Quality changes during cod (Gadus morhua) desalting at different temperatures.
BACKGROUND
To advise consumers and manufacturers regarding decreasing the time needed to desalt salted cod (a time-consuming process), there is a need to develop knowledge about quality changes at different desalting temperatures. The objective of this work was to evaluate the physico-chemical, microbiological and sensory quality changes and their causes during cod desalting at 5, 10 and 15 °C, using a cod/water ratio of 1:9 without water changes. The influence of slices with different thickness and different desalting times was also evaluated.


RESULTS
Desalting promoted a decrease in the levels of total volatile basic nitrogen, thiobarbituric acid reactive substances and free amino acids nitrogen (FAA-N). The highest FAA-N values were found in 'thicker' samples desalted at 15 °C due to the higher proteolytic bacteria number observed in these samples, which activity compensated the leaching of soluble components to the desalting solution. The water uptake and the salt leaching out of the muscle found during the processes created conditions for the bacterial growth, contributing to the spoilage at 15 °C. Based on fresh odour and 'off'-flavours results, 'thicker' samples desalted at 15 °C after 72 h were close to spoilage and on microbial levels were spoiled.


CONCLUSIONS
In order to extend the shelf life and safety of cod desalted products, desalting at temperatures above 10 °C is not advisable. © 2014 Society of Chemical Industry.
IPMA, I.P., Portuguese Institute for the Sea and Atmosphere, I.P., Division of Aquaculture and Upgrading, Avenida de Brasília, 1449-006 Lisboa, Portugal.|ICBAS-UP, Abel Salazar Institute for the Biomedical Sciences, University of Porto, Rua Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal.|CIIMAR/CIMAR, Interdisciplinary Center of Marine and Environmental Research, University of Porto, Rua dos Bragas 289, 4050-123 Porto, Portugal.|CERNAS, College of Agriculture of the Polytechnic Institute of Coimbra, Bencanta, 3045-601 Coimbra, Portugal.
Helena
H
Oliveira
IPMA, I.P., Portuguese Institute for the Sea and Atmosphere, I.P., Division of Aquaculture and Upgrading, Avenida de Brasília, 1449-006 Lisboa, Portugal.
Amparo
A
Gonçalves
IPMA, I.P., Portuguese Institute for the Sea and Atmosphere, I.P., Division of Aquaculture and Upgrading, Avenida de Brasília, 1449-006 Lisboa, Portugal.
Maria L
ML
Nunes
ICBAS-UP, Abel Salazar Institute for the Biomedical Sciences, University of Porto, Rua Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal.|CIIMAR/CIMAR, Interdisciplinary Center of Marine and Environmental Research, University of Porto, Rua dos Bragas 289, 4050-123 Porto, Portugal.
Paulo
P
Vaz-Pires
CERNAS, College of Agriculture of the Polytechnic Institute of Coimbra, Bencanta, 3045-601 Coimbra, Portugal.
Rui
R
Costa
D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001419:Bacteria / Q000254:growth & development*; D005511:Food Handling / Q000379:methods; D005516:Food Microbiology; D005519:Food Preservation / Q000379:methods*; D048389:Gadus morhua; D006801:Humans; D009132:Muscles; D009584:Nitrogen / Q000032:analysis; D009812:Odorants; D017747:Seafood / Q000032:analysis* / Q000382:microbiology / Q000592:standards; D012965:Sodium Chloride; D013649:Taste; D013696:Temperature; D017392:Thiobarbituric Acid Reactive Substances; D014867:Water
D000596:Amino Acids; D017392:Thiobarbituric Acid Reactive Substances; D014867:Water; D012965:Sodium Chloride; D009584:Nitrogen
Gadus morhua; cod; desalting; quality changes; temperature