The application of PP in the food industry: deep integration of safety cornerstone and diverse scenarios

PP (polypropylene), as a universal thermoplastic polymer, has become a key material in the entire food industry chain from production, packaging to consumption due to its excellent food contact safety, high temperature resistance, and processing flexibility. Its compliance has been certified by authoritative standards such as China's GB 4806.7-2024 "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 is widely used in various fields such as food packaging, contact equipment, and processing aids. With the tightening of environmental policies and technological upgrades, the development of modified PP, recycled PP, and bio based PP is driving them towards functionalization and greenization, which deeply meets the safety and sustainable needs of the food industry.

1、 The core feature of PP adaptation to the food industry: precise matching of performance and demand

The popularity of PP in the food industry is essentially due to its highly compatible physical and chemical properties with the core needs of food storage, processing, and consumption, especially in the four dimensions of safety, high temperature resistance, chemical stability, and processing adaptability, forming irreplaceable advantages that far exceed traditional plastics such as PS (polystyrene) and PVC (polyvinyl chloride).

1. Food contact level safety: the basic guarantee for risk-free migration

The primary requirement for food contact materials is "not harmful to human health", and PP performs outstandingly in this dimension:

Stable molecular structure: The PP main chain is a saturated carbon carbon bond with no easily breakable functional groups. At conventional operating temperatures (-20 ℃ to 120 ℃), it will not migrate harmful components such as plasticizers and heavy metals into food. Even long-term exposure to acidic foods (such as kimchi and fruit juice), alkaline foods (such as soda water), or oily foods (such as meat and cooking oil) can maintain chemical inertness and avoid affecting food flavor or causing health risks.

Odorless and low adsorption: PP has a high crystallinity (usually 50% -70%), tightly arranged molecules, low surface porosity, no odor, and is not easy to adsorb aroma components in food - this is crucial for volatile flavor foods such as coffee, tea, and spices, as it can avoid packaging "flavor absorption" and loss of food flavor.

Full compliance coverage: Global mainstream food regulatory agencies classify PP as a "safe food contact material". China's GB 4806.7-2024 specifies specific migration limits (SML) and total migration limits (OML) for PP, and EU No. 10/2011 allows PP 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. Outstanding high temperature resistance: suitable for heating and sterilization scenarios

Most plastics are prone to deformation and release harmful substances when exposed to high temperatures, while PP's high temperature resistance precisely solves the "heating pain point" in the food industry:

Melting point and temperature adaptation: PP has a melting point of about 160-170 ℃, and can be continuously used at a temperature of 100-120 ℃. It can withstand high temperatures of up to 130 ℃ in the short term. This allows it to directly hold freshly cooked hot food (such as rice, hot soup), as well as adapt to pasteurization (60-85 ℃), steam disinfection (100 ℃) in food processing, and even microwave heating (choose pure PP products without plasticizers or fillers to avoid the risk of modified PP precipitation due to additives).

Microwave heating safety: PP is one of the few plastics that can be safely used in microwave ovens. During the heating process, it will not decompose due to temperature rise and will not react with food. For example, household PP microwave oven meal boxes and takeaway PP heating meal boxes can meet consumers' "buy and heat" needs, solving the safety hazards of PS meal boxes "microwave deformation and styrene release".

3. Excellent chemical stability and mechanical properties: suitable for complex food environments

The storage and transportation environment in the food industry is complex, and the corrosion and impact resistance of PP can ensure the reliability of food packaging and utensils

Strong chemical corrosion resistance: PP has excellent tolerance to acids, alkalis, salts, and most organic solvents (such as ethanol, glycerol, edible oil, and other common food ingredients). It will not dissolve due to contact with soy sauce, vinegar, tomato sauce, and other seasonings, nor will it be corroded by cleaning agents (such as sodium hydroxide solution) in food processing. It is suitable for long-term storage of oily and acidic foods.

Good impact resistance and toughness: PP has an impact strength (notch impact strength) of 2.5-5kJ/m ², which is superior to brittle PS (1.5-2kJ/m ²). The resulting lunch boxes and containers are less prone to cracking when dropped; At the same time, the tensile strength of PP can reach 20-30 MPa, combining rigidity and toughness, which can meet the load-bearing requirements of packaging and facilitate the processing into lightweight products (such as PP film and thin-walled lunch boxes).

