Detailed Explanation of Silicon Window Controlled Atmosphere Storage Technology for Garlic Scapes

In the early 1980s, China began large-scale promotion of silicon window controlled atmosphere technology to preserve garlic scapes. It works by embedding a certain area of silicone rubber membrane in a plastic bag to automatically regulate the gas composition inside the bag, achieving the purpose of preservation. It has the characteristics of saving labor, saving time, saving energy, convenient management, stable gas composition, long storage period, low loss, and good quality. The economic benefits are significant, so it was promoted and used on a large scale in a short time.

I. Silicon Window Controlled Atmosphere Storage of Garlic Scapes

1. Forms of Silicon Window Use Cold storage silicon window controlled atmosphere has two forms: small packaging fresh-keeping bags and large plastic tents. Generally, cold storage mostly uses small packaging fresh-keeping bags, which are convenient to use and can also be sold as packaging bags when leaving the warehouse, reducing costs. Small packaging bags are made by heat-sealing 0.08 mm thick polyethylene film and a certain area of silicone rubber membrane with a high-frequency heat-sealing machine, and come in specifications of 15 kg, 20 kg, 25 kg, etc.

2. Planning of Silicon Window Area Generally, silicone rubber membrane manufacturers will provide the applicable area per ton of garlic scapes. When using, simply convert proportionally. For example, the FC-8 membrane produced by Lanzhou Institute of Biochemistry is used for garlic scapes at 0.4 sq m/ton to 0.5 sq m/ton.

3. Advantages of Silicon Window Controlled Atmosphere Preservation of Garlic Scapes ① Low loss, long storage period, good quality, and significant economic benefits. Due to the automatic regulation effect of the silicon window, the gas composition inside the bag throughout the storage period is basically stable at a relatively ideal level, which can avoid carbon dioxide poisoning, prevent quality aging, and at the same time inhibit bacterial reproduction and reduce rot. Generally, silicon window controlled atmosphere is better than the plastic bag venting method, with a product yield 5% to 15% higher, dry weight loss 2% lower, and rot rate reduced by more than 5%, so the selling price is much higher than the latter. ② Convenient management, saving time and labor, and saving energy. The silicon window fresh-keeping bag is basically the same as the venting method in management, but it eliminates more than 20 operations such as venting, rearranging, and wiping water, which can save 80% of labor, while also reducing energy consumption and bag damage during operation, lowering costs, and ensuring quality.

II. Disease Control in Controlled Atmosphere Storage of Garlic Scapes

1. Low-temperature disease Low temperature can reduce the respiratory metabolism of fruits and vegetables, delay tissue aging, inhibit microbial reproduction, reduce rot, and extend the storage period. However, if the temperature is too low, low-temperature disease will occur. The optimum temperature for storing garlic scapes is 0°C, and the minimum must not be lower than -1°C. If the scape temperature is below -1°C for a short time, the garlic scapes can still recover; if the time is too long, the cell membrane is destroyed and cannot recover, causing freezing injury, manifested as a blistered appearance, semi-transparent tissue, pigment degradation, and after thawing a boiled appearance with an off-flavor. During storage, the warehouse temperature (0°C to -1°C) and scape temperature (±0.5°C) should be strictly controlled.

2. Carbon dioxide poisoning When the carbon dioxide gas inside the bag remains above 10% for a long time, it will cause carbon dioxide poisoning, causing the organism to suffocate and die. The manifestations are: in the early stage, yellow spots and pitted spots appear on the scape stalk and gradually expand, forming sunken round pits, the scape stalk softens, and breaks into pieces. The scape bud changes from green to grayish white; with further development, the scape stalk becomes water-soaked and the epidermis falls off; when rotting, it emits a very strong alcoholic smell. When using silicon window controlled atmosphere to store garlic scapes, it is essential to choose silicone rubber membrane with stable quality, strictly configure an appropriate silicon window area according to the instructions, strictly load bags according to the specified weight, keep the warehouse temperature stable, and regularly detect the carbon dioxide concentration inside the bag and in the warehouse.

3. Microbial diseases The main microbial diseases during garlic scape storage include scape stalk mold rot, watery rot disease, thrips damage, and other microbial diseases. Under controlled atmosphere conditions, the inside of the bag remains under high humidity for a long time, and the scape tips that have already dried up at the time of storage are very prone to rot, but generally do not affect the scape stalk. Thrips are carried from the field with disease, and the cause is unknown. At harvest, there are small yellow spots on the scape stalk. If it is stored in the warehouse promptly after purchase, the gas composition is reasonable, and the warehouse temperature is stable, there is basically no disease or the disease occurs relatively late, with little harm; otherwise, it will cause great losses. Watery rot disease is caused by infection of pathogens through mechanical injuries during loading, unloading, and transportation.

4. Control measures for microbial diseases ① Ensure purchase quality, load and unload carefully, and promptly sort, store, pre-cool, and bag. ② Ensure stable warehouse temperature and reduce condensation. ③ Drug fumigation: generally use 1.4 grams of Kemeiling (containing 50% sec-butylamine) per cubic meter of warehouse volume. Fumigation should be carried out before tying the bag mouth, avoiding direct contact of the drug with the garlic scapes.

III. Key Points of Silicon Window Controlled Atmosphere Storage of Garlic Scapes

The effectiveness of silicon window controlled atmosphere storage of garlic scapes depends not only on the two necessary conditions of temperature and controlled atmosphere, but also on attention to garlic scape quality, warehousing speed, warehouse management, and other links.

1. Purchasing garlic scapes should ensure quality. The quality of garlic scapes entering the warehouse is the foundation of storage. The purchased garlic scapes should be fresh and tender, green, and have small scape buds. It is strictly forbidden to purchase garlic scapes that are aged, diseased, or have been stored for a long time after harvest. If conditions permit, factors such as cultivation, fertilization, and irrigation of the garlic scapes should also be considered.

2. Timely transport to the warehouse for pre-cooling. Garlic scape purchasing occurs during the high-temperature season, when respiratory metabolism is fast, and heat release and aging are also fast. Therefore, purchased garlic scapes should be promptly transported back to the cold storage and sorted into the warehouse for pre-cooling as soon as possible.

3. Pre-cooling, bagging, and shelving ① Cool down as soon as possible. In the initial stage of garlic scape storage, the scape temperature is high and the heat load is large. Machine room operators should defrost frequently to ensure good refrigeration effect and bring the scape temperature down in the shortest time. ② Only bag when the temperature drops below 5%; if the scape temperature is too high, it will cause excessive water accumulation in the bag. When bagging, weighing must be carried out, and the error per bag must not exceed ±10%, while avoiding puncturing the plastic bag. ③ After shelving, open the bag mouth so that the scape temperature can drop to ±0.5°C as soon as possible. At this time, wipe away accumulated water in the bag with a clean cloth, check whether the bag is damaged, and then tie the bag mouth tightly.

4. Ensuring stable warehouse temperature is the key to storage management. In order to prevent low-temperature disease, inhibit respiration, and reduce garlic scape "sweating," it is necessary to ensure stable warehouse temperature. To this end, a complete set of clear post responsibility systems and strict reward and punishment mechanisms should be established and improved. At the same time, automatic temperature recorders should be installed to check the cooling situation. In addition, regularly sample and test the gas composition to keep well informed.