Practice 6 - Yeasts and molds counting techniques

Abstract

Fungi are widely distributed in the environment and they may be associated with the normal flora of foods, and inadequately sanitized equipment and air. They grow in foods with high sugar content, high salt, low moisture, pH, and low storage temperatures. Sometimes, a food can appear mold-free when examined with the naked but mycotoxins will remain in the food. Many molds produce organic acids, vitamins, plant growth regulators, and enzymes. Many media are used for culturing yeasts and molds; the following media are more useful for culturing fungi: malt extract agar, potato dextrose agar, orange serum agar, osmophilic agar, and rose Bengal agar. Plate count and most probable number techniques are used to count yeasts and molds from foods. Membrane filter techniques are also applicable for beverages, clear liquids, and certain solid foods after homogenization.