Application of HDPE in the food industry: safety, multifunctionality, and full chain adaptation

HDPE (high-density polyethylene), as a branch of the polyethylene (PE) family with high crystallinity and density (0.941-0.965g/cm ³), has become the core material of the entire food industry chain from raw material storage, processing and production to terminal packaging and logistics transportation due to its excellent food contact safety, chemical stability and processing adaptability. Its compliance has been certified by authoritative standards such as China's GB 4806.11-2024 "National Food Safety Standard for Plastic Materials and Products in Contact with Food", EU Regulation No. 10/2011, and US FDA 21 CFR Part 177.1520. It does not contain harmful substances such as bisphenol A (BPA) and phthalates, and its application in the food industry covers multiple scenarios such as packaging, utensils, and processing aids. Additionally, its recyclability (marked as "No. 2" plastic) meets the green development needs of the modern food industry.

1、 The core advantage of HDPE in the food industry: key characteristics for adapting to food contact

HDPE can be widely used in the food industry because its physical and chemical properties are highly compatible with the safety and functional requirements of the food industry, especially in the three dimensions of safety, environmental resistance, and processability, forming differentiated advantages that far exceed some traditional plastics or metal materials.

1. Food contact level safety: basic guarantee of no migration and no odor

The core requirement for food contact materials is "not reacting with food and not releasing harmful substances", and HDPE performs outstandingly in this dimension:

No migration of harmful substances: HDPE has a stable molecular structure (with a saturated carbon carbon bond as the main chain and no easily breakable branches or functional groups), and will not migrate harmful ingredients such as plasticizers and heavy metals to food at conventional operating temperatures (-40 ° C to 60 ° C, with a short-term tolerance of 80 ° C). Even when in contact with acidic foods (such as vinegar and fruit juice), alkaline foods (such as kimchi and soda water), or oily foods (such as edible oil and meat), it can maintain chemical inertness and avoid affecting food flavor or endangering health.

Low odor and low adsorption: HDPE has high crystallinity (usually 70% -85%), tightly arranged molecules, and low surface porosity. It not only has no odor on its own, but also reduces the adsorption of food aroma - which is crucial for volatile flavored foods such as coffee, tea, and spices, to avoid packaging materials "absorbing odor" and causing loss of food flavor.

Full compliance coverage: Global mainstream food regulatory agencies have listed HDPE as a "safe food contact material". For example, China's GB 4806.11-2024 specifies specific migration limits (SML) and total migration limits (OML) for HDPE, and EU No. 10/2011 allows HDPE to be used in contact with all types of food (including infant and toddler food) without additional category restrictions, reducing compliance costs for businesses.

2. Environmental resistance and durability: adapted to the scenario requirements of the entire food chain

Food needs to go through multiple stages such as storage, processing, transportation, and sales from production to consumption, and the environmental conditions are complex (low-temperature cold chain, high-temperature cleaning, collision and extrusion, etc.). The weather resistance and impact resistance of HDPE perfectly meet these needs:

Excellent low temperature resistance: HDPE has an extremely low glass transition temperature (about -120 ℃) and can maintain good toughness even in low temperature environments of -40 ℃, without brittle cracking - making it an ideal material for frozen food packaging (such as frozen dumpling bags, ice cream buckets) and cold chain turnover boxes. Even if it is repeatedly frozen and thawed during cold chain transportation, it can maintain structural integrity and avoid food leakage or contamination.

Impact resistance and wear resistance: Compared to low-density polyethylene (LDPE), HDPE has tighter molecular chain winding and higher mechanical strength. Its tensile strength can reach 20-30 MPa, and its impact strength (notch impact strength) is 20-50 kJ/m ². The turnover boxes and trays made of HDPE can withstand stacking weight (usually 5-8 layers) and collisions during transportation, and are not easily damaged; At the same time, its surface hardness is relatively high (Shore D hardness 60-70), and its wear resistance is better than PP (polypropylene), making it suitable for repeatedly used food utensils such as kitchen cutting boards and buckets.

Strong chemical corrosion resistance: HDPE is stable to most common chemicals in food processing, and can withstand concentrations below 50% of sulfuric acid, hydrochloric acid, as well as alkaline solutions such as sodium hydroxide and sodium carbonate. It also does not react with food additives such as ethanol and glycerol, making it suitable for use in components of food processing equipment (such as conveying pipelines and cleaning tanks) to avoid corrosion by acidic and alkaline cleaning agents during processing.

