Freeze Drying Solutions: The Battle Between Sustainability and Efficiency

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Welcome back to the coolest part of the “Colorful Researchers” blog. In my first two posts, we delved into the basics of freeze-drying and spray-drying, and in my last post, we explored the crucial role of solvents in freeze-drying. But, for this post, I want to build on the ideas from Peter’s latest post, where he discussed the right-to-repair movement, the circular economy, and the importance of maintenance to improve sustainability. 

Can sustainability and efficiency be achieved when freeze-drying?

When designing and building freeze-dryers, we face a difficult task: navigating a delicate balance between achieving high efficiency in the freeze-drying processes and ensuring the sustainability of the instrument. Improving the sustainability of laboratory processes is key to BUCHIs vision and was a primary objective when designing our latest freeze dryer, the Lyovapor™ L-250. However, sustainability and efficiency are often at odds. Increasing output or efficiency usually requires more energy, which reduces sustainability and vice versa. 

As discussed in my last post, solvents are crucial to certain processes. Creating a highly efficient freeze dryer that could handle organic solvents in a sustainable way posed a significant challenge that required innovation to solve. 

The challenge reminds me of making the perfect yerba mate. Mate is the national drink of Argentina and is enjoyed in a number of other South American countries. Just as making mate requires precise steps and careful attention, freeze-drying demands exact temperatures and pressures to achieve the desired outcome. 

How can you optimize the leaves and the freeze?

When preparing a mate, you need to heat the water to the perfect temperature—too hot, and you’ll burn the yerba leaves, making the tea too bitter; too cold, and the mate will be weak and lack its characteristic flavor. You must also pour the water slowly and at the right angle to avoid flooding the yerba and ensure an even infusion. The process requires patience and precision, and many tools are required to optimize it and make it more efficient. 

Our goal in freeze-drying is similar. We must maintain specific conditions to preserve the quality of our products, whether they be pharmaceuticals, food, or biological materials. If the temperature or pressure is too high, the product can degrade or become unstable. Conversely, if the pressure is too low, the process becomes inefficient due to longer drying times and consumes more energy. 

Efficiency in freeze-drying is like achieving the perfect mate temperature; it ensures the highest quality output. However, just as overheating the water can waste energy and ruin the mate, pushing our equipment to peak efficiency often leads to higher energy consumption and a larger environmental footprint. The challenge lies in finding the right balance, where our processes are both efficient and sustainable. 

How can you and your instrument increase efficiency and sustainability?

To win the battle between efficiency and sustainability in the L-250, we had to look at each area of the design to create this instrument. First, by using natural refrigerants, we succeeded in creating an instrument that achieves a low Global Warming Potential (GWP) of just 4. The creation of an innovative compressor design led to the development of EcoStream™ technology that enables the condenser to reach temperatures as low as -85ºC, allowing the use of organic solvents in your process. On top of that, this cooling design features the lowest electrical energy consumption in its instrument class. The instrument also has sensors for endpoint determination to ensure the process does not go on too long, further saving costs and electricity consumption. 

The instrument can only do so much, though, so to further optimize efficiency, it is also important for the user to know as much as possible about the product and solvents they are using. We created a handy poster that offers a visual guide to increase the efficiency of your freeze-drying process. Be sure to check it out. 

As Peter mentioned in his blog, maintenance is key to ensuring the longevity and optimal performance of your equipment, and we considered this in the design of the L-250. To avoid damage to the pump, the instrument will remind the user when an oil change is due. 

How can you make the perfect yerba mate?

If you’ve checked out our new poster, you are armed with all the information you need to ensure a highly efficient and sustainable freeze-drying process. All you need now is the energy to get the job done, and for that, you need MATE! Mate is known for its unique, slightly bitter taste and stimulating effects, as it contains caffeine. Here’s what you need to know:

Preparation:

  • Ingredients: The dried, ground leaves of the yerba mate plant.
  • Gourd and Bombilla: Traditionally, yerba mate is prepared and served in a hollowed-out calabash gourd (google it!) called a “mate” and drunk through a metal straw with a filter at the bottom called a “bombilla”.
  • Hot Water: The water needs to be hot but not boiling, typically between 70-80°C (160-175°F).

Process: 

  • Fill the Gourd: You can adjust the amount to your preference, but it’s usually between one-third and two-thirds full.
  • Tilt and Shake: Cover the mouth of the gourd with your hand, tilt it to a 45-degree angle, and shake it a few times. This helps mix the powder and leaves and positions the finer particles toward the top. 
  • Create a Slope: Tilt the gourd to a more vertical position, ensuring the yerba remains sloped on one side. This creates a small pit on the opposite side where you will pour the water.
  • Add Cool Water: Pour a small amount of cool or lukewarm water into the pit to moisten the yerba and let it sit for a minute. This step helps protect the nutrients and avoid a bitter taste when hot water is added.
  • Insert the Bombilla: Place the bombilla into the gourd, inserting it at an angle into the moistened pit. Try not to move it once it’s in place to avoid clogging. 
  • Add Hot Water: Pour the hot water (70-80ºC) into the pit, avoiding the dry yerba on top. Fill the gourd until the water reaches the rim.
  • Sip and Refill: Sip the mate through the bombilla. Once the water is gone, refill the gourd with hot water in the same spot near the bombilla. This process can be repeated several times until the yerba loses its flavor.

As you can see, several steps are used to optimize the process, similar to freeze-drying. However, with time, you will be able to ensure the correct temperature, perform the steps at the optimal times for efficiency, and determine the ideal endpoints. In Argentina, we call the person who prepares the mate the “cebador.” They drink it first to ensure it’s ready, then refill it and pass it to others. There’s nothing better than mate with mates! And don’t worry, if the tree is not native to your area, you can buy freeze-dried yerba mate anywhere!

Bueno Chao,
Bruno