Question

Low pH Q24. Explain the range and optimal pH for each microorganism? If a food having pH of 2.5, any chances of this food can be spoiled? No growth of 4,6 pathogenes Molds Yeasts Bacteria pH: 7 0 14 Fruit juices 7 Milk -Vegetable juices Tomato products Meat, Vegetables, Soup etc. HIGH ACID FOOD LOW ACID FOOD 4,6

Answer 1

As you can see in the figure, different microbes have their own specific pH range and it is different for bacteria, fungus and yeast. Yeast can survive at very low pH (pH 1) and can tolerate alkaline pH as well (pH 8.5), wherein most of mold can survive on a great range of pH that is pH 2 to 11.

Bacteria strains are having comparatively narrow range as compared to mold and yeast and they can easily tolerate slightly acidic to alkaline environment (figure showing pH 3 to 9; although most of bacterial activity is inhibited at a pH that is below than 4). One of the most significant and rational behind acidic environment due to HCl in stomach is to prevent maximum microbial activity in the stomach (some can come along with food).

The pH 2.5 is acidic pH and some fruit juice may have this pH and low is also in the vinegar (diluted acetic acid), which is being used as pickling agent or preservation to save food for spoilage. So, generally food does not spoiled at this pH.