Maintaining product quality is critical for thriving in today’s fast-paced global e-commerce landscape. Customers expect consistent performance and reliable results, no matter where or how they purchase a product. This expectation extends to product stability—how well a product retains its intended characteristics over time and under a variety of conditions. For international shipments, factors like temperature shifts, humidity, and lengthy transit times can all impact product stability. That’s why implementing a solid stability testing program is essential, especially for businesses operating across borders. In this article, we explore three key areas of stability testing: viscosity change, sedimentation, and preservative efficacy—offering practical insights to help ensure product integrity throughout the supply chain.
Viscosity Change and Brookfield Testing
Viscosity, essentially a fluid’s resistance to flow, plays a key role in the consumer experience for products like lotions, sauces, or paints. Variations in viscosity can compromise not just performance, but also how customers perceive consistency and quality.
1.Understanding Brookfield Viscosity Measurement
Brookfield viscometers are the go-to instruments for assessing viscosity across industries. In standard tests, viscosity is measured at various speeds (shear rates) and temperatures over time. This data helps build a viscosity change curve—an invaluable tool for predicting how a product behaves through its lifecycle.
From my experience in the field, testing at multiple temperatures (such as 4°C, room temperature, and 40°C) helps reveal how a product may perform under real-world storage and shipping conditions.
2.Interpreting Viscosity Change Curves
Viscosity change curves offer a clear window into product stability. A stable formula won’t show significant changes over time. A lotion that thickens might point to emulsion breakdown, while a paint that thins could suggest separation or polymer degradation.
These shifts often first show up subtly on the curve before becoming obvious to the naked eye. For example, during seasonal changes, I’ve noticed that thinner formulations can struggle to remain stable without rebalancing the emulsifier system. Spotting these trends early can save costly recalls or customer dissatisfaction.
3.Implementing Regular Brookfield Testing
Schedule Brookfield testing at strategic checkpoints based on your product’s shelf life and storage conditions. Common intervals include initial testing, 1-month, 3-month, and 6-month stability checks, with accelerated aging tests to simulate long-term storage. Set acceptable fluctuation ranges based on historical data and industry standards, and use the results to guide formulation adjustments where necessary.
Sedimentation: Monitoring and Prevention
Sedimentation—the separation or settling of solids in a liquid—can diminish both product appearance and effectiveness. Customers typically associate visible sediment with poor quality or product age, even if it doesn’t affect function.
1.Visual Grading Standards for Sedimentation
Developing a standardized visual grading system helps ensure consistency when evaluating sedimentation. Create a photo-based reference guide showing acceptable versus concerning sediment levels. In some of the projects I’ve worked on, even a 10% sediment layer at the bottom of a serum bottle led to increased returns due to perceived “expired” product.
Such standards not only guide internal quality control but also help manage expectations with third-party manufacturers across different regions.
2.Implementing a Sedimentation Warning System
A monitoring system—ranging from simple periodic visual inspections to advanced sensor-based solutions—enables early detection of sedimentation. In high-volume production, auto-imaging tools with pattern recognition algorithms can rapidly screen for anomalies.
Even in smaller operations, a scheduled inspection routine under consistent lighting and angle can make all the difference. When caught early, sedimentation issues can often be corrected by tweaking suspension agents or altering the milling process.
3.Addressing Sedimentation Issues
To reduce or eliminate sedimentation, consider reformulating to include stabilizers like xanthan gum, adjusting the pH, or improving the homogenization process. Stabilizers and dispersing agents can be crucial in products such as nail polish, sauces, or pigmented emulsions. In my experience, fine-tuning the particle size—not just the ingredients—can greatly minimize clumping or settling over time.
Preservative Depletion Testing: Maintaining Product Integrity
Preservatives are essential to protect water-based formulations from microbial growth—especially products that are opened repeatedly by consumers, like creams or shampoos. Over time, though, preservatives can degrade, compromising safety.
1.Understanding Preservative Depletion
Depletion occurs due to interactions with packaging, exposure to light, temperature shifts, or simply as the preservative is “used up” inhibiting microbial growth. I’ve seen products in PET containers lose preservative potency much faster than in glass, due to polymer interaction. Therefore, it’s not just the preservative choice—but the packaging too—that impacts long-term efficacy.
2.Implementing Preservative Efficacy Testing
To ensure safety, preservative efficacy testing (often referred to as challenge testing) is carried out by inoculating products with specific strains of bacteria, yeast, and mold, then tracking microbial activity over time. This simulates what might happen if a consumer introduces contamination during regular use.
Most regulatory standards (such as USP <51> or ISO 11930) specify acceptable log reductions for each microorganism over specific time frames. These tests are particularly important if your product contains natural or low-preservative formulas, where microbial resistance may be more likely.
3.Strategies for Optimizing Preservative Systems
Improving a preservative system may involve switching to broader-spectrum agents, using synergistic blends, or combining with hurdle technologies like low pH, humidity control, or airtight packaging. For instance, in one project involving a sulfate-free shampoo, we improved preservation by slightly lowering pH and adding a natural chelating agent, instead of increasing preservative levels.
Always validate changes with re-testing, as seemingly minor tweaks can affect both safety and stability.
Stability testing is more than a regulatory checkbox—it’s a cornerstone of product quality and consumer trust in the global e-commerce environment. With supply chains stretching across continents and varying climate conditions, having a rigorous testing program is no longer optional.
By routinely performing Brookfield viscosity testing, establishing clear sedimentation standards, and monitoring preservative efficacy over time, businesses can catch potential issues before they reach consumers. This proactive approach not only minimizes risk but also strengthens brand reputation and encourages long-term customer loyalty in increasingly competitive markets.
Post time: Aug-25-2025