Lemon Powder (Citric Acid).

When lemon powder is sprinkled on certain foods that tend to oxidize and turn brown after being sliced, such as apples, bananas and avocados, the acid acts as a short-term preservative by denaturing the enzymes that cause browning and degradation.

Fish are marinated in lemon juice or sprinkled lemon powder to neutralize the odor. The acid neutralizes the amines  in fish by converting them into nonvolatile ammonium salts.

The citric powder plays a vital role in Indian chicken curry preparation.