Freeze drying machine
Freeze Drying Machines are widely used in pharmaceutical and other industries, as freeze drying is the only process by which water can be removed from an organic product or substance without causing any damage to the cell structure or losing volatile components.
What is Freeze Drying ？
Freeze drying technically known as lyophilisation, lyophilization, or cryodesiccation—is a dehydration process typically used to preserve a perishable material or make the material more convenient for transport. Freeze-drying works byfreezing the material and then reducing the surrounding pressure to allow the frozen water in the material to sublimedirectly from the solid phase to the gas phase.
Vacuum freeze drying technology is the most advanced technology for food dehydration processing at present. Compared with the common drying method, the freeze-dried food produced with this technology features long period of quality assurance, good re-hydration nature, good-looking color, good flavor, taste, shape and high content of nutritious components. The dried food basically remains unchanged in its volume and shape, it looks like sponge and has no shrinking. This kind drying technology can be widely used in process of vegetables, fruits, condiments, aquatic products, biological products, medicine, beverage and etc.
Laboratory Vacuum freeze-drying technology, referred to as freeze-drying, also known as sublimation drying, is a method of pre freezing water containing materials and sublimating them in vacuum. After freeze-drying, the original biological and chemical characteristics of the articles are basically the same, easy to long-term preservation, and can be restored to the form before freeze-drying after adding water, and can maintain its original biochemical characteristics.
Freeze drying machine adopts vacuum freeze drying technology to remove the inside water on condition of no damage to the raw material’s taste and nutrition.Pharmaceutical Freeze Dryer removes water from plants and organic compounds while they are in a frozen state. This locks in the freshness of herbs and plants. Their appearance, nutritional content, and potency remain the same as when they were fresh.Freeze drying completely removes water in about 24 hours.
The freeze-drying machine is a technical method in which the aqueous article is previously frozen and then the water is sublimated in a vacuum state to obtain a dry product. The freeze-dried article is easy to store for a long period of time, and the water can be restored to the pre-freeze form Keep the original biochemical characteristics, suitable for laboratory samples of freeze-drying experiments and a small amount of production.
Vacuum freeze drying is the use of physical sublimation principle, in a high vacuum environment, the frozen food in the water (ice) without melting, directly sublimation from ice to steam, so vacuum freeze drying is also known as freeze sublimation drying.Freeze dryer is use Imported compressor, stable and reliable performance;Widely used in food, biological products, chemical, Chinese medicine, health products and other fields.
Working Princple of Freeze Drying Machine
Under vacuum condition, material is freeze dried via principle of sublimation. The moisture in the pre-frozen material is directly sublimed from solid state (ice) to gaseous state (vapor), without melting. Freeze dried products are formed to be sponginess, without shrinkage and excellent in rehydration, containing little water only. The freeze dried product in sealed packaging can be stored and transported at room temperature for a long time.
The freeze drying process
Freeze drying involves the removal of water or other solvents from a given product by a process called sublimation. This occurs when the ice of a frozen product converts directly to the gaseous state without passing through the liquid phase. This enables the preparation of a stable product that is easy to use and store at ambient temperatures.
A low pressure environment is pre-requisite to allow this process to take place. In order to start the removal of water, the pressure inside the freeze dryer must be below the “triple point value” for the product, whilst also maintaining the temperature of the sample below its freeze point in the lyophilization process.
Pre-freezing – first stage of the lyophilization process
The sample is frozen, which means the water in the product is converted to ice, thereby the phase has changed from liquid to solid.
Slow pre-freezing will produce lager ice crystals, which are easier to lyophilize, whilst fast pre-freezing results in smaller crystals.
Primary drying – Second stage of the lyophilization process
In the second stage of lyophilization the sublimation process starts. The ice formed in the pre-freeze step is removed from the sample by the direct transition of the “solid” ice to a vapour without passing through a liquid phase. The resultant vapour is collected by the condenser, which has a lower temperature and pressure than the product. The vapour is thus converted back to ice on the condenser surface.
The “energy” required for this process to occur is provided by a gentle heating of the sample, which will start the sublimation process and eventually the sample will dry.
If too much energy (heat) is applied to the sample during this stage the condenser of the lyophilizer may not be able to condense the volume of vapours fast enough, the ice condenser temperature will subsequently rise along with its vapor pressure, thus increasing the risk of the sample melting.
Secondary drying – Third stage of the lyophilization process
Finally, any residual water present, which is strongly bound to the molecules of the sample, is converted to vapour and removed from the sample.
