## 4 Discussion
### Lipid Oxidation Development  
According to the present results for peroxide, TBARS, fluorescent compounds, and polyene values, an inhibitory effect (\(p<0.05\)) on lipid oxidation development was detected when the flour extract was incorporated into the packaging films. This effect was more prominent (\(p<0.05\)) as the flour extract content in the active packaging medium increased. Closely related to the current research, an antioxidant effect of aqueous extracts of _Gelidium_ flour was reported in a study considering a heated fish muscle system [39]. In this study, the inclusion of flour extracts resulted in the reduced formation of fluorescent compounds in both the aqueous and organic fractions obtained from the lipid extraction of fish muscle. Lipid oxidation mechanisms can be viewed as multistep processes in which various compounds are produced sequentially. Compounds formed in the initial stages (e.g., peroxide compounds) are more unstable and breakdown into lower-molecular-weight compounds (e.g., carbonyl compounds). In the advanced stages of lipid oxidation, both types of electrophilic compounds (peroxides and carbonyls) can react with other molecules (e.g., nucleophilic groups such as -NH2 or -SH) present in the fish muscle, leading to the formation of interaction compounds (tertiary lipid oxidation compounds), which can be identified on the basis of their fluorescent properties [52; 66]. Seeds are generally known to be rich sources of antioxidant compounds [25; 67]. The inhibitory effect on lipid oxidation observed in this study can be attributed to the presence of antioxidant compounds in the flour extract. No further investigations were conducted in the present study to analyze the specific compounds responsible for this preservative effect. However, given that a water extract of red algae flour was used, the observed antioxidant activity is likely due to the presence of hydrophilic constituents in the flour extracts. These bioactive compounds inhibit the formation of primary oxidation compounds (e.g., peroxides) and reduce the formation of secondary oxidation compounds (e.g., carbonyls). Consequently, a lower content of primary and secondary oxidation compounds results in fewer interactions with nucleophilic compounds present in the muscle. Previous works documented the antioxidant effects of aqueous extracts of red algae in both in vitro and real seafood studies, which aligns with the present findings. Thus, previous in vitro studies have shown the antioxidant behavior of water extracts obtained from _Hypnea flagelliformis_[68], _Gracilaria verrucosa_[69], and _G. gracilis_[70]. In such studies, these effects were linked to the presence of phenolic compounds (alkaloids, flavonoids, etc. ), carbohydrates, etc. Among such preservative molecules, carbohydrates have attracted special attention. Thus, polysaccharide compounds obtained from _Gracilaria corticata_[27] and _Porphyra vezogensis_[71] were found to be responsible for their remarkable antioxidant activities during the development of in vitro studies. Various studies have analyzed the carbohydrate composition of different red algal species. For example, cold aqueous extracts obtained from the red alga _Petercolatia capillacea_ were found to be rich in glucuronic acid, arabinose, and glucose, whereas hot water extracts contained high levels of glucuronic acid and fructose [61]. [PERSON] et al. [28] identified rhamnose, glucuronic acid, glucose, galactose, xylose, and L-fucose as the main components in _Gelidium pristoides_. Similarly, [PERSON] et al. [72] reported glucose, galactose, fucose, arabinose, and xylose as the primary monosaccharides in sulfated polysaccharides from _G. pristoides_. Previous research has also highlighted the antioxidant effects of incorporating algae extracts into packaging films. For example, including lyophilized _F. spiralis_ in a polylactic acid biodegradable film prevented lipid oxidation (peroxide and fluorescent compound formation) in refrigerated megrim (_L. wiffiagonis_) [63].