CSIC researchers use by-products from the food industry to develop a compostable container with antibacterial properties to reduce the use of non-renewable materials.

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Two drawbacks associated with traditional packaging are plastic production and food waste. Reducing both is the goal of the circular bioeconomy set by the European Union (EU). With this idea in mind, 2018 saw the birth of the European Ypack project which, using cheese whey and almond shells, began to develop three compostable products: a tray and two food contact films. After three years of research and seven million euros in investment, a team led by the Institute of Agrochemistry and Food Technology (IATA) succeeded in creating an active and biodegradable packaging, capable of disintegrating within a maximum of 90 days and extending the shelf life of some fresh produce by up to 48 days.

The results were presented in October 2020. “This is the first time that the full industrial implementation of the packaging has been shown, with positive studies of biodegradation, allergenicity and shelf life,” says José María Lagarón, researcher at IATA-CSIC and coordinator of the project.

The new packaging protects the food and also participates in its preservation.

This was a great step forward in research and, at the same time, a great leap forward in one of the main objectives set by the European Commission (EC): to reduce dependence on non-renewable packaging. The main reason for this is that more than 80 % of the waste found in the sea is plastic. Within this figure, a key role is played by food-related products such as plastic bags, which take 20 years to decompose, or bottles, which in some cases never disintegrate at all. The result is that each person could ingest on average between 0.1 and 5 grams of microplastics every week through food and drink.

This trend not only departs from the EU’s Circular Economy Action Plan, whose July 2021 Directive already banned the sale of single-use plastic articles (SUPs), but also affects health. “Given the possible chronic exposure to microplastics, the results suggest that their continued ingestion could alter the intestinal balance and, therefore, the state of health,” stresses Victoria Moreno, a researcher at the Food Science Research Institute (CIAL, CSIC-UAM).

Cheese whey and almond shells
Faced with this situation, applied research has been working for some time on the development of biodegradable alternatives. “The ideal packaging has a lower carbon and water footprint, is biodegradable, ecologically designed, safe and has adequate preservation properties to minimise food waste,” explains Lagarón. The project began with this premise.

Polyhydroxyalkanoates (PHAs), i.e. polyesters produced in nature by microorganisms, were chosen to produce the packaging. The new containers would thus be compostable. This means that the biological degradation of the packaging takes place within a controlled time, which in this case is a maximum of 90 days after disposal. This is possible because the researchers decided to incorporate the sustainable material poly (3-hydroxybutyrate-co-3-hydroxyvalerate), a polymer known as PHBV that is produced from cheese whey and cheapened with almond shells, into the formula.

Using nut waste, a toxic by-product of cheese production and nanocellulose, the composition of the new material was beginning to be defined. However, the idea of the project was not just to create a passive packaging that would protect the food from the outside environment, but to create an active container that would participate in its preservation. Two ingredients are responsible for achieving this goal: zinc oxide and oregano essential oil. Their incorporation into the PHBV polymer showed short (15 days) and medium-term (up to 48 days) antimicrobial effects against two bacteria that can cause food poisoning: Staphylococcus aureus (Staphylococcus aureus) and Escherichia coli. The former contributes to infections ranging from skin abscesses to toxic shock syndrome, and the latter causes abdominal cramps, diarrhoea and vomiting.

The shelf life of foods such as cucumbers, meat and fresh pasta could be extended. In addition, “the formula for combating harmful microorganisms can be used for products where the package is opened and closed several times, for example, in the case of slices of bread or slices of ham,” he adds.

In May 2020, three biodegradable products for food packaging were presented: a tray and two high oxygen barrier food contact films, one of them with active antioxidant and antimicrobial properties. However, from the start of the project, the researchers posed two questions that would become part of the work as phases: how would the end consumer respond, and is it possible to produce the packaging on an industrial scale?

Natural feel
The first question was answered by a market study involving 7,000 consumers in seven countries (Denmark, France, Hungary, the Netherlands, Portugal, Spain and Turkey). The new packaging was well liked, users were very positive about the new packaging technologies and none of them rejected the use of by-products from nuts or cheese. Its earthy colour and micro-granulated feel is reminiscent of the first recycled papers: renewable, biodegradable and functional. As the researcher points out, “the packaging conveys an idea of natural origin that appeals to the consumer”.

The new packaging degrades in less than 90 days.

The second question is answered by Lagarón, who points out that “after managing 5 tonnes of biopolymers, we managed to scale up the industrial production of two of the products. Despite complying with the spirit of the EU Directive, the production of the active film was not scaled up due to legislative barriers”. The project would end up leaving a pending task: to combine market needs, EU regulations and the development of innovative packaging materials.

Currently, “there is no harmonised EU-wide composting structure for packaging made from biopolymers”. Despite this, two of the three products developed are ready to reach the market, “now the industrial interest in commercialising the technology is missing”.

Microplastics altering microbiota
Forty-nine per cent of marine litter is single-use plastics. Although they have a life span of 12 to 15 minutes, they can take 400 to 1,000 years to disintegrate. It is in this process that the 51 billion microplastics (particles smaller than 5 mm) in the oceans are generated. As a result, humans can ingest an average of up to 5 grams per week, which has an impact on intestinal health. One example is the microplastic PET (polyethylene terephthalate), which decreases the number of beneficial bacteria and increases the number of microbial groups associated with pathogenic activity.

“Microplastics are not a homogeneous group, but present different sizes, additives and/or contaminants. Although this makes it difficult to know their biotransformations in the gastrointestinal tract, it is necessary to know the fate of these materials in the organism and their consequences,” says Victoria Moreno, the CIAL researcher leading the study. This work, carried out as part of the European PlasticsFatE project, has managed to simulate how we digest microplastics by means of a kind of artificial stomach. “Using the in vitro model of gastrointestinal digestion, we were able to host the human colonic microbiota during the intervention with microplastics,” adds Moreno. As a result, another finding: it is the first time we have observed that these particles can undergo biotransformation and reach the colon with a different structure to the original one.