The development of sustainable food products encompasses not only food but also biodegradable packaging. Biodegradable packaging can be made from a wide range of renewable resources, including plant-based materials like cornstarch, sugarcane, bamboo, dried citrus peels, and apple pomace. The use of biodegradable packaging aligns with the increasing consumer demand for eco-friendly products and sustainable practices. Many businesses are adopting biodegradable packaging as part of their commitment to corporate social responsibility and environmental stewardship – and to satisfy their customer’s needs.
Extruders are one of the technologies that play a crucial part in transforming materials, like fruit pectin, into a biodegradable packaging film.
What is Biodegradable Packaging?
Biodegradable packaging refers to packaging materials that can naturally break down and decompose into the environment without causing harm or leaving behind any toxic residues. It is designed to minimize the negative impact on the environment compared to traditional packaging materials, such as plastic.
Biodegradable packaging is used for several reasons. First and foremost, it helps to reduce the accumulation of non-biodegradable waste in landfills and oceans, which can take hundreds of years to decompose. By using biodegradable materials, we can minimize the environmental impact and promote a more sustainable approach to packaging.
Additionally, biodegradable packaging offers the advantage of being compostable, meaning it can be broken down into nutrient-rich soil through composting processes. This can contribute to the circular economy by providing a valuable resource for agriculture and horticulture.
Biodegradable packaging can be made from various renewable sources, including plant starches, cellulose, and polylactic acid (PLA), which is derived from corn or sugarcane. These materials are chosen for their ability to degrade naturally through biological processes like composting or digestion by microorganisms.
The production process of biodegradable packaging involves converting these renewable raw materials into packaging materials through different methods, such as extrusion, molding, or film blowing. The specific manufacturing process may vary depending on the type of material used.
Food Extrusion Includes Packaging Materials
Food extrusion is an established and highly versatile technique for the production of food, feed, nutritional additives and flavors, and biodegradable packaging. It enables a continuous and cost-effective means of production, and its precise control ensures a high and constant product quality.
Twin-screw extruders are extruders with two co-rotating intermeshing, self-wiping screws and are well-established tools for the mixing, compounding, and processing of materials. (Read more about twin-screw applications in this application note: Relevant process parameters for twin-screw compounding.)
How Biodegradable Films are Produced using Twin Screw Extrusion
The extrusion process begins by feeding the biodegradable raw materials, such as starch-based polymers or PLA (polylactic acid), into the extruder. These materials are typically in the form of pellets or granules. The screws rotate within the barrel, conveying the material forward while subjecting it to shear, heat, and pressure.
As the material progresses through the extruder, it undergoes several stages. First, it enters the feeding zone, where the raw materials are compressed and gradually melted. Then, it moves into the melting zone, where the heat generated by the barrel and the mechanical energy from the screws further melt the material.
Next, the molten material enters the mixing zone, where additional additives, such as bio plasticizers, fillers, or colorants, can be introduced to enhance the film’s properties. The screws facilitate thorough mixing of the additives with the molten polymer.
After the mixing zone, the molten material enters the metering zone, where it is homogenized and conveyed towards the die. The die is responsible for shaping the molten polymer into the desired film thickness and width. Various die designs can be employed to achieve different film structures, such as flat films or films with specific patterns.
Finally, the extruded film is rapidly cooled using a cooling system, which can include air or water quenching. The cooled film is then pulled through a set of nip rollers, which control the film’s tension and speed, ensuring uniform thickness and smoothness. Optionally, the film can undergo additional processing steps, such as corona treatment or surface coating, to enhance its properties.
As an example of how twin screw extrusion is used in biodegradable packaging, this short video introduces a small-scale extruder process setup transforming fruit pectin into a biodegradable packaging film. You can see the pectin powder being fed into the machine with a gravimetric twin-screw feeder, which then shows a peristaltic pump feeding water/glycerol mix, which moves the mix into a sheet die to produce the packaging film.
Summary
Extrusion is a common aspect of food development and production while also serving a crucial supporting role in the creation of new functional foods. And in some cases, extrusion can play a part in producing packaging that is environmentally friendly.
Additional Resources
- Video: Extrusion of Bio-Degradable Pectin Films
- Application note: Relevant process parameters for twin-screw compounding
- Application note:: The influence of extrusion conditions on the processability of starch compounds
- Online resources for compounding and extrusion instruments and applications