Closer to Zero: How ZBiotics Addressed Frozen Bottle Breakage
At ZBiotics, using the scientific method to solve problems is in our DNA. So, when we started getting feedback from customers that some ZBiotics Pre-Alcohol bottles appeared to be freezing and breaking during delivery, we knew we had to dive into the issue methodically and find a solution.
The solution turned out to be a long journey involving experimentation, collaboration, and iteration, ultimately leading us to where we are today: transitioning to silkscreen-printed Pre-Alcohol bottles with a reduced 14 mL fill volume for the best combination of quality and safety. But how did we get there? This is the story of how different teams came together to provide transparency, identify the factors behind the influx of broken bottles, and ultimately find a long-term solution to ensure the safety of our customers.
The problem: why were the bottles breaking?
In the winter of 2022-2023, the ZBiotics Customer Care team noticed a sudden spike in support tickets about broken bottles. Hundreds of customers reached out via email, reporting receiving bottles that were broken upon delivery. Nicole S., our Senior Customer Care Manager, and her team quickly escalated the issue to leadership, supply chain, research, and quality teams for immediate action.
Identifying the cause
By tracking emails about broken bottles, the Customer Care team was able to identify patterns in the complaints. Initially, there were no clear correlations with specific carriers or geographic locations, suggesting the issue wasn’t tied to a particular delivery company or region. However, the team noticed spikes in damage reports following cold weather snaps. This led to our first conclusion: the bottles were freezing during transit.
Since we did not have an immediate way to address the freezing bottles, we agreed upon our first solution: transparent messaging. In January 2023, we began including a frozen bottle notice in all packages of Pre-Alcohol (if you’ve ordered Pre-Alcohol, you’ve likely seen it). This notice encouraged customers to carefully check their bottles for cracks or breaks before use, ensuring they were informed and able to request a replacement or refund if necessary. This solution was a temporary fix while the team worked to identify a more permanent solution.
The role of packaging: making breaks more obvious
We take pride in our product’s premium glass bottle design. At the time, our bottles were wrapped in opaque shrink wrap with a frosted look—beautiful but ultimately problematic for this issue. Our Creative Director, Michael R., ran experiments that led us to our second conclusion: the shrink wrap was hiding cracks from view by providing enough structural support to prevent the glass from fully breaking. This created a safety risk, as glass could break upon handling.
To solve this, the VP of Supply Chain, Michael M., and Michael R. worked together to create our second solution: a transparent label. Michael R. designed a new, non-encircling transparent label, which allowed customers to immediately spot any cracks or breaks in the glass. This label also did not prevent the bottles from fully breaking, as seen in the image below. By summer 2023, all bottles transitioned to this new label design.
When water becomes a solid
While the new labels improved transparency of breakages and did not hold the glass together, they didn’t address the root issue: freezing. As you may remember from science class (or because you decided to put a full mason jar in the freezer) when water freezes it expands. Glass isn’t forgiving, so if you don’t leave enough room for the liquid to expand as it freezes, the bottle will crack. To address this, there are a handful of possible solutions, but after initially evaluating the feasibility of them, we narrowed it down to two possible solutions:
- Prevent the bottles from freezing.
- Ensure that the bottles wouldn’t break even if they did freeze.
Option one: prevent the bottles from freezing
The supply chain team worked with our fulfillment centers to explore various options to prevent the bottles from freezing during cold weather snaps. One approach was to include heat packs in packages to maintain internal temperatures above 4°C (40°F). While this was worth considering, this idea was ultimately dropped due to feasibility challenges in spring 2023. The team also considered using insulated box inserts to protect the bottles, but these also ran into feasibility and scalability challenges, which led them to rule out this solution as well.
Option two: if the bottles must freeze, don’t let them break
Chandler H., a PhD scientist working on both the research & development and quality teams, tested various freezing conditions that led to bottle breakage. His experiments involved freezing bottles at temperatures as low as -80°C (-112°F) in various orientations (we’ve all had a box or two delivered upside down!). His testing revealed that the fill volumes of the bottles significantly affected the likelihood of breakage. Bottles filled above 15.5mL were far more likely to break when frozen.
