What is freeze-drying

December 09, 2021

Freeze drying, also known as "freeze drying," is the process of freezing materials at very low temperatures and converting water from a solid to a gaseous state by sublimation to extract liquid. That is, water extracted in this way sublimates directly from a solid to a gas without passing through the liquid phase.

The main advantage of this method, freeze drying, can prolong the shelf life and storage time of the products while maintaining the three-dimensional shape and integrity of the products.

This is a preservation technique commonly used in the food industry and applies to many different types of food. It can produce high quality products.

1. Principle of lyophilization process
Lyophilization is carried out using specialized equipment in the following three main stages. The process involves:
Freezing -- the rapid freezing of food to avoid forming large ice crystals -- can damage the structure of the product.
Vacuum -- where the product is in a deep vacuum, well below the triple point of water [1] -- is the critical point at which solid, liquid and gaseous forms of the material can coexist.
Drying -- Water is removed from the material by sublimation, which directly converts solid ice to gaseous vapor without having to pass through the liquid phase again (low pressure, up to a few millibars [2] helps with this part of the process). Therefore, the structural integrity and chemical properties of the product can be highly preserved.

Foods to be freeze-dried are usually pretreated in some way. Common methods include product concentration, increased surface area, addition of ingredients such as preservatives, and IQF of smaller food materials (Individual Quick Freezing allows free flow of materials and is more suitable for the process).
Pretreatment is usually done for cycle time and product quality.

2. History of freeze-drying in food industry
Lyophilization can be traced back to the use of indigenous peoples in South America. Potatoes and other tubers grown in the lowlands will be transported to high altitudes, pressed to remove the liquid, and then cryogenically preserved overnight. This, in turn, created a durable form of food called chuno that could be used for emergency rations.

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In contrast to air-drying, another common form of food preservation, materials need to be heat treated in the Air so that no boring quality is lost in the process. However, air drying can result in physical changes, including material shrinkage and destruction of microstructure, biochemical effects and chemical reactions.

Food preservation can also be problematic when it comes to microbial infection and spoilage. Even at low temperatures, microbes can still be present, which is why food must be properly packaged and stored to avoid absorbing water.

Today, freeze-drying is used in a wide range of common foods, including freeze-dried instant coffee, ice cream, fruits and vegetables, meat and meat substitutes. The process can be used to produce high-quality foods that need to "lock in" the nutrients they need.

Shaanxi Huike Botanical Development Co., Ltd. a integrated enterprise which is focus on natural products, Plant extract related products and services.We mainly focus on pharmaceutical, functional food, Freeze-dried powder,Natural Pigment,beverages and other business services.

2021-12-9

Shaanxi Huike Botanical Development Co., Ltd.

Author:

Ms. Anne

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sales13@huikes.com

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