Temperature Control for Laboratory & Industrial Fermentation
by Dr. Dirk Frese, Ph.D., Vice President, Sales, Marketing & Service, JULABO USA
Understanding the Science Behind Fermentation
Fermentation. What is it? What does it produce? How can we make use of it to enhance society? And what are the conditions necessary to control the fermentation process?
This publication will look at the fermentation process and how scientists use fermentation and genetic engineering to solve problems, address disease, and enhance our human experience. We’ll also dive into the applied science of fermentation and how temperature affects results throughout the process. Additionally, we’ll look at how fermentation scientists can improve their workflows and outcomes using temperature control equipment with specific features and functionalities.
The History & Culture of Fermentation
Since the beginning of civilization, around 10,000 B.C., humans have used fermentation to improve their lives. It was first used in Northern Africa to sour milk for cheese, allowing people to preserve camel and goat milk supplies. Today, fermentation has applications in many industries, including medical, pharmaceutical, food, and more.
Most of us are familiar with products that depend on the fermentation process, items such as sourdough bread, wine, beer, vinegar, soy sauce, miso, kimchi, kombucha, and pickled vegetables. However, you may not know that biotechnology uses fermentation to produce pharmaceutical drugs, enzymes, vitamins, nutraceuticals, insulin, bioplastics, etc. We’ve even found uses for the byproducts of the fermentation process; for example, we use carbon dioxide, a byproduct of beer fermentation, to create a range of products, including dry ice. The applications and uses for fermentation are wide and varied, as you can see from the industry examples below.
Fermentation in Industry
Pharma, biopharma & medical
Biological fermentation has been instrumental in developing vaccines and antibody treatments to address COVID-19.
Food & beverage
In addition to many fermented foods and beverages, fermentation can produce food flavor additives, thickeners, and preservatives. Genetic engineers are even using modified yeast to add the aroma of hops to a non-alcoholic beer to enhance the consumer experience.
Cosmetics, fragrances & personal care
Cosmetic companies use microbial fermentation to produce biomelanin, an ingredient that protects against sun damage. In addition, many of the amino acids, peptides, hyaluronic acids, and active ingredients in cosmetics and skincare depend on fermentation.
Paper products
Paper producers use fermentation to degrade lignin.
Bioremediation & environmental science
Currently, fermentation is being used to explore ways to clean microplastics from the oceans and address chemical spills.
Agriculture & food waste
Through microbial fermentation, microbes are cultivated to produce biofertilizers and biopesticides to maintain crop health. Fermentation scientists are also looking into using food waste as fuel for spaceships.
Chemicals & Alternative biofuels
Fermentation converts a carbohydrate (such as starch or sugar) into an alcohol or acid. These alcohols, such as ethanol, can be used as solvents or an alternative to fossil fuels.
Material Science
Bioplastics made from corn starch, lactic acids, and vegetable oils are being used to replace non-biodegradable plastics. In addition, bioengineering is looking to find more sustainable ways to produce textiles and building materials, including using mushrooms to create alternatives to leather and self-repairing bricks for construction.
Wastewater management
Wastewater treatment centers have been using methane fermentation for years to reduce sewage sludge’s mass and volatile content.
Mining
We even use fermentation to leach metals out of metal ores.
Overview of the Fermentation Process
So what exactly is fermentation?
Fermentation is a metabolic process that uses an organism (bacteria, yeast, or filamentous fungi) to convert a carbohydrate into a simpler compound, typically an acid or alcohol. The fermentation process uses the microorganism (bacteria, yeasts, and filamentous fungi) to metabolize substrates (carbon sources of various kinds such as glucose, starch, cellulose, and other polymers) as fuel for metabolism.
In intracellular reactions, these carbon sources are broken down, creating:
- Adenosine 5′-triphosphate or ATP, the dominant energy carrier
- Primary metabolic products (CO2, ethanol, acetic acid, or similar molecules)
- Secondary metabolites
- Or just more cell material (biomass).
Both the primary metabolites (ethanol, lactic acid, and certain amino acids) and the secondary metabolites are beneficial in many products and applications. For example, secondary metabolites include terpenes, flavonoids, penicillin, and more. These secondary metabolites add color, flavor, and other characteristics, too many to mention, to the fermented product.
What conditions are necessary for fermentation?
Fermentation, in general, happens without oxygen under anaerobic conditions, meaning it occurs in the absence of oxygen. This process evolved millions of years ago when the atmosphere contained little to no oxygen.
Later as photosynthesis generated more oxygen, the microorganisms used respiration as a more energy-efficient way to create biomass and propagate. Respiration is a lot more efficient and produces so interesting and versatile for so many industries.
For fermentation to occur, the microorganisms (yeast, bacteria, or filamentous fungi) need a carbon source, phosphor, nitrogen, other nutrients, water, a controlled atmosphere, and a suitable temperature for the bacteria or fungi to multiply efficiently.
