When food is ingested through the mouth first food is a grind and chewed through teeth.
Food is swallowed down in the form of the bolus and reaches the stomach, where digestive enzymes broke down large molecules into smaller ones.
Digestion of food includes- the break down of large molecules into small molecules by a decomposition reaction.
For example- The breakdown of polysaccharides into smaller monosaccharides.
Final Answer-
Decomposition reaction includes the splitting of large molecules into small (simpler) molecules.