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
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/26933 |
| Date | 25 October 1972 |
| Creators | Cavazos, Sergio Flores |
| Contributors | Crawford, David L. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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