Dextrose Tryptone Agar W/ Starch 1146 Condalab

Dextrose Tryptone Agar with Starch is used for the cultivation of ‘flat sour’ thermophilic and mesophilic microorganisms in canned food. Flat sour spoilage should be controlled by food processors that want to ensure a long shelf life of a product and to prevent early spoilage. Flat sour spoilage is produced by two species of Bacillus, Bacillus coagulans, and Bacillus stearothermophilus. The spoilage occurs in low acid foods. These organisms produce acid without gas causing the pH to drop to between 0.3 and 0.5. Flat sour spores are not directly pathogenic microorganisms. If the product has not been cooled properly, these organisms have the potential to grow and decrease the shelf life of the canned foods. A food that has been spoiled by flat sour organisms will produce a sour smell and taste.

Tryptone provide nitrogen, vitamins, minerals, and amino acids essential for growth. Dextrose is the fermentable carbohydrate providing carbon and energy. Starch in the medium acts as a growth factor, functioning like a colloid protector and neutralizes toxic products that form during the development of the organisms. Bromocresol purple is the pH indicator. When dextrose is fermented, acid is produced and Bromocresol purple turns from purple to yellow and bacteriological agar is the solidifying agent.