What do trail mix, astronaut ice-cream, and cryogel have in common? This may sound like the introduction to a corny riddle, but they are all things you can make in your garage with a homemade freeze dryer.
The video is also posted after the break which contains a list for the parts and where they can be purchased.
Freeze drying uses a process called cryodesiccation or lyophilization. Below a certain pressure, water skips the liquid phase and goes directly to a gas, so frozen items can transition from ice to dry without a soggy step. A freeze-dryer like this has three parts. Next to the pump there must be a water trap. Lastly, there is the drying chamber where your items are placed to have their moisture taken out.
Astronaut ice cream has been made on Hackaday before. Cool project but I suspect the fly in the ointment for most people is going to be the vacuum pump. And after watching the video, if it takes 16 hours for the process to run I suspect the dry ice bill gets expensive too.
Dry ice is cheap, you can often find it in grocery stores for a few dollars a pound. If your crushing it obviously its gonna sublimate off faster. But If you leave it in block form in a well insulated environment, than its going to maintain its mass fairly well. I would say instead of using an alcohol base use acetone, as most isopropyl and denatured alcohols start to free around c, which then insultates itself keeping it from getting any colder.
The Acetone will still a liquid till around c it will slowly get conaminated with co2 and water and turn to a solid after a while if keep at these temps. But you will achieve a much lower temp and more effeicently transfer heat between the pots.
I would also recommend looking at using Neoprene as insulator as well. Closed Cell neoprene makes a great insulator for cryo materials. Its much easier to work with as well. You can always use old wetsuits too. What actual purpose is dry ice sold for in grocery stores in the USA? Likely a trip to checmical supplies company or something like that. You can buy over the internet quite easily, shipping next day in a big ploystyrene container.How Freeze Drying Works
It aint cheap. Keeps the frozen food frozen and the refrigerator cold.A freeze dryer executes a water removal process typically used to preserve perishable materials, to extend shelf life or make the material more convenient for transport. Freeze dryers work by freezing the material, then reducing the pressure and adding heat to allow the frozen water in the material to sublimate.
A freeze dryer works in three phases, with the first and most critical being the freezing phase. Freeze dryers use various methods to freeze the product. Freezing can be done in a freezer, a chilled bath shell freezeror on a shelf in the freeze dryer. The freeze dryer cools the material below its triple point to ensure that sublimation, rather than melting, will occur. A freeze dryer most easily freeze dries large ice crystals, which can be produced by slow freezing or annealing.
However, with biological materials, when crystals are too large they may break the cell walls, and that leads to less-than-ideal freeze drying results. To prevent this, the freezing is done rapidly. For materials that tend to precipitate, annealing can be used.
This process involves fast freezing, then raising the product temperature to allow the crystals to grow. The condenser also protects the vacuum pump from the water vapor.
Primary drying can be a slow process. Too much heat can alter the structure of the material. By raising the temperature higher than in the primary drying phase, the bonds are broken between the material and the water molecules. Freeze dried materials retain a porous structure.
After the freeze dryer completes its process, the vacuum can be broken with an inert gas before the material is sealed. Here are a few important terms related to freeze dryers. Is the point at which the product only exists in the solid phase, representing the minimum melting temperature.
Not all products have a eutectic point or there may be multiple eutectic points. During freeze drying, the maximum temperature of the product before its quality degrades by melt-back or collapse. Multi-component mixtures which do not crystallize and do not have a eutectic point.
The point at which the product softens to the extent that it can no longer support its own structure. This can be a problem for many reasons:. Facebook Twitter Linkedin Youtube. Freeze Dryer: What is a Freeze Dryer? Freeze Dryer vs. Lyophilizer What is a freeze dryer?
How does it work? Freezing Phase Freeze dryers use various methods to freeze the product. Problems To Avoid While Using a Freeze Dryer Heating the product too high in temperature can cause melt-back or product collapse Condenser overload caused by too much vapor hitting the condenser. Too much vapor creation Too much surface area Too small a condenser area Insufficient refrigeration Vapor choking — the vapor is produced at a rate faster than it can get through the vapor port, the port between the product chamber and the condenser, creating an increase in chamber pressure.
Important Freeze Dryer Terms Here are a few important terms related to freeze dryers. Eutectic Point or Eutectic Temperature Is the point at which the product only exists in the solid phase, representing the minimum melting temperature.
