Precise gas control for bioreactors and fermenters

Bioreactors and fermenters play a crucial role in food and beverage manufacturing, more so now in the production of new food and plant-based food products.

These technologies are essential for controlled fermentation processes, which are used for a wide range of consumable foodstuffs as well as to enhance flavour, texture, nutritional value and shelf life.

Bioreactors are used to support and control biological processes involving living organisms or their products. In food production, bioreactors are employed for the cultivation of microorganisms such as bacteria, yeast, fungi, and algae.

Typical uses include yoghurt and cheese production, sourdough in bread making and the production of enzymes and additives for flavourings and vitamins. 

Similar to bioreactors, fermenters provide an environment for the controlled growth of microorganisms, such as yeast and bacteria, to convert raw materials into valuable food products through fermentation.

They are typically used in beer brewing, wine making and the production of other fermented products such as soy sauce and miso.

Today, bioreactors are also playing a crucial role in the development of cellular agriculture, which uses cells and innovative biotechnologies to produce accessible, ethical and sustainable agricultural products.

It is most commonly used to make animal-derived foods and ingredients such as meat, seafood, dairy products, fats, egg whites and gelatin, and is an innovative approach to sustainable food production. 

The process that takes place inside bioreactors and fermenters needs to be carefully controlled to optimise the desired product, and reproducibility of the fermentation process is crucial.

Precision gas control

Fermentation requires the help of biocatalysts such as enzymes or cells and depends on optimum temperature conditions (usually 35°C to 37°C). Precise control of the process also requires accurate supply of up to four gases: oxygen (O2), nitrogen (N2), carbon dioxide (CO2) and air.

Oxygen and carbon dioxide drive the growth process, while pure nitrogen controls growth rate. Air can serve as an all-purpose gas when no specific gas supply is required.

Conventional solutions for the control of gases have involved rotameters (mechanically-acting floating flow meters), but while rotameters are simple and cost-effective flow control devices for some applications, they may not be the best choice for precision gas control in sophisticated and automated processes.

Rotameters have a relatively narrow flow range and may not be suitable for applications requiring the measurement of a wide range of gas flow rates.

As well as having a non-linear measurement response across their measurement range, they also suffer from lower precision, and their calibration and measurement accuracy can be affected by factors such as gas density changes due to variations in temperature and pressure.

As passive flow instruments, they also require integration into a control loop with a separate controller such as a PLC.

For high accuracy and reliable gas flow control, mass flow controllers (MFCs) offer greater precision, and overall cost savings of up to 35 per cent through benefits such as better accuracy, built-in control, wider flow ranges, digital communication, and higher resistance to external factors such as pressure and temperature variations.

Bürkert mass flow controllers

Unique to Bürkert, the Type 8741 and Type 8742 mass flow controllers for gases offer a wide control range from 0.010 l/min to 160 l/min with high accuracy and repeatability. A thermal MEMS sensor located directly in the gas stream achieves very fast response times and a direct-acting proportional valve guarantees high response sensitivity.

Both MFCs support numerous different control network architecture and provide analogue (0/4-20 mA or 0-5/10 V) or fieldbus interfaces, while the Type 8741 also has the option of direct industrial Ethernet connection (supporting PROFINET, EtherNet/IP, EtherCAT and Modbus TCP).

A variant of either model also offers the CANopen-based Bürkert Systembus (büS) suitable for integration into existing CANopen networks or – in combination with the Bürkert Type ME43 fieldbus gateway – for integration into all common industry standards fieldbus or industrial Ethernet networks.

Bürkert can also customise modular gas mixing units to suit the specific application. The units are configured according to specifications using the space-saving 8741 and 8742 mass flow controllers arranged side by side, including valves.

The units are supplied pre-tested for tightness, pressure and correct electrical operation. A customised assembly saves on installation costs, simplifies engineering of the bioreactor or fermenter, and does not require the ordering and storage of numerous individual parts.

Part of a wider digital solution

The modern decentralised digital technologies supported by the Bürkert MFCs helps to reduce costs and improve maintainability. In addition to the MFCs for gas control, Bürkert also offers complete automation solutions to suit all aspects of bioreactor and fermenter control.

Digital automation solutions significantly reduce the amount of cabling complexity, and all relevant data is available digitally, so that significantly more parameters can be utilised than in traditional systems.

This enables permanent diagnostics to ensure system availability at all times.

Bürkert’s portfolio of products and services can be customised to suit diverse applications within the food and beverage industry. Whether the application is brewing, precision fermentation, or alternative dairy products, Bürkert can provide expertise and experience to provide tailor-made solutions suitable for all fermentation applications

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