Mithibai College (Autonomous)
Development of Bioplastics
The use of plastic and plastic-based products has greatly stepped up in the recent past with easy availability, good performance, and unique properties. However, plastic waste is a great concern for countries all over the world as it is non-biodegradable due to the high intermolecular bonds. Due to the increasing legislative pressure, the evolution of “environmentally friendly” plastic has attracted remarkable interest.
What are Bioplastics?
Bioplastics are a type of biodegradable plastic derived from biological substances. They are earth-friendly and can be produced from various sources like bacteria, algae, pea proteins, milk proteins, wheat gluten, and egg-white albumin, etc. The requirements for biodegradable and recycled materials have increased for applications in the case of non-traditional, protein bioplastics for their antimicrobial activities and their use in packaging.
Different proteins employed in the production of bioplastics
Whey protein is used to produce antimicrobial bioplastic as it contains glycomacropeptides and a compound like an antifungal, for example, that is an anti-infective. Microbial contamination is a great concern in food packaging and medical applications. Therefore, the incorporation of biocides or polymers to produce active antimicrobial packaging materials provides an alternative for protecting food from microorganism contamination.
Wheat gluten and egg-white albumin are used for the development of new bioactive protein-based bioplastics. Milk protein-based bioplastics when used to substitute the traditional polyethylene give hard (protein) and soft polymers with different tensile strengths when different concentrations of whey proteins are used. The strength and elasticity of bioplastics depend on the moisture content of the proteins, the plasticizer added, and the molding temperatures. Pea protein-based bioplastics are studied for sustainable development and their antimicrobial effects. Biocides are shown to inhibit microorganism’s growth even if the bioplastic is not in direct contact with the substrate. Due to their antibacterial nature, bioplastics have great potential to be used in surgeries, transplants, dressings, and other medicinal purposes. However, when used alone they possess poor mechanical properties and fragility, and therefore, a substance called plasticizer is added to it. Plasticizers are low molecular weight organic compounds that promote plasticity, flexibility, and durability of polymers. Water, glycerol, natural rubber latex, etc., are some of the plasticizers that can be used to improve the flexibility of the bioplastics. Bioplastic composition consists of 5 to 95% of plasticizer by weight. Polymers of protein-based bioplastics can be made by copolymerization of monomer units into thin film or sheets by free radical polymerization. In this process, the protein is copolymerized with plasticizers – plastic-like materials. The amount of protein by volume, processing technique, quality of raw materials used, and stoichiometry play an important role in the formation of biomaterials.
The dismal science of Bioplastics and Antimicrobial incorporation
While looking at the economics, the purity of the protein and its concentration in the final product make a difference. Commercially available whey protein concentrates are produced by ultrafiltration and diafiltration to remove other components and impurities, giving high-quality WPC ≥ 75% of whey protein. Whey protein isolated (WPI) is available with ≥ 90% purity. The bioplastics prepared are tested for their mechanical and thermal quality where the tensile strength, as well as its thermal stability, is assessed. An anti-infective compound such as an amebicide (e.g. chloroquine), aminoglycosides (e.g. neomycin), anthelmintics (e.g. pyrantel), antifungals (e.g. clotrimazole), antimalarial agents (e.g. pyrimethamine/ sulfadoxine), antivirals (e.g. tenofovir), and cephalosporins, tetracyclines, and other related drugs are used to eliminate the growth of microbes on the surface and reduce contamination.
Many gram-negative and gram-positive bacteria such as bacillus subtilis and Escherichia coli are tested for the anti-bacterial nature of bioplastics and bioplastics have proved to be effective in reducing the growth of such organisms. Preservatives like sodium benzoate and sodium nitrite are added to the bioplastics at times. Although a lot of work must be done in standardizing the final product and about the disposal management, this kind of plastics are a great alternative to cure the current plastic waste-related problems. For sustainability purposes, standardization in production technology, and proper recycling systems with the correct disposal of byproducts generated must be ensured in the future.
Author Biography: Bhoomi is a master’s student pursuing Biotechnology from a prestigious institute in Mumbai, India. She aims to utilize my knowledge, skills and abilities in the industry and gain exposure to upcoming technologies while being resourceful and innovative.