Harnessing antioxidant-rich byproducts from olive and wine industries to produce corn starch films as edible coatings for minimally processed foods

Abstract

The current importance and growing demand for minimally processed foods—driven by fast-paced lifestyles—stem from their healthier profile compared to ultra-processed foods, although their susceptibility to deterioration presents significant challenges to maintaining nutritional and sensory quality. Edible coatings offer a good strategy to extend shelf life of minimally processed foods. This study aimed to develop starch-based edible coatings enriched with antioxidant-rich byproducts: olive pomace (OP) and wine lees (WL). Fresh (OP_F), freeze-dried (OP_FD), and defatted (OP_D) olive pomace; along with fresh wine lees (WL_F) were used, with total phenolic contents ranging from 1 to 6 mg GAE g⁻¹. Coatings were prepared using gelatinized starch (5 % w/v) and glycerol (30 % w/w), incorporating OP (3–5 % w/w) and WL (5–10 % w/v). SEM analysis revealed the presence of OP agglomerates within the starch matrix, while films containing WL exhibited a more uniform structure. While the addition of byproducts reduced the films water vapor barrier, it significantly enhanced UV-barrier capacity, with a notable increase of approximately 9 % upon the addition of 10 % WL_F. Films with 5 % OP_FD and 10 % WL_F showed enhanced mechanical properties, achieving 18 % greater resistance and 38 % increased rigidity, though OP_FD reduced flexibility. The studied coatings effectively slowed deterioration and preserved the color and firmness of minimally processed apples. The studies carried out in this work demonstrated that starch-based coatings, functionalized with antioxidant-rich byproducts, can effectively extend the shelf life of minimally processed foods.