Freeze drying, also known as lyophilization, is a process that removes water from frozen materials by converting frozen water directly into vapor without forming liquid water in between. It works through the phenomenon of sublimation where water passes directly from solid to vapor state below the triple point of water. The main steps are initial freezing of the material, drying where heat is applied under high vacuum to sublime the ice crystals into vapor, vapor removal through condensation, and storage of the dried material. Freeze drying is used to preserve foods and pharmaceuticals, increasing their shelf life, and allowing them to be stored without refrigeration.
Dehydration process,
Typically used to preserve a perishable material or make the material more convenient for transport,
Mostly used for light food required by astronauts, hikers
Dehydration process,
Typically used to preserve a perishable material or make the material more convenient for transport,
Mostly used for light food required by astronauts, hikers
Refrigeration is a technique used for preserving food in low temperatures. This procedure slow down or stop most bacteria from dividing and thereby multiplying, but do not kill them.
The detailed description on theory of dryer, mechanism of drying and stages of drying. Water activity, types of dryers used in food processing industry, concept of osmotic dehydration of foods is discussed.
The preservation of food by freezing has become a major industry.Preservation of a food by freezing occurs by several mechanisms. At
temperatures below 0°C there is a significant reduction in growth
rates for microorganisms and in the corresponding deterioration of
the product due to microbial activity.
Several freezing systems for food operate with direct contact between
the refrigerant and the product.
cryogenic freezer is direct contact freezer.
Oxygen is life, but in the case of foods, it is not so. When harvested, fresh fruits and vegetables
are at the peak of their quality. Their quality cannot be improved; it can only be deteriorated or
maintained. Fresh, high-quality products are the primary requirements for the national and international food industry during this current era. After harvesting, especially for fresh fruits and vegetables, continue their respiration process. The respiration rate has to be reduced to maintain quality, especially when the products are stored for an extended period or shipped to distant markets. The best way to preserve quality and extend shelf life is by cooling, and another method used to extend shelf life is the modification of the atmosphere surrounding the product. Also known as “CA storage” in the produce business, Controlled atmospheric storage is the storage in which external control systems control the atmosphere of oxygen, carbon dioxide and nitrogen (and sometimes other gases). Outside air consists of approximately 78% nitrogen (N2), 21% oxygen (O2), 0.045% carbon dioxide (CO2). CA lowers the oxygen level generally to 0.5-2.5%, depending on the type of product and the variety. CA conditions extend the shelf life of fruit and vegetables with a factor of 2 to 4.
This presentation contains all information on mixing and different mixing equipment used in food industry. The different equipment includes those for solids, liquids and semi solids. It consist of tumbling mixers, rotational screw mixers, agitators, impellers, paddle mixers, planetary mixers and so much more.
Icecream is well-likes dairy product due to its smooth creamy texture which is achieved by various types of processing and freezing. This presentation is about the types of freezers used in Icecream manufacture
Freezing helps to Inhibit the growth of microorganisms hence help in preservation of foods. So, freezing is a very easy and effective method for the preservation of fruits and vegetables and to retain them for longer duration.
Refrigeration is a technique used for preserving food in low temperatures. This procedure slow down or stop most bacteria from dividing and thereby multiplying, but do not kill them.
The detailed description on theory of dryer, mechanism of drying and stages of drying. Water activity, types of dryers used in food processing industry, concept of osmotic dehydration of foods is discussed.
The preservation of food by freezing has become a major industry.Preservation of a food by freezing occurs by several mechanisms. At
temperatures below 0°C there is a significant reduction in growth
rates for microorganisms and in the corresponding deterioration of
the product due to microbial activity.
Several freezing systems for food operate with direct contact between
the refrigerant and the product.
cryogenic freezer is direct contact freezer.
Oxygen is life, but in the case of foods, it is not so. When harvested, fresh fruits and vegetables
are at the peak of their quality. Their quality cannot be improved; it can only be deteriorated or
maintained. Fresh, high-quality products are the primary requirements for the national and international food industry during this current era. After harvesting, especially for fresh fruits and vegetables, continue their respiration process. The respiration rate has to be reduced to maintain quality, especially when the products are stored for an extended period or shipped to distant markets. The best way to preserve quality and extend shelf life is by cooling, and another method used to extend shelf life is the modification of the atmosphere surrounding the product. Also known as “CA storage” in the produce business, Controlled atmospheric storage is the storage in which external control systems control the atmosphere of oxygen, carbon dioxide and nitrogen (and sometimes other gases). Outside air consists of approximately 78% nitrogen (N2), 21% oxygen (O2), 0.045% carbon dioxide (CO2). CA lowers the oxygen level generally to 0.5-2.5%, depending on the type of product and the variety. CA conditions extend the shelf life of fruit and vegetables with a factor of 2 to 4.
This presentation contains all information on mixing and different mixing equipment used in food industry. The different equipment includes those for solids, liquids and semi solids. It consist of tumbling mixers, rotational screw mixers, agitators, impellers, paddle mixers, planetary mixers and so much more.
Icecream is well-likes dairy product due to its smooth creamy texture which is achieved by various types of processing and freezing. This presentation is about the types of freezers used in Icecream manufacture
Freezing helps to Inhibit the growth of microorganisms hence help in preservation of foods. So, freezing is a very easy and effective method for the preservation of fruits and vegetables and to retain them for longer duration.
Freezing is a unit operation in which temperature of a food is reduced below its freezing point (removal of sensible & latent heat of fusion), and a proportion of the water undergoes a change in state to form ice-crystals. Immobilization of water to ice and the resulting concentration of
dissolved solutes in unfrozen water lowers the water activity of the food. Lowering of temperature, lowers the microbial activity as well as suppresses the chemical reactions in the food. Generally,
we find two type of freezing method, quick freezing and slow freezing. In slow freezing, food products are introduced to low temperature for relatively longer time duration and hence the ice crystal formed are of larger in size, which are sometimes not at all desirable depending on
characteristic of food product. In quick freezing, relatively even lower temperature is used for food product but exposure time is less. Hence the ice crystal formed are of smaller size. Even though small ice crystal formed during quick freezing helps in preserving the texture and other characteristic of product, sometimes it may cause to temperature shock to product. Choosing the method of freezing is hence of utmost importance.
The process of freeze drying with greater emphasis on the uses in the fisheries food processing sector. The presentation shows the process involved and the different steps involved and the effect of the process on the food material.
Definition of drying
Importance of drying
Difference between drying and evaporation
Equipments
References
Definition
A stabilizing process in which a substance is first frozen and then the quantity of the solvent is reduced, first by sublimation (primary drying stage) and then desorption (secondary drying stage) to values that will no longer support biological activity or chemical reactions.
History
Freeze drying was first actively developed during WORLD WAR II transport of serum.
The main aim was to store the products without refrigeration and to remove moisture from thermolabile compounds.
Atlas in 1961 built 6 production freeze drying cabinet for Nestle group in Germany, Holland.
Principle
Lyophilization is carried out using a simple principle of physics sublimation. Sublimation is the transition of a substance from the solid to the vapour state, without first passing through an intermediate liquid phase.
Lyophilization is performed at temperature and pressure conditions below the triple point, to enable sublimation of ice.
The entire process is performed at low temperature and pressure by applying vacuum, hence is suited for drying of thermolabile compounds.
The concentration gradient of water vapour between the drying front and condenser is the driving force for removal of water during lyophilization.
Conventional food processing techniques Uma Bansal
its a presentation based on conventional food processing techniques and it contains drying methods also along with freeze drying and concentration and evaporation.
Freezing has been successfully employed for the long-term preservation of many foods, providing a significantly extended shelf life.
The process involves lowering the product temperature generally to -18 °C or below.The extreme cold simply retards the growth of microorganisms and slows
down the chemical changes that affect quality or cause food to spoil.
During freezing the cellular solution present in the food matrix is cooled to its initial freezing point, and further cooling causes the water molecule to
separate, forming ice crystal.
The migration of water molecules during crystallization led to an increase in osmotic pressure, further enhancing the water permeability of the cell membranes. This transport of water molecules, if not controlled, can eventually affect the microstructure of the frozen produce.
The freezing process occurs in two successive steps, i.e,
” NUCLEATION” and “CRYSTAL GROWTH”.
