Prevalence of Viable Lactobacillus acidophilus in Dried Commercial Products

Area of Science:

• Microbiology
• Food Science
• Probiotics

Background:

• Lactobacillus acidophilus is a probiotic bacterium used in dietary supplements.
• The viability of L. acidophilus in dried products is crucial for their efficacy.
• Consumers rely on these products for potential health benefits.

Purpose of the Study:

• To enumerate viable Lactobacillus acidophilus cells in dried dietary adjuncts.
• To compare the viability of L. acidophilus across different product types (health food, pharmaceutical, milk culture).
• To assess the impact of drying methods on L. acidophilus survival.

Main Methods:

• Enumeration of viable cells using plate count agar (PCA), MRS agar (MRSA), and MRSA with oxgall (MRSOA).
• Testing of 27 dried acidophilus products from various sources.
• Assessment of microbial contamination in health food samples.

Main Results:

• Most viable cells formed colonies regardless of plating media (aerobic, anaerobic, bile presence).
• Health food samples showed very low viable cell counts, with inconsistent L. acidophilus presence and microbial contamination.
• Pharmaceutical and milk culture samples generally had higher viable cell counts, but L. acidophilus was not always present.
• Vacuum drying was more lethal to L. acidophilus than freeze drying.

Conclusions:

• Dried L. acidophilus products, particularly from health food sources, often contain low numbers of viable bacteria.
• Product quality and L. acidophilus viability vary significantly between brands and lots.
• Drying methods critically affect the survival of L. acidophilus, impacting probiotic efficacy.