Flavor defects — Streptococcus lactis var. maltigenes: Certain strains of Streptococcus lactis var. maltigenes are known to produce which characteristic off-flavor in milk products?

Introduction / Context:
Starter culture variants can sometimes yield undesirable flavors. Streptococcus lactis var. maltigenes is historically associated with a malty, caramel-like note that is considered a defect in many fresh dairy products.

Given Data / Assumptions:

• Organism: S. lactis var. maltigenes.
• We must identify the off-flavor it produces.
• Context: milk and cream products with unexpected caramel/malty notes.

Concept / Approach:
The “malty” defect resembles burnt or caramel flavor and has been traced to specific metabolic by-products formed by S. lactis var. maltigenes. This is distinct from simple sourness (acid flavor) or bitterness caused by proteolysis and peptide accumulation.

Step-by-Step Solution:
Recall classical defect associations from dairy flavor guides.Link S. lactis var. maltigenes to malty/caramel (burnt) notes.Select the option that describes this specific flavor profile.

Verification / Alternative check:
Quality manuals document malty flavor incidents in milk associated with contamination by this variant, prompting culture controls and monitoring.

Why Other Options Are Wrong:

• Bitter: More typical of proteolysis by psychrotrophs or some sporeformers.
• Acid flavor: Expected from lactic fermentation but not diagnostic of the malty defect.
• None/Metallic: Do not reflect the characteristic malty/caramel note.

Common Pitfalls:
Attributing caramel notes solely to heat treatment (Maillard); microbial origin must also be considered when processing was normal.

Final Answer:
Burnt or caramel (malty) flavor.