Therapeutic cultured dairy — acidophilus milk: Manufacture of “acidophilus milk” for intestinal health requires a pure culture of which microorganism?

Introduction / Context:
Acidophilus milk is a fermented dairy product developed for potential probiotic benefits, particularly in supporting intestinal health. It is distinct from yogurt, which uses a defined symbiosis of two thermophilic cultures.

Given Data / Assumptions:

• Product: acidophilus milk.
• Objective: identify the specific culture required.
• Distinguish from yogurt starter cultures.

Concept / Approach:
Lactobacillus acidophilus is the defining organism for acidophilus milk. Traditional yogurt employs Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus. Although bifidobacteria are added to some probiotic milks, the classic product described as “acidophilus milk” requires a pure culture of L. acidophilus.

Step-by-Step Solution:
Identify the product type (acidophilus milk) and its historical definition.Associate the product with L. acidophilus as the required culture.Exclude yogurt starters and optional probiotic adjuncts.

Verification / Alternative check:
Dairy technology texts define acidophilus milk by inoculation with pure L. acidophilus, sometimes followed by mild incubation and cooling to maintain viable counts.

Why Other Options Are Wrong:

• L. bulgaricus / S. thermophilus: Yogurt starters, not acidophilus milk alone.
• Bifidobacterium longum: An adjunct in some probiotic milks, but not the defining culture for acidophilus milk.
• None of the above: Incorrect because one listed organism is correct.

Common Pitfalls:
Assuming all probiotic dairy products share the same microorganisms; product standards and definitions differ.

Final Answer:
Lactobacillus acidophilus.