Analysis of Safety and Testing Methods for Food Plastic Packaging Materials

The continuous development of modern economic technology and the improvement of people's living standards have also promoted the development of the modern food plastic packaging industry. The types of materials used in modern plastic food packaging are becoming increasingly diverse, and there are numerous factors that affect food safety in plastic packaging. It is not only the influence of raw materials and corresponding processing methods or additives, but also the lack of strict control over product quality and laws and regulations, which are important factors affecting food safety. This article analyzes the types of harmful substances in food plastic packaging materials. By studying the detection methods for harmful substance content and migration, the safety of food plastic packaging materials is improved and the content of harmful substances in plastic packaging materials is reduced.

The global retail market is increasingly thriving in various innovative ways, with plastic almost replacing metal, wood, glass, and paper in the packaging industry, leading to significant development of plastic packaging in the food packaging field. Due to the need to protect various environmental factors from food production to consumption. Therefore, packaging is needed to protect food, and the shelf life of packaged food may range from a few days to over a year. Therefore, the performance of packaging materials must have sufficient durability to ensure that shelf life is not affected. However, a wide variety of additives are used in the production and processing of plastic packaging materials to modify pure polymer materials and obtain the required physical properties. These plastic materials themselves and additives undergo migration effects when in contact with food, which can have a certain impact on food safety and pose a threat to human health.

1： Types and characteristics of plastic packaging materials

1. Polystyrene (PS)

Polystyrene has the characteristics of good transparency, excellent rigidity, and good hygiene

Food packaging has broad application prospects, such as disposable containers such as bottle caps, instant noodle boxes, and fast food boxes.

2. Polyethylene (PE)

Polyethylene resin is the most commonly used raw material in food plastic packaging products at present, with characteristics such as good crystallinity, high transparency, good barrier and mechanical properties, and chemical stability. Among them, linear low-density polyethylene can be made into thin film materials and is widely used in the fields of plastic bags, cling films, and inner plastic packaging films.

3. Polycarbonate (PC)

Polycarbonate has good transparency, heat resistance, and impact resistance, and is commonly used in food packaging such as baby bottles, water bottles, etc. PC is synthesized by ester exchange reaction between bisphenol A and diphenyl carbonate or reaction between bisphenol A and phosgene. Before 2009, the hygiene standards for food utensils, containers, and packaging were not revised, and the inspection of PC products met the general requirements for plastics. Bisphenol A is a raw material used in the manufacture of PC, but due to its estrogenic properties, it is known as an endocrine suppressor that may affect the reproductive and neurological development of fetuses and infants. Currently, PC products have been banned from use in baby products such as bottles.

2： Method for detecting harmful substance content

1. Liquid chromatography tandem mass spectrometry

Liquid chromatography tandem mass spectrometry is a method of determining the substance content in a mixture by dissolving it in an organic solution and utilizing the spectral changes of the compound. The specific steps for using this method are as follows: first, weigh the mixture and dissolve the weighed mixture in an organic solution; Secondly, consistent with gas chromatography-mass spectrometry, organic ions in the mixed solution are separated using technical means. During the classification process, different colored spectral bands are generated in the solution. Combined with the spectral residence time of various types of additives added, the content and properties of compounds in the mixture are determined.

2. Headspace gas chromatography method

Headspace gas chromatography is a detection method that extracts a mixture under specific conditions and uses relevant equipment for desorption injection to form different types of chromatographic bands. The specific steps of this method are as follows: first, place the mixture in a closed space, and after a period of time, collect the air in a specific environment; Secondly, the collected volatile substances are subjected to solution extraction to form spectral bands of different colors in the solution; Finally, analyze the spectral band components to determine the material properties and specific content in the mixture. This method has high detection sensitivity and is suitable for residual determination of alcohol esters, benzene and volatile organic compounds.

3. Gas chromatography-mass spectrometry method

The detection of plasticizer content in plastic materials has important applications. Yan Ming studied the use of gas chromatography-mass spectrometry to detect the content of dibutyl phthalate in different batches of samples. Among 285 batches of samples, only 13 batches containing dibutyl phthalate were detected, indicating that the use of dibutyl phthalate as an additive in food packaging materials is rare. In addition, Guo Chunhai et al. studied the content of 46 plasticizers in polyvinyl chloride films using gas chromatography-mass spectrometry.

3： Improving the safety of plastic food packaging

1. Improve corresponding laws and regulations

In recent years, China has issued a series of laws and regulations on plastic packaging for food, the latest of which was the revised Food Safety Law of the People's Republic of China by the State Council in 2015. However, there is still a lack of comprehensive laws and regulations regarding plastic food packaging.

2. Utilize modern technological means to ensure safety performance

To truly improve the material safety of plastic food, modern technology and processes can be utilized.

(1) Utilize plastic packaging materials with high safety and hygiene indicators, such as using high-purity resins, and avoid using discarded or recycled old plastics as actual materials.

(2) Continuously researching modern, hygienic, and non-toxic processing auxiliary materials, gradually improving modern plastic blending technology, ensuring that plastics are environmentally friendly, hygienic, and non-toxic when used in food packaging, and enhancing the practical performance of plastic food packaging materials.

(3) With the support of modern technology, we continuously develop modern new processing techniques and use supercritical modern technology to reduce harmful substances generated during raw material processing.

(4) Actively developing modern intelligent means for practical food packaging, strictly implementing progressive scientific design, and providing specific protection for food packaging under reasonable packaging design. Utilizing the practical characteristics of certain materials such as edibility and water solubility to increase green protection testing efforts and avoid uncertain pollution caused by human operation.

(5) Gradually increase the actual supervision and inspection of relevant plastic products, with a focus on testing substances such as antioxidants and plasticizers, as well as additives or heavy metals in plastics, to ensure the actual supervision of food packaging.

3. Popularize food safety knowledge

Law enforcement personnel should actively explore the hazards of plastic food safety, strengthen consumer safety awareness through media publicity. For example, do not use plastic packaging to contain high-temperature food; When heating in a microwave oven, use corresponding porcelain or other containers for heating, and do not use plastic products.

Conclusion: In summary, analyzing the safety of plastic packaging products for food has high practical value. In plastic packaging products for food, substances such as ethylene, acrylonitrile, styrene, vinyl chloride, plasticizers, antioxidants, etc. are common harmful substances that can pose a threat to physical health. So, by studying the operational processes of different measurement methods, on the one hand, it can enhance people's understanding of detection methods; On the other hand, the safety of plastic packaging materials can be ensured to reduce the harm of harmful substances to human health.