This led to our third conclusion: many bottles were overfilled. Initially, slight variations in fill volumes were acceptable, but the team soon realized the need for a tighter range. Our third solution was to adhere to a low-fill 15mL bottle. Bottlers were instructed to consistently fill bottles as close to 15mL as possible without exceeding it. After months of testing, we were able to begin circulation of the low-fill bottles in December 2023.
Closer to zero
The 15mL low-fill bottles were a relatively easy solution, allowing us to more immediately circulate bottles with a lower chance of breaking, but it still wasn’t fool-proof. While we saw an immediate improvement, the winter 2024 (Dec 2023 - Feb 2024) results did not meet our expectations. We then launched a follow-up endeavor, affectionately called “Closer to Zero.”
Chandler’s original study determined that bottles filled below 15mL were the least likely to break. In fact, he couldn’t get bottles filled at 14.5mL or less to break, even in frozen conditions as low as -80°C (-112°F). While this isn’t a perfect representation of what was happening to the bottles outside of the lab, the data was strong enough for us to come to our fourth solution: a 14mL fill bottle was the safest option for our customers.
However, reducing the fill volume introduced a new challenge: ensuring we did not sacrifice the efficacy of our product. Our microbiologists worked closely with the quality team to change our overall formulation, making sure that we delivered the same amount of ZB183 probiotic activity in the lower fill volume by increasing the concentration of probiotic. After extensive testing to ensure quality, safety, and performance, we successfully rolled out 14mL bottles in late fall of 2024.
Did we get closer to zero?
Yes! We are always tracking our customer support tickets, specifically monitoring reports of broken bottles (among many other things). We are happy to report that while some incidents of bottle breakage still occur, complaints have decreased by approximately 73% when comparing the percentage of broken bottles in all orders from winter 2025 (December–March) to winter 2023. As you can see in the graph below, all of our solutions steadily made improvements that were tangible to our customers.
This process was long and complex, but every step brought us closer to our goal. By using data-driven decision-making and extensive testing, we were able to significantly reduce breakage risk while maintaining product integrity and customer satisfaction. At ZBiotics, we’re committed to continuous improvement. Every challenge is an opportunity to learn, refine, and deliver the best possible product experience for our customers. We’ll always meet these challenges head-on—with science, collaboration, and a relentless drive to get it right.
Reflections from the team:
Nicole S., Sr. Customer Care Manager: “This process shows that cross-functional work is extremely important. It’s important to communicate valid concerns from our customers to the whole team so that we can all know what is going on. We all honestly care about our customers, and not just here at Customer Support, but also Supply Chain, Research & Development, Quality, and Product because we want the customers to be happy.”
Michael R., Creative Director: “We took a creative hit with this choice in order to better meet the customer for safety. Our mission, vision, and values are about our customers and about transparency. While we want our packaging to look and feel premium, we are willing to make changes in order to provide something safer for the customers.”
Michael M., VP of Supply Chain: “It is great to work for a company that puts safety first. Food safety has a new connotation for me at ZBiotics because regardless of what we do in Supply Chain, that’s the number one goal. When this first came up as a serious issue, it was received properly and we knew we needed to fix it. It was a really open discussion and we brainstormed what we could do in the immediate term, what we could do in the mid term, and then the long term. We wanted to both give the consumers visibility and fix the problem.”
Chandler H., Research Scientist: “We did the work to make sure we understood the problem. In the lab, we froze hundreds of bottles in all sorts of orientations and temperatures to get to the root of why, how, and when the glass was breaking. With our data, we determined solutions that prioritize the safety of our customers.”
By leveraging a methodical scientific approach, teamwork, and a commitment to our customers, we’ve turned a challenge into an opportunity for improvement—bringing us closer to zero broken bottles.