High protein sunflower-based edible coating to preserve roasted sunflower seeds

The application of edible coatings allows the shelf life of food products to be extended, since they provide physical resistance, reduce the moisture exchange of the product, and also reduce oxygen permeability, avoiding chemical changes such as nutrient oxidation. The objective of this study was to develop an edible coating made from sunflower protein flour and apply it to roasted sunflower seeds as a preservation procedure for this food product. Roasted sunflower seeds were prepared with and without sunflower coating and stored for 60 days at room temperature. Samples were extracted every 15 days to determine the peroxide values (PV), conjugated dienes (CD) and volatile compounds. The uncoated seeds showed the highest PV (83.7 mEqO₂/kg at Day 15 and 149.2 mEqO₂/kg at Day 60), while the coated seeds presented lower values (39.2 and 69.3 mEqO₂/kg at 15 and 60 days, respectively). Regarding the DC values, this parameter also showed the same behavior as PV. Thirteen volatile compounds were identified in analyzed samples (by GC–MS), where hexanal, 2-octenal and nonanal showed significant variations. The uncoated sunflower seeds showed a greater release of volatile compounds. According to the correlation analysis, hexanal presented the highest correlation value between CD and PV in coated (0.76 and 0.79, respectively) and uncoated seeds (0.70 and 0.91, respectively). The obtained results suggest that, although the oxidative reactions occur in roasted sunflower seeds, the application of the coating delays this deterioration process, slows down the oxidation of lipids and contributes to prolonging the useful life of this product.