Critical Temperature During freeze drying, the maximum temperature of the product before its quality degrades by melt-back or collapse. Crystalline The material forms crystals when frozen. Has a eutectic point or multiple eutectic points Fast freezing creates small crystals which are hard to dry Annealing can help form bigger crystals.Sales: Why Freeze Dry? Preserve your garden produce, create the perfect emergency food supply, make camping meals and healthy snacks.
Unlike other methods of food preservation, freeze drying does not shrink or toughen the food, and retains flavor, color, and nutrition. Taste Harvest Right freeze dryers produce food that looks and tastes better than store-bought freeze dried food. Experience the Harvest Right difference! Freeze dried food will last up to 25 years and does not need to be to be rotated like other foods. Freeze dried food is perfect for home storage. Other methods of preservation, such as canning and dehydrating, use high temperatures that destroy much of the food value.
Versatility Freeze drying works great for fruits and vegetables, but unlike other options, it also perfectly preserves meat, fish, dairy, eggs, ice cream, and even fully-cooked meals. Easy If you can press a button, you can freeze dry! Everything is automatic. Products which freeze dryer is right for you? I am very excited about using this as another way to preserve food, as I feel an urgency to prepare for times when food might not be as plentiful.
We have told everyone we know about it. Your customer service went above and beyond their duties to help. Their efforts and courtesy were extraordinary and deserve a big pat on the back. I tell everyone about your wonderful freeze dryers and fantastic service.
Blessings to you all. We are so pleased with how all of the foods come out. Everything tasted as if we had just harvested it. It is wonderful to freeze dry food that we have prepared. Drying the food ourselves is significantly less expensive than what we would have to pay to buy such food elsewhere.
We are in control of the ingredients and are able to prepare long-term food storage that meets our needs. This unit is heavy duty construction, reliable and user friendly. We have enjoyed freeze drying fruits and vegetables in season, meats, leftovers and dessert items…the only limit is your imagination.
I freeze dried both cooked and raw pork chops; the cooked pork chops tasted great cold without reconstituting them, the raw pork chops reconstituted beautifully and fried up great.Today, freeze dryers are still a fairly UNcommon household appliance. I envision a future where nearly every home has a freeze dryer and food waste becomes a thing of the past.
Note: Feel free to skip ahead to any section you want — by simply clicking any of the links above. Because freeze drying and dehydration are two standard food preservation methods.
And both methods remove water from food products. But there are major differences between dehydrated and freeze-dried food storage. Food dehydrators circulate hot, dry air across food on open racks. This causes the water to evaporate and the food to shrivel. Despite this, you lose many of the vitamins and nutrients in the process.
Plus, the taste and texture can often change dramatically. Because of this complexity, it takes dedicated, high-tech equipment to freeze dry food. Like dehydrating, you place food on large open racks to allow for air circulation. But, instead of placing the food in a high temp environment, you load the racks into a vacuum chamber. Then the freeze dryer lowers the temperature inside the vacuum chamber. To an incredible low temp around deg F. Once the food is completely frozen, a vacuum pump lowers the pressure inside the chamber.
And then the temperature is slowly raised back to normal. Sublimation is the process where solid ice changes directly into water vapor without ever becoming liquid. One of the main reasons to remove moisture from food is to prevent the spread of mold and bacteria. All living organisms need moisture to thrive.SP Scientific service professionals offer your organization a depth of expertise that is truly unique to our selected industries and markets.
We are recognized experts in applications, methodologies, lab processes and many other areas that directly impact your day-to-day operations. With SP Scientific your solution is just a call or an e-mail away. SP Scientific service professionals are highly knowledgeable and are qualified to support every instrument, software and application product that SP Scientific has brought to the market.
Freeze drying is the removal of ice or other frozen solvents from a material through the process of sublimation and the removal of bound water molecules through the process of desorption. Lyophilization and freeze drying are terms that are used interchangeably depending on the industry and location where the drying is taking place. Controlled freeze drying keeps the product temperature low enough during the process to avoid changes in the dried product appearance and characteristics.
Sublimation is when a solid ice changes directly to a vapor without first going through a liquid water phase. Thoroughly understanding the concept of sublimation is a key building block to gaining knowledge of freeze drying. As shown below on the phase diagram for water, low pressures are required for sublimation to take place. Sublimation is a phase change and heat energy must be added to the frozen product for it to occur.
In addition to providing an extended shelf-life, successful freeze-drying should yield a product that has a short reconstitution time with acceptable potency levels. The process should be repeatable with well defined temperature, pressure and time parameters for each step. Visual and functional characteristics of the dried product are also important for many applications.