4. Processing flexibility and cost advantages: adapted to large-scale production

The food industry has strict requirements for the "processing efficiency" and "cost control" of materials, and the characteristics of PP precisely meet the needs of large-scale production

Wide process adaptability: PP can be made into different forms of products through various processes such as injection molding, blow molding, extrusion, thermoforming, spinning, etc. Injection molding can produce lunch boxes and bottle caps; Blow molding can produce bottles and cans; Extrusion can produce films and pipes; Thermoforming can be used to produce trays and vacuum packaging, covering almost all forms of demand in the food industry.

Cost and energy consumption are controllable: the raw material cost of PP is lower than that of PET (polyethylene terephthalate), PC (polycarbonate) and other materials, and the processing energy consumption is lower (the molding temperature is 30-50 ℃ lower than PET), which can reduce the production cost of enterprises; Meanwhile, the density of PP is only 0.90-0.91g/cm ³, making it one of the lightest types of food contact plastics available, which can further reduce transportation energy consumption.

2、 The core application of PP in the field of food packaging: covering the storage needs of all categories of food

Packaging is the main application scenario of PP in the food industry, accounting for more than 60%. According to the food form (liquid, solid, semi-solid) and packaging function (preservation, sealing, and portability), it can be divided into three sub categories: film, container, blister, and foam. Each type of application is optimized for the characteristics of food.

1. Film packaging: the core of freshness preservation for fresh and pre packaged foods

PP film is made through extrusion technology and can be divided into CPP (cast polypropylene film), BOPP (biaxially oriented polypropylene film), IPP (blown polypropylene film), which are suitable for the preservation and packaging needs of different foods

CPP film: CPP film is made through the casting process and has the characteristics of softness, heat resistance, and good sealing. It can directly contact food and is the core packaging material for fresh and cooked food. For example, fresh meat and cooked food in supermarkets are often wrapped in CPP plastic wrap, which has good breathability and can maintain food respiration, delaying spoilage; CPP film can also be combined with aluminum foil to make "cooking bags" (such as pre packaged vegetables and miscellaneous grain packaging), which can withstand high temperature cooking at 121 ℃ and achieve the integration of "packaging sterilization consumption".

BOPP film: After biaxial stretching, the strength of BOPP film increases by 3-4 times, with high transparency (over 90% light transmittance), good glossiness, and excellent printability. It is commonly used for the outer packaging of biscuits, potato chips, chocolate, and candies. For example, the outer layer of potato chip packaging bags is mostly made of BOPP film, printed with brand patterns and nutritional information. The inner layer is made of composite PE (polyethylene) film to enhance sealing and prevent potato chips from becoming damp and soft; BOPP film can also be made into "aluminum plated film", which enhances oxygen and light resistance through the aluminum plating layer, and is used for packaging coffee and tea, extending the shelf life.

IPP film: IPP film is made through blow molding process, with good flexibility and strong tear resistance, commonly used in food shopping bags, bread bags, etc. For example, the bread bags in bakeries are mostly made of IPP film, which can directly contact the bread and have the brand logo printed on the surface; IPP shopping bags have strong load-bearing capacity (able to withstand 5-10kg) and can be recycled, gradually replacing traditional plastic bags.

2. Container packaging: storage carriers for liquid and semi-solid foods

PP containers are made through injection molding or blow molding processes, with various shapes, suitable for the storage and sales of liquid and semi-solid foods such as beverages, sauces, dairy products, etc

Injection molded containers: PP containers formed by injection molding have uniform wall thickness and stable dimensions, commonly used for yogurt cups, jelly cups, sauce jars, freshness boxes, etc. For example, the instant yogurt cups and jelly cups in supermarkets are made of injection molded PP products, which are lightweight, drop resistant, and easy to open; The household PP fresh-keeping box is designed with a sealed buckle to prevent moisture and odor, and can be heated in a microwave, making it suitable for storing household leftovers; Sauce jars (such as Douban sauce and peanut butter jars) utilize the oil resistance of PP to prevent sauce from penetrating the container, and the wide mouthed design is easy to access.

Blow molded containers: PP containers formed by blow molding can be used to make larger capacity bottles and barrels, which are used for liquid foods such as drinking water, juice, and edible oil. For example, some brands' 1-5L drinking water bottles are made of blow molded PP material, which is lightweight and impact resistant, with a transportation damage rate of less than 0.5%; PP edible oil drums, due to their high temperature resistance, can withstand hot oil during filling (60-80 ℃) and are not easily deformed, making them more suitable for long-term household use than PET oil drums.

