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Many shelf-life failures are not caused by pathogens.
Instead, they result from spoilage organisms such as yeast and mold.
These microorganisms can affect:
Product appearance
Texture
Flavor
Aroma
Package integrity
Consumer acceptance
Understanding yeast and mold results helps food manufacturers identify spoilage risks, improve product stability, and establish realistic shelf-life expectations.
PBR Laboratories provides yeast and mold testing, food microbiology testing, shelf-life studies, and food quality testing services throughout Alberta, Western Canada, and Canada.
Yeasts are single-celled microorganisms naturally present in many food production environments.
While some yeasts are intentionally used in food production, unwanted yeast growth may contribute to product spoilage.
Common Effects of Yeast Growth
Fermentation
Gas production
Package swelling
Off-flavors
Off-odors
Texture changes
Molds are multicellular fungi commonly found in:
Air
Dust
Raw ingredients
Production environments
Packaging environments
Unlike bacteria, mold growth is often visible.
Common Signs of Mold Growth
Fuzzy growth
Discoloration
Surface colonies
Off-odors
Product deterioration
Yeast and mold testing helps manufacturers evaluate:
Will the product remain acceptable throughout its intended shelf life?
How does the product perform under expected storage conditions?
Is packaging providing adequate protection?
Are sanitation and process controls effective?
Are incoming materials contributing spoilage organisms?
Results are typically reported as:
Examples:
• <10 CFU/g
• 100 CFU/g
• 1,000 CFU/g
• 10,000 CFU/g
Examples:
• <10 CFU/mL
• 100 CFU/mL
• 1,000 CFU/mL
The reporting format depends on the sample type.
Elevated yeast counts may indicate:
Microorganisms utilizing available sugars.
Changes occurring during storage.
Incoming ingredients contributing spoilage organisms.
Production environment contributing contamination.
Conditions allowing microbial growth during storage.
Elevated mold counts may indicate:
Airborne spores entering the product.
Moisture or oxygen entering the package.
Conditions supporting mold development.
Product stability concerns.
Contaminated raw materials entering production.
Bread, buns, tortillas, and baked goods.
Cheese, cultured products, and specialty dairy items.
Products containing sugars, moisture, and nutrients.
Products affected by packaging performance and moisture migration.
Raw and processed pet food products.
Spices, seasonings, powders, and dry ingredients.
One of the most important shelf-life factors. Higher water activity often increases spoilage potential.
Improper temperature control may accelerate growth.
Damaged or ineffective packaging may allow contamination.
Sugar content, acidity, preservatives, and ingredients influence stability.
Humidity and storage conditions can affect shelf life.
Manufacturers often confuse these tests.
Measures total aerobic microorganisms.
Specifically measures spoilage yeasts and molds.
A product may have:
Low APC and elevated mold
High APC and low mold
Elevated levels of both
Each result provides different information.
Determine whether counts are increasing over time.
Assess product age and storage conditions.
Review packaging integrity and performance.
Assess environmental contamination risks.
Determine whether ingredients contributed to results.
Additional testing may include:
Water Activity (aw)
Aerobic Plate Count (APC)
Coliform Testing
Shelf-Life Studies
Environmental Monitoring
Determine realistic product shelf life.
Evaluate package performance.
Compare formulations and ingredients.
Monitor consistency and stability.
Identify causes of spoilage complaints.
Support corrective action programs.
"Mold Growth Always Means Unsafe Food"
Not necessarily.
Mold growth is generally a spoilage concern, although certain molds may create additional risks depending on the situation.
"Low Moisture Means Mold Cannot Grow"
False.
Some molds can grow at relatively low water activity levels.
"Packaging Alone Determines Shelf Life"
False.
Shelf life depends on formulation, microbiology, water activity, packaging, and storage conditions.
"Yeast & Mold Testing Is Only Needed For Bakery Products"
False.
Many food products benefit from yeast and mold monitoring.
Yeast and mold testing helps manufacturers:
Improve shelf life
Reduce spoilage
Evaluate packaging performance
Monitor product quality
Support shelf-life validation
Investigate customer complaints
Understanding yeast and mold results helps identify risks before they become product failures.
The concentration of spoilage yeasts and molds within a sample.
Typically as Colony Forming Units per Gram (CFU/g) or Colony Forming Units per Millilitre (CFU/mL).
It helps evaluate spoilage potential, product stability, and shelf life.
Bakery products, dairy products, ingredients, sauces, snacks, pet food, and ready-to-eat foods.
Not necessarily. Yeasts are typically associated with spoilage rather than pathogens.
Water activity, packaging, storage conditions, environmental contamination, and formulation.
PBR Laboratories provides yeast and mold testing, food microbiology testing, shelf-life studies, water activity testing, environmental monitoring, and food quality testing services throughout Alberta, Western Canada, and Canada.
Contact PBR to discuss spoilage concerns, shelf-life validation, product stability challenges, packaging performance, and food quality objectives.
Choose PBR – Because Precision Matters, Defining Excellence in Laboratory Services Since 1984.