Lyophilization Process — An Efficient Way to Preserve Perishable Materials

What is Lyophilization?

Lyophilization, also known as Freeze drying, is the process of removing water content to increase the shelf life of food items to an extent to which conventional methods cannot do. Lyophilization involves freezing the substance, followed by a drop in pressure and the addition of heat to cause the substance’s frozen water to sublimate. Lyophilization occurs in three phases, with the first and most critical being the freezing phase which is also known as crystallization, followed by Primary Drying (Sublimation) and then Secondary drying (Absorption).

Phases Of Lyophilization Process

  1. Freezing Phase (Crystallization) — To freeze the product, there are several techniques. Freezing can be done on a shelf in the freeze dryer, in a chilled bath (shell freezer), or in a freezer. As opposed to melting, sublimation is ensured by cooling the substance below its triple point. This keeps its physical form intact. Large ice crystals, which can be created by gradual freezing or annealing, are best for lyophilization. The outcomes of freeze-drying biological materials, however, are less than ideal because when crystals are too big, they may rupture the cell walls. The freezing is done quickly to avoid this. An option for materials that precipitate is annealing. The product is quickly frozen, and then the temperature is raised to encourage crystal growth.
  2. Primary Drying (Sublimation) — Primary drying (sublimation), the second stage of lyophilization, involves lowering the pressure and heating the substance to cause the water to sublimate. The vacuum accelerates sublimation. Water vapour can stick to and solidify on the cool condenser’s surface. The vacuum pump is additionally shielded from the water vapour by the condenser. In this stage, the material’s water content is reduced by about 95%. Drying in the initial stages can take time. The structure of a substance can be changed by excessive heat.
  3. Secondary Drying (Absorption) — Secondary drying (adsorption), the last stage of lyophilization, is when the ionically attached water molecules are eliminated. The links between the substance and the water molecules are broken by elevating the temperature above that of the primary drying phase. The materials are still permeable after being freeze-dried. The vacuum can be broken with an inert gas after the lyophilization procedure is finished before the material is sealed. To 1–5% residual moisture, the majority of materials can be dried.

Advantages of Lyophilization

  1. Prolonged Shelf Life — Any particular product’s moisture content directly impacts its shelf life. By using the freeze-drying method to remove water, bacterial development is prevented. Although moisture content varies from product to product, freeze-dried goods typically have a moisture level of roughly 3%. Any given freeze-dried product’s actual shelf life will vary depending on its packaging, storage temperature, and the product itself.
  2. Application Variety — Food processors provide the flexibility and blending power to add real fruits and vegetables to a wide range of applications. Breakfast applications like hot and cold cereals, retail-ready or ready-to-eat snacks, and beverage applications like smoothies or entire fruit pieces added to beverages are all expanding categories of freeze-dried applications.
  3. Whole Food Nutrition Consumer values are shifting, and more people are seeking nutrition from real, high-quality food sources with understandable labels. Because freeze-dried foods are minimally processed, they can contain clean ingredients that are free of synthetic, artificial, and highly processed materials. Freeze-dried fruits and vegetables are also real fruits and vegetables, allowing brands to make nutritional claims.
  4. Closest to Fresh Form — Freeze drying retains nutritional value better than other drying methods, supporting consumers’ desire for whole-food nutrition. The process also preserves the original raw material’s color and shape, assuring consumers that they are eating real fruits and vegetables. Freeze-dried ingredients’ intense flavor and aroma closely resemble the raw material profile.
  5. Customization — Another advantage of freeze-drying is the ability to tailor it to specific needs and project objectives. Freeze-dried ingredients can be cut or ground into a wide range of sizes and shapes, from whole fruits and vegetables to fine powders. The finished product can be easily mixed into any blend or formulation to create a flavor profile that is entirely unique to your final product.

Disadvantages of Lyophilization

  • Water is needed for reconstitution (except for simple snacks)
  • Some people dislike the dry, Styrofoam texture of the process, which takes 24+ hours on average.
  • Some foods cannot be freeze-dried.
  • Long-term storage necessitates the use of airtight containers.
  • There are no space savings because the food’s cellular structure is mostly preserved.
  • Normal dehydration is sometimes preferable.
  • Cost of production

Application Areas

  1. Pharmaceutical and biotechnology industries — Pharmaceutical companies, frequently use freeze-drying to extend the shelf life of products like vaccines and injectables. The material can be easily stored, shipped, and reconstituted to its original form for injection by removing the water from it and sealing it in a vial.
  2. Food Manufacturing — Food is freeze-dried to preserve it and make it lightweight. The method has gained popularity in the form of freeze-dried ice cream, which is an example of astronaut food. Coffee is frequently dried by vaporization in a hot air flow or projection on hot metallic plates. Some breakfast cereals contain freeze-dried fruit. Although freeze-dried culinary herbs are available, air-dried herbs are far more common and less expensive. On the other hand, the freeze-drying process is more commonly used in the pharmaceutical industry.
  3. Industry of Technology — Lyophilization is a technique used in chemical synthesis to make products more stable or easier to dissolve in water for later use. Because it effectively removes solvents, freeze-drying can be used as a late-stage purification procedure in bio separations. It can also concentrate substances with low molecular weights that a filtration membrane would remove.
  4. Other Applications — The Document Conservation Laboratory at the United States National Archives and Records Administration (NARA) has conducted research on freeze-drying as a method of recovering water-damaged books and documents. Freeze-drying is used in bacteriology to preserve special strains. Freeze-drying is sometimes used in advanced ceramics processes to create a formable powder from a sprayed slurry mist.

Patent Analysis — Lyophilization

Intellectual Property provides evidence for deep research and flourishment of every technology. It provides deep insights into how the technology started and developed within due course of the period. In lieu of it, patents in lyophilization technology describe how the technology developed started from firstly used in 1953 with lyophilization of human blood and then spread its application to food and other industries. Today, there are 82,169 patent families around the world that are related to lyophilization or freeze drying. Among them, 45,407 are alive, and 36,762 are dead patent families.

Conclusion

As the world adapts to increasing populations and less stable food production due to climate change, there is a lot of interest in the future of Lyophilization. Lyophilization could contribute to the solution by extending the shelf life of our food products while preserving their nutrition and form. Currently, the cost and energy involved in Lyophilized foods are prohibitively expensive. A home Lyophilization machine costs between $1,995 and $38,000+. Maintenance and electricity costs are up to eight times higher than air dry methods. However, with increased use of clean, renewable energy and advancements in technology and pricing, the technology has enormous future potential. Perhaps the image of Lyophilized food is also a barrier to its adoption, with chefs such as Gordon Ramsay chastising any chef who uses frozen food. I believe that we should be seriously considering technologies that can reduce our rampant food waste problem and use Lyophilization as part of the solution to improve food hunger outcomes globally.

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