Cultured milk beverages — starter(s) used for “Bulgarian buttermilk” Which microorganism is classically credited as the primary culture for producing Bulgarian buttermilk in traditional dairy practice?

Introduction / Context:
Different cultured dairy products are defined by their starter microflora. Correctly pairing the product name with its starter(s) is fundamental for quality control and for reproducing authentic flavor and texture.

Given Data / Assumptions:

• Product: Bulgarian buttermilk (a traditional cultured milk).
• Potential cultures include thermophilic and mesophilic lactic acid bacteria.
• We seek the organism most historically linked to “Bulgarian” styles.

Concept / Approach:
“Bulgarian” cultured milk traditions emphasize Lactobacillus delbrueckii subsp. bulgaricus for characteristic acidity and flavor. While modern yogurt uses a defined mixed culture of L. bulgaricus with Streptococcus thermophilus, classic references often credit L. bulgaricus as the named organism for “Bulgarian buttermilk.”

Step-by-Step Solution:
Identify the hallmark organism associated with “Bulgarian” culture: L. bulgaricus.Differentiate from mesophilic buttermilk starters (for example, S. lactis/S. cremoris).Select L. bulgaricus as the best classical match.

Verification / Alternative check:
Dairy texts distinguish Bulgarian-style sour milk/buttermilk (linked to L. bulgaricus) from mesophilic cultured buttermilk (S. lactis/S. cremoris) and yogurt (mixed thermophiles).

Why Other Options Are Wrong:
Streptococcus lactis and S. cremoris are mesophiles used in traditional buttermilk and cheeses but not specifically “Bulgarian”; S. thermophilus is part of yogurt mixed starters; the mixed culture option describes yogurt rather than the classical “Bulgarian buttermilk.”

Common Pitfalls:
Confusing product names: Bulgarian sour milk vs. yogurt vs. mesophilic buttermilk; each has different starter definitions.

Final Answer:
Lactobacillus bulgaricus.