Autumn lettuce is known for its hardiness and suitability for long-term storage. Proper storage techniques can significantly extend its shelf life while maintaining quality. One effective method involves sowing the lettuce later in the season, allowing it to mature before the first frost. Just before harvesting, water the plants thoroughly to keep the soil moist. The next day, carefully lift the roots and let them air dry slightly. Once the leaves are slightly wilted, stand them upright in a cool, shaded area. After 4 to 6 days of this process, transfer the lettuce into a trench dug on the north side of a windbreak. Arrange the plants with their roots downward, and place them at an angle along the trench walls. Cover the stems with wet soil, then add another layer of soil on top. Continue stacking until the trench is full, ensuring the total soil cover does not exceed 30 cm. During the initial storage period, keep the soil thin to allow for gradual temperature control. As temperatures drop, gradually increase the soil thickness to prevent freezing. If the temperature inside the trench remains between 0°C and -2°C, the outer leaves may freeze slightly, but the stems will stay intact, ensuring good preservation. In case of rain or snow, cover the trench with plastic to avoid water damage, which could lead to rot. When the market needs the lettuce, dig it out as required, remove any damaged leaves, shake off excess soil, cut away old roots, and prepare it for sale. Regular monitoring is essential to detect and address any issues promptly.
Another technique involves using a "false preservation" method, particularly useful for small lettuce varieties. This approach allows the plants to grow slowly and remain fresh over an extended period. Before storage, the lettuce is placed in a shallow ditch, about 10 cm wide, positioned slightly northward. Plants are spaced approximately 10 cm apart, and after covering with soil, two-thirds of the plant is left above ground. Gently press the soil down and water it if needed, but avoid overwatering to prevent decay. In the early stages, maintain a moderate temperature, and in later periods, provide insulation to protect against cold. Adjust the soil cover as needed to keep the internal temperature stable between 0°C and 1°C. This method shares similarities with celery storage practices and requires careful management during the preparation phase.
For commercial operations, cold storage is a reliable option. Lettuce should be packed in groups of 3 to 5 plants per unit and placed in a 0.03 mm thick plastic bag. Seal the bags and store them on a vegetable rack in a refrigerated room. Maintain optimal temperature and humidity conditions to ensure freshness for up to a week.
When transporting, short-distance delivery can be done using a handcart directly to distribution centers or retail stores. For longer distances, use a temperature-controlled vehicle to maintain ideal conditions. Employ bamboo or plastic baskets that offer good support to minimize mechanical damage and reduce the risk of browning. Proper packaging and handling are crucial to preserving the quality of the lettuce during transit.
Whitening And Clearing Speckles Raw Materials
Whitening ingredients can be divided into the following categories:
1. Inhibit tyrosinase raw materials: the main function of this kind of raw materials is to inhibit the activity of tyrosinase in the skin and prevent the formation of melanin, so as to achieve the effect of whitening and spot removal. Commonly, there are vitamin C, tyrosinase inhibitors.
2. Promote the renewal of the stratum corneum raw materials: these raw materials can promote the metabolism of the stratum corneum of the skin surface, remove the surface of the pigmentation spots, so that the skin becomes smooth and delicate. Common fruit acids, salicylic acid, etc..
3. Antioxidant raw materials: these raw materials can resist the attack of free radicals, prevent the formation of melanin, protect the skin from oxidative damage, so as to achieve the effect of whitening spots. Commonly, there are vitamin E, green tea extract and so on.
4. Raw materials to block melanin transmission: these raw materials can prevent melanin from basal layer to surface layer transmission, thus reducing pigmentation and achieving the effect of whitening and eliminating spots. The common ones are aloe vera extract and peony extract.
5. Skin repairing raw materials: these raw materials mainly help to repair damaged skin and promote the skin's self-repairing ability, so as to reduce the formation of pigmentation. Common hyaluronic acid, collagen and so on.
6. sunscreen raw materials: these raw materials can block ultraviolet damage to the skin, to prevent the formation of melanin, to achieve the effect of whitening spots. Commonly, there are titanium dioxide, zinc oxide and so on.
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