The refrigeration system cools the ice condenser located inside the freeze dryer. The refrigeration system can also be employed to cool shelves in the product chamber for the freezing of the product.
The vacuum system consists of a separate vacuum pump connected to an airtight condenser and attached product chamber. Control systems vary in complexity and usually include temperature and pressure sensing ability. Choosing a control system for the freeze dryer depends on the application and use i.
Best Home Freeze Dryer On The Market Today [With Video Reviews]
Product chambers are typically either a manifold with attached flasks, or, a larger chamber with a system of shelves on which to place the product. The purpose of the condenser is to attract the vapors being sublimed off of the product. Because the condenser is maintained at a lower energy level relative to the product ice, the vapors condense and turn back into solid form ice in the condenser. The sublimated ice accumulates in the condenser and is manually removed at the end of the freeze drying cycle defrost step.
The condenser temperature required is dictated by the freezing point and collapse temperature of the product. The refrigeration system must be able to maintain the temperature of the condenser substantially below the temperature of the product.
In shelf freeze dryers, the condenser can be located inside the product chamber internal condenser or in a separate chamber external condenser connected to the product chamber by a vapor port. Manifold freeze dryers rely on ambient conditions to provide the heat of sublimation to the product.
This heat input does not melt the product because an equivalent amount of heat is removed by vaporization of the solvent. Choosing a freeze dryer depends on the product characteristics as well as many other application-based variables including the container that the product will be dried in, the shelf area or number of ports required to accommodate the quantity to be dried in each batch, the total volume of ice to be condensed and whether there are any organic solvents.
The type and shape of product being dried and its end-use also need to be considered.This is a project to try and build a reasonably priced, reasonably functional, freeze drying machine at home. Commercially available freeze drying units, even relatively small ones, are really expensive. We're talking in the thousands of dollars. This got me to thinking. In theory at least, the physics behind freeze drying and how it works aren't terribly complicated, so I figure I'll give a crack at making a decent one from scratch and save myself a few thousand bucks, and if it works other people on the internet will be able to follow my instructions and build one for themselves as well.
With more careful analysis and design I could probably use a thinner sheet, but I've never built a vacuum chamber before so I'm overdesigning the crap out of this one.
Also, you could skip this material altogether and just use the side of the pressure vessel that you cut off as the door, but I want to be able to see into the chamber. I chose polycarbonate Lexan over acrylic Plexiglass because the polycarbonate is much stronger, more resilient, and has a higher working temperature. After some consideration, I'm thinking of using some sort of pre-constructed pressure vessel as the body of the vacuum chamber.
Something like a propane tank, or a compressed air tank. My reasoning is that, at least for medium scale, if something is designed to hold psi positive pressure, then it should maybe probably be able to hold Yeah yeah yeah, I know that the structural design for the two things is not exactly the same, but I'm building in a factor of safety of nearly 10x, so I'm modestly confident that this won't implode. I'm thinking that an old 10 to 20 gallon auxiliary compressed air tank will be a good place to start with this design.
My plan is to use a torch, plasma cutter, or angle grinder cutoff wheel to cut off one end one of the rounded ends. That will leave a round, flat opening on that end. Wikipedia: Adsorption     Desiccant Types. Jump to: navigationsearch. Categories : DIY Food. Personal tools Log in.Freeze drying works by freezing the material, then reducing the pressure and adding heat to allow the frozen water in the material to sublimate.
Freeze drying occurs in three phases, with the first and most critical being the freezing phase. There are various methods to freezing the product. Freezing can be done in a freezer, a chilled bath shell freezer or on a shelf in the freeze dryer.
Cooling the material below its triple point ensures that sublimation, rather than melting, will occur. This preserves its physical form. Freeze drying is easiest to accomplish using large ice crystals, which can be produced by slow freezing or annealing. However, with biological materials, when crystals are too large they may break the cell walls, and that leads to less-than-ideal freeze drying results.
To prevent this, the freezing is done rapidly. For materials that tend to precipitate, annealing can be used. This process involves fast freezing, then raising the product temperature to allow the crystals to grow. The vacuum speeds sublimation. The cold condenser provides a surface for the water vapor to adhere and solidify.
The condenser also protects the vacuum pump from the water vapor. Primary drying can be a slow process. Too much heat can alter the structure of the material. By raising the temperature higher than in the primary drying phase, the bonds are broken between the material and the water molecules. Freeze dried materials retain a porous structure. After the freeze drying process is complete, the vacuum can be broken with an inert gas before the material is sealed.
Here are a few important freeze drying terms.