Treatment of round shrimp (3 days post-catch) in 6% condensed phosphate solution at temperatures ranging from 39 (3.9°C) to 86°F (30°C) reduced meat yield derived by mechanical peeling from 30.0 to 16.4% (wet wt.) according to the linear function y = -.2787 x + 42.7262 (P>.005). Condensed phosphate treatment at ambient potable water temperature 62°F (16.7°C) increased the meat yield over a respective water treatment control from 21.2 to 27.1% (wet wt.); refrigeration of the condensed phosphate solution to 39°F (3.9°C) raised yield to 30.0%. Elevated solution temperatures accelerated proteolytic attack degrading musculature proteins to a degree that precluded their interaction with condensed phosphate in a manner that would effectively retard heat solubilization during cooking. Condensed phosphate interacted with meat proteins more readily at high temperatures, but not in a manner which conserved yield. Exposure of round shrimp to condensed phosphate treatment temperatures greater than 62°F (16.7°C) markedly reduced cooked meat quality. Loss of more hydrated and less pigmented unformed connective tissue through cooking concentrated meat pigment, increased the force required to shear and reduced meat moisture content. Flavor panel scores for texture, flavor and over-all desirability were significantly reduced. The advantage of reducing condensed phosphate pretreatment temperature from ambient potable water (62-66°F; 16.7-18°C) to 38-40°F (3.3-4.4°C) was shown to range from 1.2 to 4.8 percentage points in yield from 2 and 8 day post-catch shrimp, respectively. A similar more accentuated advantage of condensed phosphate over a water pretreatment by post-catch storage was observed (from 4.2 to 6.0 percentage points) at 62-66°F (16.7-18.9°C). Meat quality was not markedly affected by the type of treatment solution or temperature regime (38-40 and 62-66°F). Application of yield conserving procedures (low temperature pretreatment; condensed phosphate application) increased cooked meat quality decline with respect to post-catch storage. Conserving the degraded meat fraction somewhat reduced sensory acceptability. / Graduation date: 1982

The effect of the application of condensed phosphate (Brifisol D-510, commercial mixture of sodium tripolylphosphate and sodium hexametaphosphate) to round shrimp on the yield and frozen shelf-life characteristics of cooked meat was investigated. Condensed phosphate retarded protein solubilization and increased the water-holding capacity of meat through steam precooking markedly improving yield. The effectiveness of condensed phosphate application was enhanced by the post-catch degradative changes occurring in the shrimp musculature proteins during ice storage. Cooked meat yields (wet wt.) for phosphate treated round shrimp after two, four and seven days ice storage were 30.70±0.51%, 31.22±0.03% and 29.21±0.23%, while the yields from control samples were 26.52±0.18%, 27.14±0.01% and 23.85±0.09%, respectively. The phosphorus contents of cooked meat from control shrimp were 842.54, 726.08 and 577.74 mg P₂O₅/100 gm (wet wt.) after 2, 4 and 7 days storage in ice. Phosphate treatment produced an increase of 91.20, 134.34 and 184.68 mg P₂O₅/100 gm (wet wt.) over respective control samples. The loss of solid material retarded by condensed phosphate pretreatment and increased as ice storage was extended was inversely proportional to the iron and copper contents in cooked shrimp meat. Initial levels of tyrosine, trimethylamine oxide, trimethylamine and dimethylamine in cooked meat reflected the quality of round shrimp as mediated by ice storage. Differences were related to drip loss and bacterial and enzymic degradation. The level of tyrosine in cooked shrimp meat did not significantly change with respect to frozen storage time. A higher level of trimethylamine oxide was retained in the meat from phosphate treated shrimp than respective control samples. trimethlyamine oxide decomposed during ice and frozen storage; decomposition with respect to frozen storage time followed an exponential function. Differences in initial levels of trimethylamine in cooked meat were presumably related to the bacterial load in round shrimp. Condensed phosphate treatment reduced the trimethylamine contents of cooked meat. Dimethylamine levels increased during ice storage of the raw shrimp and frozen storage of the cooked meat which supports the existence of a non-enzymatic mechanism, but did not rule out an enzymatic mechanism in the raw tissue. Dimethylamine was formed in cooked meat according to an exponential function; the rate if formation was inversely related to the magnitude of solids lost through precooking. Dimethylamine was formed more rapidly in frozen cooked meat from fresh and phosphate treated shrimp. Condensed phosphate had a significant effect on retarding toughening during frozen storage as measured by shear press. Shear press values were correlated with dimethylamine content which is co-produced with formaldehyde. In all sensory evaluations, phosphate treated shrimp yielded cooked meat that possessed a higher quality than respective control samples. Sensory quality of cooked meat was slightly different at two and four day ice storage, but flavor panels showed a significant degradation after seven days ice storage. Color, flavor and overall desirability scores from shrimp were not correlated with frozen storage. Texture and juiciness scores did not significantly change as frozen storage was extended. The frozen storage stability of cooked meat from condensed phosphate treated shrimp did not appear to differ from that of non-treated. / Graduation date: 1982

