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3 Common Methods to Safeguard Fermentation Feedstock in Your Alternative Protein Operation

The alternative protein industry has experienced significant growth in recent years due to shifts in consumer demand, driving food manufacturers to explore new ways of creating sustainable food. Those working in this relatively new space, from start-ups to established industry leaders, utilize various technologies and equipment to bring their alternative protein products to fruition.

Fermentation is a flexible process utilized throughout the industry to produce alternative proteins and ingredients. The role of fermentation in food manufacturing requires specific contaminant controls and preventive measures to safeguard fermentation feedstock and products against contamination.

Importance of Aligning Controls When Changing Operations

When an alternative protein operation changes, so do the contamination controls required to safeguard it. For example, maintaining an environment conducive to fermentation in a laboratory setting is very different from how this environment is maintained in an industrial setting.

Failing to adjust contaminant controls when changing an operation can result in unwanted consequences, including damage to equipment, compromised product quality, wasted materials and resources, product contamination and process inefficiencies.  Fortunately, there are several contamination controls used in the food and beverage industry that can be applied to fermentation feedstock and process utilities.  

Understanding Fermentation and Feedstock

While the fermentation process has been around for centuries, controlled precision fermentation used in alternative protein production is a relatively new application in the food and beverage industry. Precision fermentation is practical for alternative protein production as it helps produce similar flavors, textures, and tastes as ‘traditional food’.

Feedstock used in both traditional and precision fermentation practices can be considered as a type of utility, usually a form of liquid mixture, that helps ‘fuel’ the fermentation process.

There are numerous examples of available feedstock solutions, but to cut down on costs and find a solution fit for their process, many alternative protein manufacturers produce their own fermentation feedstock in-house. These solutions often contain a mix of water, sugar, and other nutrients. Interestingly, the in-house solutions created are similar to liquid sugar solutions used in the soda, juice, wine, beer and other beverage industries.

Alternative protein manufacturers can also draw from the extensive experience and expertise these well-established industries hold in applying contamination controls. They can learn from these tried-and-tested applications to implement effective contamination controls that safeguard their alternative protein fermentation feedstock and manufacturing process.

Contamination Control Actions: Removal vs Inactivation or Destruction of Contaminant

Contamination controls address both particulate and microbiological contaminants. Particulate is any type of undesired suspended solid, while microbiological contaminants include unwanted bacteria and microorganisms. With this in mind, a successful feedstock contamination control addresses both types of contaminants by performing the following actions:

1. Removal of contaminant through particulate and membrane filtration methods. This is generally required when particulate is present such as sand in the source water that cannot be removed via heating methods. This action may also be utilized when the manufacturer is working with heat-sensitive materials, such as proteins that can be denatured by heat.

2. Destruction or inactivation of contaminant which is achieved through either heating, cooling, or other methods such as UV radiation. For this discussion, we will be covering the most common methods in the food and beverage industry, which are heating methods that utilize autoclave or steam injection technologies. Inactivation or destruction is generally used when materials are not sensitive to heat and for addressing microbiological contaminants that may be resistant to filtration alone.

Where appropriate, manufacturers may undertake a combination of the above actions for extra protection and when addressing both particulate and microbial contaminants.

Understanding the 3 Most Common Methods: Filtration, Autoclave and Steam Injection

Evidently, the method applied is dependent on the desired contamination control action and how it will affect the manufacturing product and process. There are many process and operational considerations when it comes to choosing a method, including the fermentation feedstock used, the product, costs, safety, scalability, the type of process undertaken, ease of use, and overall effectiveness. Let’s look at each of the most common methods and their best-use cases.

Method 1 – Filtration

When the desired action is removal of the contaminant, then liquid filtration methods are implemented. While there isn’t extensive historical experience in filtering fermentation feedstock, alternative protein manufacturers can draw on the expertise available from filtering other sugar solutions in the food and beverage industry such as juices, stocks, and sodas. Best practice for liquid filtration follows a 3-step process:

Step 1: Applying a nominal particulate filter: This removes large particles and helps protect downstream filters and equipment. Overall, this step reduces particle load and the number of suspended solids.

Step 2: Applying an absolute particulate filter: This removes all particles greater than the filter micron size, based on the filter retention rating, which could be up to 99.9999999% of particles.

Step 3: Applying a membrane filter: This addresses microbiological contaminants as defined by the retention rate of the filter. Membrane filters should always be integrity tested and sterilized regularly.

Common Best-Use Case:

High Volume, low viscosity, industrial scale, continuous process, flexible budget, particulate present.

Method 2 – Autoclaves

Autoclaves perform the inactivation or destruction heating action and are ultimately pressure vessels that use steam to heat the contents placed inside them. This method is very flexible and commonplace in laboratory settings where batch processes are followed.

Given the physical nature of the equipment and the batch process, autoclaves are best suited to smaller-scale operations and are often found to be impractical at an industrial scale.

Common Best-Use Case:

Low volume, high viscosity, laboratory scale, batch process, pharmaceutical quality standards.

Method 3 – Steam Injection

Steam injection is another heating method that performs the inactivation or destruction action. It is the process of mixing steam directly with the feedstock within a fermenter or in a piping system. There are two different types of steam injection methods:

1. Batch process method: This involves injecting steam into the fermenter containing the feedstock. This process is easily accessible for manufacturers as it only requires a clean steam source.

The batch process steam injection method is easily scalable, but it’s important to note that doing so on a larger scale requires a longer cooling time. The steam also remains in the fermenter and cools which causes dilution to feedstock, this isn’t necessarily an advantage or disadvantage, but should be a key process consideration.

Common Best-Use Case:

Laboratory scale, production of different product types, no time constraints, flexible solutions required.

2. Continuous process method: This method is more relevant to those working on a large or commercial scale as industrial equipment and infrastructure are required.

During the continuous process method, steam is continuously injected into a holding loop piping system that the feedstock runs through and towards the fermenter. At the end of the piping, there is a ‘rapid expansion’ process step that facilitates flash cooling, allowing the feedstock to cool within a few minutes. Overall, this process is much faster than the batch method and uses a higher steam temperature.

Common Best-Use Case:

High volume, industrial scale, flexible solutions required, production of multiple products, continuous system.

So, What Method ‘Should’ you Choose?

It’s clear that there is no black and white answer to this question. The overall 'newness' and evolution of the alternative protein industry adds another layer of complexity as alternative protein manufacturers strive to follow the most effective process and meet evolving regulatory standards.  

With multiple options available, manufacturers must consider the aforementioned process considerations to determine which 'best-use' case they fall into.

Once these factors are determined, manufacturers will be in a better position to understand what contaminant control method they should pursue – whether that be a contamination removal strategy executed via filtration, an inactivation or destruction strategy executed by autoclave or steam injection heating methods. Some may also opt for a combination of both where appropriate.

Donaldson’s filtration experts can help alternative protein manufacturers determine find the right products for their feedstock contamination control solution. As a member of the Plant Based Foods Association (PBFA), we are dedicated to supporting manufacturing needs in the plant-based and alternative protein industry. We work closely alongside our team at Solaris Biotech – a Donaldson Brand to provide an end-to-end fermentation solution.

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