Molds are multicellular fungi which are morphologically more complex than bacteria or yeast (single-celled fungi). In foods, they are one of the main causes of food spoilage and foodborne diseases.
Molds are non-motile, filamentous, and branched microorganisms.
Their cell walls are composed of cellulose, chitin or a combination of both.
They typically grow in the form of fine branching filaments called hyphae which can aggregate to form a mycelium.1
Molds are opportunistic living microorganisms that feed on organic matter, therefore their ability to reproduce in foods. However, they can live in virtually any ecosystem or environment.
In the food industry, these microorganisms are usually seen as enemies. Yet similar to some bacteria, they can be beneficial for certain applications and are used to produce food ingredients and pharmaceutical products.
Mold in the bakery industry
In the bakery industry, along with staling, they are considered the main limiting factors for controlling products shelf-life. Molds that cause spoilage in bread include:
Appearance or defect
High-speed bakeries strive to keep mold away from their operations and products, especially in high water activity baked goods such as bread and buns. The following table highlights some of the strategies used in bakeries to prevent mold growth (or avoid their development):
Mold itself does not represent a food safety hazard for humans unless there is a serious allergy to food product bacteria. What does represent a hazard, however, is the toxins that they (especially, some species of Aspergillus) can produce. Such mycotoxins are extremely carcinogenic and mutagenic, and can cause serious diseases.3
Peanuts, tree nuts, cereals and milk can carry serious toxins that can be fatal to some people. One key consideration is that mycotoxins are not inactivated in the oven so control needs to be done at the source.
Types of mycotoxins that are poisonous to humans include:3
Post-baking mold contamination control
Post-baking steps are critical for mold control. Coming out of the oven, bread is virtually a sterile product but, upon contact with ambient air and unclean equipment surfaces, the product starts a very slow “mold recontamination process” at the crust (exposed areas). Cooling, slicing and packaging operations must, hence be carried out with high standards of hygiene to help reduce the risk of product infection.
Ray, B., and Bhunia, A. “Characteristics of Predominant Microorganisms in Food”. Fundamental Food Microbiology, 5th edition, CRC Press, Taylor & Francis Group, LLC, 2014, pp. 14–15.
Msagati, T.A.M. “Preservatives”. The Chemistry of Food Additives and Preservatives, John Wiley & Sons, Ltd, 2013, pp. 233–234.
Hutkins, R.W.. “Bread Fermentation”. Microbiology and Technology of Fermented Foods, Blackwell Publishing, 2006, pp. 261–298.