3. Processing and cost advantages: flexible adaptation to diverse food carriers

The food industry has diverse requirements for packaging and utensils, such as films, containers, pipes, and sheets. HDPE has strong processing adaptability and controllable costs, which can meet the needs of enterprises of different scales

Flexible processing technology: HDPE can be processed through various processes such as blow molding, extrusion, injection molding, and hollow forming. Blow molding technology can produce large capacity food containers ranging from 500mL to 20L (such as edible oil barrels and soy sauce barrels); Extrusion technology can produce films (such as cling film, shopping bags) and pipes (such as conveying pipelines); The injection molding process can produce small utensils (such as meal box covers and turnover box accessories), and can even be compounded with materials such as EVOH (ethylene vinyl alcohol copolymer) through co extrusion technology to enhance barrier properties (such as oxygen and water resistance), making it suitable for high demand food packaging.

Cost and recycling balance: The raw material cost of HDPE is lower than that of PET (polyethylene terephthalate), PP and other materials, and the processing energy consumption is lower (melting point is about 130-135 ℃, lower than PP's 160-170 ℃), which can reduce the production cost of enterprises; At the same time, HDPE has strong recyclability, and the recycled HDPE can be used to make turnover boxes and trays for non direct contact food, or purified and reused for food packaging (subject to compliance standards for recycled materials), in line with the green trend of "reducing plastic and carbon emissions" in the food industry.

2、 Application of HDPE in the field of food packaging: covering from end consumption to industrial storage

Packaging is the most core application scenario of HDPE in the food industry, accounting for over 70%. According to the type of food (liquid, solid, frozen, fresh) and packaging function (barrier, seal, portable), HDPE packaging can be divided into three sub categories: container, film, and sealed and shaped packaging. Each application is optimized and designed for specific food needs.

1. Container applications: Suitable for the storage needs of liquid and high viscosity foods

HDPE containers have become the mainstream packaging choice for liquid food, sauces, edible oils, and other products due to their good impact resistance, barrier properties, and the ability to be made into different capacity specifications. Typical applications include:

Large capacity liquid food containers: HDPE is the preferred material for 2.5L-20L large capacity packaging in high-frequency consumption liquid food fields such as edible oil, soy sauce, vinegar, cooking wine, etc. For example, mainstream domestic edible oil brands (such as Jinlongyu and Luhua) use blow molded HDPE material for their 5L edible oil barrels, which has the advantages of strong impact resistance and is not easily broken even during transportation, avoiding oil leakage; Secondly, it has moderate barrier properties, which can delay the contact between edible oil and air, reduce oxidation and rancidity (some high-end edible oil barrels may use HDPE/EVOH co extrusion structure to further enhance oxygen resistance); Thirdly, the thread strength of the bottle mouth is high, and it can be repeatedly opened when paired with a sealing cap, making it suitable for long-term use in households. In addition, large capacity yogurt buckets (1L-2L) and plant-based protein beverage buckets (such as soy milk and walnut milk) in the dairy industry are also commonly made of HDPE, as their odorless properties do not affect the milk aroma of dairy products.

Sauce and semi-solid food containers: For high viscosity foods such as tomato sauce, bean paste, peanut butter, etc., the "scratch resistance" and "easy demolding" characteristics of HDPE containers are particularly important. These types of containers are usually injection molded, with smooth inner walls and less residue of sauce. The oil resistance of HDPE can prevent the penetration of grease in the sauce into the container; At the same time, the container mouth can be designed with a wide mouth or a structure with a squeeze nozzle for easy access (such as squeeze tomato sauce bottles). For example, the small capacity (300g) packaging of Heinz tomato sauce and the 500g packaging of Lee Kum Kee Douban sauce are both made of HDPE material, and some containers will be made opaque with color masterbatch to prevent the sauce from spoiling due to light exposure.

Infant and toddler food auxiliary containers: In the field of infant and toddler food, HDPE is often used to make auxiliary food storage tanks, milk powder spoons, etc. due to its high safety. For example, some brands of infant Rice noodles cans (200g-400g capacity) are made of HDPE, which are lightweight and fall resistant, suitable for parents to carry; The milk powder spoon is made through injection molding technology, with a smooth and burr free surface to avoid scratching the baby's mouth. It is also made of HDPE, which is resistant to high temperatures (up to 80 ℃ in the short term) and can withstand hot water cleaning, meeting the hygiene requirements of infant and toddler products.

