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
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/27285 |
| Date | 28 August 1981 |
| Creators | Chu, Tien-iu |
| Contributors | Crawford, David L. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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