Abstract
The breakdown products of adenosine triphosphate (ATP),
adenosine diphosphate (ADP), adenosine monophosphate
(AMP), inosine mono-phosphate (IMP), inosine (Ino) and
hypoxanthine (Hx) of some fish species and heated fish
products were determined by high-performance liquid
chromatography (HPLC) and rapid paper strip method.
The K value, calculated from ATP degradation products,
the percent of the sum of Ino and Hx divided by the sum
of ATP, ADP, AMP, IMP, Ino and Hx increased almost
linearly in the muscle of all Finnish fish species
studied, when stored on ice. There were some variations
of K value among fish species and also between
individuals of the same fish species, while K-value did
not depend on the location of whitefish fillets.
The K value of cold smoked rainbow trout increased
similarly to that of unheated fish. In hot smoked fish
(whitefish, mackerel and rainbow trout) the K-value
increased during heating but not at all after subsequent
storage in a chill room. The sous vide (final internal
temperature 73°C) treated whitefish behaved like the hot
smoked fish species.
The K value of rainbow trout increased more slowly during
heating than the K value of other fish species (Baltic
herring, whitefish and mackerel) and in the case of the
hot smoked rainbow trout the K value could be an
indicator of the freshness of the raw material used. The
low K value could possibly be used as evidence of really
fresh fish.
The K value was used as a criterion when comparing the
effects of catching method on the quality of Baltic
herring. The K values of gillnet-caught fish were greater
than those of fish caught by trapnet or by trawling. The
duration of trawling time (2 h and 5 h) did not effect
the K value when the water temperature was 8 16 °C.
An intercalibration study was performed with 23 municipal
laboratories, which used the K-value, determined by means
of the HPLC method or rapid paper strip method, as a
criterion for fresh, frozen, and frozen fish stored on
ice for 7 days before freezing. The paper strip method
correlated quite well with the sensory quality of fish
while the relationship between K-value determined by HPLC
and by the paper strip method was not very good.
The determination of ATP breakdown products and the
calculation of K-value are relevant chemical methods for
evaluation of the freshness of fish. However, there is a
certain variation between individual fishes and between
fish species.
Original language | English |
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Qualification | Doctor Degree |
Awarding Institution |
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Supervisors/Advisors |
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Award date | 14 Mar 1997 |
Place of Publication | Espoo |
Publisher | |
Print ISBNs | 951-38-4955-4 |
Electronic ISBNs | 951-38-5063-3 |
Publication status | Published - 1997 |
MoE publication type | G5 Doctoral dissertation (article) |
Keywords
- adenosine phosphates
- chemical indicators
- freshness
- fishes
- fish
- products
- herrings
- trout
- chromatography
- methods
- laboratory tests
- food industry
- quality