HC Agar for Mold Counting in Cosmetics
HC Agar is a selective differential dehydrated culture medium specially formulated for mold enumeration in cosmetic samples. Chloramphenicol suppresses bacteria so that molds can grow and be counted accurately.
Formula Composition (per Liter)
| Ingredient |
Content |
| Tryptone |
2.5 g |
| Soy peptone |
2.5 g |
| Yeast extract powder |
5.0 g |
| Glucose |
20.0 g |
| Disodium hydrogen phosphate |
3.5 g |
| Potassium dihydrogen phosphate |
3.4 g |
| Ammonium chloride |
1.4 g |
| Magnesium sulfate |
0.06 g |
| Chloramphenicol |
0.1 g |
| Sodium carbonate |
1.0 g |
| Agar |
15.0 g |
| Final pH |
7.0 ± 0.2 at 25 ℃ |
Inspection Principle
Tryptone, soy peptone and yeast extract powder supply nitrogen sources, vitamins and growth factors for mold propagation. Glucose serves as the carbon source. Disodium hydrogen phosphate and potassium dihydrogen phosphate form the buffer system. Ammonium chloride and magnesium sulfate provide essential mineral ions. Chloramphenicol inhibits most bacteria to eliminate bacterial interference. Sodium carbonate adjusts the medium environment. Agar acts as the gelling agent. Tween 80 helps disperse cosmetic samples and neutralize residual preservatives.
Directions for Use
Weigh 54.5 g of this medium powder together with 20 mL Tween 80, heat and dissolve in 1000 mL distilled water. Dispense into containers, autoclave at 121 ℃ for 15 minutes, and reserve for later use.
Note: This medium contains magnesium sulfate. A small amount of micro precipitation after sterilization is normal.
Microbial Performance Test for HC Agar
Prepare the medium following the instructions. Inoculate designated quality control strains and incubate aerobically at 28 ± 1 ℃ for 72 ± 2 hours.
