Characterization of the collagen protein in smooth pink shrimp (Pandalus jordani)

The collagen content and composition of collagens in different age classes of shrimp were determined. Their physical and chemical characteristics were investigated. The interrelationship of shrimp size and muscle collagen content to raw and cooked meat yield was established. Total collagen content f...

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Bibliographic Details
Main Author: Akel, Phillip John
Other Authors: Crawford, David L.
Language:en_US
Published: 2011
Subjects:
Online Access:http://hdl.handle.net/1957/26044
Description
Summary:The collagen content and composition of collagens in different age classes of shrimp were determined. Their physical and chemical characteristics were investigated. The interrelationship of shrimp size and muscle collagen content to raw and cooked meat yield was established. Total collagen content for three lots of round shrimp with weights averaging 2.58±.39, 5.27±.55 and 7.72±.96 g was determined to be 2.36, 3.35 and 3.47 mg collagen/g total musculature N, respectively. Unformed collagen comprised 53.85, 35.52 and 0.86% of the total collagen content, respectively. Maturation, as reflected by shrimp size, was accompanied by a near linear increase in formed collagen. A molecular weight of 310,000 for shrimp collagen was determined using SDS gel electrophoresis. The accuracy of this determination was compromised by limited mobility and lack of standard reference proteins of appropriate molecular weight, but did establish a molecular weight in a range common to other collagens. Variations in the amino acid composition of formed and unformed collagen reflected the function of the tissues in the musculature from which they were derived. Formed collagen contained higher amounts of glycine, proline and hydroxylysine than unformed collagen, providing a chemical basis for its structural function in formed connective tissues. Remaining amino acids, except histidine, glutamate and arginine were contained in higher amounts in unformed collagen. Unformed collagen also contained a substantial amount of unidentified components which were suspected to be amino sugar derivatives. Only trace amounts of these components were found in formed collagen. Shrimp collagen contained unusually low levels of glycine, only trace amounts of hydroxyproline and substantial quantities of tryptophan. Glycine and hydroxyproline are important amino acids in mammalian collagens, but tryptophan is usually not present. Shrimp collagen also contained higher levels of threonine, tyrosine, hydroxylysine, valine, methionine, leucine, isoleucine and phenylalanine than most other reported collagens. These variations in amino acid composition seem to reflect a requirement for a structural protein possessing unique characteristics commensurate with the anatomical structure of the species. The yield (% dry wt.) of raw and cooked (100 sec; 101°C in steam) derived through hand peeling round shrimp, was correlated (P>.001) in a positive manner by well defined power functions. Raw meat yield (% dry wt.) declined during ice storage in a linear (P>.001) manner at a rate dependent upon shrimp size. The more rapid loss of solids from large shrimp reduced yield differences as storage was extended. Raw meat losses during ice storage ranged from 0.298 to 0.318 g raw meat dry matter/100 g round shrimp/day for 2.5 and 7.5 g shrimp respectively. Dry matter weight loss from raw meat through the washing action of melting ice, was replaced in a linear (P>.05-P>.005) manner with water to maintain yield (% wet wt.) during storage. Ice storage expanded cooked yield (% dry wt.) differences between shrimp sizes. Meat losses through cooking mediated by ice storage, ranged from 0.421 to 0.303 g cooked meat dry matter/100 g round shrimp/day for 2.5 and 7.5 g shrimp, respectively. The age class dependent content and composition of collagens in the musculature of shrimp was reflected in the recovery of raw and cooked meat. Meat from small shrimp contained higher levels of unformed collagen which possessed less dry matter and degraded more rapidly in ice storage. Proteolytic action on elevated levels of unformed collagen was not reflected in the rate of ice storage losses. But, it markedly increased heat induced solubilization of solids and enhanced moisture retention through steam precooking over larger shrimp. Maturation of shrimp associated with more formed and less unformed collagen reduced solids solubilization and moisture retention through steam precooking. === Graduation date: 1982