## 3 Results and Discussion
### Fatty Acids Composition  
Monousaturated and polyunsaturated essential fatty acids are of significant nutritional importance due to their numerous beneficial physiological effects, including their role in regulating blood lipids. Walnuts are a rich source of polyunsaturated fatty acids, exceeding 70% of their total fatty acid composition [51]. The composition of fatty acids is shown in Figures 4 and 5. Amounts of 99.14-99.33% of all fatty acids are saturated palmitic acid (C16:0), stearic acid (C18:0), monousaturated oleic acid (C18:1n9c), linoleic acid (C18:2n6c), and polyunsaturated \(\alpha\)-linolenic acid (C18:3n3c). Linoleic acid was measured in the largest amount (57.04-60.18%) in the samples at the beginning of the experiment, and the values are similar to previous studies [52; 53] between 57.32-59.09% during the eighth month of storage. This was followed by oleic acid with a  
Figure 3: Tocopherol content of the PE and PLA packaging samples during storage (\(\upmu\)g/g). PE (polyethylene), PLA (polylactic acid), A–E- (air without edible coating), A–E+ (air, with edible coating), N–E- (nitrogen without edible coating). value between 20.13-27.97%, then \(\alpha\)-linolenic acid with 8.9-11.38%. The smallest amounts of palmitic acid (5.49-6.3%) and stearic acid (2.04-3.04%) were detectable in the walnut samples. The proportion of polyunsaturated fatty acids is between 67.72-70.45%, while that of saturated is only 8.07-8.78%. [PERSON] and [PERSON] [54] investigated the fatty acid composition of different types of nuts from east Anatolia. Their results show a close similarity with the fatty acid composition of our examined Milotai 10 walnut. In the case of the four tested varieties, 49.33-54.41% linoleic acid was detected, followed by oleic acid with 22.63-27.25%, while palmitic acid was detected in the smallest amount (5.61-5.82%). [PERSON] et al. [55] also showed an average of 8.8% saturated and 72.84% polyunsaturated fatty acids in the case of six walnut varieties. [PERSON] et al. [56] also published similar results, with 9.5% saturated acid and 63.3% polyunsaturated fatty acids content. During storage, only minimal changes occurred in the fatty acid composition of the nut samples. This is based on the different chemical reactions, which lead to the degradation of the C-C double bonds forming secondary oxidation products. This phenomenon can cause a reduction in nutritional value of the walnut [51]. The treatments had no significant effect on any fatty acid (\(p>0.001\)). For more detailed statistical analysis see Tables S4-S9. Fatty acid analysis revealed stable levels across all packaging materials and treatments, with minor fluctuations in palmitic (C16:0), stearic (C18:0), oleic (C18:1n-9c), linoleic (C18:2n-6c), and linolenic (C18:3n-3c) acids. Nitrogen treatment (N-E-) demonstrated slightly better preservation of fatty acid composition, particularly in PE and MPP packaging. Atmospheric treatment and PLA packaging showed minor increases in peroxide value, indicating mild oxidation, but overall, the fatty acid content remained stable across all treatments. In conclusion, the findings suggest that fatty acids are largely preserved in walnuts across all packaging types, with nitrogen-treated MPP and PE demonstrating the most effective maintenance of fatty acid stability. The atmospheric treatment resulted in slight oxidation, as evidenced by a minor increase in peroxide value, but this effect was not considerable over the storage period. A similar result was also reported by [PERSON] et al. [51]. Walnut oil samples were stored at 60 \({}^{\circ}\)C for 60 days and only a minimal change was observed in the amount of fatty  
Figure 4: Fatty acid content of the MPP and PP packaging samples during storage (%). MPP (metallized polypropylene), PP (polypropylene), A–E- (air without edible coating), A–E+ (air, with edible coating), N–E- (nitrogen without edible coating). acids during storage, mainly in the case of linoleic acid.