3. Blister and foam packaging: protection of fresh and fragile food

PP is made into blister packaging by thermoforming or foam packaging by foaming, which is mainly used for protection of fresh, fruit, eggs and other vulnerable foods:

PP vacuum forming tray: PP vacuum forming tray is made through thermoforming process, and can be customized with grooves according to the shape of the food to fix the position of the food and avoid collision damage during transportation. For example, eggs, strawberries, and cherries in supermarkets are commonly packaged in PP vacuum formed trays, with grooves designed to fit the product shape and high transparency, making it convenient for consumers to choose; PP vacuum tray can also be heat sealed with BOPP film to form a sealed packaging, enhancing the freshness preservation effect.

PP foam packaging: PP foam (EPP, foamed polypropylene) has the characteristics of light weight, good cushioning and high temperature resistance, and is commonly used for cold chain transportation packaging of high-end fresh food (such as seafood and imported fruit). For example, the commonly used EPP foam box for seafood distribution has better thermal insulation performance than traditional EPS (expanded polystyrene) foam, and can be reused and degraded, meeting environmental requirements; EPP foam can also be made into egg holder and fruit holder to protect the product from being squeezed through the buffer structure.

3、 The application of PP in food contact utensils and processing aids: extending from consumption to production scenarios

In addition to packaging, PP, with its characteristics of "high temperature resistance, easy cleaning, and impact resistance", is widely used in food contact utensils and processing auxiliary equipment, becoming an important link between food production and consumption.

1. Food contact utensils: direct use scenarios for household and commercial use

PP utensils are widely used in home kitchens, catering industries, and food processing plants, covering the entire process from cooking to consumption:

Home kitchen appliances: The most common ones are PP microwave lunch boxes, rice cooker liners (PP coated), chopsticks, cutting boards, water filter baskets, etc. Among them, the microwave lunch box needs to use "random copolymer PP" to improve high temperature stability and avoid heating deformation; PP chopsticks are less prone to mold (better than wooden chopsticks), easy to clean, and resistant to wear and tear; PP cutting board has moderate hardness and will not wear down cutting tools like glass cutting board, nor will it breed bacteria like wooden cutting board.

Commercial catering utensils: Disposable PP meal boxes, soup bowls, straws, spoons, etc. in the catering industry are the core utensils for takeout and fast food. Disposable PP meal boxes can withstand hot food at 100 ℃ and are not easily deformed or leaked, making them safer than PS meal boxes; PP straws replace traditional PVC straws, do not contain plasticizers, can tolerate hot drinks (below 60 ℃), and meet the requirements of the "plastic ban"; Food bowls, spoons, shovels and other tools in commercial kitchens are also commonly made of PP, which is impact resistant and cost-effective, suitable for bulk procurement.

Infant and toddler food utensils: PP has become the preferred material for baby food bowls and bottle accessories (such as straws and nipple bases) due to its high safety. The baby food bowl is made of "antibacterial PP" (added with silver ion antibacterial agent), which can inhibit bacterial growth; The bowl body is drop resistant to prevent babies from falling and breaking when using it; Some complementary food bowls also come with suction cups, which are fixed on the table to prevent tipping over and are suitable for use in infants and young children.

2. Processing assistance field: support and guarantee for food production

In industrial settings such as food processing plants, slaughterhouses, and dairy factories, PP's corrosion resistance and durability make it a core material for processing equipment and logistics auxiliary components

Logistics turnover equipment: PP made turnover boxes, pallets, and logistics baskets are the core tools for transporting food raw materials and finished products. PP turnover boxes have strong impact resistance, can stack 6-8 layers, and are resistant to low temperatures (-20 ℃ without cracking), suitable for cold chain logistics (such as fresh and frozen food transportation); PP pallets have strong load-bearing capacity (able to withstand 1-2 tons) and a non slip surface to prevent goods from slipping off; Logistics baskets are used for sorting fruits and vegetables, with good breathability to prevent them from accumulating and spoiling.

