Safety Analysis and Development Trend of Food Packaging Materials

Food packaging is the last process of the modern food industry. It plays an important role in protecting, promoting and facilitating food storage, transportation and sales. To a certain extent, it has a direct or indirect impact on food quality, which not only endangers the health of consumers, but also affects the healthy development of my country’s entire food packaging industry and even the food industry. Food packaging is closely related to food safety. Food packaging must ensure the sanitation and safety of packaged food. At present, the food containers and packaging materials allowed for use in my country can be divided into plastic products; natural and synthetic rubber products; ceramic and enamel containers; aluminum, stainless steel, iron containers; glass containers; food packaging paper; composite film, composite film bag; bamboo and wood; cotton and linen, etc.

Safety Analysis of Food Packaging Materials

Plastic

Plastic is a polymer material made of high molecular polymer-resin as the basic component, and then adding some various additives to improve its performance. As a rising star of packaging materials, plastic packaging materials have become the fastest growing packaging materials in the world in the past 40 years due to their rich raw materials, low cost, excellent performance, light weight and beautiful appearance. The migration and dissolution of toxic and harmful substances remaining in plastic packaging materials lead to food contamination, mainly in the following aspects.

Toxicity of the resin itself
The unpolymerized free monomers, cracking products (vinyl chloride, styrene, phenols, nitrile rubber, formaldehyde), degradation products and toxic substances produced by aging in the resin all have an impact on food safety. The US Food and Drug Administration pointed out that it is not polyvinyl chloride (PVC) itself but the vinyl chloride (VCM) remaining in PVC that may cause cancer after oral ingestion, and therefore prohibits PVC products from being used as food packaging materials. The free monomer vinyl chloride (VCM) of polyvinyl chloride has an anesthetic effect and can cause contraction of blood vessels in the human limbs and produce pain. It also has carcinogenic and teratogenic effects. It forms vinyl chloride oxide in the liver, which has a strong alkylation effect and can combine with DNA to produce tumors [1]. Residual substances in polystyrene such as styrene, ethylbenzene, toluene and isopropylbenzene pose a threat to food safety. Styrene can inhibit the reproduction of rats and reduce the weight of the liver and kidneys. Low molecular weight polyethylene dissolves in oils and fats to produce a waxy smell, affecting product quality. The extent to which these harmful substances affect food safety depends on the concentration of these substances in the material, the tightness of the combination, the nature of the food in contact with the material, the time, temperature and solubility in the food .
Surface contamination of plastic packaging
Because plastics are easily charged, they are easy to absorb dust impurities and microorganisms, thus contaminating food.
Toxicity of additives such as stabilizers, plasticizers, and colorants added during the manufacturing process of plastic products
A scientific study conducted by Professor Li Shuguang of the Basic Medical College of Tongji University and his research team showed that plasticizer pollution in my country’s food is almost everywhere. The study found that almost all brands of plastic barrels of edible oil contain two plasticizers, “dibutyl phthalate (DBP)” and “dioctyl phthalate (DOP)”, while iron barrels of edible oil contain almost none .

Pollution of food caused by a large number of toxic additives, heavy metals, pigments, viruses, etc. in illegally used recycled plastics
The recycling and reuse of plastic materials is the general trend. Due to the complexity of recycling channels, harmful substances often remain on the recycling containers, making it difficult to ensure complete cleaning and processing. In order to cover up the quality defects of recycled products, some often add a large amount of paint, resulting in a lot of paint pigment residues, causing food pollution. Due to regulatory reasons, even a large amount of medical waste plastics are recycled, which poses a hidden danger to food safety.
Ink pollution
The main substances in ink are pigments, resins, additives and solvents. Ink manufacturers often consider the impact of resins and additives on safety, but ignore the indirect harm of pigments and solvents to food safety. Some inks will add some promoters, such as siloxanes, to improve adhesion. Such substances will cause the group to break bonds at a certain drying temperature and generate substances such as methanol, which will cause harm to the human nervous system. The ink printed on plastic food packaging bags has a greater impact on food safety because some toxic substances such as benzene are not easy to volatilize. In recent years, the pass rate of plastic food packaging bags in various places has been generally low, only 50% to 60%. The main unqualified items are excessive benzene residues, etc. The main reason for the excessive benzene is the use of benzene-containing solvents to dilute the ink during the printing process of plastic packaging.
Adhesives for composite films
Adhesives can be roughly divided into polyether and polyurethane adhesives. Polyether adhesives are gradually being phased out, while polyurethane adhesives are available in two types: aliphatic and aromatic. Adhesives can also be divided into water-based adhesives, solvent-based adhesives, and solvent-free adhesives according to their type of use. Water-based adhesives will not have much impact on food safety, but due to functional limitations, they have not been widely used in my country [4]. Solvent-based adhesives are still mainly used in my country [5]. In terms of food safety, most people simply believe that if the residual solvent is not high, it will not affect food safety. In fact, this is only one-sided. 99% of the solvent-based adhesives used in my country are aromatic adhesives [6]. They contain aromatic isocyanates. After packaging food with this kind of bag and then steaming it at high temperature, it can migrate into the food and hydrolyze to form aromatic amines, which are carcinogens. my country currently does not have a national standard for adhesives used in food packaging, and there are no heavy metal content indicators in the corporate standards of various manufacturers and suppliers. However, there are strict restrictions on aromatic amines in foreign food packaging. For example, the EU stipulates that its migration amount is less than 10ppb .

