What might contribute to the cessation of the fall in pH over time during yogurt production?

The cessation of the fall in pH during yogurt production can primarily be attributed to the increase in lactose concentration. As yogurt cultures ferment lactose, they convert it to lactic acid, which lowers the pH. However, as the fermentation progresses, the available lactose begins to diminish, leading to a steady-state situation where the production of lactic acid stabilizes. This stabilization results in a slowdown in the reduction of pH. Thus, the increase in lactose concentration contributes to maintaining consistent fermentation activity initially, but as it decreases, the rate of acid production also diminishes, leading to the cessation of pH decline.

Other factors such as temperature changes or the activity of different bacteria can influence fermentation but are less directly linked to the observed stabilization of pH concerning lactose concentration. The overall fermentation dynamics are significantly shaped by the availability of lactose, making it the crucial factor in understanding why the pH stop falling over time.