Probiotic stability during refrigeration
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Probiotic Stability During Refrigeration: Key Insights
Probiotic Viability in Refrigerated Foods
Refrigeration is widely used to maintain the stability and viability of probiotics in various food products. Across different studies, it has been consistently observed that probiotic counts decrease gradually during refrigerated storage, but many products can maintain viable counts above the recommended therapeutic threshold for extended periods. For example, foxtail millet probiotic powder retained probiotic viability above 1 billion CFU/g for up to 105 days at 7°C, which is longer than at room temperature storage . Similarly, a novel nutraceutical formulation with Limosilactobacillus fermentum maintained high viable cell counts (>6 log CFU/g) for up to 90 days at 4°C, especially under low humidity conditions .
Impact of Refrigeration Temperature on Probiotic Survival
The specific temperature within the refrigeration range can influence the survival of different probiotic strains. In yogurt, storage at 2°C resulted in the highest viability for Lactobacillus acidophilus, while Bifidobacterium lactis showed better survival at 8°C over a 20-day period . This suggests that optimal storage temperatures may vary depending on the probiotic species present in the product.
Effects of Refrigeration on Probiotic-Containing Beverages and Foods
Refrigerated storage of cereal-based probiotic beverages, such as those made from teff, led to a gradual decrease in probiotic cell counts over 25 days, along with increased acidity and reduced pH. Despite these changes, the beverages remained microbiologically safe and acceptable in sensory evaluations for at least 10 days . In refrigerated pickled vegetable products, certain acid-resistant strains like Lactobacillus casei survived for up to 63 days at 4°C without significant loss of viability .
Role of Encapsulation and Protective Agents
Microencapsulation techniques, such as using alginate and chitosan coatings, have been shown to significantly improve probiotic survival during refrigerated storage. Encapsulated Lactobacillus acidophilus in vegan milks maintained suitable counts (>6 log CFU/mL) for up to 7 days at 7°C, with much less reduction compared to free cells . Similarly, freeze-dried probiotics with protective agents showed no significant differences in viability compared to controls during refrigerated storage, indicating that refrigeration itself is a strong stabilizing factor . Encapsulation also enhanced probiotic survival in fruit juices during refrigeration .
Influence of Food Matrix and Prebiotic Ingredients
The composition of the food matrix and the addition of prebiotic ingredients can further support probiotic stability. For instance, yogurts supplemented with pineapple peel or inulin maintained higher probiotic counts after 28 days at 4°C compared to non-supplemented controls, and also showed increased functional properties such as antioxidant activity . In buffalo milk yogurt, probiotic cultures remained viable for 21 days at refrigeration temperature, with a gradual decline in pH and increase in acidity, but still providing health benefits .
Conclusion
Refrigeration is effective in preserving probiotic viability in a wide range of food products, often maintaining therapeutic levels for several weeks to months. The survival of probiotics during refrigeration can be further enhanced by encapsulation, the use of protective agents, and the inclusion of prebiotic ingredients. However, the optimal storage temperature and duration may vary depending on the probiotic strain and food matrix. Overall, refrigerated storage remains a reliable method for ensuring the stability and functionality of probiotic foods and supplements 1234+6 MORE.
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