HCL peroform following fuction that's why it is imp.:-
1) Hydrochloric acid denatures proteins
2)Hydrochloric acid also activates a substance called pepsin, via its conversion from a substance called pepsinogen. It is pepsin that mainly digests the protein we eat.
3) Indirectly HCl assists digestion further down the gastrointestinal tract by acting as antiseptic in the stomach.
4) Lastly, HCl allows for proper mineral absorption as it assists in ionizing minerals, like calcium and magnesium to name a few.