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A new alginate-based rapid method for determining coliforms in milk.
Su-sen Chang1, Peter M Gray, Gun-Jo Woo
1Department of Food Science and Human Nutrition, Washington State University, Pullman, Washington 99164-6376, USA.
Journal of Food Protection
|November 25, 2003
Summary
A novel alginate method rapidly detects coliforms in food, significantly reducing testing time. This accurate, simple technique offers a faster alternative for coliform monitoring.
Area of Science:
- Microbiology
- Food Safety
- Analytical Chemistry
Background:
- Coliform monitoring is crucial for food safety.
- Conventional methods like violet red bile agar (VRBA) are time-consuming.
- Rapid and accurate detection methods are needed.
Purpose of the Study:
- To develop and evaluate a new rapid method for coliform detection using alginate.
- To compare the effectiveness of the alginate method with the conventional VRBA method.
- To assess the applicability of the alginate method for field studies.
Main Methods:
- A new method utilizing the instant gelling properties of alginate and calcium.
- Bacterial samples diluted in peptone water with CaCl2 and added to modified purple broth base medium.
- Coliform concentration determined by color change and gas production time in alginate tubes.
Main Results:
- The alginate method showed strong correlation with the conventional VRBA plating method.
- Detection time was reduced by 12 to 14 hours compared to VRBA.
- The method demonstrated effectiveness for various coliform types, including cold-injured ones, in milk and raw milk samples.
Conclusions:
- The alginate method is an accurate, rapid, simple, and economical approach for monitoring total coliforms in food.
- Its ease of application makes it suitable for field studies.
- This method significantly improves upon the time constraints of traditional coliform detection techniques.