Offering contract brewing services can be a boon to business, but welcoming external brands into your production facility can introduce a number of biosecurity and operational risks. This guide details how a host brewery can implement strict microbiological gatekeeping and allergen segregation to protect its own flagship brands from contamination.

In this last article in our series on contract brewing we are looking at the potential risks to businesses offering these services and also, how to mitigate them. Transitioning from brewing exclusively for your own brand to acting as a host facility fundamentally reshapes your brewery’s risk profile.

Navigating this space successfully requires balancing the revenue potential against operational safeguards. Cross-contamination can taint a flagship IPA, destroy batch consistency, or trigger costly recalls that permanently damage your own brand’s reputation.

Ensure safeguards are in place

As a result, there are a number of protocols that businesses can put in place. For Mark Gammons at Murphy and Son, when it comes to working with yeast, a beer produced by a contract partner would ideally utilise an off the shelf yeast culture.

“The prerequisites of a set viability and vitality aside, often the purity of a house strain comes into play. Ensuring that there is no background wild yeast or contaminants, that could become dominant can be difficult,” he explains.

“Some heritage strains might not be purely one yeast strain, but a combination of a few. Replicating the yeast profile and conditions brewery to brewery will be crucial. Alongside the consideration of the impact of multiple yeast strains for the contract brewer.”

The same duty of care, Gammons says, should apply to isolating high-risk ingredients such ass unpasteurised fruit purées or wild cultures. “The impact of high-risk ingredients is scary enough within your own brewery. These are magnified when applied to contract brewing such brands,” he says.

Isolation throughout the process

Complete isolation throughout the processes, he stresses, would be essential and that means assessing and safely storing any raw materials, utilising specific equipment for testing, such as different beakers, lab equipment and tools.

“Ensuring any cross contamination is impossible often comes down to team mentality, successful communication of the risks and impacts to all team members. Successful verification of cleaning once the product has been packaged is key to building in a good high risk operation.” Says Gammons

At Kersia UK, technical sales consultant Belinda Jennings, says there are a number of ways breweries can achieve this. “They should isolate high-risk ingredients such as unpasteurised fruit purées and wild or sour cultures through dedicated equipment, segregated storage and handling areas, colour-coded transfer hoses, controlled personnel movement/access/PPE, and enhanced cleaning verification to prevent cross-contamination of mainstream beer production,” explains Jennings.

She adds that brewers should avoid locating Brett, mixed and fruit fermentations adjacent to critical products destined for filtration or packaging.

Avoiding the cross-contamination risk

In modern brewing it is not uncommon for beers to feature a wide range of ingredients and adjuncts. Sometimes these are used for the body of the beer while others are for flavour and aroma. Regardless, there is a need for validation protocols to ensure complete allergen cross-contamination prevention.

For Jennings, ATP testing should be considered a “routine release tool”, while ELISA testing should be regarded as the highest level of verification and validation whenever allergenic ingredients such as lactose, nuts or oat-derived ingredients are introduced into the process.

“ATP and protein swabbing can provide rapid confirmation that organic residues have been removed following CIP, but ATP and protein tests alone cannot prove the absence of allergens,” she says.

“For that reason, many breweries supplement ATP monitoring with allergen-specific ELISA testing, using swabs or rinse water samples to verify that allergenic proteins have been successfully eliminated from product contact surfaces.”

She adds that combining validated CIP procedures (Chemical concentration, temperature, flowrates, contact time) with ATP and allergen-specific testing provides much stronger assurance than any single method alone.

Allergens and the tests to consider

And while allergen swab testing for breweries have been available for several years, building these into your Hazard Analysis Critical Control Point (HACCP) plan as well as day to day CIP operations allows confidence in your segregation of allergens.

“All allergens should now be covered under their own risk assessment within the brewery. Allowing controlled ones needs engagement across the whole team, so that the impact of any specific cleaning protocols can be checked,” says Gammons.

“External verification from an accredited laboratory would also be essential. Not just for internal checking and verification but for audit trail, as well as ensuring process standards. When dealing with contract partners, having an assured schema provides confidence and allows for transparency.”

When working with a partner brewery there are also considerations regarding cleaning-in-place (CIP) for both parties to stay on top of. It is therefore key to fully consider the impact of the whole supply chain. For Gammons, technical elements are often linked heavily to the brewing and manufacture without consideration for the risks in cross contamination at packaging, as well as a lack of understanding of the raw materials themselves.

“A brewer can be confident in his own operation, but lack the full detail of what is biologically driving that process. It might feel that some brands are business as usual for a contract brewer, but oversight into what is uniquely driving that brand can be missed,” he says.

Common mistakes to avoid with CIP

And at Kersia UK, Jennings outlines that one of the most common mistakes when external brands are brought into the brewery is the assumption that food-safe ingredients are automatically brewery-safe. Businesses can often underestimate the microbiological risks associated with unpasteurised fruit, botanicals, barrel-aged ingredients or non-standard yeast cultures and therefore fail to provide adequate contamination controls. 

She adds: “Another frequent issue is the reliance on standard CIP programmes without considering whether the cleaning regime has been validated for allergen removal, wild yeast control or high-soil ingredients such as fruit purées and lactose which may well require enhanced cleaning and verification procedures.

“Many proposals also overlook equipment segregation, transfer routing and post-production CIP, focusing on how the beer will be produced rather than how the brewery will safely return the tank and associated equipment back into mainstream production. The most successful onboarding processes are those that include a detailed risk assessment in your HACCP plan, microbiological review, allergen control plan and clearly defined tank release criteria before brewing begins.”