Introduction to Infusion Powders Used in Culture Media

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News 9 10 月, 2024

Introduction

Infusion powders are essential raw materials in microbiological culture media, widely used to promote the rapid growth and development of microorganisms. These powders are derived from plant or animal tissues through a series of processes, including soaking, heating, pH adjustment, filtration, and spray drying. Infusion powders are rich in growth-promoting factors, vitamins, and carbohydrates, making them crucial for microbial cultivation. This article summarizes various types of infusion powders, their preparation methods, specifications, and microbiological limits, based on domestic and international standards.

Types of Infusion Powders

1. Peas Infusion Powder

Preparation: Pea flour (50g) and sodium chloride (100g) are added to 1000mL of purified water, boiled for 1-2 hours, soaked for 12-24 hours at 2-8°C, filtered, and spray-dried.
Specifications: Total nitrogen 4-5%, amino nitrogen ≥2%, moisture ≤6%, pH (2% solution) 6.5-7.5.
Microbial Limits: No pathogenic bacteria or Bacillus spores detected; total colony count ≤5000 CFU/g.
Application: Ideal for blood agar and chocolate agar preparation.

2. Corn Infusion Powder

Preparation: Corn flour (50g) is added to 1000mL of purified water, heated at 65°C for 1-2 hours, filtered, and spray-dried.
Specifications: Total nitrogen 1-2%, amino nitrogen 0.3-0.6%, moisture ≤6%, pH (2% solution) 6.0-7.0.
Microbial Limits: No pathogenic bacteria or Bacillus spores detected; total colony count ≤5000 CFU/g.
Application: Suitable for Candida albicans and yeast culture.

3. Potato Infusion Powder

Preparation: Peeled potatoes (500g) are boiled in 1000mL purified water for 30-60 minutes, replenished with water, filtered, and spray-dried.
Specifications: Total nitrogen 4-5%, amino nitrogen ≥2%, moisture ≤6%, pH (2% solution) 5.0-7.0.
Microbial Limits: No pathogenic bacteria or Bacillus spores detected; total colony count ≤5000 CFU/g.
Application: Best for fungal cultivation due to high carbohydrate content.

4. Malt Infusion Powder

Preparation: Malt powder (15g) is added to 1000mL of purified water, heated at 60-70°C for 1-2 hours, filtered, and spray-dried.
Specifications: Total nitrogen 0.8-1.1%, amino nitrogen 0.3-0.6%, moisture ≤6%, pH (1.5% solution) 6.0-7.0.
Microbial Limits: No pathogenic bacteria or Bacillus spores detected; total colony count ≤5000 CFU/g.
Application: High maltose content makes it ideal for yeast and fungal cultivation.

5. Beef Extract Powder

Preparation: Fresh beef (500g), after removing fat and fascia, is minced, soaked in 1000mL purified water for 12-16 hours, heated to 70-80°C, then boiled for 1-2 hours, and spray-dried.
Specifications: Total nitrogen 11.5-12.5%, amino nitrogen 3-4%, moisture ≤6%, pH (2% solution) 6.5-7.5.
Microbial Limits: No pathogenic bacteria or Bacillus spores detected; total colony count ≤5000 CFU/g.
Application: Rich in amino acids and nitrogen sources, suitable for general bacterial culture.

6. Beef Heart Infusion Powder

Preparation: Fresh beef heart (500g) is soaked in 1000mL purified water for 20-24 hours, heated, boiled, and spray-dried.
Specifications: Total nitrogen ≥12%, amino nitrogen ≤3%, moisture ≤6%, pH (2% solution) 6.5-7.5.
Microbial Limits: No pathogenic bacteria or Bacillus spores detected; total colony count ≤5000 CFU/g.
Application: Suitable for cultivating fastidious microorganisms requiring rich growth factors.

7. Beef Brain Heart Infusion Powder

Preparation: Fresh beef heart (500g) and brain (400g) are soaked, heated, boiled, and spray-dried.
Specifications: Total nitrogen ≥12%, amino nitrogen ≤3%, moisture ≤6%, pH (2% solution) 6.5-7.5.
Microbial Limits: No pathogenic bacteria or Bacillus spores detected; total colony count ≤5000 CFU/g.
Application: Excellent for culturing fastidious organisms like Mycoplasma and Streptococcus.

8. Beef Liver Infusion Powder

Preparation: Fresh beef liver (500g) is processed, soaked, heated, boiled, and spray-dried.
Specifications: Total nitrogen ≥11%, amino nitrogen ≤3%, moisture ≤6%, pH (2% solution) 6.0-7.0.
Microbial Limits: No pathogenic bacteria or Bacillus spores detected; total colony count ≤5000 CFU/g.
Application: Rich in glycogen, vitamins, and amino acids, suitable for promoting the growth of bacteria in anaerobic conditions.

9. Stomach Digestive Powder

Preparation: Fresh pig stomach (350g) is digested in 1000mL water at 51-55°C for 18-24 hours, filtered, and spray-dried.
Specifications: Total nitrogen ≥12%, amino nitrogen ≥2.0%, moisture ≤6%, pH (2% solution) 5.5-7.5.
Microbial Limits: No pathogenic bacteria or Bacillus spores detected; total colony count ≤5000 CFU/g.
Application: Suitable for culturing Erysipelothrix and Pasteurella.