CONVENIENCE AND HEALTH FOODS 3 (1+2)

Lesson 14 : Self Heating Systems For Ready To Eat Foods

Chemicals used in self heating systems

Most of the systems make use of following exothermic reaction for heating the RTE food.

• Hydration of anhydrous calcium oxide
• Electrochemical reaction of alloy of magnesium and iron in an electrolytic presence of oxidizing agent.

1. Calcium oxide undergoes reaction with water and releases 0.28 Kcal heat energy per gram of substance.




This reaction is used in heating the beverage products in can, called self heating ready meals.

2. Alloy of magnesium and iron reacts with saline water to give magnesium hydroxide, hydrogen and large amount of heat. This heat is utilized in “Flameless food heaters”




3. Another type of reaction exothermic in nature is used for warming RTE retort processed foods in flexible pouches. Polyhydroxy alcohols in presence of potassium dichromatic (K2Cr2O7), potassium permanganate (KMnO4), sodium peroxide (Na2O2) etc generates heat that catches fire and liberates 4.15kcal heat per gram of the substance.
• Such oxidation reactions are utilized for warming RTE foods.
• The food gets heated within 8-15 minutes.