With the aim to reinforce laboratory competence in the field of testing the quality of fish from aquaculture, a study on the precision of fatty acid (FA) analyses in fish meat and fish feed was undertaken. Different methods were performed in laboratories. In situ transesterification method and extraction of lipids from the fish were followed by capillary gas chromatography with flame ionization detection. The reproducibility (R) values of the majority of FAs were less than 3% of their absolute values. Differences in calculating ionization detector response factors and/or autoxidation caused by faulty sample-handling could lead to variation in quantification of FAs in fish, especially for FA C22:6n-3. Statistical analysis showed a significant correlation between the two laboratories' quantifications of FAs in fish and fish feed (Pearson's correlation coefficient; r = 0.987, r = 0.994, and r = 0.997; for fish Z [trout], fish Š [rainbow trout], and fish feed, respectively). Overall, adequate accuracy was obtained in this study. The proposed method provides a fast and efficient means of identifying fish and feed for quality control purposes.
The objective of this paper is to investigate variability in chemical composition, total fatty acid and cholesterol content in m. longissimus dorsi (MLD) of Mangalitsa, swallow-belly (LM) and white (BM), and Swedish Landrace pigs (SL). Compared to SL, the total fat content has been 14.2% higher in BM, while it has been 10.2% higher in LM. SL fatteners contained significantly less cholesterol in MLD compared to LM and BM (−13.6 and −14.8%, P≤0.05). A higher percentage of SFA (+8.5 and +10.1%, P≤0.05) and PUFA (+8.0 and +9.4%, P≤0.05) has been established in MLD, originating from SL fatteners, compared to both Mangalitsa strains. The total MUFA content was higher in LM and BM than in SL (P≤0.05). A phenotypic correlation between protein content and ashes with water content in MLD has been positive (0.81 and 0.88), while the correlation between water content and total fats has been found to be negative (−0.99). A negative phenotypic correlation between MUFA and SFA, as well as PUFA and MUFA (−0.97 and −0.98) has been established, statistically significant at the level of P≤0.001. A positive phenotypic correlation between PUFA and SFA (0.90), statistically significant at the level of P≤0.001, has been found.