The application of PET in the food industry: from packaging innovation to green upgrading

The application of PET in the food industry: from packaging innovation to green upgrading

PET (polyethylene terephthalate), as an excellent thermoplastic polyester material, has become one of the core materials in the packaging field of the food industry due to its high transparency, excellent barrier properties, lightweight, and safety compliance. Its compliance has been certified by authoritative standards such as China's GB 4806.6-2024 "National Food Safety Standard for Plastic Materials and Products in Contact with Food", EU Regulation No. 10/2011, and US FDA 21 CFR Part 177.1310. It does not contain harmful substances such as bisphenol A (BPA) and is widely used in various food sub sectors such as beverages, baking, fresh produce, and oils. With the upgrading of environmental protection needs, the development of recycled PET (rPET) and biobased PET is further driving them towards green and high-value directions, which is deeply in line with the sustainable development trend of the food industry.

1、 The core advantage of PET adaptation to the food industry: dual guarantee of performance and safety

PET stands out in the food industry due to its highly matched physical and chemical properties with the functional requirements of food packaging, especially in the four dimensions of barrier protection, visual display, processing adaptation, and safety and environmental protection, forming a unique competitiveness that far exceeds traditional glass, metal, and other plastic materials.

1. Excellent barrier performance: the key to extending the shelf life of food

Food spoilage is often related to contact with oxygen, moisture, light, and volatile substances. The barrier properties of PET can address this pain point in a targeted manner

Oxygen and water resistance: PET has a tight molecular structure, with a barrier rate for oxygen that is 3-5 times that of PP (polypropylene) and a barrier rate for water vapor that is 10-20 times that of PE (polyethylene). When used for bottled beverages, it can effectively delay the oxidation and discoloration of fruit juice and the leakage of carbonated beverages, extending the shelf life of carbonated beverages to 6-12 months and fruit juice to 3-6 months; When used for packaging edible oil, it can reduce the rancidity caused by contact between oil and oxygen, and extend the shelf life by 20% -30% compared to HDPE (high-density polyethylene) oil drums.

Resistance to volatility and chemical resistance: PET has strong barrier properties against aroma components in food, such as the mellow aroma of coffee and the fruity aroma of fruit juice, which can prevent flavor loss; Simultaneously resistant to acid and alkali, as well as oil and fat, it will not dissolve or undergo chemical reactions when in contact with acidic or oily foods such as soy sauce, vinegar, and tomato sauce, ensuring the purity of the food flavor.

Light avoidance modification potential: By adding color masterbatch (such as brown and green) to make opaque PET containers, it can block ultraviolet rays and prevent the degradation of nutrients (such as vitamin C and B vitamins) in photosensitive foods such as milk and vitamin drinks due to light exposure, further extending the shelf life.

2. High transparency and lightweight: balancing display effect and logistics efficiency

Food packaging not only needs to be "protected", but also "displayed". PET has significant advantages in visual presentation and logistics cost control:

Crystal grade transparency: The transmittance of PET can reach 90% -92%, close to glass but without the brittleness of glass. The container made of PET can clearly display the color and shape of the contents, such as the clarity of bottled water, the brightness of juice, and the colorful candy, greatly enhancing the visual appeal of the product and stimulating consumers' desire to purchase. For example, high-end mineral water brands such as Evian's PET bottles create a "high-end texture" by optimizing bottle shape and transparency, comparable to glass bottle packaging.

Lightweight and impact resistant: The PET density is only 1.38g/cm ³, and the weight of the container made is 1/8 of that of a glass bottle and 1/3 of that of a metal can of the same capacity. Taking 500mL beverage bottles as an example, PET bottles weigh only 12-15g, while glass bottles weigh about 180g, significantly reducing transportation energy consumption (PET packaging can reduce transportation fuel consumption by 30% -40% per 10000 tons); At the same time, the impact resistance of PET is more than 10 times that of glass, and the damage rate during transportation is less than 0.1%, far lower than the 2% -5% of glass bottles, reducing enterprise losses.

3. Flexible processing performance: adapted to diverse food packaging needs

There are various forms of food packaging (bottles, cans, films, trays, etc.), and PET can be customized through various processes to meet the packaging needs of different foods

Rich molding process: PET can be made into various specifications of bottles (from 50mL small capacity seasoning bottles to 2L large capacity beverage bottles) through injection molding stretching blow molding (ISBM); Produce thin films through extrusion stretching (such as BOPET biaxially oriented PET film); Made into trays and meal boxes through thermoforming, suitable for various types of food such as liquid, solid, and semi-solid. For example, carbonated beverage bottles need to withstand an internal pressure of 0.3-0.5MPa, and the "biaxial stretching" process can improve the compressive strength of PET bottles to avoid expansion and deformation.

