Probiotics: quality assurance begins with strain stability

Published: 26-Jul-2021

Emerging research continues to reveal the benefits of a healthy gut – whether it’s enhanced immune health, improved cognitive function or better digestive well-being. Buffy Stahl, Technology Scouting and Open Innovation Leader, and Sarah Hansen, Probiotic Development Scientist, IFF Health, report

With probiotics offering a proactive and holistic approach to bolstering gut health, it’s no surprise that consumers have taken note. In fact, the probiotics market is expected to reach $57.4 billion by 2022, registering a CAGR of 7.7% throughout 2016–2022.1

Before brand owners incorporate probiotics into their product portfolio, however, they should note that sustaining strain efficacy can be a formidable challenge.

Because probiotics are sensitive to heat, water, pH and even oxygen levels, supplements must be carefully crafted to ensure stability throughout every development stage — from formulation to transportation to consumer shelves.

By formulating for strain stability, following manufacturing best practices and partnering with a trustworthy supplier, brand owners can deliver high-quality, efficacious products tailored to consumer demand.

It’s alive!

One of the key factors to consider when formulating with probiotics is that they’re living organisms, so they must remain in a state of suspended animation before consumption, which is done through processes such as freeze drying. In this state, they’re alive but don’t grow or utilise any nutrients.

However, living organisms are not made to stay in this state, so the bacteria will slowly begin to die and render the probiotic useless. The probiotic culture, which is made up of billions of bacterial cells, will decrease in potency with time, which means the culture has an expiration date or “shelf-life.”

This varies depending on storage temperature, dosage form or packaging. It is critical to understand and optimise each formulation for probiotic stability and ensure the expiration date is properly labelled on the supplement packaging to deliver an efficacious dose.

To refrigerate or not refrigerate?

Because probiotics are heat-sensitive, the bacteria are at risk of dying as the temperature rises above freezing. One of the easiest solutions to this challenge is to simply refrigerate the supplement.

Manufacturing refrigerated probiotic supplements both protects the bacteria and allows formulators to add less overage — the initial input of live strains in a probiotic supplement.

Probiotics: quality assurance begins with strain stability

Because the majority of bacteria will remain alive through the duration of the supplement’s shelf-life, a refrigerated product requires less overage than a shelf-stable one.

However, many brand owners shy away from refrigerated probiotics because of added transportation and storage costs. Hot trucks, arid retail environments or unaware consumers that leave products in the heat may also negatively impact the efficacy of refrigerated probiotics.

For standard unrefrigerated products, ensuring efficacy throughout its shelf-life is feasible, but it takes a bit more work. Formulators can use common stability methods — such as increasing the amount of overage within the product — to ensure the probiotic strains provide consumers the necessary health benefits.

Although most of the bacteria will die before consumption, enough will survive to yield a beneficial result. Although this may save money on transportation and storage, formulators should keep in mind that shelf-stable probiotics may use up to ten times more overage than their refrigerated counterparts.

Packaging to combat environmental factors

Temperature is just one factor that plays a role in keeping friendly bacteria alive. Probiotic supplements must stay dry as well; water can activate the probiotic and take it out of suspended animation.

Brand owners must carefully evaluate their packaging to ensure the supplement remains dry during transportation, storage and product placement in a retail environment.

Investing in high-quality, effective packaging is crucial, as is knowing which packaging works best for specific dosage forms. A common manufacturing challenge is identifying packaging that’s inexpensive but also a good barrier for protecting the product from water exposure.

For capsules, the combination of a bottle with a desiccant usually offers the best protection from environmental factors. A desiccant protects the product from water and humidity to extend the product’s shelf-life; molecular sieve desiccants are very effective at this job.

Probiotics: quality assurance begins with strain stability

Not all bottles are created equal, though, as the amount of moisture the material allows to penetrate inside is an important consideration. Polyethylene terephthalate (PET) plastic makes an attractive bottle, but it’s terrible for probiotic stability because it allows too much moisture to enter.

Glass bottles have impressive moisture barrier properties but can make transportation difficult, owing to their weight and fragility. Although blister packaging can be an inexpensive option, the seal integrity and moisture vapour transmission rate of the materials must be carefully evaluated to find successful solutions.

An experienced supplier can help to recommend the right type of packaging for different delivery formats. They can also provide input on temperature regulation, as well as accurate expiration dates for each strain.

Partnering with a trustworthy supplier will help to ensure quality control throughout the entire process, from raw materials to the finished product.

Probiotics delivered differently

Beyond traditional dosage forms such as tablets and capsules, consumers are becoming increasingly interested in innovative delivery formats for digestive health. However, maintaining strain stability in alternative delivery formats, such as food and beverage, can be its own challenge.

Although some food and beverage formats — such as chocolate, yoghurt and powdered drinks — lend themselves well to preserving strains, others, such as kombucha, prove a bit more challenging.

To incorporate probiotics into high-water content and high-temperature processed products, spore-forming bacteria may be the solution. One example is the highly stable and robust, Bacillus subtilis Bss-19 strain, which is adept at surviving some of the toughest functional applications when traditional lactic acid bacteria (such as Lactobacilli or Bifidobacteria) may not be ideal.

Spores create an opportunity for brand owners to launch products in on-trend formats such as gummies, fermented teas, bars and snacks, wherein conditions may not support probiotics from the more established lactic acid bacteria category.

For example, spores work well in gummy formats, despite the fact that the process involves robustly high temperatures. In addition, probiotic spores are strong enough to survive stomach acid and provide benefits to the small intestine, bolstering gut health.

Beyond new delivery formats, brand owners can also consider pairing probiotics with trending botanicals to maximise end-product marketability.

Well-known natural ingredients, such as echinacea and elderberry, may reveal synergistic effects with certain probiotic strains to further bolster immune health, whereas botanicals such as cranberry may be paired with studied probiotic strains that support women’s health.

Pairing probiotics with other ingredients can impact strain stability, so it’s essential to work with a supplier who has tested these combinations strenuously to confirm their compatibility.

Emerging formats and combinations require in-depth formulation expertise to ensure the claims on the package are valid throughout the product’s shelf-life. Collaborating with a supplier who has expertise in other ingredients and in a range of delivery formats will help to streamline processes while providing a quality end product.

A sense of stability

Although temperature, packaging and delivery formats are important considerations for strain stability, the most important factor when formulating a stable product is the strain itself.

Stability ranges dramatically among strains — even those that are 99% similar can have vastly different stability in product formulation. Suppliers should be testing each strain individually to make sure they are able to maintain stability throughout a product’s shelf-life and in final applications.

At IFF Health, we monitor strains using different temperatures, packaging and storage types. The data is then used in formulating products with our premium probiotic strains, to guarantee a potency that lasts for 18–24 months.

This is the only way to identify the necessary environment each strain requires for shelf stability and we use this data to inform customers how to best deliver their products. Although this is standard industry practice, not all strain suppliers have done the testing to be able to provide this information.

Formulators should take heed to confirm this information with any potential supplier; otherwise, they risk developing products that won’t provide the promised benefits.

When sourcing for strain stability, formulators should also seek suppliers that utilise efficient fermentation and concentration drying processes, as well as stability technology. These processes ensure that the probiotic reaches consumers in its most active, optimal form.

As the demand for probiotics grows and more products infiltrate the marketplace, brand owners can stand out from their competition by developing efficacious products that yield noticeable benefits.

And, by working with a partner who understands the importance of strain stability, and has the technical expertise to back it up, brand owners will be well equipped to deliver novel products in innovative formats that meet consumer demand.


  1. Allied Market Research, Probiotics Market Report 2014–2022,

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