2. Intelligent Packaging
Intelligent packaging is defined as a technology that can communicate and facilitate decision-making to deliver information, enhance safety, assure quality, expand shelf-life, and provide notification of any complication by monitoring alterations in the external and internal environment of packages
[13,34][11][12]. It aims to observe the product and convey information to consumers, such as the content of a package, the manufacturing date, and storage conditions. The indicator for this intelligent packaging is generally a small item placed either inside or attached to the outside of the package
[4]. This information can be used to improve supply chain management, prevent food waste, and enhance the consumer experience.
Intelligent Packaging Indicator
The function of indicators is to measure and provide a signal for any reaction. Intelligent packaging indicators regulate the presence and absence of any constituent within the range of their concentration and reaction towards foodstuffs. The indicator is projected by visual changes, such as the modification of colour intensities
[4]. Three main indicators are used: time–temperature indicators (TTIs), freshness indicators, and gas indicators.
Temperature is one of the factors affecting the shelf life of foodstuffs. The alteration in temperature over time can lead to the growth of microorganisms, which may eventually cause the food to deteriorate and become unsafe for consumption. TTIs may also notify of changes in foodstuffs caused by enzymes, mechanical, chemical, or electrochemical factors. Thus, in the use of TTIs, the temperature of food products must be maintained during handling and transportation before being received by the end consumers
[4].
Following that, the freshness indicator performs a similar function to TTIs, but it aids in directly notifying the quality of food products. The freshness indicator will react when metabolites are formed by the growth of microbes in the foodstuff. It will show irreparable visual changes upon the increase in bacteria in the products. Given that this indicator is dependent on metabolites, factors such as the nature of packed foodstuff, flora spoilage, and packaging variety must be considered because they are related to the establishment of metabolites
[35][13].
Gas indicators also ensure food safety and quality. Foodstuff, especially fresh food, starts to decay or is spoiled by microbial fermentation after being packed because of the production and multiplication of carbon dioxide in the packaging. The gas changes with storage time and temperature, which is determined by the type of food, respiratory characteristics, packaging material, and product headspace. Thus, gas indicators may help in tracking the gas level in the headspace of packages to determine the quality of foodstuff
[12][14].
Some intelligent packaging also incorporates active packaging features, such as indicators that can detect the presence of microorganisms or changes in the chemical composition of the food product. Additionally, packaging that incorporates colour changes of active materials indicates the status of the food product, such as changes in temperature, humidity, or other environmental factors, and provides information about the quality and safety of the food product
[36,37][15][16]. These colour-changing active packaging systems can be considered intelligent packaging because they have the added capability of providing information to the consumer in addition to their functional benefits.
The accuracy of intelligent packaging indicators can vary depending on several factors, including the technology used, the type of information being monitored, and the environment in which the system is used
[38][17]. It is also important to realise that, while this technology can indicate food quality, it is not a guarantee of food safety and should be used in conjunction with other food safety measures, such as proper handling, storage, and preparation
[7,39][7][18].
3. Active Materials for Intelligent Food Packaging Indicator
Active materials play a role in controlling the environment inside the package, increasing the shelf life, and preserving the quality and visual appearance of packed foods. Interestingly, reviews on food packaging with these active materials as additives are abundant
[40,41][19][20]. Two groups of sources are used as additives: synthetic and natural active compounds. Synthetic compounds, such as metal ions, metal oxides, copper, zinc oxides, titanium dioxides, ammonium salts, and ethylenediaminetetraacetic acid, have been widely used as additives for thousands of years. When used in low concentrations, they have been shown to be the most effective in terms of function and to have the least systemic toxicity to humans. Regardless, controversies and contradictory findings regarding the long-term safety of these synthetic additives to human health must be addressed
[41,42][20][21].
Natural or bioactive compounds with specific functional properties, such as essential oils, plant extracts, and minerals, have all been studied for use in active packaging
[43,44][22][23]. The appropriate bioactive compound is chosen based on a variety of factors, including its efficacy, compatibility with the food product, and intended end-use application. Therefore, bioactive compounds, especially those from plant sources, are being introduced as alternatives, given that plants consist of pigments, such as chlorophyll, carotenoid, anthocyanin, and betalain. These natural pigments can also be derived from fruits and vegetable wastes and by-products, such as seeds, peels, skins, and leaves
[9]. These natural pigments contain a variety of bioactive compounds with physiological effects, such as antioxidants and antimicrobials, and can protect tissues and cells from free radicals and singlet oxygen damage; they can also extend the shelf life of fresh or processed food
[10,45,46][10][24][25].
