Fact sheet on moulds

General
Molds are a heterogeneous group of filamentous fungi. Most molds belong to the taxonomic groups of sac fungi (Ascomycota) and zygote fungi (Zygomycota).

Molds are widespread in our environment and therefore are also found in many foods. They can be useful in foods but can also cause spoilage and, through the formation of mycotoxins, pose health hazards to consumers.

→ More specific information on a member of the sac fungi: see fact sheet on yeasts

Characteristics

• Spore-forming
• Toxin producers (mycotoxins)
• Form visible mycelium

Origin / Occurrence

• Molds are widespread in our environment (e.g. soil, plants, air, water, humans, …)
• They occur especially in plant-based foods (e.g. cereal products, nuts, herbs, spices, vegetables and fruits), but also in foods with noble molds (numerous cheeses and raw sausage varieties)

Significance

• Molds can cause food spoilage, be hazardous to health, but also be beneficial
• Depending on the food category, a certain number of molds is tolerated in most foods. However, if these are exceeded or visible mycelium is present, this indicates spoilage of the food or even a potential health risk
• Some molds can pose a health risk to consumers because they can produce very toxic mycotoxins (e.g. aflatoxins, ochratoxins, fusarium toxins, patulin, …)
• Health risks from consuming molds can include gastrointestinal complaints as well as poisoning, liver damage, allergies and respiratory diseases
• Moldy raw and intermediate products must not be further processed, as the toxins can be very resistant (e.g. heat-resistant) and may survive processing steps
• When using noble molds, e.g. in some cheeses and raw sausage types like Camembert and salami, a high number of molds and a high total viable count are to be expected. For these foods these test parameters must not be criticized due to high counts
• Some molds can still grow at low water contents and/or low pH values

Conditions for growth

• Temperature:
  • Optimum: +25 °C to +35 °C
  • Minimum: 0 °C
  • Generally no growth above +50 °C
• pH value: growth at pH 3.0 to 7.0 (depending on the species)
• a_w value: growth at a water activity of min. 0.62 to 0.85 (depending on the species)
• Some molds are osmophilic or osmotolerant or acid-tolerant. This means they can also grow at low water activity and low pH
• Oxygen requirement: aerobic

Inactivation by heating

• At +72 °C for at least 2 minutes most molds are killed (Attention: check core temperature) → Note: there are also heat-resistant mold species (e.g. Neosartorya fischeri, Byssochlamys nivea, Talaromyces flavus, and Eupenicillium spp.). In addition, the formation of heat-resistant mycotoxins is potentially possible.
• Mold spores are killed at a core temperature of +80 °C

1. Check incoming goods for e.g. incoming/transport temperature, shelf life, packaging, deviations or anomalies
2. This also applies to goods before use in production. In case of doubt, do not use the food and consult a supervisor
3. Review microbiological specifications. If necessary, request laboratory testing of suspicious products or ask the supplier for results
4. Verify effectiveness by follow-up testing

1. Request traceability of the cold chain during transport from the supplier
2. Check incoming and storage temperatures
3. Monitor refrigeration temperatures/cold chain during processing, transport and sale
4. If overripening (or excessive shelf life) is suspected, perform appropriate storage tests
5. Verify effectiveness by follow-up testing

1. Check processes, production records and documentation
2. Inactivation of most molds at a core temperature of +72 °C for at least 2 minutes. Mold spores are inactivated from +80 °C. Warning: mycotoxins are often very heat-stable
3. Check correctness of processes and temperatures
   1. Generally holding temperatures above +60°C are required
   2. Rapid cooling: after 3 hours a core temperature of at least +7°C must be reached (special caution is required for large quantities)
4. Verify effectiveness by follow-up testing

1. Check implementation of cleaning and disinfection:
   1. Hygiene plan
   2. Execution of cleaning and disinfection e.g. dosing of disinfectant, contact time, use of suitable and clean materials and cleaning cloths
2. Avoid moisture residues and biofilms. Ensure good drying of equipment, devices and surfaces
3. In case of elevated airborne counts, implement appropriate measures to reduce the number of molds
4. Train employees regarding potential errors and corrective measures
5. Repeat cleaning and disinfection
6. Verify effectiveness by visual on-site inspections, environmental testing and follow-up testing