**5. Food packaging**

Food packaging controls the storage environment and creates conditions extending food storage and shelf life. Some commonly used packaging materials are a) flexible paper, thin laminates, or plastic film; b) semi-rigid material such as aluminum foil, laminates, paperboard, and thermoformed plastic; and c) rigid material such as metal, glass, or thick plastic [24]. The most commonly used packaging material is plastic, which is cheap, lightweight, and easy to form in different shapes and sizes. In addition, plastic films with selective permeability properties to gases, carbon dioxide, and oxygen can be selected for storage [24, 25]. These films have led to the development of modified atmospheric packaging systems. By selecting the right barrier properties of the packaging materials, the shelf life of food products can be extended. For example, intermediate moisture foods need to be protected from moisture during storage. Therefore, low moisture permeability packaging materials, such as polyvinyl chloride, polyvinylidene chloride, and polypropylene, can be used [26]. In the case of foods with high fatty acids, low gas permeability films can be used to reduce oxidation reactions. In the case of fresh fruits and vegetables, as they respire, packaging material such as polyethylene, which has high gas permeability, can be used. Currently, smart package systems offer properties that meet the special needs of certain foods [27]. For example, packages made with oxygen-absorbing materials remove oxygen from the inside, thus protecting oxygen-sensitive products from oxidation [28]. However, temperature-sensitive films exhibit an abrupt change in gas permeability when they are subjected to a temperature above or below a set constant. These films change from crystalline to amorphous at a given temperature, causing the gas permeability to change substantially. There are significant health and environmental concerns regarding using petroleum-based packaging materials such as plastics, polyethylene, and styrofoam, as they can release toxins into the foods when heated and can be dangerous to consumers, also they do not decompose for a long time, creating environmental issues. Packaging films made from biodegradable are gaining much importance in overcoming environmental issues. The packaging materials are made from polyhydroxyalkanoates (PHAs), biodegradable, and synthesized by various microorganisms, replacing petroleum-based plastics. These materials are environmentally friendly and, simultaneously, can be completely degraded by various microorganisms in a short time (less than a year).
