Starch is a good source of biodegradable material for food packaging, originating from wheat, corn, rice, and potatoes
[18]. It is widely viewed as a sustainable substitute to plastics for food packaging. Moreover, various foods, such as fruits, vegetables, snacks, and dry products, can be packaged using starch as a biodegradable film
[19]. The three ways starch can be used in producing biodegradable films are as follows: firstly, small amounts of starch can be used in the preparation of starch compositions with other plastics. The essence of this is to improve the biodegradability of traditional, oil-based starch materials. Secondly, the preparation of starch composites with the starch content comprising more than half of the mass. Thirdly, the use of extrusion, processing with mixtures of granular starch in biodegradable preparation processes
[20]. The increase in the use of starch-based biodegradable films for food packaging is an outcome of its numerous advantages. These include their contribution to reducing fossil content, their lack of toxins, their origin being plant sources (renewable resources), their biodegradability and biocompatibility, the low cost and abundance of starch, their safety for consumption when used in food packaging, their reduced energy consumption, their role as an eco-friendly disposal solution, and the absence of a net increase in CO
2 in the global ecosystem. Despite these advantages and benefits, disadvantages include poor mechanical properties, low water stability, high moisture sensitivity, presence of a poor moisture barrier because of strong hydrophilic behaviour, their brittle behaviour at room temperature, and their high moisture content
[1]. To overcome these disadvantages of using starch as a biodegradable material, a thermoplastic starch matrix could be filled with nanofillers, thus improving these properties. In a study by Nafchi et al.
[21], the addition of nanoscale particles enhanced the mechanical and barrier properties of starch. Montmorillonite (MMT) nano-clay has been recommended as promising nanoscale filler for biodegradable packaging. Hence, the use of MMT in food packaging can be attributed to its reduced cost, high stability, and high level of effectiveness.
[22]. More information on MMT nanoclay is detailed here. Studies have shown that the properties of starch-based films are responsible for its rigidity and reduced flexibility. Hence, other polymers could be used as additive compounds
[1]. Different sources of biopolymers, such as polysaccharides, proteins, and lipids, can act as biodegradable films
[23].
Starch is mainly sourced from plants but can also originate from roots, tubers, cereals, and legumes. Considering its inherent biodegradability, abundance, and annual renewability, starch is a promising natural polymer. Interestingly, previous studies have revealed that starch contains two kinds of microstructures: linear and branched. Hence, it is regarded as a heterogeneous material. The linear structure is known as the amylose (crystallizable form of starch made up of long unbranched polysaccharide chains), while the branched structure is called the amylopectin (non-crystallizable form of starch with branched polysaccharide chain).