How can fruit tray blister packaging extend the shelf life of fruit and reduce moisture loss and oxidation through a sealed design?
Publish Time: 2025-08-25
In modern fresh produce retail and high-end fruit consumption markets, packaging is no longer just a container to protect the product; it is also a critical component in extending shelf life, maintaining quality, enhancing visual appeal, and ensuring food safety. Plastic fruit trays, with their precise structure, excellent sealing, and enhanced display quality, are becoming an ideal packaging format for high-value fruits such as strawberries, blueberries, cherries, and grapes. One of their core advantages is their scientific sealing design, which creates a barrier at the microscopic level, effectively delaying moisture loss and oxidation, significantly extending the fruit's shelf life.Fruit remains alive even after being picked, continuously respiring, consuming sugars, water, and nutrients while releasing heat, carbon dioxide, and ethylene gas. This process accelerates softening, discoloration, mold, and decay. Fruit trays utilize a high-precision thermoforming process. Transparent plastic sheets (such as PET or PP) are heated and softened, then fitted into a mold to create a grooved structure that closely matches the shape of the fruit. The tray is then heat-sealed to the base or backing card, creating a sealed or semi-sealed microenvironment. This tight-fitting structure minimizes free space within the package, restricting airflow and, consequently, reducing the fruit's respiration rate and moisture evaporation.Sealing design is primarily determined by the material selection. Plastic sheets used in fruit trays typically possess excellent barrier properties, effectively blocking the intrusion of moisture, dust, and microorganisms. Furthermore, the material's inherent low oxygen permeability slows the rate at which oxygen enters the package, inhibiting aerobic respiration and oxidation reactions in the fruit. For example, some high-end fruit trays utilize a multi-layer co-extruded material with an EVOH (ethylene vinyl alcohol copolymer) barrier layer, which significantly enhances its barrier properties against oxygen and moisture vapor, further slowing the loss of nutrients like vitamin C and preventing browning of the fruit peel.Secondly, the stability of the heat-sealing process determines the reliability of the seal. The seal width, temperature, and pressure between the blister and the tray are precisely controlled to ensure a secure, leak-free, and airtight seal. This high-quality seal prevents air from entering during transportation, handling, or temperature fluctuations, preventing internal humidity fluctuations and condensation due to the "breathing bag" effect. Condensation is a major cause of fruit rot. Water droplets adhering to the fruit's skin soften the surface and promote the germination of mold spores. A good seal, combined with a moderately permeable microporous design, controls humidity while allowing for a small amount of gas exchange, maintaining a relatively stable internal gas composition and creating a "modified atmosphere" that is conducive to freshness preservation.In addition, the blister's individually positioned design indirectly enhances freshness preservation. Each piece of fruit is secured in its own dedicated groove, isolating it from the surrounding fruit and preventing mechanical damage caused by squeezing and friction in traditional bulk or tray packaging. Minor scratches or tears can accelerate moisture loss and microbial intrusion, but the fruit tray effectively eliminates this risk. The sealed structure also prevents localized accumulation of ethylene gas released by the fruit, slowing the ripening process. This makes it particularly suitable for ethylene-sensitive berries.In cold chain environments, the sealing properties of fruit trays also play a crucial role. While low temperatures inhibit microbial growth, temperature fluctuations can cause condensation within the packaging. A well-sealed blister minimizes air exchange between the inside and outside of the packaging, reducing the likelihood of condensation and keeping the fruit dry.In summary, the plastic fruit tray's multiple sealing features, including high-barrier materials, precision molding, reliable heat sealing, and structural insulation, create a stable, clean, low-oxygen, and low-humidity microenvironment, effectively slowing the fruit's respiratory metabolism, water evaporation, and oxidation reactions. This not only extends shelf life and reduces waste, but also maintains the fruit's freshness, taste, and appearance during transportation and distribution, making it an indispensable freshness preservation solution in the modern fruit supply chain.