2. Film applications: Suitable for the protection needs of fresh, frozen, and portable food

HDPE film is made through extrusion technology and can be divided into single-layer film and composite film. Depending on the thickness and performance differences, it is applied in fresh food preservation, frozen packaging, food shopping bags and other scenarios:

Fresh food cling film and wrapping film: HDPE cling film (usually 10-20 μ m thick) has good breathability and moisture permeability, which can form a "microenvironment" on the surface of fresh meat, vegetables, and fruits - allowing a small amount of oxygen to enter, delaying anaerobic spoilage of food, and also discharging some water vapor to avoid condensation water causing food mold. Compared with PVC (polyvinyl chloride) cling film, HDPE cling film does not contain plasticizers, has higher safety, and has good low temperature resistance. It can be used for refrigerator storage (0-4 ℃); The fresh food wrapping film (thickness 30-50 μ m) used in some supermarkets is a blend of HDPE and LDPE film, which combines the strength of HDPE and the flexibility of LDPE. When wrapped on the surface of meat and cooked food, it is not easily damaged and can block external bacterial contamination.

Packaging bags for frozen food: packaging bags for frozen food such as quick-frozen dumplings, quick-frozen rice dumpling, frozen steak (storage temperature -18 ℃ to -25 ℃), mostly using HDPE single film or HDPE/LLDPE (linear low-density polyethylene) composite film. The core advantage of this type of film is its low temperature resistance - it can still remain soft at -25 ℃, will not crack due to freezing, and has strong puncture resistance, which can prevent ice crystals in frozen food from puncturing the packaging bag; At the same time, HDPE film has good printability and can clearly print information such as food ingredients and shelf life. The printing ink is not easily peeled off, which meets the safety requirements of food labels. For example, frozen dumpling packaging bags from brands such as Sanquan and Nianxiang are mostly made of HDPE material on the outer layer and LLDPE on the inner layer, balancing strength and sealing.

Food shopping bags and portable bags: Food shopping bags (thickness ≥ 20 μ m) used in supermarkets and convenience stores, as well as portable bags for bread and pastries, are mostly made of HDPE material. HDPE shopping bags have the characteristics of light weight (10% -15% lighter than PP bags under the same thickness), strong load-bearing capacity (can withstand 5-10kg weight), good tear resistance, and can be recycled (some biodegradable HDPE shopping bags can also slowly degrade in natural environments); Bread bags often use HDPE microporous film, which creates tiny breathable holes on the film to release the carbon dioxide produced by bread fermentation, avoiding bloating inside the bag and preventing bread spoilage, while maintaining the soft texture of the bread.

3. Sealing and shaped packaging applications: adapted to the customized needs of special foods

Some foods, such as nuts, tea, and coffee, require higher sealing and barrier properties for packaging. HDPE can be customized into packaging through composite or special molding processes with other materials

Nut and dried goods sealed jar: Dried goods such as nuts, melon seeds, and red dates are prone to moisture absorption and mold growth, and have high oil content that is prone to oxidation, requiring high sealing packaging. HDPE sealed cans are usually injection molded and equipped with silicone sealing rings, which can achieve dual protection against moisture and oxidation. The can body is opaque, which can avoid the loss of nutrients in dry goods caused by light exposure; Some brands also add desiccants to the cans, and the chemical stability of HDPE can prevent the desiccants from reacting with the container, ensuring food safety. For example, the nut canned products of Three Squirrels and Liangpinpuzi are partially made of HDPE material, which is suitable for long-term home storage.

Composite packaging of coffee and tea: Foods such as coffee powder, black tea, and green tea are extremely sensitive to oxygen and moisture. HDPE is often compounded with EVOH (oxygen barrier layer) and aluminum foil (light and oxygen barrier layer) to create multi-layer composite packaging (such as HDPE/EVOH/HDPE, HDPE/aluminum foil/LLDPE). Among them, HDPE serves as the outer and inner layers, providing mechanical strength and heat sealing properties, while EVOH or aluminum foil serves as the intermediate barrier layer, preventing oxygen and moisture from entering and extending the shelf life of food. For example, the small bag packaging (single pack) of instant coffee is mostly made of HDPE on the inner layer and a composite layer of HDPE and aluminum foil on the outer layer, which can ensure that the coffee powder maintains its flavor during the shelf life; HDPE/aluminum foil composite film is commonly used for vacuum packaging of tea, which can further delay tea oxidation under vacuum conditions.

