Effects of edible coatings based on ultrasound-treated whey proteins in quality attributes of frozen Atlantic salmon (Salmo salar)

The effects of ultrasound-treated whey protein coatings on frozen Atlantic salmon quality parameters were evaluated. The experiment was performed using an ultrasonic bath at a frequency of 35 kHz and three sonication times (1, 15 and 60 min). The yield, the thaw yield, the drip loss in thawing, the drip loss after chilled storage and the cooking loss of fish samples were not influenced by the ultrasound treatment of coatings when compared to fish samples with untreated whey protein coatings. Decreases in yield, drip loss in thawing and drip loss after chilled storage were observed in samples from whey proteins sonicated 60 min in relation to those sonicated 15 min. The ultrasound treatment of whey proteins did not modify the colour of frozen and thawed fillets but increased L* and whiteness of cooked samples in comparison with untreated whey protein coated samples. All whey protein coatings decreased the lipid oxidation of fish fillets. However, the ultrasound treatment of coatings significantly delayed the lipid oxidation of salmon pieces in comparison with those coated with untreated proteins. The sensory properties of salmon samples were not negatively affected by these coatings.Industrial relevanceFreezing is a very usual method of fish preservation; some changes during frozen storage that decrease product quality can occur, such as lipid oxidation. The results obtained in this investigation show that ultrasound applied to whey protein coatings could be useful for the reduction of the lipid oxidation of frozen salmon. These treated coatings could be a good alternative to conventional packaging and, at least, they could partially substitute plastic packaging. The edible coatings can contribute to reduce the plastic packaging residues of frozen seafood industry and the environmental contamination.

► Frozen salmon quality as affected by ultrasound treated-whey protein edible coatings.
► Ultrasound-treated coatings do not modify yields and drip losses of salmon fillets.
► Cooked salmon colour is modified by the ultrasound-treated whey protein coatings.
► Ultrasound-treated protein coatings delay the lipid oxidation of frozen salmon.
► The sensory properties of salmon are not negatively affected by the treated coatings.