Which one of the following is the first enzyme to mix with food in the digestive tract?

Digestion begins in the mouth, where food is mechanically broken down by chewing and mixed with saliva [1]. Saliva contains the enzyme salivary amylase (also known as ptyalin), which is the first enzyme to mix with food in the digestive tract [1]. This enzyme initiates the chemical digestion of carbohydrates by breaking down complex starch molecules into simpler sugars like maltose [4]. While other enzymes like pepsin and trypsin are critical for digestion, they are introduced later in the process; pepsin is secreted in the stomach for protein breakdown [6], and trypsin is secreted by the pancreas into the small intestine [3]. Cellulose is not an enzyme but a complex plant polysaccharide that humans cannot digest. Therefore, amylase is the first enzyme to act on the food bolus [6].

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 5: Life Processes > Activity 5.3 > p. 85
2. [2] Science-Class VII . NCERT(Revised ed 2025) > Chapter 9: Life Processes in Animals > Table 9.1: Action of saliva on starch > p. 124
3. [4] Science-Class VII . NCERT(Revised ed 2025) > Chapter 9: Life Processes in Animals > Beginning with the mouth cavity > p. 123
4. [5] Science-Class VII . NCERT(Revised ed 2025) > Chapter 9: Life Processes in Animals > Stomach > p. 125
5. [6] https://www.ncbi.nlm.nih.gov/books/NBK537005/
6. [3] Science , class X (NCERT 2025 ed.) > Chapter 5: Life Processes > Activity 5.3 > p. 86