Methods and Requirements for Packaging Fruits for Transport (II)

Plastic: The method of using plastic inner packaging is the same as that of paper, and there are many types. It is more attractive than paper packaging and has significant advantages in controlling product water loss and respiration, but the cost is higher. People also use soft wood shavings, foam plastic, or fiber surface layers as inner packaging.

    In short, the choice of packaging is limited by the cost of the fruit and vegetable products themselves. Factors such as product value, packaging cost, the role in protecting product quality, and selling price need to be considered. The cheapest material for fruit and vegetable packaging is baskets and bags made from locally grown plant materials. However, actual situations tell us that using this type of packaging results in considerable physical damage to the products. For example, bamboo baskets have many limitations. First, they are large in volume, making it difficult to handle them with care; second, they are often overfilled, putting great pressure on the products. In addition, they are not conducive to stacking during transportation and storage. Therefore, some experts argue that such materials are unsuitable for packaging and should be phased out in favor of other packaging materials. Based on China's actual situation, bamboo and similar natural materials have low costs. As long as the packaging containers are made smaller, have lids, and handling operations are properly improved, bamboo basket-type packaging can still be used.

    2. The role of packaging in product quality

    Packaging is used to protect products, and it plays this role in the following aspects:

    1. Preventing mechanical damage

    Mechanical damage suffered by products during circulation can be attributed to four different causes: compression, impact, friction, and cutting. Different fruits have varying sensitivity to these mechanical damages, so these differences should be considered when selecting packaging containers and methods.

    External compression on the packaging container first acts on the container itself. When the mechanical strength of the container cannot withstand external pressure, the product will be compressed. The mechanical strength of the packaging container can be enhanced by using trays, honeycomb pads, etc., inside the box. Sometimes adding a lid can also improve the container's ability to support the load from above. In practice, it is often the influence of the external environment that weakens the mechanical strength of the container, causing compression. For example, in high-humidity environments, after condensation occurs, or after being soaked by rain, commonly used corrugated fiberboard boxes quickly lose strength due to moisture absorption. Therefore, such cardboard boxes are not entirely satisfactory for use in high-humidity cold storage. In previous years, the Ministry of Commerce promoted calcium-plastic boxes for fruit packaging. These boxes have low water absorption, overcoming the drawback of moisture absorption in cardboard boxes. However, they are costly and become brittle and prone to cracking in low-humidity conditions.

    Impact is caused by sudden forces, such as rough handling during loading and unloading, dropping of packages during transport, or sudden braking. Vibration is common during transportation. The damage from vibration lies in causing abrasion, which can range from light surface scuffing to scraping off part of the fruit flesh. All these injuries caused by abrasion can lead to browning due to the exposure of tannins and similar substances in the damaged tissue to air, harming product quality, especially appearance. More harmful is that these injured surfaces become windows for disease infection and increase the respiration rate of the fruit, thereby accelerating spoilage.

 Preventing impact and vibration damage to products involves two aspects: on one hand, there should be no relative displacement between individual products, and between the products and the packaging container, to avoid vibration damage. On the other hand, the packaging container should be filled, but not overfilled or too tight; otherwise, compression and bruising will increase. Products can be individually wrapped and separated, or fruit products can be packaged in grids and layers, with cushioning materials placed to reduce vibration. However, this inevitably increases costs, so the reduction in losses and the increase in benefits achieved by using such packaging must be compared to decide whether such packaging is needed. In short, handling with care is the best way to reduce physical damage.