Bioplastics or biodegradable polymers are the materials which are derived from the renewable sources (Azmin et al., 2020). As defined by ASTM, “the material containing organic carbon of renewable origin such as agricultural, plant, animal, fungal, microorganisms, marine or forestry materials living in a natural environment in harmony with the environment” is referred to as bio-based. Bioplastics offer significant potential to slash fossil energy consumption by 95%, diminish a product’s carbon footprint by 40% and curb greenhouse gas emissions by 200% (DiGregorio, 2009). The depletion of fossil fuel reservoirs and the detrimental environmental effects arising from the poor degradability of conventional plastics have spurred the search for alternative base materials for plastic production.
Read: March Issue of Food Infotech Magazine.
While Bioplastics are generally regarded as environmentally friendly they do come with limitations, notably high production costs. However, this challenge can be addressed by leveraging locally available renewable resources, such as agricultural wastes or by-products (Jain and Tiwari, 2015). Various types of bioplastics exist, with cellulose, starch, fibre and protein, Bioplastics being the most prevalent. Starch-based bioplastic stands out due to its widespread availability, minimal carbon footprint and renewable nature within the industry. However, starch alone lacks thermoplastic properties; therefore, it requires the addition of a filler to modify and improve the mechanical characteristics of the bioplastic (Augustin et al., 2014). Cellulose, starch, fibre and protein can all be derived from agricultural waste generated during the processing of essential food products.
Plastics can be biodegradable or non-biodegradable and they can be produced using resources derived from either bio- or fossil fuels. Biodegradable plastics are created from fossil fuels or a combination of fossil fuel and renewable components, whereas bioplastics are entirely made from renewable resources. (Álvarez-Chávez et al., 2012)
The classification of bioplastic is depicted in fig. 1. Among these, biodegradable plastics sourced from polysaccharides, particularly starch, emerge prominently. Starch, abundantly found in cereals, legumes and tubers serves as a readily available and renewable feedstock for the production of bio-based plastics. Examples of these include corn, rice, wheat, cassava and potatoes (Sagnelli, et al., 2016; Tamara, et al., 2020). In nature, starch is a biopolymer that is found in large quantities. Specifically, cassava has about 80% of the dry starch mass.
The biopolymer is made up of two different forms of glucose: branching amylopectin and linear and helical amylose, which are connected by glycosidic bonds. The physicochemical characteristics and functions of plastic are regulated by the equivalent ratio of amylose to amylopectin; an increment in amylose molecules will enhance the polymer’s tensile qualities.
According to Marichelvam et al. (2019), pure form of starch is a white-coloured, environment friendly, non-toxic, absorbable biological macromolecule that is semi-permeable to carbon dioxide and cannot be softened in cold water or alcohol. The starch monomers will be retrograded, the film made from pure extracted starch would be fragile and it will absorb moisture (Ghanbarzadeh, et al., 2011). Compatible additives known as plasticizers, such as glycerol, ethylene glycol, xylitol, sorbitol and citric acid are added to the mixture to enhance these qualities. Plasticizers are used to increase the plasticity and flexibility. Thermoplastic starch has the potential to replace the polystyrene (PS). Additionally, oil coatings were applied to the starch films to enhance their mechanical and permeability qualities, which are beneficial for wrapping uses. According to Tsang et al. (2019), the primary source of bio-based plastic is now crop-based food stock, which is valued for its carbohydrates and biopolymers.
The accumulation of non-biodegradable waste is significantly harming the environment, prompting research into innovative biodegradable materials derived from biomass, plants and microorganisms. Future advancements in bioplastics could enhance manufacturing efficiency and open up new possibilities for their utilization. Additionally, given their sustainability, the bioplastics market is anticipated to expand in the coming years.
References:
1. Tsang, Y.F, Kumar, V., Samadar, P., Yang, Y., Lee, J., Yong, S.O., Song, H., Kim, K.H., Kwon, E.E. and Jeon, Y.J. (2019). Production of bioplastic through food waste valorization. Environment International, 127, 625-644.
2. Ghanbarzadeh, B.; Almasi, H. and EntezamI, A.A. (2011) Improving the barrier and mechanical properties of corn starch-based edible films: Effect of citric acid and carboxymethyl cellulose. Industrial Crops and Products, 33 (1), 229-235.
3. Marichelvam, M.K.; Jawaid, M. and Asim, M. (2019) Corn and Rice starch-based bioplastics as alternative packaging materials. Fibers, 7(4), 32.
4. Azmin, S. N. H. M., & Nor, M. S. M. (2020). Development and characterization of food packaging bioplastic film from cocoa pod husk cellulose incorporated with sugarcane bagasse fibre. Journal of Bioresources and Bioproducts, 5(4), 248-255.
5. DiGregorio, B. E. (2009). Biobased performance bioplastic: Mirel. Chemistry & biology, 16(1), 1-2.
6. Jain, R., & Tiwari, A. (2015). Biosynthesis of planet friendly bioplastics using renewable carbon source. Journal of Environmental Health Science and Engineering, 13, 1-5.
7. Agustin, M. B., Ahmmad, B., Alonzo, S. M. M., & Patriana, F. M. (2014). Bioplastic based on starch and cellulose nanocrystals from rice straw. Journal of Reinforced Plastics and Composites, 33(24), 2205-2213.
8. Álvarez-Chávez, C. R., Edwards, S., Moure-Eraso, R., & Geiser, K. (2012). Sustainability of bio-based plastics: general comparative analysis and recommendations for improvement. Journal of cleaner production, 23(1), 47-56.
About the Authors:
