Pro Tip: Understand microbiological control to prevent mold before a baked product’s expected shelf life comes to an end.

As bakers, when we experience mold before the end of a product’s expected shelf life, we often look first at the formula. Should we add more calcium propionate? Should we lower the pH? Should we use cultured wheat, cultured corn, vinegar or another fermented ingredient?

These ingredients can help, but microbiological control is about much more than adding acids or preservatives. We must understand molds, yeasts and bacteria, how they enter the bakery, what they need to grow, and how sanitation and chemistry work together.

What happens after baking?

At approximately 200°F internal temperature, baking destroys the microorganisms responsible for most contamination and spoilage. The bread leaves the oven at its cleanest microbiological point. Most contamination happens afterwards during cooling, conveying, slicing, filling or packaging.

Mold can travel through the air, flour dust, equipment, clothing, tools and employee traffic. It needs oxygen, available water, nutrients and the right temperature to grow. This is why mold normally appears first on the bread’s surface.

Spoilage yeasts can enter through air, equipment, ingredients and people. They can grow in moist or sugary products and may create off flavors, odors, discoloration, gas or fermentation inside the package.

Bacteria are often associated with moisture, standing water, drains, condensation, people and poorly cleaned equipment. They can be transferred by hand, tools, water, belts, slicers, fillings and packaging equipment.

Standard bread is generally less favorable for bacterial growth than many high-moisture foods. However, bread with fillings, toppings, dairy ingredients, eggs, meats or significant handling after baking require additional attention.

Sanitation is the foundation

A preservative can slow microbial growth, but it cannot correct a contaminated cooling spiral, dirty slicer, uncontrolled airflow, standing water, condensation or equipment that cannot be properly cleaned.

The area from the oven discharge to the sealed package should be treated as a protected, high-hygiene zone. A strong sanitation program should include:

• Controlled employee and equipment traffic
• Proper cleaning followed by complete drying
• Equipment disassembly and inspection
• Control of crumbs, dust, water and condensation
• Attention to fans, filters, drains and overhead structures
• Regular testing based on the product and risk
• Corrective actions followed by verification

The sanitation team cleans the equipment, and the QA/QC team verifies the results using simple swab tests. The results should be recorded and tracked so recurring problem areas can be identified.

Do not test only where you expect to pass. Test where you need to learn. One result is only a number. Tracking results by location, line, shift, product, sanitation cycle and season helps tell the real story.

Understand the chemistry

Propionic acid is one of the main tools bakers use to control mold in baked goods. It can be delivered through conventional ingredients such as calcium propionate or through certain cultured wheat, cultured corn and other fermented ingredients.

The ingredient name may be different, but the important questions remain the same: How much propionic acid does it provide, and how effectively can it work at the bread’s finished pH?

At pH 5.8, about 10% of the propionic acid is in its active form. That increases to approximately 32% at pH 5.2 and 54% at pH 4.8.

The lesson is simple: adding more of an ingredient does not always provide better mold control. We need to understand how much propionic acid is being delivered and control the finished-product pH so it can work effectively.

Cultured ingredients may also contain other organic acids and fermentation compounds. Their strength can vary, so they must be tested in the actual formula and process rather than treated as direct one-for-one replacements.

Water activity must also be understood. Moisture tells us how much water is present. Water activity tells us how much of that water is available for microorganisms to grow.

Build a complete program

There is no single ingredient that can deliver shelf life or food safety by itself. The strongest bakery programs combine sanitation, equipment design, testing, pH, water activity, preservatives, cooling and packaging.

Chemistry should support a good microbiological control program, not replace it. The oven gives us a clean product. Everything after the oven must be designed to protect it.

Richard Charpentier is a classically trained French baker, CMB, holds a degree in baking science from Kansas State University, and is owner and chief executive officer of Baking Innovation. Connect with him on LinkedIn.