Advances in Packaging Technologies and Smart Polymers

 

Summary

In recent years, new and innovative smart polymer applications have developed alongside consumer demand for health, comfort, and environmental compatibility. The packaging industry's primary expectations include the effect of polymer-based packaging material on food, effectiveness, suitability, and functional properties. Following this, environmental compatibility and biodegradable characteristics are required. When used in the food sector, continuous contact, ease of degradation, and the potential to cause food waste create a basis for the application of special packaging techniques. Target packaging products are expected to possess characteristics such as delaying oxidation, preventing microbial attack, applying time and temperature sensors, and maturity indicators. This study examined new technologies applicable in the production of smart packaging and the subject of active and intelligent packaging. Applications of renewable packaging, an important and new technology in the food packaging sector, were discussed.

Introduction

Global plastic production during the 2004-2014 period amounted to 225–311 million tonnes, of which 59 million tonnes belonged to Europe. In production, polyethylene (PE) holds the highest share (29.3%) followed by polypropylene (PP) (19.2%). Today, plastics consume 5% of oil production. It is estimated that this ratio could increase to 20% within 35 years. To meet the increasing demand for plastics, plastic production is expected to double by 2034 and quadruple by 2050 (Briassoulis and Giannoulis, 2018). With increasing demand for plastics, only 5% of plastics are recycled effectively. Problems stemming from plastics, through the application of global economy principles, have resulted in significant reductions, particularly in the flow of plastic packaging waste. Research conducted shows that in Europe, of 25.8 million tonnes of plastic waste, recycling rates reached 29.7% and energy recovery 39.5%. Most of these plastics are not biodegradable. Some plastic composite materials are difficult to recycle and reuse due to various levels of contaminants they contain, such as colorants, printing inks, and adhesives. As plastic packaging constitutes the majority of total plastics, waste has been increasingly replaced by biodegradable-compostable bio-based plastics, reflecting growing environmental concerns. This is supported by the fact that technological developments for innovative bio-based plastics are advancing rapidly. Biodegradable (under compost conditions) bio-based packaging products show variety, from fillers to rigid plastics to foam products. Examples of bio-based compost polymers frequently used in food packaging applications include polylactic acid (PLA), PLA blends, starch blends, and polyhydroxyalkanoates (PHA). Furthermore, the development and use of non-biodegradable products and the continuous increase in the use of bio-based plastics such as bio-polyethylene (bio-PE) in shopping applications, bio-polyethylene terephthalate (bio-PET) for bags and bottles are steadily increasing.

Advances in Food Packaging Techniques

As a result of consumer preferences for lightly processed foods, many materials have been developed for products with extended shelf life and improved comfort (Dobrucka and Cierpiszewski, 2014). Changing lifestyles, practical, new and innovative packaging techniques promote production and use without compromising food safety and quality characteristics (Dainelli et al., 2008). Excessive packaging use in the food segment, microwave use, packaging of meals in smaller sizes, and increasing demand for ready-made foods have provided an environment for rapid growth of new packaging techniques (Restuccia et al., 2010). Figure 1 presents the reaction formation in heat-controlled polymer production. Figure 1. Different approaches in the formation of heat-responsive micelles Another important reason for innovative food packaging is the increasing microbiological problems from food sources. In addition to preserving food quality, it has begun to necessitate the use of packaging with antimicrobial effects (Appendini and Hotchtkiss, 2002). Innovations in packaging can be enumerated as metal cans, aseptic packaging, flexible packaging, and indicator colorants in aluminium foils. Moreover, in the 20th century, further advances in packaging technology led to the application of smart packaging and active packaging using oxygen scavengers, antimicrobial agents, respiration controllers, and aroma/odor absorbers (Brody et al., 2008). Changes emerging in the packaging industry will strengthen the economy, increase food safety and quality, and minimize product losses (Vanderroost et al., 2014). Active packaging emerged to meet consumer demand for natural, recyclable, and biodegradable packaging materials (Lopez-Rubio et al., 2004). Active packaging extends storage life and increases the food safety margin by changing the condition of the food (De Kruijf et al., 2002). The principle underlying production and use is based on the inclusion of specific components within the material. Here, the polymer and its inherent properties are used as a packaging agent (Gontard, 2000). A new development in active packaging use is the addition of certain additives that impart antimicrobial properties to polymers (Suppakul et al., 2003). These polymeric matrices are designed to have the potential to release active agents (antioxidants and antimicrobials) or contain compounds that retain unwanted food components (ethylene, oxygen, and water) (Flores et al. 2007). Potential scavengers such as cyclodextrins used act as a final application irreversibly and are inorganic metals or salts (Lopez-de-Dicastillo et al., 2011). Packaging additives are limited due to toxicity in their transfer to food products. (Gomez-Estaca et al., 2014). Active use of edible films and coating technology can contribute to reducing oxidative damage by decreasing the oxygen transmission rate to foodstuffs. Antioxidants can be added to edible films and coating materials. Furthermore, these natural additives are good sources of various bioactive phenolic compounds (Bakkali et al., 2008) and are used as an excellent form. The effect of antimicrobial agents in packaging is in active form. Packaging material is used that aims to reduce or inhibit microbial activity in packaged food or within food packages. The use of antimicrobial agents in packaging materials can be done by gradual diffusion directly through the food surface, direct addition, or steaming. Oxygen scavengers used in packaging inhibit oxidative reactions by eliminating oxygen and can be added directly to the package case, as labels, or in pouch form. Among oxygen scavengers, iron oxide is commonly used because it reacts with oxygen to reduce concentration to the greatest extent (Kerry et al. 2006). Figure 2 shows an example of oxygen-controlled smart packaging application. Figure 2. Example of oxygen-controlled smart packaging application Carbon dioxide scavengers are placed within packaging materials. Carbon dioxide reduces the respiration rate of fresh foods and thus prevents vacuum difference and collapse (Vermeiren et al., 1999). Carbon dioxide can be added in many different ways: Absorbent pads and forms such as moisture-mediated bicarbonate are used in packages (Brody et al., 2008). In active packaging, moisture control agents such as natural clay can be used. Calcium oxide and silica gel are also preferred as desiccants for dry foods, while internal moisture regulators are preferred for foods with high moisture content. Moisture absorbing agents can be designed as porous structures or porous water vapor barrier plastic cartridges containing desiccants. In package moisture regulators, moisture removal, maintaining desired relative humidity and reduction contain voids for this purpose. The system designed to prevent moisture loss in moisture regulators should contain extra moisture content (Brody et al., 2001).

Conclusion

These unique materials present remarkable, innovative, and functional properties that fully adapt to existing environments. Molecular mechanisms designed selectively to preserve biological function have been developed that provide the release of active components as a result of specific chemical reactions. The expectation from smart polymers is that the reaction occurs only when the system requires it. In the active packaging system, the selection of agent type is important. The selected agent should be compatible with the packaging material and able to create uniform distribution in the food or package. The wide range of application areas in the polymer world makes it easier for us to reach products with desired properties.