WJEC Level 3 Certificate in Food Science and Nutrition

9 Moulds Moulds belong to the group of plants known as fungi , which includes mushrooms. There are many types of moulds, but they all have similar characteristics. Moulds are small plants, and when they grow on the surface of foods, they are visible without a microscope. They need optimum conditions in which to grow and multiply: ⦁ A suitable temperature: 20°C–30°C is optimum, but they can grow in cooler temperatures such as in refrigerators ⦁ A suitable pH ⦁ A supply of moisture: moulds grow particularly well in humid conditions (a high level of water vapour in the air) and on moist foods, but there are some that can grow on dry foods ⦁ A supply of energy and nutrients ⦁ The right level of oxygen (some species of moulds are aerobic and some are anaerobic ) ⦁ Sufficient time. Moulds consist of the following parts: ⦁ Hyphae (‘roots’), which penetrate the surface of the food and spread into an interconnected mass called a mycelium ⦁ Groups of stalks, which are all linked together and each has a sporangium (plural: sporangia), containing spores , at the top: Aerobic – needs oxygen to grow and multiply Anaerobic – can grow and multiply without oxygen Key terms Sporangium Surface of the food Hyphae spreading into the food Whole network of the hyphae is called the mycelium Developing sporangium Spores escaping into the air from burst sporangium bacterial cell, in which the bacteria remains inactive until the right conditions return, then they germinate (the spore breaks open and the bacteria becomes active again). As they germinate, the bacteria spores produce deadly toxins (poisons). Spores can be very resistant to heat and acids and so are difficult to destroy: Micro-organisms