Do Disposable Plastic Food Serving Trays Affect Food Preservation?
author: Iris
2025-12-12
I. Basic Characteristics and Preservation Mechanism of PP Material
1.1 Physicochemical Properties of PP Material
PP material has excellent physicochemical properties, which directly affect its preservation effect. In terms of temperature resistance, PP material can withstand temperatures up to 120℃ and as low as -20℃, with some products even able to withstand extreme temperature ranges from -30℃ to 70℃. This wide temperature adaptability makes it suitable for both refrigerated storage and microwave heating, providing convenience for food preservation. In terms of mechanical properties, PP material has good toughness and strength, with a tensile strength ≥30MPa, making it resistant to breakage and effectively protecting food.
The thickness of PP food serving trays significantly affects their preservation performance. Commercially available PP trays are typically 0.2-2mm thick, with standard trays ranging from 1.5-3mm. Studies show that increasing thickness significantly improves tray performance: when the thickness increases from 0.5mm to 0.7mm, drop strength increases by more than 40%; for every 1cm increase in thickness, the insulation time can be extended by 1-1.5 hours. This positive correlation between thickness and performance indicates that appropriately increasing the thickness of the PP food serving tray helps improve preservation.
1.2 Food Safety Certification of PP Material
The safety of PP material in food contact applications is one of the most pressing concerns for consumers. In China, PP materials must comply with GB 4806.7-2023, the National Food Safety Standard for Plastic Materials and Articles for Food Contact. This is China's mandatory safety standard for plastic materials and articles for food contact. This standard specifies stringent requirements for raw materials, additives, physicochemical indicators, and migration limits to ensure that PP materials do not release harmful substances into food under normal use conditions.
In the international market, PP materials require multiple stringent certifications. In the United States, PP materials must comply with FDA 21 CFR 177.1520, which covers contact requirements for all food types. In the European Union, PP materials must comply with (EC) No 1935/2004 Framework Regulation and EU 10/2011 Regulation on Plastics for Food Contact. These international standards set strict limits on the migration of PP materials, such as a total migration limit of ≤10 mg/dm², ensuring their safety in food contact applications.
Actual test data show that PP materials exhibit excellent safety performance. According to the test report, the average total migration of PP samples was 4.7 mg/dm², far below the national standard limit of ≤60 mg/dm². More importantly, PP material does not contain plasticizers, and the bisphenol A migration was only 1/20th of the limit. This data fully demonstrates the safety of PP material in food contact applications. When in contact with food components such as water, acid, oil, and alcohol, PP material exhibits stable performance and extremely low leaching. Even under high-temperature conditions, the heavy metal migration is far below the national standard requirements.
1.3 Analysis of the Preservation Mechanism of PP Trays
The preservation mechanism of PP food serving trays is mainly based on its unique molecular structure and barrier properties. The structural characteristics of the PP molecular chain determine its moderate air permeability, which has a differentiated impact on the preservation of different types of food. For foods requiring a certain degree of air permeability, such as fresh fruits and vegetables, the moderate air permeability of PP trays allows for the exchange of oxygen and carbon dioxide, maintaining normal respiration in the food while preventing excessive water loss.
The water resistance and chemical stability of the PP material are crucial components of its preservation mechanism. Due to the presence of methyl side chains in the PP molecular chain, it possesses excellent hydrophobicity, effectively preventing water penetration. This property is particularly important for foods that release water easily, such as meat and seafood, as it prevents water accumulation in the tray and creates an environment conducive to bacterial growth. Simultaneously, PP material does not chemically react with food, avoiding the generation of odors and the loss of nutrients.
The preservation effect of PP trays is also closely related to their surface properties. High-quality PP trays have a smooth and flat surface, are easy to clean, and effectively reduce the adhesion of bacteria and dirt. Some high-end PP food trays for parties also employ special surface treatment technologies, such as the addition of antibacterial agents and anti-fogging coatings, to further enhance preservation effects. For example, food serving trays containing MEIBOSS inorganic silver antibacterial agent achieve a 99.6% inhibition rate against Staphylococcus aureus, and the antibacterial performance decays by less than 5% after 50 washes.