The relationship between the decomposition of trimethylamine oxide in Pacific shrimp and shrimp meat quality was investigated to evaluate the use of the trimethylamine oxide system as a quality control indice. Changes in the levels of trimethylamine oxide and its decomposition products in whole shrimp stored on ice and in its derived raw and cooked meat and in raw shrimp meat stored under refrigeration (1-2°C) were investigated. The concentration dependency of the decomposition of trimethylamine oxide to dimethylamine and formaldehyde in frozen storage (-18°C) and the heat sensitivity of the trimethylamine oxide decomposition systena was evaluated. A statistical relationship between amine and formaldehyde levels in whole shrimp and raw and cooked meat stored under laboratory conditions and obtained from commercial processing plants with flavor panel scores was developed. Trimethylamine oxide levels decreased in a linear manner in whole shrimp, and in the raw and cooked meat during iced storage. This apparent disappearance was related to the washing action of melting ice and its degradation to trimethylamine, dimethylamine and formaldehyde. Levels of dimethylamine and formaldehyde increased in a parallel manner during iced storage. Trimethylamine levels increased steadily during the first four days of storage, followed by rapid increase during the latter four days reflecting a microbial out-growth. Trimethylamine oxide levels in raw shrimp meat held at 1-2°C decreased during the first four days of storage at a relatively slow rate, followed by a sharp decline during the remainder of an eight day storage period. Trimethylamine levels were shown to remain relatively constant during the first four days of storage, followed by a rapid increase in levels reflecting the decline of trimethylamine oxide levels. Dimethylamine and formaldehyde levels increased rapidly in a linear manner during the storage period. Dimethylamine and formaldehyde levels in frozen raw shrimp meat increased during storage (-18°C) in a linear manner. The rate of dimethylamine formation was shown to depend upon initial trimethylamine oxide levels and/or enzyme concentration. A rate dependency on trimethylamine oxide for formaldehyde was not established. The presumably enzyme-catalyzed mechanism of dimethylamine formation was found to be completely inactivated by the exposure of the raw meat to water at 100°C for 15 seconds. Flavor panel scores for cooked meat derived from whole shrimp stored on ice declined in a linear manner over an eight day storage period. Scores for these samples of shrimp meat and samples obtained from commercial processing plants correlated well with trimethylamine oxide, dimethylamine, and formaldehyde levels in whole shrimp and derived raw and cooked meat. Trimethylamine levels, indicative of microbial out-growth provided correlations inferior to these indices. The magnitude of change observed in trimethylamine oxide levels accurately reflected flavor panel scores. The simplicity of its determination supports its use in quality control practices. / Graduation date: 1976

Arthur H. Tang. / Thesis (M. Phil.)--Chinese University of Hong Kong. / Bibliography: l. 74-78.

This study is an investigation of the endogenous, or internal, rhythms of activity in the ocean shrimp, Pandalus jordani, Groups of shrimp were kept in constant light and temperature conditions in the laboratory, and activity was monitored visually and with infrared photography. Other groups of animals were exposed to 24-hour light-. dark cycles of blue-green light; the activity of these animals was recorded with infrared photography after the light cycle was terminated. It was found that shrimp not exposed to a light-dark cycle did not display any rhythms of activity in constant conditions in the laboratory. After exposure to the light cycle, some shrimp swam significantly more during the 'night" hours in constant conditions. These shrimp 'entrained" to the light cycle; they synchronized their activity with the periodicity of the light cycle, and retained the periodicity in the absence of the rhythmical light cues. The relationship of these results to the nocturnal vertical migration of ocean shrimp in the field is discussed. It is suggested that shrimp possess a biological clock which synchronizes with rhythmical light cues and mediates vertical swimming, and that the rhythmicity of the vertical migration in the field is endogenous, with internal and external factors interracting with the internal rhythm. Conclusions are summarized and areas for further research are suggested. / Graduation date: 1974

Graduation date: 1980

Callianassa californiensis (Dana), a burrowing crustacean inhabitant of estuarine mudflats along the Pacific coast, is subjected to severely hypoxic interstitial water twice each tidal cycle. A preliminary approach was made to understanding the metabolic mechanisms employed by Callianassa during periods of anoxic stress. Percent glycogen in the hepatopancreas and chela muscle, blood lactic acid, and blood glucose were determined for animals subjected to periods of anoxia. Blood lactate and glucose analyses were performed on animals at various intervals during a post-anoxia recovery period. Callianassa was found to accumulate the anaerobic end product, lactic acid, at a steady rate during anoxia. The blood glucose concentration was shown to increase with initiation of anoxia until about 12 to 14 hours when it tended to reach an equilibrium. Glycogen utilization did not appear to be important during short periods of anoxic stress, but for periods longer than 12 to 14 hours, glycogenolysis became important in maintaining glucose substrate for glycolysis. During the post-anoxia recovery period, the accumulated blood lactate was oxidized and blood glucose was reduced to the normal concentration. The possibility of the existence and role of free blood oligosaccharides as a source of glucose during anoxia was discussed. / Graduation date: 1971

Graduation date: 1975

The nature of a natural antioxidant present in shrimp was investigated. Shrimp extracts were prepared using different solvents to ascertain the best extraction method. The antioxidant activity was determined using the (β-carotene-linoleate model system and the oxygen weighing method. Ethanol proved to be the best solvent for extracting the natural antioxidant. Different shrimp materials extracted with ethanol proved to be equally effective as antioxidant sources. The non-lipid nature of the antioxidant was established by separating the lipid from the non-lipid material and measuring its antioxidant activity. The phenolic nature of the antioxidant was further established and its isolation achieved by means of preparative thin layer chromatography. The Rf values with different solvents and its wavelength of absorption maxima were determined. Its chemical nature was further investigated using different visualizing reagents. The colorimetric quantitation of the antioxidant factor revealed that it is present in very low concentrations in its natural source. Its effectiveness as an antioxidant at low concentrations together with the fact that it is a natural product makes it a valuable compound of potential use in the food industry. / Graduation date: 1978

No description available.