The fungi responsible for the deterioration of food products vary according to the characteristics of each product (physical-chemical characteristics, processing).

In bakery products, normally contamination from raw materials, such as wheat flour, is eliminated in the cooking step (oven). After leaving the oven, the products will go to the cooling and slicing stages, which are the most critical stages for the occurrence of fungal contamination.

About 90% of bread contamination by fungi occurs in the cooling, slicing and packaging stages, as fungal spores from flours are dispersed in the air in the form of aerosols. These aerosols are a source of contamination and are deposited on the surface of freshly baked bread during the cooling stage, resulting in recontamination of the product.

Monitoring air quality is important so that preventive or corrective measures are taken, according to air analyses, detecting and quantifying microorganisms present in the air and being able to generate limits of low, intermediate and high risk of food contamination.

In order to improve air quality and restrict the access of spores to baked goods, it is necessary to improve the hygiene of the manufacturing area: avoiding the accumulation of product residue in machines, trays, slicers; keeping floors, walls, ceilings clean, as well as any surface that comes into contact with the product; keeping the flour handling areas separate from the cooling and packing areas. The effectiveness of the Good Manufacturing Practices must also be verified according to the standards described by ANVISA and its importance must be emphasized with the collaborators.

How is the air collected?

There are several methodologies for ambient air analysis, the most common being:

• Plaque analysis by natural air sedimentation;

• Air suction with appropriate equipment with attached plate.

In both methodologies, a Petri dish is used with a specific culture medium for fungi, and air is collected at strategic points in the manufacturing plant where the greatest contamination of the final product is likely to occur.