Thesis (Ph. D.)--College of William and Mary. / Typescript (photocopy). Vita. Includes bibliographical references (leaves 198-215).

Bibliography: p. [i.e. leaves] 165-215.

For the past six years a bacterial infection has been the cause of large losses of adult, spawning, American shad (Alosa sapidissima) in the Coos, Millicoma and Smith Rivers of Oregon. There was a sizable commercial fishery for shad in these rivers and losses of fish due to this infection represented an important economic loss to the industry. This study was undertaken to determine the causative agent of the disease and describe the pathology of the disease. Fifteen strains of bacteria were isolated from diseased shad in the Coos, Millicoma, and Smith Rivers. Cultural and morphological studies, physiological reactions, animal infection, serological tests, and determination of the mole percent guanine + cytosine showed that the causative agent belonged in the genus Aeromonas. Since the shad disease isolates could cause "red leg" disease in frogs and "red mouth" disease in trout, they were named Aeromonas hydrophila. The disease was shown to be a bacterial hemorrhagic septicemia. Externally, the diseased shad had large hemorrhagic areas on their sides and reddening of the head and fins. Very little pathology could be seen internally. The causative organism was recovered from the spleen, liver, kidney, heart, blood and external lesions of the diseased animals. A review of the literature revealed that there was confusion in the nomenclature of the three motile species of bacteria included in the genus Aeromonas. Many authors felt that the three species (A. liquefaciens, A. hydrophila, A. punctata) were one distinct species. Comparative tests performed on the shad disease isolates and known cultures of Aeromonas failed to reveal major differences between these organisms. Attempts were made to separate the three species on the basis of the mole percent guanine + cytosine and thermal denaturation temperature (Tm) of the bacterial DNA. Three shad disease isolates had Tm values of 94.3, 94.6, and 94.2��C with corresponding mole percent guanine + cytosine values of 60.9, 61.7, and 60.7. An isolate of Aeromonas liquefaciens obtained from the Communicable Disease Center (CDC) in Atlanta, Georgia had a Tm of 94.1��C and a mole percent guanine + cytosine of 60.3. Aeromonas hydrophila (CDC) had a Tm of 95.4��C and a mole percent guanine + cytosine of 63.4 while A. punctata (CDC) had a Tm of 93.5��C and a mole percent guanine + cytosine value of 59.0. The mole percent guanine + cytosine results indicated that the shad disease bacterium was closely related to A. liquefaciens. The three known cultures of Aeromonas each had a distinct mole percent guanine + cytosine value. / Graduation date: 1968

Thesis (Honors)--College of William and Mary, 2009. / Includes bibliographical references (leaf 25). Also available via the World Wide Web.

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Thesis (M. Sc.)--University of Adelaide, 1989? / Includes bibliographical references (p. [i.e. leaves ] 165-215).

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Thesis (M.S.)--Auburn University, 2008. / Abstract. Includes bibliographical references (p. 43-52).

Machine separated flesh from American shad (Alosa sapidissima) was evaluated for preparing heat set gel products. Round fish frozen for 15) to 10 months at -18°C served as raw material for processing investigations. The effectiveness of various additives and processing procedures for improving gel strength and sensory characteristics were determined. Addition of 0.5% polyphosphate to sols enhanced the hardness (P [greater than or equal to] .005), cohesiveness (P [greater than or equal to] .01) and springiness (P [greater than or equal to] .001) of heat set gels. Small amounts (0.5 and 1.0%) of dried egg white also improved hardness, cohesiveness and springiness (P [greater than or equal to] .001). Employing a two stage heat setting regime (40°C for 30 min followed by 90°C for 20 min) strengthened (hardness, cohesiveness and springiness) (P [greater than or equal to] .001) gels over a one stage (90°C for 30 min) heat set. Two stage heating improved gel strength when sol fonnulations contained additives that improved, lowered or exerted no effect on gel strength. Concentrations of dried egg white (1.0, 2.0, 3.0 and 4.0%) and potato starch (1.0, 2.0 and 5.0%) did not improve gel strength. Dried egg white (>1%) did not alter (P > .05) any physical parameters of gel texture. Potato starch (>1%) reduced gel hardness (P [greater than or equal to] .001). More basic pH conditions produced by the addition of 0.1 and 0.2% sodium carbonate to sols did not alter gel hardness or springiness (P < .05) and only caused a slight inprovement in cohesiveness (P [greater than or equal to] .001). Ihe cryoprotectants sorbitol, (0.0, 2.0, 4.0, 6.0 and 8.0%) and sucrose (0.0, 2.0, 4.0 and 6.0%), reduced gel strength in a concentration dependent manner. Gel hardness was reduced in a linear manner as fish protein was replaced with sorbitol (r =.976) or sucrose (r =.965) in sols formulated to contain 74 + 1.5% moisture. Cohesiveness was reduced in a similar manner (r = .942) by sorbitol, but not by sucrose. Gel springiness was not altered by additions of sorbitol or sucrose. Incorporation of sucrose into formulations reduced sensory preference for the texture, flavor, appearance and overall desirability of heat set gels. Analysis of covariance of texture preference scores and physical measurements of texture reveal a strong linear correlation with hardness (P =.0004), but not with cohesiveness (P =.6675). Within the range of sucrose levels evaluated, harder gels were preferred. Washing was evaluated for improving the strength and sensory preference for heat set gels containing 0.5% polyphosphate and 0.5% dried egg white. Sols were set by heating for 30 min at 40°C followed by 90°C for 20 min and exposed to wood smoke. Gel hardness and springiness were reduced by washing (P [greater than or equal to] .05), but not cohesiveness (P > .05). This was surprising, since the gel strength enhancing effect of washing is well documented. Sensory preference for the flavor, color, texture or overall desirability of heat set gels was not affected (P > .05) by washing. Mean overall desirability scores for gels prepared from unwashed minced flesh of 5.25 and 5.27 for washed minced flesh were only slightly above a neutral preference (5.0 = neither like nor dislike). Round shad yielded 65.06% planks, 41.20% minced flesh and 40.10% refined flesh. A single exchange wash followed by dewatering yielded 23.02% pressed flesh based upon round weight which was reduced to 20.68% by refining. Processing minced flesh into washed and refined flesh recovered 51.37% of total solids. The yield through refining was 97.33 and 89.83% respectively for unwashed and washed flesh. The protein and lipid content of flesh was not altered (P > .05) by washing, but ash content was reduced (P [less than or equal to] .001). / Graduation date: 1989