Spinach has a high moisture content and intense respiration activity, making it difficult to store even under low temperatures. Freeze-drying technology addresses this by converting water in spinach into ice crystals, which are then sublimated under vacuum to achieve long-term preservation. Freeze-dried spinach retains its original color, nutritional components, and is easy to process, store, and transport, significantly enhancing its commercial value. Utilizing "BOTH" Freeze Dryer for spinach processing not only extends shelf life but also preserves nutritional quality, meeting diverse application needs.
Freeze-Drying Process Flow
1.Raw Material Pretreatment
Select fresh, tender spinach with large leaves, discarding yellowed, diseased, or insect-damaged leaves. Clean the selected spinach in a bubble washing tank to remove soil and impurities. Drain surface water, cut into 1cm segments using a vegetable cutter, and blanch in 80–85°C hot water for 1–2 minutes. Blanching inactivates oxidative enzymes to preserve color and nutrients, eliminates surface microorganisms and insect eggs, removes air from tissues, reduces vitamin and carotenoid loss, and breaks down surface wax to enhance moisture removal. After blanching, immediately cool the spinach in cold water to room temperature to maintain crispness.
2.Cooling and Pre-Freezing
Residual surface water droplets post-cooling can cause clumping during freezing, hindering drying. Remove droplets using a vibrating dewatering machine or air-drying, then spread spinach evenly on stainless steel trays at a thickness of 20–25 mm. During freeze-drying, heat transfers inward through the drying layer while vapor escapes outward. Excessive thickness leads to uneven drying, while insufficient thickness risks partial melting, flavor loss, and nutrient degradation.
3.Vacuum Freeze-Drying
Place spinach into a laboratory freeze dryer. Begin with pre-freezing at -45°C for ~6 hours to ensure complete internal freezing. Proceed to vacuum freeze-drying, where ice crystals sublimate into vapor under reduced pressure and controlled heating. The freeze dryer’s cold trap captures sublimated vapor to prevent recondensation.
4.Post-Processing and Packaging
After drying, conduct quality checks (e.g., screening, grading) and package using vacuum sealing or nitrogen flushing to prevent oxidation and moisture absorption. Packaged freeze-dried spinach can be stored long-term at room temperature, facilitating transport and sales.
Key Advantages of Freeze-Dried Spinach (Demonstrated by "BOTH" Freeze Dryers):
Nutrient Retention: Preserves vitamins and minerals effectively.
Texture Recovery: Rehydrates to near-fresh texture.
Extended Shelf Life: Stable for years at ambient conditions.
Transport Efficiency: Lightweight and compact.
Critical Considerations from "BOTH":
1.Homogenization Importance:
Segmented spinach (leaves, stems, roots) varies in density and moisture content. Perform "homogenization" during the final desorption drying phase to ensure uniform moisture distribution, preventing quality issues from uneven drying.
2.Packaging and Storage Requirements:
Freeze-dried spinach is highly hygroscopic. Package in environments with <35% relative humidity. Store in dark, dry, clean warehouses with 30–40% humidity to prevent moisture absorption and degradation.
Freeze-drying technology resolves spinach’s perishability challenges while boosting its value-added potential. Families or companies seeking freeze-dried solutions are welcome to collaborate with "BOTH" Freeze-Drying for advanced preservation and quality assurance.
If you are interested in our Freeze Dryer Machine or have any questions, please feel free to Contact us. As a professional manufacturer of freeze dryer machine, we offer a variety of specifications, including household, laboratory, pilot, and production models. Whether you need equipment for home use or larger-scale industrial equipment, we can provide you with the highest quality products and services.
Post time: Mar-06-2025