Easy to print and decorate: PET has moderate surface tension and can be directly used for screen printing, offset printing, or labeling. The printed patterns are clear, have strong adhesion, and are not easy to peel off - this is crucial for brand identification and nutrition labeling. Some high-end food packaging will also use PET hot stamping and frosted treatment to enhance product quality, such as PET window packaging for chocolate gift boxes and PET laminated paper boxes for baked goods.

4. Safety and environmental attributes: meet the core requirements of the food industry

The primary prerequisite for food contact materials is "safe and non-toxic", and PET has excellent performance in both safety and environmental protection:

No harmful substance migration: The PET molecular chain is stable and will not migrate harmful ingredients such as plasticizers and heavy metals into food at normal operating temperatures (-20 ℃ to 60 ℃), even when in contact with high-temperature foods (such as hot drinks below 60 ℃); After long-term verification by FDA and other institutions, its safety can meet the strict requirements of infant and toddler food packaging.

Strong recyclability: PET is one of the plastics with the highest recycling rate in the world (marked as "No.1" for recycling). After recycling, it can be physically regenerated into rPET bottles, fibers, trays, etc., or chemically regenerated into monomers to synthesize PET resin. At present, the global PET bottle recycling rate has reached 45% -50%, and some European countries (such as Germany) even exceed 90%, which is in line with the policy orientation of "reducing plastic and carbon emissions" in the food industry.

2、 The core application of PET in the field of food packaging: covering all categories of food scenes

Packaging is the most important application area of PET in the food industry, accounting for over 80%. According to the form of food (liquid, solid, semi-solid) and consumption scenarios (ready to drink, storage, ready to eat), it can be divided into four sub directions: bottled beverages, oils and sauces, baking and snacks, fresh and pre made dishes. Each type of application is optimized for food characteristics.

1. Bottled beverages: the most mainstream application scenario of PET

Bottled beverages are the largest consumer market for PET, with over 70% of global PET food packaging used in this field, covering categories such as drinking water, carbonated beverages, fruit juice, tea drinks, dairy products, etc. The core advantages lie in "lightweight, impact resistance, and barrier adaptation":

Drinking water and carbonated beverages: 500mL-2L PET bottles are the standard packaging for carbonated beverages such as bottled water, cola, Sprite, etc. This type of PET bottle adopts the "injection molding stretching blow molding" process. After being biaxially stretched, the longitudinal and transverse strength of the bottle body is increased by 3-4 times, and it can withstand the internal pressure of carbonated beverages (0.3-0.5MPa) to avoid bursting during transportation; Meanwhile, the lightweight design reduces the transportation cost per 10000 bottles by more than 50% compared to glass bottles. For example, the weight of Coca Cola's 500mL PET bottle has decreased from 20g in 2000 to 12g currently, reducing both material consumption and logistics energy consumption.

Juice and tea beverages: Juice (such as orange juice and apple juice) and tea beverages (such as green tea and black tea) are sensitive to oxygen and prone to oxidation and deterioration. PET bottles can increase the oxygen barrier rate by 5-10 times through "barrier coating" (such as silica coating, EVOH coating) or "multi-layer co extrusion" (PET/EVOH/PET) technology, extending the shelf life of juice from 1 month at room temperature to 6 months and tea beverages from 3 months to 9 months. For example, the 1L PET bottle of Huiyuan Juice adopts EVOH multi-layer structure, which can be stored at room temperature for 6 months without refrigeration.

Dairy products and plant-based protein drinks: Room temperature milk, yogurt drinks, soy milk and other dairy products have higher requirements for hygiene and barrier properties. PET bottles need to undergo an integrated process of "sterile blowing sterile filling" to avoid microbial contamination during the production process; At the same time, white PET bottles are made by adding light blocking agents (such as titanium dioxide) to block ultraviolet rays and prevent protein and vitamin degradation in dairy products. For example, Yili's room temperature yogurt PET bottles feature a white light blocking design, with a shelf life of up to 6 months, making long-distance transportation convenient.

2. Oils and sauces: suitable for high viscosity and chemical resistance requirements

Edible oil, soy sauce, vinegar, salad dressing and other oily and sauce based foods have the characteristics of high viscosity, easy oxidation, and strong corrosiveness. The chemical resistance and barrier properties of PET make it an ideal packaging material:

Edible oil packaging: 1-5L PET oil drums are gradually replacing traditional glass bottles and HDPE drums, with the advantages of high transparency, allowing consumers to visually observe the color and clarity of the oil; Secondly, it has good oil resistance and will not dissolve or release substances due to long-term exposure to oils and fats; The third is that the bottle mouth design is suitable for pouring oil to avoid leakage. For example, 1.8L and 5L edible oils from brands such as Jinlongyu and Fulinmen are packaged in PET, and some high-end olive oil bottles also enhance their usability through bottle design features such as narrow mouth and anti slip patterns.