II. Preservation Effect of PP Trays on Different Food Types
2.1 Preservation Effect on Fresh Meat
PP trays demonstrated excellent preservation effects on fresh meat, primarily due to their moderate permeability and excellent chemical stability. According to experimental data, fresh meat packaged in PP trays had a shelf life extended by 2 days compared to traditional foam trays at 0-4℃, and the total bacterial count decreased by 40%. This significant improvement is mainly attributed to the better gas barrier properties and antibacterial performance of the PP material.
In a specific meat preservation experiment, researchers conducted a 7-day storage test on chicken breast. The results showed that chicken samples with an initial total bacterial count of 4.17 log CFU/g exceeded the acceptable limit (7.00 log CFU/g) on day 5 when stored in PP containers. In contrast, chicken samples using antibacterial packaging materials (such as films containing silver ions or SANAFOR antibacterial agents) maintained acceptable levels for up to 7 days. This indicates that although PP food serving trays themselves have limited antibacterial properties, proper packaging design and temperature control can still effectively extend the shelf life of meat.
The impact of PP trays on meat preservation is also reflected in their control over changes in meat quality. Experimental data show that under 4℃ storage conditions, the pH value of chicken in PP containers increased from an initial 6.15±0.06 to 7.09±0.03 on day 7, while the pH value of samples using antibacterial packaging showed a smaller increase. Changes in pH value reflect the freshness of meat; excessively high pH values can lead to discoloration and off-odors. While PP trays cannot completely prevent this change, they still have certain advantages compared to other materials.
It is worth noting that the thickness and structural design of PP food trays for parties have a significant impact on meat preservation. Thicker PP food serving trays (e.g., 2-4mm thick) have better mechanical strength and insulation properties, better protecting meat from damage during transportation and storage. Meanwhile, the airtight design of the PP tray is also crucial. Good sealing performance prevents odor leakage and the entry of external contaminants, further enhancing the preservation effect.
2.2 Fruit Preservation Effect
PP trays exhibit diverse effects in fruit preservation, primarily depending on the type of fruit and storage conditions. For relatively storable fruits like pomegranate seeds, studies show that when sealed in a 40-micron-thick PP film within a PP tray and stored at 5°C for 10 days, the pomegranate seeds showed no obvious signs of rot and maintained good quality. Titratable acidity increased slightly (from 0.27% to 0.30%), and total phenolic content decreased slightly (from 1492 mg/l to 1393 mg/l), but these changes remained within acceptable ranges.
In preservation experiments with leafy vegetables, PP food serving trays demonstrated a significant improvement in preservation effectiveness. A Shanghai-based fresh food e-commerce company saw its shelf life for leafy greens extend from 3 days to 5 days and its spoilage rate decrease by 42% after adopting PP trays. This improvement is primarily attributed to the superior humidity control and breathability of the PP material. PP trays maintain an appropriate humidity environment, preventing excessive water loss and wilting of vegetables while avoiding excessive humidity that leads to rotting.
For perishable berries such as strawberries, PP modified atmosphere packaging (MAP) boxes demonstrated excellent preservation effects. According to the company's test data, strawberries remained fresh for 5 days in PP MAP boxes, and leafy greens could stay fresh for a week without wilting. This preservation effect mainly relies on the controllable breathability of PP material, which can regulate the gas composition within the packaging, reducing oxygen concentration and increasing carbon dioxide concentration, thereby inhibiting fruit respiration and microbial growth.
The effectiveness of PP food serving trays in preserving fruit is also related to their surface treatment technology. Some PP trays employ anti-fog coating technology, which effectively prevents fogging on the inner surface of the tray, maintaining good visibility while avoiding damage to the fruit from fog droplets. Furthermore, the chemical inertness of PP material ensures that it will not react with organic acids, vitamins, or other components in fruits, preserving the original flavor and nutritional components of the fruit.
2.3 Preservation Effect of Baked Goods
The application of PP trays in the preservation of baked goods is relatively limited, but they still exhibit certain advantages under specific conditions. Preserving baked goods mainly faces two challenges: maintaining the crispness of the product and preventing moisture loss and flavor degradation. The properties of PP material give it a unique advantage in the preservation of certain baked goods.
