Corn starch based biocomposite films reinforced with cellulosic nanocrystals extracted from corn husks (Zea mays L.): Characterization and application in cherry tomato packaging

Abstract

In this study, corn starch-based biocomposite films reinforced with cellulosic nanocrystals isolated from corn husks (CCNC) were developed and characterized with the intention of effectively utilizing lignocellulosic by-products. CCNCs were extracted by depolymerization process of corn fibers in an alkaline treatment followed by bleaching, acid hydrolysis and mechanical dispersion. Biocomposite films were formulated with corn starch (CS), sodium alginate (SA), glycerol (G) and different concentrations of CCNCs (0–8 % w/w) using the casting method. The results of the characterization of CCNCs showed a smooth and porous surface with an average length between 100 and 250 nm, a thermal stability higher than 400 °C due to its crystallinity (70.08 %). Meanwhile, the addition of 4 %-8 % CCNCs to the corn starch polymer matrix significantly improved the mechanical properties, with higher tensile stress, a 30 % reduction in WVP and a significant decrease in transmittance accompanied by a crack-free surface. Cherry tomatoes in biocomposite films reinforced with 6 % and 8 % CCNC proved effective in reducing weight loss and had relatively stable content of total soluble solids and pH value during storage up to 10 days at 26 °C. Therefore, it is proposed that CCNCs extracted from corn husks, integrated into starch films, have great potential in the packaging industry, representing a viable option to replace plastic packaging in the food sector.