Paper

Paper packaging materials occupy a very important position in food packaging due to their unique advantages. In some developed countries, paper packaging materials account for 40% to 50% of the total packaging materials, and my country accounts for about 40%. National standards have regulations on the hygiene indicators, physical and chemical indicators and microbial indicators of food packaging base paper. Pure paper is hygienic, non-toxic and harmless, and can be decomposed by microorganisms under natural conditions, without pollution to the environment. The sources of harmful substances in paper and their impact on food safety mainly exist in the following aspects.

Pollution caused by papermaking raw materials themselves
The raw materials for producing food packaging paper include wood pulp, straw pulp, etc., which contain pesticide residues. Some use a certain proportion of recycled waste paper to make paper, because although the waste recycled paper has been bleached, it only removes the ink pigment, while harmful substances such as lead, cadmium, and polychlorinated biphenyls can still remain in the pulp; some use moldy raw materials to produce, so that the finished product contains a large amount of mold.
Additives in the papermaking process
Papermaking requires the addition of chemicals to the pulp, such as impermeable agents, sizing agents, fillers, bleaching agents, dyes, etc. Most of the leached substances in paper come from the additives, dyes and inorganic pigments of the pulp. Various metals are often used, and these metals can be dissolved even at the mg/kg level and cause disease [2]. For example, in the paper processing process, especially when using chemical pulping, paper and paperboard usually have certain chemical residues, such as alkali and salts left over from the sulfate pulping process. The Food Safety and Sanitation Law stipulates that fluorescent dyes or fluorescent brighteners are prohibited from being used in food packaging materials, as they are carcinogens [7]. In addition, antifungal agents or formaldehyde used in resin processing can also be dissolved from paper products.
Pollution caused by ink
my country does not have special inks for food packaging. The inks printed on paper packaging are mostly organic solvent-based gravure inks containing toluene and xylene. In order to dilute the ink, benzene-containing solvents are often used, resulting in excessive residual benzene solvents. Benzene solvents are not allowed to be used in the GB9685 standard, but they are still used in large quantities; secondly, the pigments and dyes used in inks contain heavy metals (lead, cadmium, mercury, chromium, etc.), aniline or condensed ring compounds, which cause heavy metal pollution, and aniline or condensed ring dyes are obvious carcinogens. When printing, they are stacked together, causing the non-printed surface to contact the ink, forming secondary pollution. Therefore, the harmful substances in paper packaging printing inks have a serious impact on food safety. In order to ensure the safety of food packaging, the use of benzene-free printing will become a development trend.
Pollution during storage and transportation
The surface of paper packaging is contaminated by dust, impurities and microorganisms during storage and transportation, which affects food safety.

Metal

Metal packaging materials are one of the traditional packaging materials and have been used for food packaging for nearly 200 years. Metal packaging materials are processed into various forms of containers with metal sheets or foils as raw materials for packaging food. Due to the advantages of high barrier properties, high and low temperature resistance, and easy recycling of waste, metal packaging materials are increasingly used in food packaging. The biggest disadvantage of metal as a food packaging material is its poor chemical stability and acid and alkali resistance. In particular, it is easy to corrode when used to package highly acidic foods, and metal ions are easy to precipitate, thus affecting the flavor of the food. The main safety problem of iron containers is that zinc will migrate to the food after the galvanized layer contacts the food, causing food poisoning. Aluminum materials contain elements such as lead and zinc, and long-term intake will cause chronic cumulative poisoning; aluminum has poor corrosion resistance and is prone to chemical reactions to precipitate or generate harmful substances, and it is difficult to control the impurities and harmful metals of recycled aluminum; stainless steel products contain a large amount of nickel, which makes the surface of the container black when subjected to high temperature. At the same time, its fast heat transfer makes it easy to gelatinize and denature unstable substances in food, and may also produce carcinogens. Stainless steel cannot come into contact with ethanol, which can dissolve nickel and cause chronic poisoning in the human body. Therefore, it is generally necessary to apply paint on the inner and outer walls of metal containers. The inner wall coating is an organic coating applied to the inner wall of the metal can, which can prevent the contents from direct contact with the metal, avoid electrochemical corrosion, and increase the shelf life of food. However, the chemical pollutants in the coating will also migrate to the contents during the processing and storage of cans, causing pollution. Such substances include BPA (bisphenol-A), BADGE (bisphenol-A diglycidyl ether), NOGE (phenolic varnish glycerol ether) and their derivatives. Bisphenol-A epoxy derivatives are an environmental hormone that enters the body through canned food, causing endocrine imbalance and genetic mutations.