For baked goods that require maintaining a crisp texture, such as cookies and breadcrumbs, the moderate permeability of PP trays is a key advantage. Compared to completely sealed packaging, PP trays allow for a small amount of moisture and gas exchange, preventing condensation inside the packaging and thus maintaining the crispness of the product. At the same time, the oil resistance of the PP material effectively blocks the penetration of oil from baked goods, preventing the tray from being contaminated with oil and keeping the packaging clean.
In preservation experiments of baked goods containing dairy products, such as cream cheese, researchers found that packaging materials have a significant impact on the oxidative stability of the product. Experiments show that the sensory scores of cream cheese stored in thermoformed food serving trays made of PP/PE, after 2-6 months in the dark, are significantly affected by the color of the packaging material, particularly in terms of its sunshine and acidity flavors. Transparent PP food trays for parties accelerate photo-oxidation under light conditions, while black or opaque PP trays effectively prevent this problem. This indicates that color selection has a significant impact on the preservation of baked goods when choosing PP trays.
The preservation effect of PP food serving trays on baked goods is also reflected in their ability to maintain product texture. Due to the good flexibility and impact resistance of the PP material, it can protect baked goods from mechanical damage during transportation and storage. This protective effect is particularly important for fragile baked goods such as cakes and pies. Furthermore, the microwaveability of PP trays makes them an ideal packaging choice for ready-to-eat baked goods, allowing consumers to heat the food directly in the tray without transferring it to other containers.
III. Comparison of Short-Term and Long-Term Preservation Effects of PP Trays
3.1 Short-Term Preservation Effect (2-6 hours)
In short-term preservation scenarios, PP trays are mainly used in supermarket displays, food delivery, and temporary home storage. Based on actual application data, PP trays demonstrate excellent performance in short-term preservation. At room temperature, PP trays can maintain a low temperature (0-4℃) inside the container for 2-3 hours, and even with a delivery distance of up to 1 hour, the food temperature will not exceed 6℃. This performance is significant for food delivery and short-distance transportation.
In supermarket displays, the short-term preservation effect of PP trays is mainly reflected in maintaining the appearance and quality of food. The high transparency of PP material provides excellent display effects, fully showcasing the color and shape of food. Simultaneously, the moderate permeability of PP food serving trays maintains the gas balance within the packaging, preventing significant quality changes in a short period. Especially for fresh meat, PP trays can maintain their fresh color for several hours, preventing darkening due to oxidation.
Food delivery is a key application scenario for short-term preservation of PP trays. Experimental data show that using PP material in catering turnover boxes, combined with appropriate insulation measures, can maintain a temperature of 60-70℃ for 1.5 hours for hot food, meeting the basic temperature requirements for food delivery. For cold food, PP trays, combined with ice packs and other cooling measures, can maintain the food at a low temperature during delivery, preventing rapid microbial growth.
The short-term preservation effect of PP trays in temporary home storage is also noteworthy. In daily life, consumers often need to temporarily store leftover food for several hours, and PP food serving trays are the first choice due to their convenience and safety. Experiments show that PP trays can maintain the quality of food at room temperature for several hours, especially for fruits, vegetables, and other foods that are not easily perishable, where the short-term storage effect is even better.
3.2 Long-term preservation effect (1-7 days)
In long-term preservation scenarios, the performance of PP trays varies depending on the type of food, but overall, they can meet the short-term storage needs of most foods. According to experimental data, meat products packaged in PP trays can be preserved for 3-5 days at 0-4℃, a shelf life sufficient for a family's weekly consumption needs. In contrast, traditional foam trays typically only last about 3 days, highlighting the significant advantage of PP trays.
In long-term storage experiments with leafy green vegetables, PP trays demonstrated a significant improvement in preservation. Studies showed that leafy green products packaged in PP trays had a shelf life extended from 3 days to 5 days, with a 42% reduction in spoilage. This improvement is primarily attributed to the superior humidity control and antibacterial properties of the PP material. PP trays maintain suitable humidity within the packaging, preventing excessive water loss from vegetables while avoiding spoilage due to excessive humidity.
For specially designed PP food serving trays, such as modified atmosphere packaging (MAP), the long-term preservation effect is even more pronounced. Experimental data show that fruits and vegetables packaged in PP MAP can achieve a shelf life of 15 days, a significantly better result than ordinary PP trays. Modified atmosphere packaging (MAP) creates a low-oxygen, high-carbon dioxide environment by controlling the gas composition within the packaging, effectively inhibiting the respiration of fruits and vegetables and the growth of microorganisms.
