Development of starch-based bionanocomposites reinforced with nanofibrils of oat and wheat industry wastes and their post-harvest application in fruits and vegetables

Abstract

The increasing demand for food packaging, coupled with the constant effort in trying to reduce the impact on the environment, stimulates the study about the development of new materials, which are biodegradable and exhibit properties similar or even superior to those of traditional polymers. In this context, the fruit and vegetable post-harvest sector demands new preservation technologies that are effective in maintaining quality and that are "eco-friendly". This study aimed to develop and characterize cassava starch-based bionanocomposites reinforced with cellulose nanofibrils obtained from oat and wheat straws and test their application as edible coating in post-harvest fruits and vegetables, using as models whole strawberries and fresh cut carrots. It was found that the addition of nanofibrils promoted improvement in the mechanical and barrier properties of the bionanocomposite, by increasing stiffness and decreasing hydrophilicity. Maximum addition values (30 - 50%) of nanofibrils were responsible for the best performances in the tests. The elaborated bionanocomposites were tested as edible coating in the cold storage of whole strawberries and fresh cut carrots. For strawberries, the coatings were effective in delaying the events related to senescence, such as surface darkening, tissue softening, fungal growth and synthesis of anthocyanins, vanillin and resveratrol. For carrots, a lower incidence of surface whitening and a lower tendency to lignification was observed when coated with the bionanocomposites. The feasibility of obtaining cellulosic nanofibrils from oat and wheat straws was confirmed, as well as their effectiveness in improving the mechanical and barrier properties of cassava starch-based bionanocomposites. The elaborated bionanocomposites were effective as edible coating in the maintenance of postharvest quality of whole strawberries and fresh cut carrots. The elaborated bionanocomposites can be used in future studies, which explore different application methodologies and different food matrices, in order to optimize their properties and expand the application possibilities.