Glass

Glass is an ancient packaging material. More than 3,000 years ago, the Egyptians first made glass containers, and since then, glass has become a packaging material for food and other items. Glass is a molten product of silicates, metal oxides, etc. It is an inert material that is non-toxic and harmless. The biggest features of glass as a packaging material are: high barrier, bright and transparent, good chemical stability, and easy to shape. Its usage accounts for about 10% of the total packaging material.

Dissolution of toxic substances during melting
Generally speaking, the internal ions of glass are tightly bound. After high-temperature melting, most of them form insoluble salt substances with excellent chemical inertness, which do not react with the packaged food and have good packaging safety. However, glass products that are not melted well may have the problem of toxic substances dissolving from the glass raw materials. Therefore, glass products should be soaked in water or heated with dilute acid. Food and medicine with strict packaging requirements can change soda-lime glass to borosilicate glass. At the same time, attention should be paid to the quality of glass melting and molding processing to ensure the safety of the packaged food.
Excessive heavy metal content
High-end glassware such as high-foot wine glasses often add lead compounds, and the amount added is generally as high as 30% of the glass. This is a more prominent safety issue in glassware.
Safety hazards of colorants in colored glass
In order to prevent harmful light from damaging the contents, various colorants are used to color the glass. The main safety issue of metal salts added is the migration of substances dissolved from the glass. For example, the added lead compounds may migrate into wine or beverages, and silicon dioxide may also be dissolved .

Ceramics

Compared with containers made of metal, plastic and other packaging materials, ceramic containers can better preserve the flavor of food. For example, fermented bean curd packaged in ceramic containers is of better quality than fermented bean curd packaged in plastic containers because ceramic containers have good air tightness and the arrangement between ceramic molecules is not very tight, which cannot completely block the air, which is conducive to the later fermentation of fermented bean curd .
The hygienic and safety issues of ceramic packaging materials used in food packaging mainly refer to the dissolution of heavy metal elements lead or cadmium in the glaze layer on the surface of glazed ceramics. It is generally believed that ceramic packaging containers are non-toxic, hygienic and safe, and will not have any adverse reactions with the packaged food. However, long-term studies have shown that glazes are mainly composed of various metal oxides and their salts such as lead, zinc, cadmium, antimony, barium, copper, chromium, and cobalt, most of which are harmful substances. Ceramics are fired at 1000-1500°C. If the firing temperature is low, the colored glaze fails to form insoluble silicates. When using ceramic containers, toxic and harmful substances are easily dissolved and contaminate food . For example, when containing acidic foods (such as vinegar, juice) and wine, these substances are easily dissolved and migrate into food, causing safety problems. Both domestic and foreign regulations have allowed limit values ​​for the amount of lead and cadmium dissolved from ceramic packaging containers.
The above is a brief introduction to the safety of food packaging materials and main materials. With the development of the national economy, policy adjustments and changes in consumer concepts, we have begun to establish a scientific, targeted and practical food packaging safety control system based on the experience of developed countries; gradually establish and improve new regulations on food packaging materials, and formulate a food packaging quality standard system in line with international standards. As consumers, it is particularly important to increase their awareness of self-protection. From the survey on consumers’ trust in the hygiene and safety of food packaging materials, it can be seen that people believe that glass, ceramics, and metals are safer [9], but these materials also have safety hazards. Consumers lack safety knowledge, such as being unable to recognize the information on the label, which affects their acceptance of safety information .

Development trend of food packaging materials

Advocating low-carbon and environmentally friendly packaging
In the food production industry chain, advocating environmental protection and low carbon will be the general trend, and the environmental pollution and resource waste caused by discarded packaging are receiving more and more attention. It has become a consensus to implement packaging reduction, resource utilization, harmlessness, low carbonization and safety, and reuse packaging. The food packaging experience of Europe and the United States is worth learning and reference. For example, Sweden and other countries have implemented the reuse of polyester PET beverage bottles and PC milk bottles for more than 20 times, the Dutch Wellman Company and the American Johnson Company have 100% recycled PET containers, and some paper packaging can be recycled after use. Any consumer material that is not properly handled will cause pollution.
Establish a reasonable consumption and use system to reduce environmental pollution
In the field of packaging materials, polymer materials are developing faster than glass, metal and paper. The main reason is that polymers have good functions.

