pH is the measure of the acidity of a product in solution. Specifically, pH measures the concentration of hydrogen ions in a solution. The lower the pH, the higher the acidity and the higher the pH, the more basic a solution is. The pH of foods will foremost impact the taste, as high-acidity foods taste sour. The biochemical effect of food pH is the effect pH has on microbial growth, which is the predominant mechanism of food spoilage. Most of these microorganisms grow best under neutral conditions.