: 1965