# Enhancement of the Storage Potential of Farmed Rainbow Trout (Oncorhynchus mykiss) by Using Algal (Cystoseira myrica and Cystoseira trinodis) Extract–Ice Combinations

## TL;DR

This study shows that using algal extracts with ice can improve the storage quality of farmed rainbow trout during chilling.

## Contribution

A novel strategy using algal extracts in ice systems to enhance fish storage quality is proposed.

## Key findings

- Alga-treated fish showed lower pH, lipid hydrolysis, and oxidation compared to controls.
- Water and water–ethanol extracts had higher inhibitory effects on microbial activity.
- Higher total polyphenol levels were found in water-based algal extracts.

## Abstract

An attempt to apply extracts of the brown algae Cystoseira myrica and Cystoseira trinodis for the quality enhancement of fish was carried out. Aqueous, ethanolic, and aqueous–ethanolic (1:1, v/v) extracts of both algae were included, respectively, in the icing system employed for the chilled storage of farmed rainbow trout (Oncorhynchus mykiss). Chemical and microbiological quality indices were determined for a 0–16-day storage period. At the end of the experiment, all alga-treated fish revealed lower (p < 0.05) pH values and lower (p < 0.05) lipid hydrolysis (free fatty acid assessment) and oxidation (thiobarbituric acid index) development when compared to Control samples. Regarding microbial activity development (aerobe, psychrophilic, Enterobacteriaceae, proteolytic, and lipolytic counts), lower average values were detected in most cases in fish corresponding to alga-treated batches; preservative effects were found more important at advanced storage times. In general, water and water–ethanol extracts led to higher (p < 0.05) inhibitory effects than their counterpart ethanol extracts. Higher (p < 0.05) total polyphenol values were detected in water and water–ethanol extracts of both algae than in their counterpart extracts obtained only with ethanol. A novel, simple, and practical strategy for the quality enhancement and commercialization of chilled farmed rainbow trout is proposed by employing different extracts obtained from both Cystoseira species.