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[Spoilage microorganisms encountered in ultra-high temperature processed milk]
Zhonghua Minguo Wei Sheng Wu Ji Mian Yi Xue Za Zhi = Chinese Journal of Microbiology and Immunology
|May 1, 1984
Summary
Spoiled milk contained various microorganisms, primarily Bacillus species, suggesting contamination during the filling process. These microbes can thrive in different temperature conditions, impacting milk quality.
Area of Science:
- Food Microbiology
- Dairy Science
- Microbial Spoilage
Background:
- Ultra-high temperature (UHT) processed milk is expected to have a long shelf life.
- Microbial spoilage can occur despite processing, leading to economic losses.
- Identifying spoilage microorganisms is crucial for preventing future contamination.
Purpose of the Study:
- To identify the microorganisms responsible for the spoilage of UHT processed milk.
- To determine the potential sources of contamination in milk production.
- To characterize the temperature tolerance of isolated Bacillus strains.
Main Methods:
- Isolation and identification of aerobic and facultative anaerobic microorganisms from spoiled UHT milk.
- Microbial identification using standard microbiological techniques.
- Analysis of isolated strains for temperature growth characteristics (mesophilic, thermophilic, psychrotrophic).
Main Results:
- 40 microbial strains were isolated from spoiled UHT milk, including 13 Bacillus species (B. cereus, B. licheniformis, B. brevis, B. pumilus) and 27 non-sporeforming bacteria and yeasts.
- The identified microorganisms suggest contamination likely occurred during the filling operation.
- Isolated Bacillus strains exhibited mesophilic, thermophilic, and psychrotrophic properties.
Conclusions:
- Contamination during the filling stage is the primary cause of spoilage in UHT processed milk.
- The diverse temperature adaptability of Bacillus strains contributes to milk spoilage.
- Effective control measures during filling are essential to maintain UHT milk quality.