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Introduction to Active Food Packaging System

Sweety Kalita1, Amar K. Mohanty2,3, Manjusri Misra2,3, Avik Mukherjee1, and Santosh Kumar1

1 Department of Food Engineering and Technology, Central Institute of Technology Kokrajhar, Kokrajhar, Assam, India

2 School of Engineering, Thornbrough Building, University of Guelph, Guelph, Ontario, Canada

3 Department of Plant Agriculture, Bioproducts Discovery and Development Center, Crop Science Building, University of Guelph, Guelph, Ontario, Canada

1.1 Introduction

The realm of food packaging is rapidly growing within scientific research and industry driven by rising global demands, and the continuous, stringent updates and amendments of food safety regulations. Food packaging is crucial in safeguarding food quality and shelf life. Shifts in consumer lifestyles have heightened interest in fresh, high‐quality, and clean products with a prolonged shelf life, which has consequently prompted the necessity for advanced packaging technology [1–3]. Furthermore, with the passage of time, the scope of food packaging has progressed from basic containment to intricate systems that actively engage with the packaged food, giving rise to active food packaging systems. Active packaging has become essential across diverse sectors of the food industry [4]. Active packaging systems were first developed in the 1980s, and are now integrated with active compounds to retain or enhance quality aspects and safety of the packaged food [5]. Depending on the active components added into the active packaging, they are designed to reduce respiration, inhibit microbial growth, and/or mitigate moisture migration by releasing active agent(s), absorbing moisture or gases, blocking certain deteriorations, or buffering pH alterations [6, 7]. Broadly, active packaging falls into two main categories: nonmigratory, which involves scavengers that remove/absorb undesirable substances from headspace of the packaging without any release of an active agent into the packaged food (called an active scavenging/absorbing system), and migratory packaging, which includes emitters that facilitate sustained release of the active compounds inside the package (called an active emitting/releasing system) (Figure 1.1) [4, 8, 9]. Active agents are incorporated into packaging systems as separate entities (for example, a pad or sachet), combined with polymers (e.g., composite film or coating), or applied to the film or packaging surface (e.g., by coating a layer of active agent on the packaging material). Furthermore, the active agent either firmly fixes or immobilizes onto the film surface. The flexible active films can be mono‐, bi‐, or multilayered (Figure 1.2). Continuous technological progress is driving the evolution of novel active packaging systems, leading to elevated levels of food safety and quality, along with decreased waste and enhanced sustainability [11].

Figure 1.1 Active scavenging/absorbing and active emitting/releasing systems.

Figure 1.2 (a) Mono‐layered film with an active agent. (b) Bi‐layered film, in which the inner layer contains an active agent. (c) Bi‐layered film having immobilized active substance on the film surface. (d) Active scavenging. (e) Active emitting systems.

Source: Reference [10], 2022/MDPI/CC‐BY‐4.0.

Food packaging made of biodegradable polymers is a sustainable alternative to the synthetic plastic‐based packaging, and the former is gaining increased popularity due to consumer awareness about the detrimental effects of petroleum‐based plastic packaging on human and environmental health [12]. Moreover, many natural compounds (e.g., certain secondary metabolites of some plants and microorganisms) act as antimicrobial and/or antioxidant active agents that can be blended into biopolymer‐based active food packaging systems [12, 13]. Polysaccharides, such as chitosan, cellulose, and starch, proteins such as gelatin, whey, and casein, and lipids such as beeswax, carnauba wax, and shellac wax are being studied extensively for the development of active packaging [14–16]. In this chapter, an in‐depth exploration of active packaging systems is presented, covering gas and moisture scavengers, ethylene absorbers, antioxidant‐releasing systems, CO2 emitters, and antimicrobial packaging. This chapter also reviews scientific research highlighting the benefits and challenges regarding the application of these novel systems for the packaging of perishable foods.