Table 1 exhibits the synthetic and natural active compounds that are currently being used as additives for intelligent food packaging indicators.
Table 1. Synthetic and natural active food packaging materials.
Compound |
Food |
Function |
References |
Roses |
Shrimp |
Freshness indicator |
[47][26] |
Sodium bicarbonate and citric acid |
Chicken |
Gas indicator |
[48][27] |
Red beet |
Fish/shrimp |
Freshness indicator |
[49][28] |
Betalain |
Meat |
Freshness indicator |
[50][29] |
Dragon fruit |
Fish |
Freshness indicator |
[51][30] |
Zinc oxides |
Apple |
Microbial indicator |
[52][31] |
Thyme herb |
Bread |
Freshness indicator |
[53][32] |
Nisin |
Ham |
Microbial indicator |
[54][33] |
Purple sweet potato |
Meat |
Time–temperature indicator |
[55][34] |
Pomegranate |
Orange fruit |
Microbial indicator |
[56][35] |
Roselle |
Pork |
Freshness indicator |
[57][36] |
Red cabbage |
Pasteurised Milk |
Time–temperature indicator |
[58][37] |
Eggplant |
Milk |
Freshness indicator |
[59][38] |
Clove essential oil and zinc oxide |
Shrimp |
Microbial indicator |
[60][39] |
Red cabbage |
Milk |
Freshness indicator |
[61][40] |
Jambolan fruit |
Shrimp |
Time–temperature indicator |
[62][41] |
Lactoferrin |
Fresh sausages |
Microbial indicator |
[63][42] |
Black rice bran |
Pomfret/shrimp |
Freshness indicator |
[64][43] |
There have been a number of studies on the incorporation of active materials into a packaging or coating matrix in order to improve stability and serve as an intelligent indicator. For example, a previous study reviewed the use of anthocyanin-rich extracts from red cabbage as active ingredients in smart bio-based food packaging systems and sensors
[65][44]. The study found that red cabbage anthocyanins act as colourimetric pH-responsive agents that enable reliable real-time monitoring of the qualitative qualities of packaged food products and help maintain the shelf life by inhibiting microbial growth and oxidative deterioration. Another study reviewed the current developments in the production of intelligent, active, and bioactive biopolymer-based films containing betalains
[49][28]. The study discovered that betalains are adaptable natural pigments with a variety of bioactivities, making them ideal colourimetric indicators due to their ability to detect changes in food pH as well as their antibacterial and antioxidant properties.
These studies show that bioactive materials could be added to a packaging or coating matrix to make it more stable and act as an intelligent indicator of the quality and safety of food. It is important to note, however, that the specific properties and effectiveness may vary depending on a variety of factors, including the specific active ingredients used, the type of packaging matrix, internal gas composition control, and the specific food product being packaged
[66][45]. The use of bioactive materials in intelligent food packaging should be carefully designed to ensure the stability and effectiveness of the bioactive compounds. For instance, the incorporation of these compounds into a PLA matrix can help to protect them from degradation and oxidation
[67][46].
Halal Bioactive Materials for Intelligent Packaging
Polymers are typically made from petroleum-based raw materials. Because of the global problem of pollution, alternative eco-friendly and biodegradable polymers are in high demand. Biopolymers are classified into three types based on their origin and method of production: directly extracted from biomass, synthesised bioderived monomers, and microorganisms
[68][47]. Animal-based and plant-based materials are both viable options for producing edible films and intelligent packaging. The use of either type of material depends on factors such as the intended application, the desired properties of the packaging, and the sustainability and ethical considerations of the material
[69][48]. The primary concern for Halal consumers is the use of additives derived from indefinite sources in the manufacture of polymer resins.
