3.2. The Quality of Raw Wild and Farmed Pikeperch Fillets
The chemical composition of raw fillets obtained from wild and farmed pikeperch is shown in
Table 3.
The fillets from wild pikeperch had a higher moisture (78.9%) and ash (1.2%) contents and pH (6.7), but a lower fat (0.4%) and protein (19.3%) content than farmed pikeperch (76.7%, 1.1%, 6.5, 1.1%, and 20.8% for moisture, ash, pH, fat, and protein, respectively). These differences in the chemical composition resulted from differences in the feed of wild and farmed fish, including the fat content which was 0.6% and 14% in wild and farmed pikeperch fodder, respectively. Similar to results of the present study, a higher fat content in farmed vs. wild pikeperch was noted by Jankowska et al. [
23]. This might be attributed to a higher fat content in farmed pikeperch feed, but also to different life conditions—food availability, mobility, and energy demand. Generally, the wild and farmed fish used in the present study had a lower fat content than that noted by other authors. Bouriga et al. [
7] reported that the fat content in wild pikeperch was 1.9%, whereas protein was 17.7% and ash was 1.1%. A higher protein content, similar to that noted in the present study, was found by Çağlak and Karsli [
24] in wild pikeperch (from 17.8% to 19.4% regarding of the season, for spring and autumn, respectively). These differences in the chemical composition between the results of the present study and those obtained by other authors in terms of wild fish might be caused by multiple factors such as the living environment, food availability, and a fishing season [
24]. The results of the present are slightly different from those obtained by Ćirković et al. [
25] for farmed pikeperch. They reported the following chemical composition: protein 19.3%, fat 0.4%, moisture 79.3%, and ash 1.0%, which are lower in terms of fat and protein contents than the results of our study and might be produced by differences in fodder offered to fish (natural food produced with benthic and planktonic organisms in Ćirković et al. [
25] and high-energy formulated feed in the present study). The harvest time did not affect the results because fish in both studies were caught in autumn (October and November in Ćirković et al. [
25] and the present study, respectively). The results of the proximate composition of farmed pikeperch were similar to those reported by Ljubojević et al. [
26] for farmed pikeperch available in the Serbian market; however, the fat content (1.8%) was lower than in the present study.
In terms of colour, wild and farmed fish differ only in redness (a*), which was higher in wild pikeperch (
Table 3). Higher a* values in the fillets of wild fish compared to farmed were also noted by González et al. [
27] in yellow perch (
Perca flavescens) and might be attributed to multiple factors such as lower fat content, blood vasculature, higher deposition of melanin due to dietary effects, or enzymatic reactions from tyrosine. Despite differences in pH values, there were no differences in expressible water contents (
Table 3). Similar findings were noted in a previous study conducted using wild and farmed northern pike (
Esox lucius) [
14]. The expressible water is a measure of the ability of muscle tissue to hold moisture and is regarded as an important technological feature. Lower ability to hold moisture is manifested in an excessive drip loss in the package, which in turn decreases the attractiveness of packed fresh fish and their fillets and negatively affects fish tissue texture [
28]. Both the ability of muscle tissue to hold moisture and colour are affected by pH value [
28,
29]. The results obtained in the present study thus indicate that although there were significant differences in the pH value of farmed and wild fillets, they were too small to affect the expressible water content and the same water holding capacity, as well as the chroma and hue of wild and farmed pikeperch fillets.
Table 4 contains values obtained for each fatty acid detected in fat extracted from the muscle tissue.
Significant differences in fatty acid composition and concentration in the muscle tissue of wild and farmed pikeperch were noted. Generally, the proportions of SFA, MUFA, and PUFA in the wild pikeperch were similar and accounted for 32 to 35% of total fatty acids. The most prevailing fatty acids were C16:0 (palmitic acid) and C18:1cis9 (oleic acid), which accounted for 22% and 17% of total fatty acids, respectively. In farmed fish, a higher proportion of MUFA was noted in comparison to SFA and PUFA (52% of total fatty acids vs. 20% and 28%, respectively). The most abundant fatty acids were similar to those noted in wild pikeperch, but in different proportions—C16:0 accounted for only 15% and C18:1cis9 for as much as 36% of total fatty acids (
Table 4). The abundance of palmitic acid (C16:0) and oleic acid (C18:1n-9) in pikeperch fat was also found by Bouriga et al. [
7]. Fatty acid proportions noted in the present study slightly differ from the results obtained by Çağlak and Karsli [
24], who noted that PUFA’s proportion accounted for 43.3% of total fatty acids, whereas MUFA’s accounted for 19.6% in wild pikeperch, and the study by Jankowska et al. [
23], who reported the following fatty acid composition in wild pikeperch: 27.8% SFA, 21.4% MUFA, and 50.8% PUFA. Differences between wild and farmed pikeperch in fatty acid composition were noted in terms of MUFA and PUFA by Jankowska et al. [
23]. In their study, wild pikeperch had a significantly lower MUFA and higher PUFA than farmed fish receiving an artificial feed. However, no differences were found in n-3 and n-6 fatty acids [
23]. The differences between the results obtained in the present study and reported by Jankowska et al. [
23] result from different fatty acid compositions of the feed used in those studies and indicate the role of the feed in shaping the fatty acid composition of fish muscle tissue. This is supported by the results of Ćirković et al. [
25] who reported a fatty acid composition (SFA%, MUFA%, and PUFA%) in farmed pikeperch fed natural fodder similar to those obtained in the present study in wild pikeperch. Interestingly, in the present study, in farmed fish fat additional fatty acids such as C22:1 n-11 and C22:1 n-9 were detected, which were not present in the fat extracted from wild pikeperch fillets. This was a result of the presence of those fatty acids in the feed of farmed pikeperch.
