Mold
What is Mold?
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
Origin
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:
| Mold | Appearance or defect |
| Aspergillus niger | Black |
| Aspergillus glaucus | Green, grey-green |
| Aspergillus flavus | Olive green |
| Penicillium sp. | Blue-green |
| Rhizopus nigricans | Grey-black |
| Mucor sp. | Grey |
| Neurospora sitophila | Pink |
| Control factors | Comments | Best control levels / Strategies |
| Water availability (aw) | Lower water activity can effectively slow down mold growth. | Formulate bread to water activity levels below 0.95
Ingredients that help lower aw:
|
| pH | Low pH or acidic environments can limit mold growth. Acidic conditions can also impact the performance of mold inhibitors. | Lower the product pH to below 5.6
Low pHs can be achieved through:
|
| Organic material | Difficult to control since they are essential parts of bakery systems. Any animal or plant material can be used as food for mold.
Control here is focused on preventing accumulation of product on food-contact surfaces such as equipment, conveyors and others. |
Proper documentation and implementation of GMP’s prerequisite programs (e.g. cleaning and sanitizing, employee practices, hygienic design).
Food management systems (e.g. HARPC of FSMA, HACCP, ISO 22000). |
| Temperature | Cooler storage and processing facility temperatures can slow down mold growth rate.
Kill-steps during processing (e.g. baking, extrusion cooking, pasteurization). Molds and yeast are usually inactivated when the interior temperature of the product reaches about 135–140°F (55–60°C). |
Processing facility temperature: use HVAC systems to maintain temperatures around 68°F (20°C)
Product storage temperature: 60°F (15°C) Bake to internal temperature of 205°F (96°C). Thermal profiling is recommended. Cooling to loaf internal temperature of 95–105°F (35–40°C) before packaging to prevent condensation. Freezing and frozen storage. |
| Mold spores | Fungal spores are particularly widespread in bakeries due to their presence in flour and potential spread throughout the production environment via air movement.
Lack of proper cleaning and sanitation practices, recycling of extracted air and/or use of unfiltered air in the bakery increases the presence and accumulation of mold spores. |
Use of ultraviolet or infrared radiation to inactivate mold and mold spores.
Use of modified, vacuum atmosphere or anti-microbial packaging to inhibit mold growth. Proper documentation and implementation of GMP’s prerequisite programs (e.g. air and water quality). |
| Preservatives | Undissociated (uncharged) weak acids diffuse through the microbial cell membrane to the cytoplasm, hindering cellular metabolic activities.2 | Use of mold inhibitors
|
Food safety considerations
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
- Aflatoxin
- Vomitoxin
- Ochratoxin
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.
References
- 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.
I bake cookies using frozen raspberries as topping. After a day mold appears on the raspberries. Is there anything I can do to prevent mold formation please.
Hi Rohith, we are addressing questions in our forum, so others can participate and contribute. Please post your questions here: https://bakerpedia.com/forums/ Thank you!
We are working in Tropical country in Asia and have this problem more often.
Thanks for very informative and practical article.
There are TWO kind of fungus called: Mold n Rope.
In Bread (any fermented dough from Yeast) we use: CA-Calcium Acitate , CP-Calcium Propionate to control Mold and Acetic Acid (diluted) to control Rope.
In Cake (Not fermented by Yeast) we use Sorbic Acid in Pound Cake but in Sponge Cake it doesn’t work.
Can you please help a good combination for both types of cake may be separate formulation to be used in Pond and/or Sponge.
Thanks n Regards!
Hi Afzal, great question. Do you mind posting in our forum, so our team and others can participate and contribute? https://bakerpedia.com/forums/
Hello there, Our facility is located in a tropical season which humidity and temperature fluctuates. Our product nowadays are encountering early molds. We are controlling human traffic, strengthen sanitation program and reviewing processes such as cooling. But other products are still encountering problems such as mold. Is there any other ways or steps to eliminate these recurring issues? Thanks a lot
Hi Vincent, great question! If you post it in our forum, our team and community can share advice there: https://bakerpedia.com/forums/ Thanks!
I have a fungus complain in cake kindly resolve my issue to long shelf life in market what should I do I m in Pakistan
Hi Tabish, that’s a great question. If you post it in our forum, our team and community may be able to help you: https://bakerpedia.com/forums/ Thanks!
Hi i have a mold problem in our dinner roll production..kindly resolve my problem to long shelf life in the market..which kind of preservative I use in this ?could u suggest me ?
Hello Soniya, that’s a great question! If you post it on our Baking Industry Professionals group, our team and community may be able to help with an answer.
Hi, I’m working in bakery manufacturing. I have problem in high yeast count on environmental monitoring after cleaning process, Before cleaning yeast counts are zero.
Hi Malinda, great question! If you post it on our Baking Industry Professionals group, our team and community may be able to help with an answer.