Milk protein digestion is a multi-stage process primarily occurring in the stomach and small intestine, where enzymes break down the proteins into smaller, absorbable units.
Stages of Milk Protein Digestion
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Stomach: Digestion begins in the stomach.
- Gastric acid (hydrochloric acid) denatures the milk proteins, causing them to unfold. This makes them more accessible to enzymes.
- Pepsin, an enzyme secreted by the stomach, begins to break down the milk proteins into smaller peptides.
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Small Intestine: The partially digested milk proteins then move to the small intestine, where the bulk of protein digestion takes place.
- The pancreas releases enzymes, including trypsin and chymotrypsin, into the small intestine. These are proteases, enzymes that specifically target and break down proteins and peptides.
- These proteases further break the peptides into even smaller peptides and, eventually, into individual amino acids.
- Enzymes present in the intestinal lining, such as peptidases, finalize the protein digestion, breaking down the remaining small peptides into single amino acids.
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Absorption: Once the milk proteins are fully broken down into individual amino acids, they are absorbed through the lining of the small intestine and enter the bloodstream. These amino acids are then transported throughout the body to be used for various functions, such as building and repairing tissues.
Enzymes Involved in Milk Protein Digestion
| Enzyme | Location | Action |
|---|---|---|
| Pepsin | Stomach | Breaks down proteins into smaller peptides |
| Trypsin | Small Intestine | Breaks down peptides into smaller peptides and amino acids |
| Chymotrypsin | Small Intestine | Breaks down peptides into smaller peptides and amino acids |
| Peptidases | Intestinal Lining | Breaks down small peptides into amino acids |
In addition to protein digestion, the small intestine also handles the digestion of milk fats with the help of lipases and bile. These break down fats into diglycerides, monoglycerides, and free fatty acids.
