How to Store and Preserve Garlic Scapes for Freshness? A Detailed Guide to Practical Techniques

Garlic scapes are nutritious, with a crude protein content of about 10% and sugar 8%. Each 100 grams of garlic scapes contains 20-30 mg of vitamin C, 20 mg of calcium, 45 mg of phosphorus, and 1 mg of iron. In addition, garlic scapes are also rich in allicin. Therefore, they are deeply welcomed by consumers.

I. Storage Characteristics and Varieties

Garlic scapes are the young flower stems of garlic. After harvest, metabolism is vigorous, the surface of the scape lacks protective tissue, and the temperature at harvest is high, so they are prone to water loss, aging, and rot. The garlic scapes turn yellow and become hollow, fiber increases, the scape bud swells and splits, and aerial bulbils grow, reducing edible quality.

Garlic scapes are produced in Yongnian in Hebei, Acheng in Heilongjiang, Qishan in Shaanxi, and Jingchuan in Gansu, among other places. However, the garlic scapes from Cangshan in Shandong and other places have the best quality. The scapes are thick and long, suitable for long-term storage. Garlic scapes can only be stored for 20-30 days at room temperature, but with refrigerated controlled-atmosphere storage methods, garlic scapes can be stored for 7-10 months.

II. Storage Conditions

The storage temperature for garlic scapes is 0+0.5°C, the relative humidity is 85%-95%, the oxygen concentration is 2%-5%, and the carbon dioxide concentration is 0%-8%. During storage, as long as either the oxygen or carbon dioxide indicator reaches the limit standard, the bag must be opened immediately for ventilation. Each ventilation period is 2-3 hours. The oxygen and carbon dioxide concentrations in the bag or tent should be measured every day or every other day (only representative bags need to be measured). When the carbon dioxide concentration is about to exceed the upper limit, it can be absorbed with slaked lime. Slaked lime can be made by adding water to quicklime, and it can only be used after the powdered slaked lime has dissipated heat and cooled. Slaked lime should be stored under sealed conditions, otherwise it will become ineffective by absorbing carbon dioxide from the air.

III. Harvesting and Pre-storage Preparation

1. Harvesting

Garlic scapes are generally harvested in May when the temperature is relatively high. When pulling the plants, avoid doing so at noon, and try to prevent breaking the scapes and damaging the scape stems. Tie the harvested garlic scapes into small bundles, put them into gunny sacks or other packaging containers, and immediately transport them to a cold storage facility for pre-cooling.

2. Pre-storage Preparation

Before the garlic scapes are put into storage, the cold storage facility and the tools used must be disinfected. They can be fumigated with 10 grams per cubic meter of sulfur, or sprayed with 1%-2% formaldehyde. After sealing for 20-48 hours, ventilate to remove residual medicinal odor. Other utensils should be soaked in a 0.5% bleaching powder solution, then air-dried for later use. Before the garlic scapes are put into storage, first pre-cool the cold storage facility to 0°C. After the garlic scapes arrive, they should immediately be piled in the pre-cooling room, cold storage facility, or a cool, ventilated place to remove field heat and respiration heat. After the garlic scapes have cooled to 0°C, carry out the processing and sorting before storage. Processing should be done in the cold storage facility or in the vestibule. Remove diseased and damaged scape stems. Align the buds of healthy scape stems and tie them at the stem part 3-5 cm from the bud with plastic string, with each bundle weighing about 0.5-1.0 kg. Cut off the tip of the scape top, leaving 4-6 cm of the scape top; alternatively, the scape top may not be cut.

IV. Storage Methods and Their Management

1. Refrigerated storage with natural oxygen reduction in plastic film bags

When the scape temperature is 0°C, place the garlic scapes with the scape tops facing outward in polyethylene or polyvinyl chloride plastic bags 0.06-0.08 mm thick, 100-110 cm long, and 70-80 cm wide. Put 18-20 kg of garlic scapes in each bag, tie the bag mouth tightly, and place it on a rack or in a packaging container. When the oxygen in the bag drops to 1%-2% and carbon dioxide is about 12%, open the bag for ventilation so that the oxygen in the bag rises above 18% and carbon dioxide drops to about 1%-2%, then reseal the bag. For garlic scapes stored in small packages in a 0°C cold storage facility, the ventilation cycle is about 10-15 days. In the middle and later stages of storage, the ventilation cycle gradually shortens to 7-10 days.

2. Controlled-atmosphere refrigerated storage in plastic film bags with silicon windows

Place garlic scapes at a scape temperature of 0°C, with the scape tops facing outward, into silicon-window bags that are the same in thickness, length, and width as the above plastic film bags but are embedded with a silicone rubber window of 9×13 cm. Place them on vegetable racks or in packaging containers. Because silicon-window bags have a certain permeability to oxygen and carbon dioxide, they can basically meet the gas composition requirements of garlic scapes, so during storage there is no need to open the bags for ventilation.

3. Controlled-atmosphere refrigerated storage in plastic film tents

When using polyethylene or polyvinyl chloride film tents for controlled-atmosphere storage, first spread a 0.23 mm thick film on the floor of the cold storage facility, with length and width matching the length and width of the stack or shelf, so as to seal the large tent. Put the processed and pre-cooled garlic scapes into plastic boxes, 20 kg per box, and stack them on top to form a stack. Make a rectangular large tent from 0.23 mm thick film and cover it outside the box stack. When closing the tent, place 3 empty boxes on top of each stack, or make the tent top into a ridge shape, to prevent condensed water from dripping. After the plastic tent is closed, roll up its edges together with the plastic film spread on the ground, and press tightly with bricks or other objects to create a sealed environment. Air-inflation and air-extraction cuffs and gas sampling ports should be left on both sides of the plastic tent. After sealing the tent, a molecular sieve nitrogen generator can be used to adjust the gas composition and input nitrogen into the bag. Rapid oxygen reduction can quickly lower the oxygen content in the tent to the suitable range for garlic scapes; natural oxygen reduction can also be used. The respiration of garlic scapes is used to lower the oxygen content in the tent. Add an appropriate amount of slaked lime in the tent to absorb excess carbon dioxide. When the oxygen in the tent is too low, fresh air can be introduced. Because the temperature inside the plastic bags or plastic tents is relatively high, it is easy to cause microbial reproduction, so 0.5 ml/L sec-butylamine can be added to prevent the growth of gray mold or black mold.