Roti Bank Hyderabad: A Beacon of Hope and NourishmentRoti Bank
One of the top cities of India, Hyderabad is the capital of Telangana and home to some of the biggest companies. But the other aspect of the city is a huge chunk of population that is even deprived of the food and shelter. There are many people in Hyderabad that are not having access to
Ang Chong Yi Navigating Singaporean Flavors: A Journey from Cultural Heritage...Ang Chong Yi
In the heart of Singapore, where tradition meets modernity, He embarks on a culinary adventure that transcends borders. His mission? Ang Chong Yi Exploring the Cultural Heritage and Identity in Singaporean Cuisine. To explore the rich tapestry of flavours that define Singaporean cuisine while embracing innovative plant-based approaches. Join us as we follow his footsteps through bustling markets, hidden hawker stalls, and vibrant street corners.
At Taste Of Middle East, we believe that food is not just about satisfying hunger, it's about experiencing different cultures and traditions. Our restaurant concept is based on selecting famous dishes from Iran, Turkey, Afghanistan, and other Arabic countries to give our customers an authentic taste of the Middle East
2. introduction
Freeze drying is a process whereby water or other solvent is
removed from frozen material by converting the frozen water
directly into vapor without the intermediate formation of liquid
water. Freeze drying also known as lyophilization.
3. PRINCIPLE
The main principle of freeze drying is a phenomenon called
sublimation. where the water passes directly from solid state to the
vapour state without passing through liquid state.
Sublimation of water can take place at pressures and temperature
below triple point i.e. 4.579 mm of Hg and 0.0099 degree Celsius.
4. STEPS IN FREEZE DRYING
Initial freezing : The materials which are to be freeze dried are frozen
to a temperature at which no liquid phase is present. The
temperature required for freezing is different for different types of
food depending on their chemical composition. But in general -
60°C ensure complete freezing
Drying : The frozen products are taken into a high vacuum drying
chamber and heat is supplied to remove the ice crystals formed
due to freezing. Byte application of heat, the ice crystals change
directly to vapour without going through a liquid phase because of
high vacuum. The ice sublimes below the pressure of 4.7 mm of Hg.
The heat required for sublimation is supplied directly to the foods
from the source by radiation.
5. Water vapour removal : It is necessary to remove the water vapour to
make the food perfectly dry. The water vapour formed is pumped out
of the chamber and is brought in contact with refrigerator coils where it
again forms ice crystals. The collected ice can be removed by heating
with the steam. The ice turns in to water and is drained out.
Storage and Packing : After removal of moisture, the packing of the
food stuff is done either in vacuum or in the presence of inert gas. It
prevents contamination of the product by pollutants in the air and
prolongs the lifeof the product. Freeze dried foods can be stored with
out refrigeration inthe air tight dry containers for months. This type of
food normally used bynavy, military and people working on ships.
Reconstitution : The consumer has to reconstitute the freeze dried
foody mixing with water to the required extent. Now it regains its
flavored retains very nearly to the original fresh condition and ready for
consumption. The off-seasonal vegetables and fruits can be made
available to the consumer all round the year.
6. Equipment
The main components of freeze drying equipment are.
Refrigeration system
Vaccum system
Control system
Product chamber or manifold
condesner
7. Refrigeration system - cools the condenser located inside the freeze dryer. It
also cool shelves in the product chamber for the freezing of the product.
Vacuum system - consists of a separate vacuum pump connected to an
airtight condenser and attached product chamber.
Control systems - include temperature and pressure sensing ability.
Advanced controllers use the programming of a complete “recipe” and
monitor freeze drying process. It depends on the application and use.
Product chambers - a larger chamber with a system of shelves on
which to place the product.
Condenser – It is to attract the vapors being sublimed off of the
product. The sublimated ice accumulates in the condenser.
temperature of the condenser substantially below the temperature
of the product
8. APPLICATIONS
Pharmaceutical companies use freeze drying to increase the life of
products such as vaccines and other injectbles
Freeze drying is used to preserve the food and make it very light
weight
Bakery and confectionary
Fish,Meat etc.
9. Advantages
Light weight which reduces the cost of shipping
Requires no refrigeration storage cost reduced
Reconstruted quickly by adding water
Have long shelf life when packed
Physical structure of food is not altered
10. Disadvantages
Engineering skills for production
Advanced technology
Increased handling processing time
Freeze-drying costs about five times as much as conventional
drying.
