Which of the following is a sign of growth of microorganisms in emulsions?

• A. Partitioning
• B. Gas emission
• C. Odor
• D. Changes on rheological properties

Answer: (B)

Gas emission is a direct byproduct of microbial metabolism in emulsions. When microorganisms grow, they ferment or respire substrates in the dispersed system and release gases such as carbon dioxide or hydrogen. The resulting bubbles or foaming inside the emulsion are a clear, observable sign that microbial activity is occurring and the population is increasing.

Partitioning describes how components distribute between oil and water phases and doesn’t reflect microbial growth. Odor can indicate spoilage but isn’t as reliable or specific, since scents can arise from non-microbial chemical changes. Changes in rheological properties can happen for reasons other than growth, such as physical instability or formulation factors. Therefore, gas emission best signals microbial growth in emulsions.