## 3 Results and Discussion  
### Total Polyphenol Content  
Table 1 shows the total polyphenol content of the samples. The initial values ranged between 13.68-16.67 mg GAE/100 g, and the data are similar to [PERSON] et al. [39] and [PERSON] et al. [40] as measured in their study. During the storage time, the TPC values showed increasing and decreasing tendencies alternately. In the case of samples containing coating (E+), in the eighth month there was an increase of 5.3% and 4.1% for PE and PPM, while a decrease of 15.34% was observed for PP. In the case of PLA, after a temporary increase, the total polyphenol content returned to the initial value at the end of the storage period. However, without coating (E-), only the PE samples values increased, while the PP decreased by 8.5%, MPP by 12.0%, and PLA by 20.8%. A decreasing tendency was also detected in the case of the sample with nitrogen between 14.2 and 22.8%. This can be explained by transformation of polyphenols by glycosylation, which means replacing hydroxyl groups with O-glycos or linking with C to form C-glycosides [41]. Glycoslation is one of the major modification reactions occurring in various biological processes resulting in the formation of a wide range of natural products and can affect the stability of plant polyphenols [42; 43]. It can be seen that the change in total polyphenol content over time was significantly changed by the packaging materials (<0.001). The difference between the treatments is significant from the fourth month. In the fourth month, the difference was significant in all cases, and the direction of the change was also opposite in many cases: using MPP packaging material, in a nitrogen-enrichedatmosphere (N+), or coating with walnut pomace extract (E+), in the fourth month, all the polyphenol contents of the samples that could be determined spectrophotometrically decreased significantly; in the case of the other combinations, this value increased somewhat. In the sixth month, there was a significant difference only between the atmospheric and extract coated samples and in the eighth month there was only a significant difference between the nitrogen-enriched and extract-containing samples. As illustrated in Table 1, the total polyphenol content across different packaging types and treatments demonstrated considerable fluctuations over the eight-month storage period. The retention of polyphenol levels was generally higher in metallized polypropylene (MPP) packaging in comparison to other packaging materials. This suggests that MPP offers superior protection against polyphenol degradation. Polyethylene (PE) also demonstrated favorable performance, maintaining higher polyphenol levels than PLA, particularly in combination with nitrogen treatment (N-E-). The nitrogen treatment (N-E-) was observed to preserve polyphenols more effectively across all treatments, with the levels in MPP remaining stable. This suggests that nitrogen may play a role in slowing down the degradation process. In contrast, samples coated with extracts (A-E+) generally exhibited slightly lower polyphenol content. However, the coating appeared to provide some degree of protective effect in PP, with polyphenol levels only exhibiting a slight decrease from 16.81 mg/g at month two to 13.74 mg/g at month eight. Overall, the combination of nitrogen treatment (N-E-) with metallized polypropylene (MPP) emerged as the most effective approach for preserving total polyphenol content throughout the storage period. This combination not only maintains lower degradation rates but also ensures that higher quality is retained over time. Nitrogen treatment with PE also demonstrated favorable outcomes, particularly during the initial two months of storage.