After my country joins the WTO, due to the reduction of tariffs, the import tax on plastic resins will drop by 60%, and my country’s plastic packaging industry will have greater room for development . According to reports , the annual growth rate of paper containers in the United States in the past five years was 3.2%, the annual growth rate of metal containers was 2.5%, the annual growth rate of glass containers was 0.5%, and the annual growth rate of plastic containers was 5.5%. Food packaging materials need to be evaluated throughout the process. From an economic point of view, the transportation and storage costs of degradable materials are relatively high. For consumers, paper packaging costs more than plastic packaging (about 2 times more) . It can be seen that plastic will continue to be the most commonly used and most convenient packaging material in food packaging. Therefore, it is necessary to establish a reasonable consumer use system to reduce and gradually eliminate its pollution to the environment.
Strengthen the research and development and safety assessment of functional packaging materials
In the future, food packaging materials will pay more attention to functionality under the premise of safety. Paper food packaging materials strengthen the functions of moisture-proof, fresh-keeping, sterilization, antiseptic (antioxidant), water resistance, acid resistance, oil resistance and deodorization; degradable packaging materials strengthen the systematic research and evaluation of their stability, degradability and economy, such as safety evaluation under different temperature, humidity, pH, oxygen content and oil-containing food and microwave conditions. Therefore, scientific research departments should increase systematic research on food packaging materials and develop products that meet food hygiene requirements and are non-toxic and harmless to the human body and the environment.
Accelerate the revision and formulation of standards and establish a quality standard system in line with international standards
At present, some of my country’s food packaging hygiene standards and regular sampling items were formulated in the early 1990s. The existing old standards cannot meet the testing of new materials and are no longer suitable for product safety requirements. In view of the current situation of outdated standards, management departments should refer to international advanced standards to accelerate the revision, improvement and updating of existing standards. my country has a certain gap with developed countries in safety evaluation and testing technology, which affects the evaluation ability of new substances and new materials. Some monomers and additives cannot be detected, and even if they are detected, their sensitivity is very limited. Therefore, we should strengthen the construction of the detection and evaluation capabilities of technical support institutions, carry out research on trace detection technology and ultra-trace detection technology for some monomers and additives, establish methods for detecting multiple types of chemical substances, improve various detection standards, and develop fast and effective detection methods and detection equipment as soon as possible. At the same time, we should continue to strengthen cooperation with international organizations, such as the Codex Alimentarius Commission (CAC), the World Health Organization (WHO), the Food and Agriculture Organization of the United Nations (FAO), etc., and formulate and improve the safety evaluation procedures, evaluation mechanisms and management methods of food packaging materials as soon as possible.
Improve the safety assurance system of food packaging materials
Accelerate the promotion of the market access system for packaging material quality and safety, and actively carry out compulsory certification work. For enterprises that have obtained production licenses, post-certification supervision should be strengthened, and a sound long-term safety mechanism should be established. The relatively successful experience of Europe and the United States is worth learning from, and we should establish a sound food packaging access system and regulatory measures, such as food and packaging quality and safety certification system, food and packaging recall system, and establish a traceable food and packaging safety database. GMP and HACCP systems are currently recognized by the world as the most effective and economical food safety systems [14]. my country should implement the GMP and HACCP mandatory certification system in the food packaging materials industry as soon as possible to build a strong barrier for my country’s food packaging safety.
Strengthen corporate self-discipline and social responsibility
For ordinary consumers, it is very difficult to identify whether food packaging has safety hazards. The relevant departments should introduce relevant measures to regulate corporate production and ensure the safety of food packaging materials from the source of production. The legal awareness, self-discipline and social responsibility of production enterprises are directly related to food safety issues. As an important part of food processing, the food packaging industry should gradually establish annual inspections, regular inspections and supervision and spot checks, and increase the supervision of small and family workshops and the punishment of illegal enterprises. In addition, the situation of unclear functions of supervisory departments, repeated supervision and regulatory loopholes should be changed to improve management efficiency and encourage enterprises to produce according to standards and operate in accordance with the law. Food packaging materials not only involve environmental protection issues, but more importantly, they involve public health and safety issues. The safety of food packaging materials is equivalent to food safety. Strengthening the quality and safety of food packaging materials not only ensures food safety, but also ensures the health of consumers and social stability and harmony.

Conclusion

Food packaging materials are essential not only for preserving food quality but also for ensuring public health and safety. While materials like plastic, paper, metal, and glass are widely used, each comes with its own set of risks, including contamination, migration of toxic substances, and environmental concerns. To address these challenges, it is crucial to continue improving safety standards, conducting thorough research, and establishing rigorous testing protocols. Moreover, promoting environmentally friendly and functional packaging materials, along with strengthening regulatory frameworks and corporate self-discipline, will be key to advancing food packaging safety. By taking these measures, we can safeguard both the health of consumers and the future of the food packaging industry.