Scientific Publications with referee

Change in water-holding capacity of halibut muscle during cold storage.

Vannbindingsevne er vist å være en funksjonell egenskap som godt beskriver kvalitet av muskel post-mortem.

To lagringsforsøk, i henholdsvis 15 og 18 dager, ble gjennomført for å studere endringer i vannbindingsevne under kjølelagring. For å undersøke eventuell effekt av fordervelsesbakterier på muskelens vannbindingsevne ble lagringsforsøkene gjennomført både med og uten bakterier tilstede. Bakterievekst ble hemmet ved at filetene ble dyppet i en 3mM NaN3-løsning før lagring. Vannbindingsevne ved målt ved hjelp av en sentrifugeringsmetode. Ved normale lagringsbetingelser økte væskeslippet i begynnelsen av lagringsperioden for deretter å avta etter ca. 8 dager. Når bakterieveksten var hemmet kunne ingen slik reduksjon observeres før 18 dagers lagring. Bakterievekst i normalprøvene resulterte ikke i noen økning i muskel pH og kunne dermed ikke forklare den bedrede vannbindingsevnen utover i lagringsperioden. Væskeslippet ble videre analysert for å studere mekanismene bak endringene i vannbindingsevne under lagringen. I begge eksperimentene var total mengde protein i væskeslippet korrelert til mengde væskeslipp. Hydroxyprolin ble kun funnet i væskeslippet fra muskel varmet opp til 50°C men ingen signifikant endring som funksjon av lagring ble observert. Dette indikerer at ingen omfattende løseliggjøring av kollagenet hadde funnet sted under lagringen. Det ble detektert hexuronsyre i væskeslippet men ingen tidsavhengig økning kunne observeres. I normalprøvene så det tvert i mot ut til at mengden hexuronsyre avtok i den siste delen av lagringsperioden. Gelatinolytisk aktivitet i muskelvevet ble undersøkt ved hjelp av gelatin zymografi. Resultatene viste at prøver med fordervelsesbakterier til stede hadde høyere gelatinolytisk aktivitet. Den økte proteolytiske aktiviteten fører trolig til mer degradering av proteiner inkl. kjerneproteiner i proteoglykaner, som videre trolig bidrar til økt vannbindingsevne.

Facts

Year 2003
Abstract A useful tool for describing quality in muscle foods post-mortem is to measure the water-holding capacity of muscle (WHC). Two storage experiments were carried out to study the changes of WHC in halibut muscle during chilled storage for 15 and 18 days, respectively. To investigate the effect of normal spoilage bacteria on WHC, the storage experiments were performed both in the presence and absence of bacteria. Bacterial growth was inhibited by soaking the muscle in 3mM NaN3 prior to storage. A centrifugal technique was used to measure WHC. Under normal conditions, the liquid loss (LL) initially increased followed by a decrease after approximately 8 days. When bacterial growth was inhibited, no such reduction in LL was observed before day 18. Under normal storage conditions, no increase in muscle pH due to bacterial growth that could explain the improved WHC, was detected. The expelled water was analysed in order to investigate the mechanisms behind the changing WHC during storage. In both experiments, the total amount of protein lost from the muscle tissue correlated to the amount of LL. Hydroxyproline could only be observed in the LL from muscle heated to 50°C and no significant changes were observed during storage. This indicates that extensive solubilisation of collagen did not occur during the storage period. Hexuronic acid was detected in the LL but no time dependent increase could be observed. In the normal samples, the amount of hexuronic acid in the LL actually appeared to decrease in the last part of the storage period. Gelatinolytic activities in the muscle tissue during storage were investigated by gelatine zymography. The results showed that samples with spoilage bacteria present had higher gelatinolytic activities. The increased proteolytic activities are likely to result in more degradation of proteins including core protein of proteoglycans, which then contribute to the increased WHC.
Reference Olsson, G.B., Ofstad, R., Lødemel, J.B., Olsen, R.L. 2003. Change in water-holding capacity of halibut muscle during cold storage. LWT - Food Science and Technology, Vol 36, pp 771-778.
Publisher LWT - Food Science and Technology,

Related persons

  • Gunn Berit Olsson

    Director of Research, Fish health

    Phone: +47 77 62 90 71

    Cellphone: +47 474 62 565

  • Ragni Ofstad

    Research Director, Raw materials and Process Optimisation

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