Sauce and seasoning: PET packaging for sauces such as soy sauce, vinegar, tomato sauce, salad dressing, etc. is often designed with "wide mouthed bottle+screw cap" or "squeeze bottle". Wide mouthed bottles are easy to access viscous sauces (such as tomato sauce), and the screw cap has good sealing and can be repeatedly opened; Squeezing bottles use the flexibility of PET to achieve quantitative extrusion of sauce, avoiding waste. For example, Lee Kum Kee's soy sauce PET bottles use leak proof screw caps, while Haitian's salad dressing uses extruded PET bottles, both of which balance sealing and ease of use.

3. Baking and Snacks: Focusing on Visual Display and Preservation

Baking and snack foods such as cookies, cakes, chocolates, nuts, etc. have extremely high requirements for packaging's "display" and "freshness". PET meets these needs through forms such as films, trays, and cans

BOPET film packaging: Biaxially oriented PET (BOPET) film has the characteristics of high strength, high transparency, and good temperature resistance (short-term resistance to 120 ℃), and is commonly used for outer packaging of biscuits and chocolates. For example, the "pillow packaging" of cookies is mostly made of BOPET film on the outer layer and PE film on the inner layer, forming a "barrier seal" composite structure that can display the shape of the cookies and prevent moisture; Chocolate packaging is made of BOPET film and aluminum foil composite, which blocks oxygen and light, preventing chocolate from melting or oxidizing and turning white.

PET cans and trays: Nuts, candy and baked Dim sum are usually packed in PET cans. Transparent cans can display the contents. With a sealing cover, they can prevent moisture and oxidation and extend the shelf life (for example, the shelf life of nuts is extended from one month to three months); PET tray is made by thermoforming, which is used for one-time storage of cakes and Dim sum. It is light and shatter resistant, and its surface can be coated to improve sealing, which is suitable for instant sale in bakeries. For example, in the nut gift box of three squirrels, individual nuts are often individually packaged in PET cans, balancing freshness and portability.

4. Fresh and pre made dishes: adapted to cold chain and ready to eat needs

With the development of fresh e-commerce and pre packaged food industry, the application of PET in low-temperature food packaging is gradually increasing, and its core advantages lie in "low temperature resistance, easy molding, and microwaveability":

Fresh food tray and cling film: PET trays are made by thermoforming, with a thickness of 0.3-0.5mm, and have good low temperature resistance (-20 ℃ not brittle). They are used for storing fresh meat, seafood, and fruits. Paired with BOPET cling film or stretch film, they form sealed packaging to prevent blood leakage and cross contamination; Some PET trays also contain antibacterial agents to inhibit bacterial growth and extend the shelf life of fresh produce by 1-2 days.

Prefabricated dish packaging: Prefabricated dishes (such as frozen dumplings and heated ready to eat dishes) are commonly used in PET/PP composite meal boxes, where PET serves as the outer layer, providing strength and oil resistance, and PP serves as the inner layer, which can be microwave heated (resistant to 120 ℃). This type of food box is sealed by "heat sealing" or "snap closure" and is suitable for cold chain transportation (-18 ℃ freezing). Consumers can directly heat it in the microwave after purchase without changing the container. For example, Meituan Maicai and Hema Fresh often use PET/PP composite meal boxes for their pre made dishes, balancing convenience and safety.

3、 Innovative application of PET in the food industry: from material modification to scene expansion

In addition to traditional packaging, PET has continuously expanded its application boundaries in the food industry through material modification and process innovation, covering functional packaging, intelligent packaging, and auxiliary tools, promoting the upgrading of food packaging to "multifunctional, high value-added".

1. Functional PET packaging: Enhancing food preservation and safety levels

Through physical or chemical modification, PET can achieve antibacterial, high barrier, biodegradable and other functions, suitable for the special needs of high-end food:

Antibacterial PET: Food grade antibacterial agents (such as zinc oxide nanoparticles and silver ions) are added to PET resin to make packaging that can inhibit pathogenic bacteria such as Escherichia coli and Staphylococcus aureus. It is used for packaging fresh meat and infant food to reduce the risk of microbial contamination. For example, a Japanese company developed antibacterial PET bottles for packaging infant and toddler food, with an antibacterial rate of 99% and a shelf life extension of 20%.

High barrier PET: By using "atomic layer deposition" technology to coat the inner wall of PET bottles with a layer of nano-sized alumina or silica coating, the oxygen barrier rate is increased by 10-20 times. It can be used for foods such as beer and wine that require extremely high barrier properties (beer shelf life is extended from 3 months to 6 months), replacing traditional glass bottles and reducing transportation costs.

Degradable PET: Packaging made by adding biodegradable ingredients such as PBAT (polybutylene adipate terephthalate) to PET can gradually degrade in the natural environment and is used for disposable food packaging (such as snack bags and trays) to reduce plastic pollution. For example, a biodegradable PET film developed by a European company for fruit packaging can be completely degraded under composting conditions within 6 months.