1.2 Types of Active Food Packaging

1.2.1 Active Scavenging/Absorbing System

Active scavenging/absorbing food packaging systems effectively scavenge/remove undesirable components/gases that are either present in the package or emanate from the food item into the packaging headspace. Ethylene scavengers for fresh fruits and vegetables, oxygen scavengers (OSs) for cut fruits and vegetables, fish, meat, edible oil, and moisture absorbers for milk powder, processed tea leaves, biscuits, crackers, and chips are effective for shelf‐life extension of packaged products [17]. The various active scavenging systems are explained in the subsequent discussions.

1.2.1.1 Ethylene Scavenger

Ethylene (C2H4), a plant hormone, intricately regulates diverse physiological functions within plants, such as growth, ripening, and senescence with both positive and negative consequences. Its positive impact involves expediting the ripening process in fresh produce, while its negative effects lead to a diverse array of rapid undesirable changes [18, 19]. The process of fruit ripening generates ethylene, aldehydes, and other gases, amplifying the ripening progression. Ethylene influences ripening through two distinct forms: through endogenous ethylene, produced by the plant itself, and through external ethylene, originating from neighboring crops, automotive emissions, and polymers [20]. Ethylene also possesses the capability to trigger the expression of ripening‐associated genes via signal transduction pathways [21]. Ethylene production can be controlled by preventing its synthesis, oxidation and by its absorption during the handling and transportation of fresh produce [20]. Notably, ethylene exerts pronounced effects on the quality of fruits and vegetables with even minute concentrations, as low as 0.1 μl/l, significantly impacting their growth and development [22]. Consequently, the implementation of ethylene control measures, such as the use of ethylene scavengers, becomes indispensable for curbing product losses and safeguarding food quality by delaying postharvest ripening processes [23]. Ethylene scavengers can effectively reduce ethylene levels in packaging, chemically or physically, as the gas is highly reactive due to its double bond [9]. Chemical methods typically employ potassium permanganate (KMnO4) embedded in materials such as porous sachets, which oxidize ethylene into acetate, and ethanol without affecting the produce. However, KMnO4 cannot be used in direct contact with food due to its toxicity and lack of efficacy in high‐moisture environments [24, 25]. Other alternatives for ethylene removal include metal oxides, layer silicates, zeolites, nanoparticles, and activated carbon, which can be incorporated into packaging materials or provided inside the packaging in sachets [9, 19, 26]. These active materials/scavengers fall into two main categories: absorbers, which physically trap ethylene, and scavengers, which chemically react with ethylene. They can be incorporated in the film or in the form of sachets, and are commonly used in packaging for fruits and vegetables. The reduction of ethylene gas in the vicinity of fresh produce postpones fruit maturation by slowing down metabolic activities, resulting in a substantial extension of the shelf life of the produce [17, 22, 27]. Numerous scientific studies have explored the application of ethylene scavengers in active food packaging. Notably, Joung et al. [28] used encapsulated potassium permanganate (P)‐based ethylene scavenger in halloysite nanotubes (HNTs) and revealed a reduction in ethylene production and respiration rates, as well as a delay in loss of firmness and color changes for 21 days in cherry tomatoes wrapped with the developed nanocomposite film. Furthermore, Kaewklin et al. [29] reported that the use of chitosan and TiO2 nanocomposite films as an ethylene scavenger for postharvest management of climacteric fruits resulted in ethylene photodegradation, potentially contributing to the delay of the ripening process, and their shelf‐life extension. Upadhyay et al. [30] developed an optimal ethylene scavenging film using a nanocomposite of corn starch (CS) and gum acacia (GA) with 20% sepiolite that demonstrated effectiveness in packaging broccoli florets for six days at 23 °C storage. Moreover, the cellulose nanofiber/TiO2 nanotubes‐Cu2O‐based film exhibited the capability to scavenge ethylene gas generated in the headspace during storage, resulting in delayed tomato discoloration, softening, and weight loss [31]. Another noteworthy development in the realm of ethylene scavengers involves innovative films containing nano‐clay and nano‐silica that have been incorporated with KMnO4, which...