The long-term preservation effect of PP trays is also closely related to their thickness and structural design. Thicker PP food trays for parties (e.g., 2-4mm thick) have better insulation performance and mechanical strength, better protecting food during long-term storage. Meanwhile, some PP trays employ multi-layer composite structures, such as PP/EVOH/PP structures, where the EVOH layer has extremely high gas barrier properties, effectively preventing the penetration of oxygen, carbon dioxide, and water vapor, significantly extending the shelf life of food.
3.3 Differences in Preservation Effects under Different Storage Conditions
Storage conditions have a decisive impact on the preservation effect of PP trays, with temperature being the most critical factor. Experimental data clearly demonstrate the influence of temperature on preservation effects: under storage conditions of 20℃, the TBARS value and ethane concentration of heat-sterilized meat are lower; while under conditions of 37℃, these indicators increase significantly. This indicates that for every 10°C increase in temperature, the rate of food spoilage can potentially double. Therefore, proper temperature control is a prerequisite for PP food serving trays to achieve their preservation effect.
Humidity is another crucial storage condition. While PP material has good water resistance, its water vapor transmission rate (WVTR) is 1-20 g/m²·day. This means that in high-humidity environments, PP trays may not completely prevent external moisture from entering. Therefore, when storing easily absorbing foods (such as biscuits and rusks), PP trays with a lower WVTR should be selected, along with drying measures.
Light conditions also significantly impact the preservation effect of PP plastic trays for food. Studies have shown that transparent PP food serving trays accelerate the photo-oxidation reaction of food under light conditions, especially for oily foods (such as cream cheese). Light exposure can lead to rancidity of fatty acids, producing unpleasant flavors. Therefore, for light-sensitive foods, opaque or black PP trays should be selected, or light-protected measures should be taken during storage.
The gaseous environment is a key factor affecting the long-term preservation effect of PP trays. For foods requiring modified atmosphere storage, the permeability of PP trays is both an advantage and a challenge. On the one hand, moderate permeability allows food to breathe; on the other hand, excessive permeability can lead to an imbalance in the gas composition within the packaging. Therefore, depending on the modified atmosphere requirements of different foods, it is necessary to select PP trays with specific permeability rates or to use sealed packaging combined with modified atmosphere technology.
IV. Factors Affecting the Preservation Effect of PP Trays and Optimization Suggestions
4.1 Influence of Material Factors
The preservation effect of PP trays is primarily affected by the properties of the material itself. The density of PP material is typically 0.90-0.92 g/cm³, which gives it the advantage of being lightweight, but also affects its barrier properties to some extent. Studies have shown that by changing the molecular structure and crystallinity of PP, its barrier properties can be significantly improved. For example, BOPP (biaxially oriented polypropylene) film produced using a biaxial stretching process effectively improves its oxygen and water vapor barrier capabilities. If this technology is applied to food serving tray production, it will significantly improve the preservation effect.
The thickness of the PP tray is a key factor affecting its preservation performance. Market data shows that the standard thickness of PP trays is 1.5-3mm, but in special applications, it can reach 0.2-2mm or even thicker. Experiments have shown that increasing thickness brings multiple benefits: when the thickness increases from 0.5mm to 0.7mm, drop resistance increases by more than 40%; for every 1cm increase in thickness, the insulation time can be extended by 1-1.5 hours. Therefore, when choosing PP trays, the appropriate thickness should be selected based on the specific application scenario. For foods requiring long-term storage or transportation, thicker plastic trays for food are recommended; for short-term use or lightweight foods, thinner trays can be chosen to reduce costs.
The surface treatment technology of PP trays also has a significant impact on preservation performance. Some high-end PP trays employ special surface treatments, such as antibacterial coatings, anti-fogging coatings, and barrier coatings. Experimental data show that trays with added MEIBOSS inorganic silver antibacterial agent achieve a 99.6% inhibition rate against Staphylococcus aureus, and the antibacterial performance decay rate is less than 5% after 50 washes. Anti-fog coatings prevent fogging on the inner surface of trays, maintaining good visibility while preventing damage to food from condensation droplets. Barrier coatings further enhance the gas and moisture barrier properties of PP trays, extending food shelf life.
