Why acid value of stale sample of oil is greater than fresh sample?

The acid value of a stale sample of oil is greater than that of a fresh sample due to the breakdown of triglycerides into free fatty acids during oxidation and hydrolysis processes. Over time, exposure to heat, light, and moisture can accelerate these reactions, leading to increased acidity. Additionally, microbial activity can contribute to the formation of free fatty acids, further raising the acid value in stale oils. This increase indicates degradation and a decline in oil quality.