For Muslim consumers, the use of biopolymer materials or additives derived from non-halal sources such as animal blood and protein such as collagen, gelatine, and keratin from the non-halal animal is prohibited. According to MS 2565:2014 Halal Packaging–General Guidelines published by the Department of Islamic Development Malaysia (JAKIM), “halal packaging” refers to packaging materials and containers that comply with Islamic law, which includes not only the ingredients used in the packaging but also the manufacturing process and handling procedures
[70][49]. The guidelines provide a set of criteria that must be met for packaging to be considered halal, such as ensuring that the materials used are from permissible sources and that there is no contamination from non-halal substances during the production process.
Bioplastics derived from starch, cellulose-based materials, chitosan derived from shrimp and crab shells, and bamboo fibres are some examples of halal biomaterials for food packaging. These materials are renewable, biodegradable, and compostable, making them eco-friendly and sustainable packaging options for food. In addition to meeting the requirements of Islamic law, packaging made from halal biomaterials is an environmentally responsible solution for the packaging industry. In the current Malaysian market, NLYTech Biotech located in Simpang Ampat, Pulau Pinang, and ADA Biotech based in Butterworth, Pulau Pinang are prominent manufacturers specializing in the production of halal-certified biomaterials for packaging applications. These manufacturers use a variety of halal-certified biomaterials, such as broken rice flour, tapioca starch, bamboo, natural food-grade colouring, and even used coffee grounds, to create environmentally friendly and halal-compliant packaging solutions. Their commitment to using permissible sources under Islamic law and meeting the stringent requirements for halal certification exemplifies the industry’s commitment to meeting the needs of Muslim consumers who seek environmentally friendly and ethical products.
Meanwhile, halal bioactive materials for intelligent food packaging refer to materials that comply with Islamic law and are utilised in the development of intelligent food packaging. These materials interact with the food product and provide information about the food’s freshness or safety, thereby preventing food spoilage and food waste caused by spoilage. Ultimately, the primary distinction between halal and non-halal intelligent packaging materials is that halal materials must be derived from Islamic law-compliant sources
[71][50]. Another distinction is the manufacturing process. Halal bioactive materials must be produced in a halal-compliant manner, such as by avoiding cross-contamination with prohibited substances or by using equipment that has not been exposed to prohibited substances.
There is no discernible difference in terms of performance between halal and non-halal bioactive materials. Both can significantly improve the preservation and shelf life of food products. Examples of halal bioactive materials for intelligent food packaging indicators include pH indicators that change colour in response to changes in the acidity of the food product, oxygen indicators that change colour in response to changes in the oxygen levels inside the package, and microbial indicators that change colour in response to the growth of bacteria and other microorganisms in food products. Due to consumers’ growing concerns about the use of synthetic additives in food products, the food industry has increasingly turned to natural colourants as an alternative to synthetic colourants
[72][51].
In the market of food colouring, natural pigments such as carmine, annatto, and curcumin are prevalent. The excellent tinctorial qualities of cochineal carmine, a dye produced by
Dactylopius coccus insects, are highly prized. It is a high-demand functional dye due to its superior antioxidant activity, which is comparable to that of well-known antioxidants such as quercetin, ascorbic acid, and Trolox
[73][52]. According to Islamic law, cochineal carmine is halal because the insects used to produce it are not killed or harmed during extraction, and an insect whose blood does not flow is deemed pure. The Malaysian Fatwa Committee and the Malaysian Food Regulations have permitted the use of cochineal dye because it is manufactured in accordance with Good Manufacturing Practises and does not pose a health risk
[74][53]. There have been previous attempts to improve the mechanical and gas barrier properties of polyvinyl alcohol (PVA) films using a carminic acid-containing edible gel
[75][54].
It should be emphasised that while the current halal certification of packaging materials available in the market is not specifically aimed at the development of bioactive materials for intelligent food packaging, it is still a critical step towards creating an industry-wide halal intelligent food packaging. This initiative demonstrates a strong commitment to advancing sustainable and halal-friendly practices in the packaging industry, and it sets the stage for future research and development of packaging materials that incorporate halal bioactive components for enhanced food safety and quality. By embracing these innovative solutions, the industry can continue to evolve and meet the growing demand for environmentally friendly and ethically sourced packaging solutions.