The purity of materials and the use of additives are also crucial factors affecting preservation. Food-grade PP materials require strict control over the types and amounts of additives to ensure no harmful substances migrate into food. High-quality PP food serving trays should use high-purity food-grade raw materials, avoiding the use of recycled or industrial-grade materials. Simultaneously, the appropriate use of functional additives such as antioxidants and light stabilizers can improve the stability of PP trays under different environments, indirectly improving preservation.
4.2 Influence of Environmental Factors
The storage environment has a decisive impact on the preservation effect of PP trays, with temperature being the most critical factor. Experimental data clearly show that for every 10°C increase in temperature, the rate of food spoilage can potentially double. In studies of heat-sterilized meat, the TBARS value and ethane concentration under 20°C storage conditions were significantly lower than those under 37°C conditions. Therefore, proper temperature control is a prerequisite for PP trays to achieve their preservation effect. For different types of food, appropriate storage temperatures should be selected based on their characteristics: fresh meat typically requires refrigeration at 0-4℃, while some fruits may require higher storage temperatures to prevent chilling injury.
Humidity is another important environmental factor. Although PP material has good water resistance, its water vapor transmission rate (WVTR) is 1-20 g/m²・day, meaning that in high humidity environments, PP food serving trays may not completely prevent external moisture from entering. For easily absorbing foods (such as biscuits and breadcrumbs), PP trays with lower WVTR should be selected, along with drying measures. Conversely, for foods that require maintaining a certain level of humidity (such as fresh vegetables), the moderate permeability of PP trays is advantageous, as it can maintain suitable humidity within the packaging and prevent excessive water loss.
Light conditions have a significant impact on the preservation effect of PP trays. Studies have shown that transparent PP trays accelerate the photo-oxidation reaction of food under light conditions, especially for oily foods, where light can lead to rancidity of fatty acids and produce unpleasant flavors. Therefore, when storing light-sensitive foods, opaque or black PP trays should be chosen, or light-protection measures should be taken during storage. For scenarios such as supermarket displays where transparent packaging is necessary, PP materials with UV-blocking properties can be considered.
The gaseous environment is a key factor affecting the preservation effect of PP trays, especially for foods requiring modified atmosphere storage. The permeability of PP plastic trays for food is both an advantage and a challenge—moderate permeability allows food to breathe, but excessive permeability can lead to an imbalance in the gas composition within the packaging. Therefore, depending on the modified atmosphere requirements of different foods, PP trays with specific permeability should be selected, or sealed packaging combined with modified atmosphere technology should be used. For example, fresh fruits and vegetables require a low-oxygen, high-carbon dioxide environment within the packaging, while some meats require a high-oxygen environment to maintain their vibrant color.
4.3 The Impact of Usage
Proper usage can fully realize the preservation potential of PP trays. The first step is pre-treatment before packaging. Food should be properly treated before being placed on PP trays, such as washing, draining, and cutting, to remove surface moisture and contaminants. Especially for meat and seafood, surface blood should be removed as much as possible to reduce the environment for bacterial growth. For foods that need to maintain their shape, absorbent paper or pads can be used to absorb excess moisture.
Packaging techniques have a significant impact on preservation. When packing food, minimize the amount of air inside the packaging, especially for easily oxidized foods. Vacuum packaging or filling with an inert gas (such as nitrogen) can be used to reduce oxygen content. For liquid or semi-liquid foods, avoid overfilling to prevent spillage during transportation. Ensure the trays are well-sealed to prevent external contaminants from entering.
Management during storage and transportation is equally important. PP food serving trays should be stored in a clean, dry, and well-ventilated environment, avoiding direct sunlight and high temperatures. During transportation, appropriate transport vehicles and insulation measures should be used to ensure a stable temperature. For perishable foods, transportation time should be minimized to reduce temperature fluctuations. Also, avoid subjecting the trays to heavy pressure or impacts to prevent food damage. Post-use treatment also affects the reusability of PP trays. Plastic trays for food should be washed promptly after use to remove residual food and stains. Use a mild detergent when washing, avoiding strong acids or alkalis to prevent damage to the tray surface. After washing, trays should be thoroughly dried and stored in a clean, dry place. For food serving trays with antibacterial coatings, avoid using chlorine-based disinfectants, as these may compromise the antibacterial effect.
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