Food Microbiology

Concept: Yogurt is a fermented dairy product produced by the action of specific lactic acid bacteria. The primary microorganisms involved are Lactobacillus bulgaricus and Streptococcus thermophilus, which work symbiotically. These bacteria ferment lactose (milk sugar) into lactic acid, leading to:

• Coagulation of milk proteins (casein)
• Development of characteristic sour taste
• Improved digestibility and shelf life

Step 1: Identify the type of fermentation.
Yogurt production involves lactic acid fermentation carried out by beneficial bacteria.
Step 2: Analyze the given organisms.

• Saccharomyces cerevisiae – yeast used in baking and brewing
• Lactobacillus bulgaricus – lactic acid bacteria used in yogurt
• Aspergillus niger – fungus used in enzyme production
• Escherichia coli – pathogenic bacterium

Step 3: Select the correct organism.
Among the options, Lactobacillus bulgaricus is the primary organism responsible for yogurt production.