Can Plastic Picnic To-Go Boxes Be Placed in a Sterilizer?

I. Basic Characteristics and Heat Resistance of the Three Materials

1.1 PP (Polypropylene) Material Characteristics

1.2 MFPP (Modified Filled Polypropylene) Material Characteristics

1.3 PET (Polyethylene Terephthalate) Material Characteristics

II. Suitability Analysis of Three Materials in Different Sterilization Cabinets

2.1 Suitability of PP Material picnic to-go boxes in Sterilization Cabinets

• Deformation Risk: Although PP's theoretical temperature resistance reaches 120℃, under sustained high temperatures above 125℃, some PP picnic to-go boxes may experience slight deformation, especially thinner boxes or those with complex structures.
• Additive Leaching: Most commercially available PP products contain various additives. At high temperatures, these additives may leach out more rapidly, producing odors or potentially harmful substances.
• Microplastic Release: Recent research has found that even microwave-safe PP materials release large amounts of microplastics at high temperatures. Heating a PP food container in a microwave for 3 minutes can release 4.22 million microplastic particles and 2.1 billion nanoplastics per square centimeter. This release may be even more pronounced in a high-temperature sterilizer at 125°C.

• Choose reliable PP food containers labeled "suitable for high-temperature sterilization."
• Avoid using excessively thin or complex PP food containers.
• Control the sterilization time; it should not exceed 15 minutes.
• Check the food containers for deformation or odor after sterilization.
• Replace PP food containers regularly; it is recommended to replace them every 6-8 months.

• Ventilate promptly after ozone disinfection to reduce ozone residue
• Avoid prolonged exposure of PP food containers to ozone environments
• Regularly check the appearance and performance changes of the PP food containers

2.2 Suitability of MFPP Food Containers in Sterilization Cabinets

• Choose MFPP products labeled "suitable for high-temperature sterilization"
• Avoid using them in environments exceeding 130℃
• Control sterilization time to avoid prolonged high-temperature exposure
• Performance in UV and Ozone Sterilization Cabinets

2.3 Suitability of PET Food Containers in Sterilization Cabinets

• Severe Deformation: PET shrinks and softens rapidly above 70℃, and at 120℃, it will completely lose its shape, becoming a lump of plastic waste.
• Release of Harmful Substances: At high temperatures, PET releases trace amounts of the heavy metal antimony and small molecules harmful to the human body. These substances may contaminate other tableware, causing long-term health effects.
• Damage to Sterilization Cabinet: Melted PET may stick to the inner wall of the sterilization cabinet or the heating element, causing equipment damage and even safety accidents.
• Production of Toxic Gases: PET releases toxic gases during high-temperature decomposition, which may contain carcinogens.

• Deformation Risk: PET's maximum heat resistance is 70℃, and some UV sterilizers may approach this limit during operation. If the sterilization time is too long or the lamps age, causing localized temperature increases, the PET food container may still experience slight deformation.
• UV Aging: UV light accelerates the aging process of PET, causing the material to become brittle and yellow. Long-term use of UV sterilization may shorten the lifespan of the PET 3-compartment to-go boxes.
• Microcrack Risk: PET material is inherently brittle, and prolonged UV exposure may cause microcracks. These cracks can become hiding places for bacteria and viruses, negatively impacting the sterilization effect.

• Choose high-quality PET food containers with appropriate thickness
• Control the disinfection time, not exceeding 20 minutes
• Avoid frequent use of UV disinfection
• Regularly check the food containers for deformation or cracks
• Performance in Ozone Disinfection Cabinets

• Accelerated aging: Ozone reacts with PET molecules in an oxidation reaction, causing the material to become brittle and discolored. Long-term exposure to ozone may cause cracks and loss of transparency on the surface of PET food containers.
• Release of harmful substances: Under the strong oxidizing effect of ozone, PET may accelerate the release of additives and residual monomers, which may be harmful to the human body.
• Performance degradation: The oxidation reaction will damage the molecular structure of PET, leading to a decrease in its mechanical properties and a shortened service life.

• Strictly control the disinfection time, not exceeding 30 minutes each time;
• Ventilate promptly after disinfection to reduce ozone residue;
• Avoid prolonged direct contact between PET food containers and ozone;
• Replace PET food containers regularly, and discontinue use immediately upon noticing signs of aging.

 

III. Material Deformation and Hazardous Substance Release Risk Assessment

3.1 Deformation Risk Assessment

3.2 Hazardous Substance Release Risk Assessment

• Additive Leakage: Most commercially available PP products contain various additives, which may leach out at high temperatures. Although the leachate levels in food-grade products are within safe limits, monitoring is still necessary.
• Microplastic Release: Recent research shows that PP releases large amounts of microplastics at high temperatures. This release may be even more severe in a 125°C high-temperature sterilizer. Studies have found that when PP food containers are filled with food at 78°C, they release approximately 12,000 microplastic particles per square centimeter within 15 minutes.
• Aging Products: PP may produce aging products during long-term use or under high-temperature conditions. Although the amount is small, it still requires attention.

• Filler Safety: Fillers such as talc and calcium powder added to MFPP are generally safe, but it is necessary to confirm that these fillers meet food contact material standards.
• Increased Latents: The presence of fillers may alter the microstructure of the material, potentially increasing the release of other substances in some cases.
• Processing Aids: MFPP may use more processing aids during production, and the behavior of these aids at high temperatures needs to be monitored.

• Heavy Metal Antimony: PET releases trace amounts of the heavy metal antimony at high temperatures, a pollutant harmful to human health.
• Residual monomers: Incompletely polymerized terephthalic acid and ethylene glycol may remain in PET, and their release will accelerate at high temperatures.
• Small molecules: PET decomposes at high temperatures, producing various small molecules, some of which may be harmful to humans.
• Microplastic release: PET generates a large amount of microplastics during deformation, which may enter food or the environment. 3.3 Long-Term Use Risk Assessment

• PP and MFPP will gradually age under long-term exposure to high temperatures, ultraviolet light, or ozone, manifesting as brittleness, yellowing, and cracking.
• PET ages the fastest, especially under high temperatures.
• Aging leads to a decline in material performance and increases the risk of releasing harmful substances.

• Decreased Heat Resistance: The heat resistance of aged materials will decrease.
• Decreased Mechanical Strength: Cracks and breakage are more likely to occur.
• Decreased Sealing Performance: The lid may no longer seal, affecting usability.
• Health Accumulation Risk: Long-term ingestion of microplastics may have health effects, although the specific effects are still under investigation.
• Long-term accumulation of harmful substances may increase health risks.