Temperature Control for Fermentation
Fermentation requires precise control of multiple parameters to manufacture the desired product and reproduce the same effect every time. These parameters include: sterility to start, and then various unit operations, including atmosphere, reagent and/or feedstock addition, agitation, and temperature. In addition, fermentation produces heat as a byproduct that can raise the fermenter temperature above the desired range, causing the production of unwanted byproducts and reducing the yield of the desired product. Therefore, temperature control remains key to high-yielding and reproducible fermentations.
How to Select a Temperature Control Unit for Fermentation Applications
Fermenters with jacketed external walls or internal coils often use a circulating temperature control unit (TCU) to control the process temperature. Most fermentations occur in the range of 20˚C to 85˚C, with exceptions (such as lager beer fermentation). TCUs with the appropriate heating/cooling capabilities provide the proper temperature conditions for fermentation and allow you to remove heat from the process, ensuring high yields and batch-to-batch reproducibility.
The size of fermenters varies greatly from bench-scale (<5L) to production scale. Several factors determine which TCU you will need for your application, including the size of your fermentation vessel and the TCUs’ heating and cooling capacities. You’ll also want to consider the heat output during the fermentation process to ensure you select a TCU with the proper cooling capabilities.
To properly size a TCU for a fermentation application, you’ll want to consider:
- Size of the fermentation vessel
- Desired process temperature range
- Fermentation process volume
- Required time to temperature, if applicable
- Required heating/cooling capacity (if known)
- Heat output of the fermentation process (if known)
- The fluid volume of the vessel jacket or coil assembly
If you do not know the required heating and cooling capacities or heat output, JULABO USA’s experts can help. We use a variety of calculations and safety factors to ensure you get a TCU that meets your fermentation needs.
Finding a TCU that Enhances your Fermentation Workflow
In addition to sizing the TCU for your fermentation process, you’ll also want to consider how the TCU fits into your workflow. Many TCUS, like the ones offered by JULABO USA, feature technologies that can significantly enhance the fermentation workflow.
Automation & Communication Interfaces
Most manufacturers use some form of automation to control the fermenter and control unit operations. Automation eliminates the potential for human error, increases precision, and greatly improves batch-to-batch reproducibility.
When selecting temperature control equipment, look for a unit that integrates with a programmable logic controller (PLC) to streamline the fermentation temperature control. You’ll also want to consider the I/O (input/output) interface to the PLC. I/O options include analog (voltage or current), RS232/RS485, Ethernet, USB, Modbus, Profibus, or Ethercat communication portals.
If the fermenter does not have remote temperature monitoring, then a TCU with an external temperature control function (such as Pt100 or thermocouple) will be helpful. Adding a PT100 or thermocouple will allow you to control and monitor conditions inside the process.
To determine which I/O interface works best with your workflow, you can consult directly with JULABO’s team of experts to help you choose the best unit for your workflow.
JULABO TCUs for Fermentation Temperature Control
Benchtop to 20L vessels use refrigerated/heating circulators from the DYNEO DD and MAGIO MS series. These products have either 1kW or 2kW heaters and up to 1kW cooling power. I/O options: DYNEO DD has USB with options for analog or RS232; MAGIO MS has USB, Ethernet, RS232/RS385, and Modbus, with an analog option.
The FL chiller product line offers general cooling for fermenters ranging from 0.3kW to 20kW cooling power. The FL chillers incorporate RS232 communication. Heaters can also be added into the FL units, extending the upper-temperature limit of +95˚C.
Larger fermentation vessels (>20L) work well with the SemiChill and PRESTO products. The SemiChill line ranges from 2.5kW to 10kW cooling power with customizable options, including heaters and I/O. The PRESTO single-stage products range from 0.5kW to 25kW cooling capacity and 2.3kW to 27kW heating power, using glycol/water as the heat transfer fluid. PRESTO units incorporate USB, Ethernet, RS232, and Modbus communication with options for analog, Profibus, and Ethercat.
Your local JULABO account manager can help you find the best TCU (temperature control unit) for your application and workflow. There’s a lot to consider, so a personalized product recommendation from JULABO can help you make an informed decision based on the size of your application and your workflow goals.
Conclusion & Next Steps
Fermentation continues to drive many innovations and solutions due to its advantages over other chemical and industrial processes. Fermentation usually consumes less energy than chemical processes, produces less or compostable waste, can generate fuels, and is often safer than other industrial processes. With more and more genetic engineering and research into how organic organisms such as bacteria, fungi, and yeast can be used, we expect to see growing demands for fermentation temperature control.
If you are looking for ways to optimize your fermentation temperature control or looking for a way to scale your fermentation process, JULABO USA can help. While fermentation products are common, the process itself can be complex. We’ll help you think through scenarios, calculate heating and cooling capacities, and achieve optimal results with your fermentation process. Get started with a free consultation.
