AUTHOR=Sáez M. Isabel , Galafat Alba , Vizcaíno Antonio J. , Rodríguez Cristina , Hernández de Rojas Alma , Alarcón F. Javier , Martínez Tomás F. 

TITLE=Long-term effect of a short pulse of dietary supplementation with algae on the quality of turbot (Scophthalmus maximus) frozen fillets

JOURNAL=Frontiers in Marine Science

VOLUME=Volume 9 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2022.957217

DOI=10.3389/fmars.2022.957217

ISSN=2296-7745

ABSTRACT=This study evaluates the potential long-term effects of a feeding pulse with algae-enriched diets on the quality of frozen turbot (Scophthalmus maximus) fillets. A feeding trial was carried out with juvenile turbot fed with six different experimental diets, two of which were enriched with the macroalgae Ulva rigida (U diets), other two with a microalgae blend (M diets), plus a non-supplemented control diet (CT), and finally, a commercial aquafeed (COM). Two inclusion levels were considered in algae-enriched diets (50 and 100 g kg-1), so that they were designed as U5 and U10 for U. rigida, and M5 and M10 for microalgae-enriched diets. The duration of feeding pulse with the functional diets was 60 days, and then, all specimens were fed with COM diet for a further 150-d period until reaching a body size close to the commercial standard (around 750 g). Subsequently, fish were sacrificed, fillets were removed from the pigmented flank, and kept at -20 ºC for 5 months. Then, fillets were thawed and muscle proximal composition and fatty acids profile were analysed, and fillet quality parameters were assessed during a 10-d cold storage period at 4 ºC. Possible deferred effects of algae-enriched diets on fillet quality were compared against control (CT) and commercial (COM) diets. The results obtained indicated that a 60-d administration pulse of algae-enriched diets induced some long-term changes in both the nutritional and organoleptic quality of turbot fillets. In this regard, the algae-enriched aquafeeds improved muscle antioxidant response throughout the cold storage period, prolonging the shelf life of thawed turbot fillets. In addition, this feeding pulse on pre-growing stage of the productive cycle was able to modify the skin and muscle pigmentation of fish of commercial size. U10 diet increased protein content, improved muscle texture, reduced fillet total lipid content, and favoured muscle selective retention of n3 polyunsaturated fatty acids. Thus, the results obtained indicate that a two-month feeding pulse with algae-supplemented diets during pre-growing phase may represent a promising strategy to improve the nutritional and organoleptic quality of frozen turbot fillet, as well as to extend their shelf- life during the post-thawing cold storage.