Temperature Range Required for Lactobacillus paracasei Survival
Lactobacillus paracasei optimally survives at temperatures between 28°C and 37°C (82.4°F and 98.6°F), with significant reduction in viability occurring at temperatures above 72°C (161.6°F). 1, 2
Optimal Temperature Range
- L. paracasei grows well at temperatures between 28°C and 37°C (82.4°F and 98.6°F), similar to most clinically significant slowly growing bacteria 3
- Long-term viability is maintained when stored at 4°C, -20°C, or -80°C, with no significant reduction in viable counts over extended periods 4
- Room temperature storage (25°C) leads to almost complete inactivation after eight months 4
Heat Resistance Properties
- L. paracasei demonstrates considerably better heat resistance compared to other Lactobacillus species (e.g., L. salivarius), with a decimal reduction time of 11.1 minutes at 59°C 1
- The bacterium can survive spray drying processes with air outlet temperatures of 80-85°C, resulting in viable counts of approximately 3.2 × 10^9 CFU/g in the final powder 1
- Complete inactivation (6 log10 reduction) occurs after 15 minutes at 72°C, regardless of the suspension medium 2
- L. paracasei cannot survive temperatures of 90°C for 2 minutes 4
Factors Affecting Temperature Tolerance
- The addition of protective agents like gum acacia (10% w/v) significantly improves survival during thermal processing and subsequent storage 5
- When protected with gum acacia, L. paracasei shows 10-fold greater survival during spray drying at higher temperatures (100-105°C) 5
- The survival rate after low-temperature vacuum drying is comparable to freeze drying, making it a viable preservation method 6
- Fermentation conditions prior to drying significantly impact heat resistance, with interactions between fermentation pH and drying parameters being strain-specific 6
Storage Temperature Considerations
- For maximum viability, L. paracasei should be stored at refrigeration temperatures (4°C) or frozen (-20°C or -80°C) 4
- When stored in powder form at 4°C, L. paracasei can maintain constant survival levels of approximately 1 × 10^9 CFU/g for at least 2 months 1
- Survival during powder storage is inversely related to storage temperature, with significantly reduced viability at higher temperatures 1
- With protective agents like gum acacia, survival rates can be improved 20-fold at 4°C and over 1000-fold at 15°C and 30°C during 4 weeks of storage 5
Clinical Applications
- When used in probiotic formulations, maintaining the cold chain is crucial for preserving L. paracasei viability 1, 4
- For therapeutic applications, L. paracasei can be administered in various forms including fermented dairy products, freeze-dried or spray-dried powders, and capsules 1, 5
- The addition of protective agents should be considered for probiotic formulations to enhance survival during processing and storage 5