Thermomechanical Plasticization of Fruits and Vegetables Processing Byproducts for the Preparation of Bioplastics

Abstract

Byproducts of the processing of foods are usually non‐edible residues that are typically discarded, even though they contain large amounts of natural polymers with great potential in bioplastics and biocomposites preparation. Herein, a new method of production of vegetable‐waste‐derived biocomposites is developed. It consists of the thermomechanical processing of different residues in the presence of small amounts of water, representing an advancement in the state‐of‐the‐art in the complete conversion of fruit and vegetable biomass into biocomposites. In particular, carrot pomace (CP) is processed by compression molding at different temperatures, pressures, and times. Selected processing conditions are also applied to other food processing byproducts. The morphological, mechanical, barrier, optical, and antioxidant properties of the obtained biocomposites and their interaction with water in terms of moisture content, water solubility, and moisture absorption are reported here. Results indicate that biocomposites obtained by this method present similar properties compared to biocomposites prepared by acid or alkaline hydrolysis of biomass reported in the literature, but still inferior compared to bioplastics currently in the market. Improvements in the materials' interaction with water are highlighted here as the necessary next step to achieving the transition toward greener bioplastics.

Properties of Biocomposites Made of Extruded Apple Pomace and Potato Starch: Mechanical and Physicochemical Properties

“…Another reason is the hydrophilic nature of lignocellulosic components, which are also found in EAP [ 67 ]. For comparison, biocomposites made from pomace such as residues from the processing of carrots, oranges, or spinach, at maximum air saturation with water vapor RH 100%, absorbed up to 40–60% of moisture from the air [ 68 ]. Referring to the results obtained and the research of other authors, it can be concluded that materials made from extruded (EAP) apple pomace and (SP) starch should not be subjected to hourlong exposure to high-air-humidity conditions, RH 75, 90%.…”