Processing equipment components: PP can be used to produce conveying pipelines, valves, storage tanks, cleaning tanks, and other components for food processing equipment. For example, the juice conveying pipeline in the juice processing plant is made of PP material to avoid the migration of heavy metals that may be caused by metal pipelines, and its acid resistance can withstand the corrosion of organic acids in juice; The food cleaning tank is made of PP board welded together, with a smooth surface and less food residue, making it convenient for high-temperature cleaning and disinfection; PP storage tanks are used to store soy sauce, vinegar and other sauces, with good corrosion resistance and lower cost than stainless steel storage tanks.

Filtering and separation materials: PP made filter mesh and filter cloth can be used for raw material screening and separation in food processing. For example, flour processing plants use PP sieves to screen flour and remove impurities; During the refining process of edible oil, PP filter cloth is used to filter oil residue and improve the purity of the oil; PP filter material is acid and alkali resistant, easy to clean, reusable, and reduces production costs.

4、 The development challenges and future trends of PP in the food industry

Although PP has significant advantages, it still faces challenges such as modification costs and recycling in practical applications. In the future, it will develop towards functionalization, greening, and high-end direction, further expanding its application boundaries.

1. Current challenge: Balancing performance and cost constraints

Insufficient low-temperature toughness: Ordinary PP is prone to brittleness below -10 ℃, which affects the service life of cold chain turnover boxes and frozen food packaging. Modification is required by adding toughening agents (such as EPDM ternary ethylene propylene rubber) to improve low-temperature performance, but it will increase material costs by about 10% -20%.

Limited barrier properties: PP has lower barrier properties against oxygen and water vapor than materials such as PET and EVOH. When used alone for high preservation demand foods (such as fresh meat and seafood), it needs to be compounded with other materials, increasing process complexity and cost.

Purity control of recycling: During the PP recycling process, impurities such as PE and PS are easily mixed in, and the properties of the recycled material (such as tensile strength and impact strength) will decrease by 10% -30%, making it difficult to directly use for food grade packaging. Purification and modification are needed to restore performance and increase recycling costs.

2. Development trend: Technology upgrade drives application upgrade

Functional development of modified PP: By chemical modification or adding functional fillers, special materials such as "high barrier PP", "antibacterial PP", and "degradable PP" are developed. For example, nano composite PP made by adding montmorillonite can increase the oxygen barrier rate by 5-10 times and can be used for fresh meat packaging; Antibacterial PP with added zinc oxide nanoparticles, with an antibacterial rate of 99%, used for baby tableware; Degradable PP with added starch can degrade in natural environments for 6-12 months and is used for disposable food packaging.

The food grade application of recycled PP: With the upgrading of recycling technology (such as near-infrared spectroscopy sorting and melt filtration purification), the purity of recycled PP continues to improve and can be used for food grade packaging (such as turnover boxes and outer films that do not directly contact food). The European Union has approved the use of recycled PP for contact with certain foods, and China has also specified the requirements for the use of recycled plastics in GB 4806.7-2024. It is expected that the use rate of recycled PP in the food industry will reach 25% by 2025.

Large scale production of bio based PP: Bio based PP uses renewable resources such as corn and sugarcane as raw materials, with a carbon footprint 40% -60% lower than traditional PP. At present, international companies such as BASF and Dow Chemical have achieved mass production of bio based PP for food packaging and utensils. In the future, with the maturity of technology, costs will gradually decrease, and it is expected to replace more than 30% of traditional PP

Integrated solution: PP enterprises will transform from "material suppliers" to "solution providers", providing an integrated solution of "packaging design material supply processing services" based on food characteristics. For example, in the pre packaged food industry, we provide a complete set of packaging including PP steaming bags, PP vacuum trays, and sealing films to meet the needs of cold chain transportation and heating for consumption.

5、 Summary: PP - the core support for safety and efficiency in the food industry

From microwave lunch boxes and fresh-keeping boxes in home kitchens, to fresh plastic wrap and yogurt cups in supermarkets, to turnover boxes and conveyor pipelines in food factories, PP is deeply integrated into the entire food industry chain with its core advantages of "safety compliance, high temperature resistance, and easy processing". Its characteristic of no harmful substance migration ensures food consumption safety; High temperature resistance solves the pain points of heating and sterilization in the industry; The flexibility of processing and cost advantages are adapted to the demand for large-scale production. In the future, with the upgrading of modification and recycling technologies, PP will play a more important role in the food industry, not only as a "basic material", but also as a key force in promoting the safe, green, and efficient development of the food industry.