The large and diverse group of microscopic foodborne yeasts and molds (fungi) includes several hundred species. The ability of these organisms to attack many foods is due in large part to their relatively versatile
environmental requirements. Yeasts tend to grow within food and drink matrices in planktonic form and they tend to ferment sugars, growing well under anaerobic conditions. Molds, on the other hand, tend
to grow on the surface of objects in the shape of a visible ‘mycelium’ made up of many cells.
Both yeasts and molds cause various degrees of deterioration and decomposition of foods. They can invade and grow on virtually any type of food at any time. They invade crops such as grains, nuts, beans, and fruits in fields before harvesting and during storage. They also grow on processed foods and food mixtures.
| S.N. | Characteristics | Mold | Yeast |
| 1 | Habitat | Typically found in damp, dark or steam-filled areas. | Very common. Can be found on fruit and berries, in the stomach of mammals and on skin, among other places. |
| 2 | Cell | Multicellular (multiple celled) | Unicellular (one cell) |
| 3 | Shape | Filamentous fungi, Threadlike | Round or oval in shape |
| 4 | Appearance | Fuzzy appearance and can be an orange, green, black, brown, pink or purple in color. | White and thready. |
| 5 | Hyphae | Molds have microscopic filaments called hyphae. | Yeasts do not have true hyphae. Instead they form multicellular structures called pseudo-hyphae. |
| 6 | Types | There are 400,000 types of molds. | There are 1500 types of yeasts. |
| 7 | Sporing | Mold is a sporing fungi | Yeast is a not a sporing species of fungi. |
| 8 | Reproduction | Sexually and asexually reproduce into multi-cellular form. | They reproduce mostly asexually (budding). |
| 9 | Asexual Spores | Sporangiospores and Conidia | Blastospore |
| 10 | Sexual Spores | Zygospores, Ascospores, and Basidiospores | No Sexual Spores. |
| 11 | Colorful | Molds are very colorful compared to yeast. | Yeast are less colorful compared to molds (colorless). |
| 12 | Examples | Alternaria, Aspergillus, Fusarium, Mucor, Penicillium, Rhizopus, Trichophyton, etc. | Saccharomyces cerevisiae, Cryptococcus neoformans, etc. |
| 13 | Energy Production | Secrete hydrolytic enzymes that degrade biopolymers such as starch, cellulose and lignin into simpler substances that can be absorbed. | Convert carbohydrates to alcohol and carbon dioxide in anaerobic through fermentation. Also obtain carbon from hexose sugars. |
| 14 | Uses | Useful in biodegradation, food production (cheese) | Making of alcoholic beverages which contain ethanol, used in baking, bioremediation, industrial ethanol production, probiotics, and food addictive or flavors. |
| 15 | Health Hazards | Can cause allergic reactions and respiratory problems. | Can cause infection in individuals with compromised immune systems. |