Yogurt Fermentation Experiment
Observing Bacterial Fermentation Process
Observe how milk transforms into yogurt through bacterial fermentation. Compare different temperature conditions and their effects on the fermentation process.
Room Temp (20°C)
20°C
Warm (37°C)
37°C
Too Hot (50°C)
50°C
Medium Culture
1-2
3-4
5-6
7
8-9
10-11
12-14
Time: 0 hours
Room Temp pH
7.0
Warm pH
7.0
Hot pH
7.0
Observation:
The experiment will show how milk ferments into yogurt at different temperatures. Watch the pH decrease as lactic acid bacteria multiply and convert lactose to lactic acid.
Yogurt Fermentation Science
1. Bacterial Action:
Lactobacillus bacteria convert milk sugar (lactose) into lactic acid, which causes milk proteins to coagulate.
2. Temperature Effect:
37°C is optimal for bacterial growth. Too cold slows fermentation, too hot kills bacteria.
3. pH Changes:
As lactic acid accumulates, pH drops from ~7 (milk) to ~4 (yogurt), giving yogurt its tart flavor.
