Development of new active nanocomposite packaging films containing polyhedral oligomeric silsesquioxane for walnut (Juglans regia L.) kernel packaging

Active nanocomposite films made from low-density polyethylene (LDPE) and polyhedral oligomeric silsesquioxane (POSS) were prepared as of food packaging material for walnut kernels (Juglans regia L.) oil protection against lipid oxidation. N-Phenylaminopropyl-POSS (NP-POSS), octaammonium-POSS (QA-POSS) and methacryl-POSS (M-POSS) were utilized as convenient additives. Intact and crushed walnut kernels were stored in conditions set to accelerate oxidation (24 h of light, 38°C, and 33% RH). On the 14th day, peroxide value (PV) was determined as 14.13 meq O₂/kg in intact walnut kernel oil (WKO), whereas the PV of walnuts was measured as 5.94 meq O₂/kg and 7.95 meq O₂/kg wrapped with 5 wt% NP-POSS and 3 wt% QA-POSS containing the film, respectively. At the end of the storage, K₂₃₂ values were measured as 4.42 and 6.12 packaged with control films, whereas K₂₃₂ values ranged 2.72 and 3.14 in samples packaged with 5 wt% NP-POSS. Similarly, K₂₃₂ value of WKO wrapped with QA-POSS containing films was detected as 2.89 and 3.20 in intact and crushed walnut samples, respectively. The p-anisidine value of WKO wrapped with pure LDPE reached 4.86 and 7.33 for WKO obtained from the intact and crushed walnut kernel, and the lowest p-anisidine values observed intact (2.07) and crushed (3.84) samples of packaged with 5 wt% NP-POSS, respectively. The results have shown that novel nanocomposite food packaging films, including NP-POSS and QA-POSS, for vacuum-packed walnut kernels are sufficient to protect against oxidation.