This water has invariably a vapour pressure lower than that of water in its “free” form.Removal of the water in this final stage of lyophilization will be performed at higher product temperatures, consequently, any biological activity of the sample will not be impaired or affected. This usually involves increasing the temperature and lowering the pressure to provide enough energy to break down the molecular bonding. A process called desorption.
Applications of Freeze-Drying
The process of freeze-drying can be employed in the following fields
1. Food industry – Food needs to be preserved by freeze-drying for consumption by individuals in the fields of space exploration, hikers, military personnel, as well as the availability of dehydrated foods such as noodles, soups, etc. The most common form of freeze-dried food is instant coffee.
2. Dairy industry – Dairy products which usually required refrigeration were preserved by freeze-drying during World War II. Dairy solids and liquids both can be preserved by this technique, and do not require the use of chemical preservatives. The decreased volume of the product after freeze-drying proves to be an added advantage in the event of transportation of products. Dairy products which can be preserved by freeze-drying include milk, yogurt, ice-cream, cheese, etc. These products can then be supplied to bakeries, dairies, restaurants, etc.
3. Nutraceuticals – In the case of nutraceuticals, the process of freeze-drying used for stabilization as well as increasing the shelf-life of the products. Liquid nutraceuticals are converted to the powder form, which helps in preserving them for a longer time. Nutraceuticals which can be preserved by freeze-drying include seaweeds, aloe vera, tea, etc.
4. Starters and Cultures (edible cultures) – In the case of regular drying methods, the resultant product loses its quality. This might bring about adverse changes in the properties of the product. Products preserved using this technique include probiotics, buttermilk, etc.
5. Pharmaceuticals – Pharmaceutical companies use freeze-drying as a tool to increase the shelf-life of drugs and vaccines. If a liquid drug is converted to its powdered form and stored in a vial, it can be easily reconstituted as necessary. Pharmaceuticals subjected to the freeze-drying process include vaccines, hormones, proteins, plasma, antibiotics, etc.
6. Research – Botanical samples are preserved by freeze-drying to be used for research purposes. Laboratory samples which can be preserved by freeze-drying include active pharmaceuticals, ingredients, pathological samples, microbiological cultures, viruses, bacteria, antibodies, etc.
7. Document Recovery – The process of freeze-drying can be used for recovery and saving of documentation facing damage through fire, floods, etc. 18 Freeze drying using vacuum can be used to restore books damaged by water as well as paper containing water-soluble inks.
8. Floral – The moisture content present in flowers is eliminated through vacuum extraction, followed by freezing at low temperatures. This prevents floral shrinkage, and maintains the structure and quality of flowers. Flowers which can be preserved using freeze-drying include aster, carnation, daffodil, hyacinth, rose, etc.
9. Taxidermy – Freeze-drying is not an alternative to taxidermy but can be considered as an asset to taxidermy. Animals possessing a large quantity of lipid content need to be processed accordingly in order to achieve optimal quality of freeze-drying. Animals which can be preserved using freeze-drying in taxidermy include birds, fish, dogs, cats, museum specimens, etc.
10. Pet Food – Removal of moisture is necessary for long-term preservation of pet food. However, this removal of moisture can have an adverse impact on the nutrition and quality of the product. Freeze-drying helps in preservation as well as maintenance of product quality. Pet foods which are subjected to freeze-drying can be regarded to be as close to a naturally-occurring diet. These foods can be shaped accordingly for transportation and convenience purposes. Reconstitution of pet food can be done using water, or can be consumed by pets in the powder form.
Advantages of Freeze Dried Foods
1. Taste fresh Freeze-dried foods, like frozen, retain virtually all their fresh-food taste and nutritional content. Freeze-drying removes the water, not the flavor.
2. Look fresh Freeze-dried foods maintain their original shape and texture, unlike dehydrated foods, which shrink and shrivel due to high-temperature processing. Freeze-drying removes water under low temperatures which keeps intact the moisture channels and food fibers. Just add water, and in minutes every fresh food detail returns.
3. Weigh less than fresh Freeze-dried foods have 98% of their water removed. This reduces the food’s weight by about 90%. Because of its light weight per volume of reconstituted food, freeze-dried products are popular and convenient for hikers. More dried food can be carried per the same weight of wet food, and remains in good condition for longer than wet food, which tends to spoil quickly. Hikers reconstitute the food with water available at point of use.
4. Stay fresh Freeze-dried foods can be stored at room temperature, without deterioration or spoilage. This is because freeze-drying and packaging remove both water and oxygen – the two primary causes of food deterioration.