3、 The application of HDPE in the field of food utensils and processing aids: a scenario extension from production to consumption

In addition to packaging, HDPE is widely used in food utensils (tools that come into direct contact with food) and processing auxiliary equipment (supporting components in the production process). Its durability and safety make it an ideal material to replace metal and glass.

1. Food utensils applications: adapted to the direct contact needs of households and businesses

HDPE appliances are widely used in the home kitchen and catering industry due to their impact resistance, easy cleaning, and no odor. Typical products include:

Home kitchen utensils: The most common one is HDPE kitchen cutting board, which has the advantages of: firstly, moderate hardness, no knife marks like wooden cutting boards (reducing bacterial growth), and no tool wear like glass cutting boards; Secondly, it has good water resistance, is not easy to absorb water and mold, and can withstand hot water cleaning at 80 ℃, making it convenient for disinfection; Thirdly, it is lightweight, 30% -40% lighter than wooden cutting boards, making it more convenient to use. In addition, HDPE can also be used to make food grade water buckets (such as the inner liner of water dispenser buckets), rice basins, storage boxes, etc. The HDPE inner liner of water dispenser buckets needs to meet higher hygiene standards (such as the "migration limit" requirements in GB 4806.11-2024) to ensure the safety of drinking water.

Commercial and disposable utensils: In the catering industry, HDPE can be used to make disposable cold drink cups (such as milk tea cups, cola cups), yogurt cup lids, meal boxes, etc. Disposable HDPE cold drink cups have good low temperature resistance (can hold ice cream or cold drinks at -5 ℃), are not easily deformed, and can print brand logos on the surface; The yogurt cup lid is made through injection molding technology, which has good sealing and can prevent yogurt leakage. It is also easy to open (just tear it off). In addition, tools such as food bowls, spoons, and shovels in commercial kitchens are often made of HDPE, which is wear-resistant, impact resistant, can be used repeatedly for a long time, and has a lower cost than stainless steel utensils.

Infant and toddler food utensils: HDPE is one of the mainstream materials for infant and toddler food bowls and water cups. For example, baby food bowls are usually made of HDPE material, which is characterized by strong drop resistance (even if dropped from the table, it is not easy to break, avoiding scratching the baby); The second is high temperature resistance (can withstand hot washing with 100 ℃ water or washing in a dishwasher); Thirdly, it has no odor and will not affect the taste of complementary foods. Some high-end infant and toddler equipment will also use "antibacterial HDPE" (with added silver ion antibacterial agent) to further reduce bacterial growth and meet the hygiene requirements of infant and toddler products.

2. Application in the field of processing assistance: supporting the safety and efficiency of food production

In industrial settings such as food processing plants, slaughterhouses, and dairy factories, HDPE's corrosion resistance and impact resistance make it a core material for processing equipment and logistics auxiliary components. Its main applications include:

Food turnover boxes and pallets: From raw material transportation to finished product distribution, a large number of turnover boxes and pallets are required for food, and HDPE is the preferred material for such products. HDPE turnover boxes have the following advantages: firstly, they have strong impact resistance, and are not easily damaged even if they collide or stack (usually 6-8 layers can be stacked) during logistics transportation, avoiding leakage of raw materials or finished products; Secondly, it has good low temperature resistance and can be used for cold chain turnover (such as transportation of fresh meat and dairy products), without cracking due to low temperature; Thirdly, it is easy to clean and disinfect, with a smooth surface and no dead corners. It can withstand high temperature and high pressure cleaning (80-90 ℃) commonly used in food factories and chemical disinfectants (such as sodium hypochlorite solution), avoiding cross contamination. For example, the fresh milk transportation turnover boxes of large domestic dairy companies such as Yili and Mengniu are all made of HDPE material and can be reused more than 50 times, reducing logistics costs.

Food processing equipment components: HDPE can be used to make conveying pipes, valves, storage tanks, cleaning tanks, and other components during the food processing process. For example, the juice conveying pipeline in a juice processing plant uses HDPE material to avoid the migration of heavy metals that may be caused by metal pipelines (such as stainless steel), and the acid resistance of HDPE can withstand the corrosion of organic acids (such as citric acid and malic acid) in juice; The cleaning tank of the food factory is welded with HDPE sheet, which has a smooth surface and is not easy to leave food residue, making it convenient for daily cleaning and disinfection. In addition, HDPE can also be used to make food grade pump bodies, filter housings, etc., ensuring food contact safety during processing.