2. Intelligent PET packaging: achieving visual monitoring of food quality

Combining IoT technology, PET packaging can be upgraded to "smart packaging", which can monitor food freshness in real-time and enhance consumer safety

Freshness indicator PET bottle: Add a "chemical sensor" to the label or body of the PET bottle. When food spoils (such as expired milk producing lactic acid), the sensor will change color (such as from blue to red), and consumers can visually judge whether the food is fresh. For example, a milk PET bottle developed by a certain American company has a pH sensitive sensor embedded in the label. When the milk spoils, the label turns red to prevent consumers from drinking expired milk.

Traceability of PET packaging: Printing "QR codes" or "RFID chips" on PET bottles or films, consumers can scan and view information such as production time, place of origin, and testing reports of the food, achieving "full traceability"; Enterprises can also track logistics information through RFID chips to optimize supply chain management. For example, PET bottles of high-end imported olive oil often have traceability QR codes printed on them to enhance brand trust.

3. Food aids: expanding the non packaging applications of PET

In addition to packaging, PET can also be used for food contact utensils, replacing some traditional materials with its characteristics of "temperature resistance and easy cleaning":

Food grade PET trays and molds: PET trays and cake molds are commonly used in the baking industry, with a temperature resistance of up to 120 ℃. They can be used in ovens, are lightweight, and easy to demold, making them easier to clean than metal molds; PET trays are also used for assembly line transportation in food processing plants, which are wear-resistant and not easily deformed.

Disposable PET tableware: PET can be used to make disposable meal boxes, spoons, and forks, with high transparency and good oil resistance, suitable for takeout and fast food scenes; Some PET tableware can be modified for microwave heating, balancing convenience and safety, replacing traditional PS (polystyrene) tableware and reducing white pollution.

4、 Challenges and Development Trends of PET Application in the Food Industry

Despite the significant advantages of PET, it still faces challenges in terms of recycling purity and cost control in practical applications. In the future, it will develop towards the direction of biochemistry, biobased, and functionalization, further consolidating its core position in the field of food packaging.

1. Existing challenge: dual constraints of recycling and cost

Insufficient recycling purity: During the PET recycling process, impurities such as PVC (polyvinyl chloride) and PP are easily mixed in, especially PVC and PET, which have similar densities and are difficult to separate by flotation, resulting in insufficient purity of recycled PET and making it unsuitable for food grade packaging; In addition, the labels and caps (mostly made of PP material) of PET bottles need to be manually or mechanically peeled off, which increases the cost of recycling.

High end modification costs are relatively high: the production cost of modified materials such as high barrier PET (such as coatings, multi-layer co extrusion) and antibacterial PET is 20% -50% higher than that of ordinary PET, which limits their application in mid to low end food packaging; The cost of bio based PET (using plant starch as raw material) is 1.5-2 times that of ordinary PET, and technological breakthroughs are still needed for large-scale application.

Low temperature performance weakness: Ordinary PET is prone to brittleness below -10 ℃, and when used for frozen food packaging, it needs to be compounded with PP, increasing process complexity and cost.

2. Development Trend: Parallel Greening and High Value Development

The food grade application of recycled PET (rPET): With the upgrading of recycling technologies such as near-infrared spectroscopy sorting and chemical depolymerization purification, the purity of rPET continues to improve and can be used for food grade packaging. The European Union has approved rPET for bottled water, fruit juice and other food products, requiring a minimum regeneration ratio of 25%; Domestically, efforts are also being made to promote "bottle to bottle" closed-loop recycling, and it is expected that the usage rate of food grade rPET will reach 30% by 2025. For example, Coca Cola has committed to using over 50% rPET for all PET bottles by 2030, reducing the consumption of virgin plastics.

Large scale production of bio based PET: Bio based PET uses renewable resources such as sugarcane and corn as raw materials, and its carbon footprint is 30% -50% lower than traditional PET. At present, international giants such as DuPont and Teijin have achieved mass production of bio based PET for food packaging (such as some mineral water bottles from Danone using 30% bio based PET). In the future, with the maturity of technology, costs will gradually decrease and it is expected to replace more than 50% of native PET.

Integrated packaging solution: PET enterprises will transform from "material suppliers" to "solution providers", providing an integrated solution of "packaging design material supply filling services" based on food characteristics. For example, in the pre packaged food industry, we provide a complete set of packaging including "microwaveable PET/PP meal boxes+sealing film+traceability labels" to meet the needs of cold chain logistics and ready to eat meals.

5、 Summary: PET - the core driving force of food packaging innovation

From the lightweight revolution of bottled beverages, to the visual display upgrade of baked snacks, and to the innovation of ready to eat packaging for pre made dishes, PET is known for its excellent performance and safety