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Effect of high hydrostatic pressure (HHP) on the bacterial count and quality of shucked oysters

The effects of various pressure treatments (OK, 30K, 60K, 75K psig) and
packing medium (water or cocktail sauce) on shucked oysters were investigated.
The pH, moisture content, microbiological tests (including aerobic plate count
(APC) and anaerobic plate count (ANPC)), enzyme assays (i.e. α-amylase, β-amylase,
lipase and peroxidase activities) were conducted to determine the quality
of pressure treated oysters during a 6 week shelf-life study. The moisture content
in water-packed oysters under OK, 30K, 60K and 75K psig pressure treatments was
slightly increased during storage, while that in cocktail sauce-packed samples was
significantly lower than in water-packed samples. Addition of cocktail sauce
lowered the pH in oysters, which effectively inhibited the microbial growth, but
altered the appearance. The microbial shelf-life of water-packed oysters with
pressure treatment of 60K and 75K psig was extended several weeks compared
with the controls while 30K psig had less of an effect. Pressure treatments did not
inhibit enzyme activities in oysters, however, the addition of cocktail sauce was
significant in inhibiting the enzyme activities in this study. / Graduation date: 2000

Identiferoai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/26558
Date16 July 1999
CreatorsShiu, Shu-Er
ContributorsMorrissey, Michael T.
Source SetsOregon State University
Languageen_US
Detected LanguageEnglish
TypeThesis/Dissertation

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