The market for semi-moist pet food and treats is an indulgence-driven market, but “what makes them attractive makes them microbiologically vulnerable,” according to Charlie Connolly, business development manager at Symrise Pet Food.
Connolly spoke April 28 during the 2026 Petfood Forum in Kansas City, Missouri, USA.
Pet owners like semi-moist food and treats because of their high palatability, convenience, soft texture, treat-style feeding and their resemblance to human food.
Semi-moist products can be anywhere from 14% to 65% moisture, but are typically between 15% and 30%. This is the ideal environment for yeast and molds and makes them high risk, Connolly said.
Beyond those characteristics, other conditions can contribute to product spoilage, including raw materials contamination, drying default, packaging default, equipment contamination, airborne contamination, humidity variation, and high ambient humidity and temperatures.
Therefore, Connolly said, antimicrobials are necessary to manage yeasts and mold in semi-moist products. They sit in a “microbial middle ground” – they are too wet to be shelf stable without intervention but too dry for conventional high-moisture preservation strategies such as sterilization.
The need for antimicrobials in semi-moist products is framed by regulatory and scientific requirements, but driven by consumer expectations: pet owners want ingredient transparency, don’t want synthetic preservatives used, and there is an increasing demand for “natural” ingredients.
However, Connolly said, “just because something is natural doesn’t necessarily mean it’s effective.” It must still meet microbiological performance standards.
Fermentation-derived antimicrobials
Connolly highlighted fermentation-derived antimicrobials as a natural solution to fight yeast and mold. Organic acids are the primary contributors to the antifungal activity of fermentation-derived antimicrobials.
When selecting a natural antifungal system, consider:
- Finished product pH
- Sugar/humectant system
- Packaging oxygen transmission rate
- Shelf-life expectations
- Environmental conditions and climate
The best results are achieved when antimicrobial selection is matrix-specific and validated in the finished product, Connolly said. Validation is essential, as microbial ecology varies across formulations and processing conditions, and because the antimicrobial solution interacts differently with each matrix.
Validation must include assessments for efficacy and palatability. The efficacy assessment should include real-time shelf-life studies and inoculated fungal challenge studies. Antimicrobial performance must be demonstrated under worst-case conditions. For palatability, the preservation strategy must protect not only safety, but product acceptance.
Beyond antimicrobials, the hurdle technology principle uses multiple sub-lethal stresses act synergistically to reduce the probability of microbial survival and adaptation. This included raw materials monitoring, water activity control, sanitation and air quality control, and packaging optimization.
