Smart packaging film prepared from subcritical water-modified oat starch and betalain of beetroot extract reinforced with cellulose nanofibrils

In this study, the smart food packaging films from subcritical water-modified native oat starch (NOS) were developed using betalain from beetroot as a pH biosensor was studied. NOS was mod-ified by SCW at varying temperatures; henceforth modified oats starch (MOS) was designated as MOS@115, MOS@130, MOS@145, MOS@160, MOS@175, and MOS@190. FTIR, XRD, and gel permeation chromatography (GPC) results confirmed the crystallinity loss and molecular weight reduction of NOS. Improved cold water solubility and decreased viscosity were observed with in-creased temperature, which favored excellent film-forming features with improved elasticity. However, the modified starch's water-holding capacity and swelling rate increased until a certain temperature and afterward decreased. Improved physical and mechanical properties of the film were obtained after reinforcing with cellulose nanofibrils (CNF, 5 wt% of starch). Finally, MOS with betalain was efficiently demonstrated to monitor chicken spoilage. Thus, SCW treatment was investigated to be an efficient way to modify starch in an eco-friendly way for food packaging development.