Jankowska et al. [
23] showed that the content of DHA in the farmed pikeperch lipids was twice as high as that in the artificial feed and four times that in the natural food offered. In the present study, the proportion of DHA increased in muscle tissue of wild and farmed pikeperch, but the increase was not so high (about 30% in wild and 9% in farmed pikeperch in respect to the feed). The increase in DHA in muscle tissue might be explained by the desaturation of native forms of polyunsaturated acids taken up by the fish from the feed. The process involves the introduction of double bonds into a molecule by desaturases Δ6, Δ5, Δ4, and chain elongation, mediated by elongases. Jankowska et al. [
23] concluded that shorter chain n-3 acids (C18) in the feed are elongated and desaturated in the pikeperch body, and as a result, longer-chain polyunsaturated acids, mainly DHA, are formed.
Differences in fatty acid proportions and a higher content of fat in farmed pikeperch produced differences in the concentration of particular fatty acids in fresh fillets (
Table 4). Although the proportion of PUFA (valuable from a nutritional perspective), including n-3 fatty acids, was higher in wild fish, the farmed fish was a better source of those acids due to their higher concentration (mg/100 g). Nevertheless, farmed fish contained a higher amount of SFA and MUFA than wild ones. The n-6/n-3 ratio was lower in wild pikeperch, although in both studied fish it was low and beneficial from a nutritional perspective. Çağlak and Karsli [
24], who studied the quality of pikeperch caught in Beyşehir Lake (Turkiye) in four different seasons, found that the amount of PUFA (89.85–109.11 mg/100 g) was higher than SFA (55.08–81.89 mg/100 g) and MUFA (29.16–78.89 mg/100 g). The results for farmed pikeperch obtained in the present study are similar to those reported by Çağlak and Karsli [
24]; however, in farmed fish, a higher concentration of MUFA than PUFA and SFA was found.
3.3. The Quality of Cooked Wild and Farmed Pikeperch Fillets
There were slight differences in the quality of cooked fillets between wild and farmed pikeperch. In terms of the chemical composition, the fish differed in fat content, which was higher in farmed pikeperch, and protein content, which was higher in wild fish fillets (
Table 5). The moisture content in sous-vide pikeperch noted in this study was similar to that reported by Gladyshev et al. [
30] for pikeperch cooked using different cooking methods (boiling and stewing in water and in a convection steam oven), which ranged from 75.6% to 79.4%. Although farmed fillets showed a lower average cooking loss than wild pikeperch fillets (20% vs. 22%), the difference was not significant (
Table 5).
Fillets differed also in colour—those obtained from farmed pikeperch were lighter and had a higher redness (a* values). A higher lightness of sous-vide farmed pikeperch fillets corresponded with a significantly higher fat content in those samples, which is a known factor affecting muscle tissue [
31]. However, the sous-vide fillets did not differ in chroma or hue and thus would be similarly perceived by consumers. In terms of the sensory quality, the fillets did not differ and were scored similarly (
Table 5). This finding indicates that from a sensory point of view, both fish types are similarly suitable for preparing dishes.
As was noted in the raw fillets, the sous-vide cooked fillets obtained from wild and farmed pikeperch differed in fatty acid composition (% of total fatty acids) and concentration (mg/100 g). Although wild pikeperch fillets had a higher proportion of the sum of PUFA and n-3 fatty acids, sous-vide cooked fillets obtained from farmed fish were a better source of those fatty acids in the human diet due to higher concentrations of these components (
Table 6). Generally, a fatty acid concentration (a sum of SFA, MUFA, and PUFA) noted in sous-vide wild pikeperch (3.6 mg/g of wet tissue) was similar to that reported by Gladyshev et al. [
30] for boiled (3.7 mg/g) and stewed (3.4 mg/g) wild pikeperch. The n-6/n-3 ratio noted in their study in boiled and stewed pikeperch were also similar to that noted in the present study (0.4), which is a low value and beneficial from a nutritional point of view [
32]. In farmed sous-vide pikeperch fillets, the ratio was higher but still low (1.0,
Table 6); therefore, sous-vide pikeperch obtained from both a lake and a farm is a valuable food product. This is supported by similar EPA and DHA concentrations in sous-vide fillets of wild and farmed pikeperch (
Table 6). The consumption of fish rich in these fatty acids might result in a decrease in the n-6/n-3 ratio of a diet and prevent many chronic diseases connected with inflammatory processes, such as cardiovascular diseases, inflammatory bowel disease, cancer, and rheumatoid arthritis, as well as psychiatric and neurodegenerative illnesses [
32].