## 3 Results and Discussion
### Characterization of Fried Mackerel Fillets
#### 3.3.3 Nutritional Characterization of Fried Mackerel Filllets  
During frying, several factors influence the nutritional composition of the food matrix, namely its own composition (such as water content, macro- and micronutrients levels), the time/temperature combination, oil composition, namely the proportions of saturated fatty acids (SFA), monounsaturated fatty acids (MUFA) and PUFA, oil-to-food ratio, among others [42]. The application of coatings to fillets prior to frying aims to create a barrier against oil absorption and water loss. Therefore, it is expected that coated fillets will have a lower lipid content while retaining more moisture in the tissues. The microstructure of alginate and carrageenan coatings, which is the internal network created by the polymer chains, has a key role in the barrier effect to oil and moisture. Furthermore, the addition of extracts can change the polymer interactions, modifying the microstructure and the coating functionality [43]. To evaluate the effect of the coatings, several nutritional parameters of the fried fish fillets were analyzed. Figure 5 presents the results for moisture, ash content, and total lipids. Carrageenan with _P. canaliculata_-coated fillets (Car Pc) showed the highest moisture content (61.04 \(\pm\) 0.26%), which was significantly higher than that of Car (60.11 \(\pm\) 0.17%) and control (59.29 \(\pm\) 0.19%) samples. Conversely, alginate-coated fillets (Alg) stand out for the lowest moisture content (57.87 \(\pm\) 0.19%). Comparing the two base coating solutions for moisture values, it may be concluded that carrageenan more efficiently preserves water within fish tissues. Additionally, the presence of algae extracts increased water content in the food matrix, as confirmed by statistical analysis, thereby enhancing the succulence of the fish fillets (Figure 5A). [PERSON] et al. (2021) [44] found that higher values of moisture in fried  
Figure 4: Textural attributes of fried mackerel fillets. Distance at failure (**A**), cutting strength (**B**) and work of shear (**C**). Uncoated fried fillets (Control); fillets coated with alginate solution (Alg); fillets coated with alginate solution supplemented with _P. canaliculata_ (Alg Pc); fillets coated with carrageenan solution (Car); fillets coated with carrageenan solution supplemented with _P. canaliculata_ (Car Pc). Figure 5: Composition of fried mackerel fillets concerning moisture (**A**); ash (**B**) and total lipid content (**C**). Uncoated fried fillets (Control); fillets coated with alginate solution (Alg); fillets coated with alginate solution supplemented with _P. canaliculata_ (Alg Pc); fillets coated with carrageenan solution (Car); fillets coated with carrageenan solution supplemented with _P. canaliculata_ (Car Pc). For each parameter, the same letter means significant differences (_p_ < 0.05) between samples. Spanish Mackerel (about 65%) resulted in improved textural attributes, characterized by lower hardness and chewiness. This conclusion sustains the results obtained for the effect of _P. canaliculata_ in coated fried fillets concerning textural attributes and moisture content. Regarding ash content, which is related to inorganic matter, no statistically significant differences were observed for all the samples analysed (Figure 5B). This parameter ranged from 1.54 \(\pm\) 0.09% FW (Car Pc) to 1.68 \(\pm\) 0.12% FW (Alg Pc). Carrageenan coating solutions slightly decreased the fat content of fish fillets compared to the control sample. Moreover, the addition of algae extract improved the efficiency of both alginate and carrageenan coating solutions as oil barriers. The lowest fat content was observed in Car Pc (11.57 \(\pm\) 0.19% FW) and Alg Pc (11.88 \(\pm\) 0.19% FW). Conversely, alginate-coated fillets showed the highest fat content (14.79 \(\pm\) 0.41% FW), with a statistically significant difference compared to the control (12.5 \(\pm\) 1.3% FW).