Abstract
In recent years, new and innovative smart polymer applications have developed with the consumer’s demand for health, comfort and environmental compatibility.
According to the expectations of the packaging sector; the effect of polymer-based packaging material on the types of foods, their effectiveness, suitability, functionality have important roles. It is then required to carry biodegradable properties that are environmentally compatible.
If they are used in the food sector, they are in constant contact, easily degradable and may cause waste of food, thus providing the basis for the application of special packaging techniques.
Targeted packaging products are expected to have features such as delaying oxidation, preventing microbial attack, applying time, temperature sensors, and indicators of maturity. In this study, new technologies, active and smart packaging that can be applied in the production of smart packaging have been investigated.
The applications of renewable packaging which is an important and new technology in food packaging sector are discussed.
Introduction
Worldwide plastics production in 2004-2014 was 225–311 tons, of which 59 million tons belong to Europe. Polyethylene (PE) has the highest share in production (29.3%) followed by polypropylene (PP) (19.2%). Today, plastics consume 5% of oil production.
This ratio is expected to increase to 20% in 35 years. To meet the growing demand for plastics,plastics production is expected to double by 2034 and quadruple by 2050 (Briassoulis and Giannoulis, 2018). With the growing demand for plastics, 5% of plastics are recycled effectively.
The problems from plastics have led to a significant reduction in the flow of plastic packaging waste, especially with the application of global economic principles. Research has shown that the recycling of 25.8 mt of plastic waste in Europe is 29.7% and energy recovery is 39.5%. Most of these plastics are not biodegradable.
Some of the plastic composite materials are difficult to recycle and reuse because of the various impurity levels such as colorants, printing inks and adhesives they contain. Since plastic packaging constitutes the majority of total plastic, waste has been replaced by biodegradable - compostable bio-based plastics in favor of increasing environmental concerns.
It is supported by the fact that technological advances for innovative bio-based plastics are progressing rapidly. Biodegradable (under compost conditions) bio-based packaging products range from fillers to hard plastics and foamed products.
Examples of biobased compost polymers commonly used in food packaging applications are polylactic acid (PLA), PLA mixtures, starch mixtures and polyhydroxyalkanoates (PHA).
Furthermore, the development and use of non-biodegradable products, and the continued use of bio-polyethylene terephthalate (bio-PET) for bio-based plastics, bags and bottles such as biopolyethylene (bio-PE) in exchanges are increasing.
Developments in Food Packaging Techniques
Many materials have been developed for products with improved shelf life and comfort as a result of consumer preferences for light processed foods (Dobrucka and Cierpiszewski, 2014). Changing lifestyle, practical, new and innovative packaging techniques, food safety and quality features without compromising production and use is encouraged (Dainelli et al., 2008).
Factors such as excessive use of packaging in the food segment, the use of microwaves, smaller size packaging of food, and the increasing need for ready-to-eat foods have led to the rapid growth of new packaging techniques (Restuccia et al., 2010). The production of heat-controlled polymer are schematically depicted in Figure 1.
Figure 1. Different approaches in the production of thermo-responsive micelles
Another important reason for innovative food packaging is the increasing microbiological problems caused by food. In addition to preserving food quality, it has begun to require the use of packaging with antimicrobial effect (Appendini and Hotchtkiss, 2002).
Innovations in packaging, metal cans, aseptic packaging, flexible packaging, indicator colorants in aluminum foils are some examples. Moreover, further advances in packaging technology in the 20th century began to be used in the application of oxygen cleaners, antimicrobial agents, respiratory controllers and aroma/odor absorbers in intelligent packaging and active packaging (Brody et al., 2008). Changes in the packaging industry will strengthen the economy, improve food safety and quality, and minimize product losses (Vanderroost et al., 2014).
Active packaging has emerged to meet consumer demand for natural, recyclable and biodegradable packaging materials (Lopez-Rubio et al., 2004). Active packaging extends the storage life and increases the food safety margin by changing the state of the food (De Kruijf et al., 2002).
The principle underlying the production process and its use depends on the inclusion of certain components in the material. Here, the polymer and its specific properties are used as packaging means (Gontard, 2000). A new development in the use of active packaging is the addition of certain additives that give antimicrobial properties to the polymers (Suppakul et al., 2003).
These polymeric matrices are designed to contain compounds that have the potential for releasing active agents (antioxidants and antimicrobials), or which retain unwanted food components (ethylene, oxygen and water) (Flores et al. 2007). Potential cleaners, such as cyclodextrins used, act irreversibly as a final application and are inorganic metals or salts (Lopez-de- Dicastillo et al., 2011).
Packaging additives are limited due to toxicity in the transition to food products. (Gomez-Estaca et al., 2014). Active use of edible films and coating technology may contribute to reducing oxidative damage by reducing the rate of oxygen delivery to food. Antioxidants and coating material can be added to the edible film. In addition, 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 the package is in active form.
Packaging should be made to reduce or inhibit microbial activity in packaged food or in the food package. The use of antimicrobial agents could be as in packaging materials, or the preparation thereof by direct addition to stepped diffusion through food installations or by steaming.
Oxygen cleaners used in the package, eliminating oxygen, inhibiting oxidative reactions, can be added directly to the package casing in the form of labels or bags.
Of the oxygen cleaners, iron oxide is commonly appearing because it reacts with oxygen to clean the longest distance (Kerry et al. 2006). Figure 2 shows an example of oxygen-controlled smart packaging application.
Figure 2. An example of an oxygen controlled smart packaging application
Carbon dioxide cleaners are placed in 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 various ways: Forms such as absorbent pads and moisture-mediated bicarbonate are included in the packages (Brody et al., 2008). In addition, in the case of foods containing high moisture content of calcium oxide and silica gel dry foods as desiccants,
internal moisture regulators are preferred. Moisture absorbing agents may be designed as porous structures or as porous water vapor barrier plastic media containing desiccant. Moisture regulators in the package, moisture removal,
optional bonds Moisture regulators are designed to prevent moisture loss in the system can contain extra moisture content (Brody et al., 2001).
Conclusion
These unique materials offer amazing, innovative and functional features that fit precisely into environment. Molecular devices have been developed which are selectively designed for the protection of biological function and which enable the release of active components through a certain chemical reaction.
The expectation of intelligent polymers is that the reaction takes place only when required by the system. In the active packaging system, the choice of agent type is important.
The selected agent must be compatible with the packaging material and be able to form a homogeneous distribution into the food or package. The wide range of applications in the polymer world makes it easier for us to reach products with the desired properties.
Assoc. Prof. Dr. Feza Geyikçi - Ondokuz Mayıs University / Engineering Faculty - Chemical Engineering Department