Cold chain and storage auxiliary components: In cold chain warehouses, HDPE can be used to make shelf partitions, floor panels, insulation box linings, etc. For example, the partitions of cold chain shelves are made of HDPE sheet, which has good low temperature resistance (maintaining strength even at -40 ℃) and anti slip surface to prevent goods from slipping off; HDPE insulation box lining has good thermal insulation, which can be used together with insulation materials (such as polyurethane foam) to extend the heat preservation time of cold chain food (such as fresh e-commerce distribution insulation box, the lining is mostly HDPE).

4、 The application trend of HDPE in the food industry: greening, functionalization, and high-end

With the upgrading of the demand for "safety, green, and efficiency" in the food industry, the application of HDPE is no longer limited to traditional scenarios, but is developing towards three directions: recycling, functional modification, and high-end customization, further expanding its application boundaries in the food field.

1. Compliant application of recycled HDPE: promoting circular economy in food packaging

Under the global trend of "reducing plastic and carbon emissions", the application of recycled HDPE (rHDPE) in the food industry has become a hot topic. At present, through advanced recycling processes such as chemical depolymerization and physical purification, rHDPE can meet food contact grade standards and be used to make packaging for non direct contact food (such as outer films, turnover boxes), or packaging for direct contact food (such as edible oil drums, yogurt bottles) after strict testing. For example, the European Union has approved rHDPE for use in contact with some liquid foods (such as drinking water and edible oil), and China has also specified the requirements for the use of recycled plastics in GB 4806.11-2024. In the future, rHDPE will become an important raw material for food packaging, helping the food industry achieve its goals of "carbon peak and carbon neutrality".

2. Functional modified HDPE: Suitable for the special needs of high demand foods

To meet the packaging needs of high-end foods such as organic and functional foods, HDPE can be modified to obtain more functions, such as:

Antibacterial HDPE: Packaging or utensils made with food grade antibacterial agents (such as silver ions and zinc oxide) can inhibit the growth of pathogenic bacteria such as Escherichia coli and Staphylococcus aureus, and are suitable for perishable foods such as fresh meat and infant food;

High barrier HDPE: By blending or co extruding with materials such as EVOH and MXD6 (polyhexamethylenediamine), the oxygen and water barrier properties of HDPE are improved, making it suitable for foods such as coffee, tea, and nuts that require high barrier properties and extending its shelf life;

Degradable HDPE: By adding biodegradable components such as starch and polycaprolactone to HDPE, the resulting packaging can slowly degrade in natural environments, reducing plastic pollution and making it suitable for disposable food packaging such as shopping bags and meal boxes.

3. High end customized applications: adapted to the needs of the segmented food industry

With the subdivision of the food industry (such as pre packaged meals, meal replacement foods, and low-temperature dairy products), the application of HDPE is developing towards customization. For example, the pre packaged food industry requires packaging that is both microwave heatable and highly sealed. HDPE can be modified to improve its high temperature resistance (short-term resistance to 120 ℃) and combined with PP to create microwave heatable meal boxes; Meal replacement foods (such as protein powder and meal replacement milkshakes) require "small capacity+portable" packaging. HDPE can be made into small capacity sealed cans of 10-30g through injection molding technology, making it convenient for consumers to carry around. In addition, HDPE can also be combined with other materials such as paper and aluminum foil to create "plastic paper composite packaging" that balances environmental friendliness and functionality, and is suitable for the brand positioning of high-end food.

5、 Summary: HDPE - the cornerstone material for safety and efficiency in the food industry

HDPE, with its core advantages of "safety compliance, strong environmental resistance, and flexible processing", is deeply integrated into the entire chain of the food industry, from cling film and edible oil drums in home kitchens, to turnover boxes and conveyor pipelines in food factories, to frozen packaging bags and insulated boxes in cold chain logistics. Its characteristics of no harmful substance migration, low temperature resistance, and impact resistance ensure the safety of food from production to consumption; Its low-cost and recyclable characteristics are suitable for the efficiency and green development needs of the food industry. In the future, with the upgrading of regeneration technology and modification processes, HDPE will play a more important role in the food industry, not only as a "basic packaging material", but also as a key support for promoting the safe, green, and high-end development of the food industry.