*2.2. The Sustainable Industrial Consumption of Biocomposite Materials*

Ngram Viewer allows conducting the content analyses by tracing the frequency of the selected concepts and keywords (plastic waste, biocomposite, microplastic) during the specified time period (since the year 2000). Ngram Viewer digitalized how often these selected terms or concepts appear in digitalized texts of the literature accumulated within Google, in particular, Google Books [90].

Accordingly, the analytical information of Ngram Viewer demonstrates that the topicality of the term "biocomposite" has been dynamic since the late 1970s until the turn of the century, then showing a rapid increase, especially from 2013. For comparison, studies on "plastic waste" have been investigated since the middle of the last century. It should be highlighted that, simultaneously with the rapid rise of the use of the term "microplastic", the curve of "biocomposite" also increases in parallel.

The use of all three researched concepts has grown rapidly over the last ten years (see Figure 4). This justifies the wider applicability of these terms in the theoretical or scientific literature and other sources used by practitioners. In the figure, the horizontal axis indicates the specific time period, while the vertical axis shows the rate of the occurrence of that particular concept or keyword from all search strings (so called n-grams) in a particular year [90].

**Figure 4.** The frequency of using keywords "biocomposite", "plastic waste", and "microplastic", which was created by the authors with Ngram Viewer.

The analytical results of the Ngram Viewer screening verify and confirm the relevance and significance of selected concepts and keywords for the further in-depth literature review. Given that "what makes the Ngram Viewer a valuable research tool is not primarily its accuracy, but rather its potential for quick-and-dirty heuristic analysis" ([90], p. 9), this illustrates the dynamic changes and trends on the interest of particular terms, keywords, and concepts.

The creation of a model of sustainable industrial consumption that would help reduce the environmental problems associated with conventional plastics, including microplastic pollution in habitats, still seems a utopian idea in the near future, given that conventional plastics (polypropylene—PP, polyethylene terephthalate—PET, high-density polyethylene— HDPE, etc.) play a key role in the economy [91].

While the world is struggling with the recycling of conventional plastics, another way to respond to this problem would be to develop and use bio-based or biodegradable plastics as a sustainable alternative to petroleum-based plastics [92]. These materials mainly help to preserve fossil reserves by replacing fossil carbon. They also provide additional benefits: biocompatibility, biodegradation, and carbon dioxide (CO2) sequestration, which are important for reducing global warming [93].

It is important to emphasize that the terms "bio-based plastic" and "biodegradable plastic", which are often used in the scientific literature, are fundamentally different. Biodegradable polymers are materials that are capable of degrading when subjected to aerobic, anaerobic, or microbial processes. Biodegradability can be defined as the ability of compounds to degrade completely under the influence of various factors, including the

size, thickness, and composition of the material. However, it should be stressed that biobased plastics are produced from renewable sources and can be either biodegradable (e.g., polymerized starch or polylactide) or non-biodegradable (e.g., bio-polyethylene), which is a significant part of the environmental impact assessment. It should also be mentioned that bio-polyethylene is only recyclable for a few cycles until it significantly loses its original properties [94,95].

Many initiatives have been introduced to promote the concept of sustainable packaging. The Sustainable Packaging Coalition (SPC) in 2011 formulated the industry-accepted definition of seven conditions specifying the following seven criteria for sustainable packaging [96]:


The SPC definition is widely recognized and includes the functional, environmental, and technological dimensions of sustainable packaging. Therefore, sustainable packaging may protect the product and communicate its properties, including reusing materials and reducing waste throughout the packaging life cycle from production to consumption, as well as during the disposal and post-disposal phases [97,98].

Sustainable packaging has to be designed with innovative bio-based plastic packaging materials and meet the following parameters:


Monoplastic materials are preferred because the recycling of such packaging material preserves functional properties and chemical safety. The sum of the climate and environmental impacts of packaging/food systems should be assessed throughout their life cycle and reduced to the chosen design [99,100].

Designing a more sustainable food packaging is a difficult task, as many different parameters need to be considered. Life Cycle Assessment (LCA) tools are available and should be used to quantify and compare the environmental impact of different types of packaging, considering the overall product framework. LCA should be able to make informed and holistic decisions about how to improve the sustainability of food packaging [50,100].

Some of the factors hindering the introduction of more sustainable packaging solutions on the market are consumer awareness of unknown technologies, costs, regulatory issues, and the belief that sustainable packaging fails to protect food (e.g., moisture barriers) [100].

With the introduction of the concept of sustainable development, there is also a rapidly growing interest in the use of biodegradable polymers in the production of new composite materials [101,102]. One of the fastest-growing industries is polylactic acid, which differs from the commonly available form of thermoplastic polymers. It is mainly derived from renewable resources such as maize starch or sugar cane [103].

Recently, during the COVID-19 pandemic, consumers showed an increased desire for their personal safety and health [104,105]. This affects the safety standards and requirements for packaging materials, and in addition to the flexibility or rigidity, the durability or physical integrity of materials; thus, there is a growing interest in the use of sustainable and natural materials [8,106,107]. It means that at the same time, while considering the possibilities to adopt sustainability characteristics, the packaging materials must provide adequate

isolation properties against water vapor, gases, odors, and other protection against various external factors. Polylactic acid (PLA) is one of the most recognized biodegradable materials [108], which is not only used in the food industry but also in the biomedical and pharmaceutical industries [109,110]. As reported by Cohn et al. [111], PLA is recognized as safe for use in the food contact. Nevertheless, the final properties of PLAs may vary and depend on their chemical–physical, barrier, thermal, and mechanical properties. These properties can be adapted to the intended use by altering the structure of the PLA (amorphous and crystalline ratio, different meso-lactide ratio, and molecular weight) [108].

Previous research [8,107,108] proved that biodegradable polymers are promising and potentially in-demand materials not in the near future but already in the reality of today's packaging and delivery systems. However, there is still a scope to explore ways for improving the applicability of these materials, both in terms of their characteristics of the technical feasibility and in terms of their desirability and cost-effectiveness to use them by various industries. The main advantage of biocomposite materials is found not only in their natural origin but also in providing a closed circle "from nature to nature" as these materls decompose into the naturally occurring components.
