Garlic Paste

Have you tried heat treatment to inactivate the enzymes responsible for color change?

A small amount os SMBS (sodium metabisulphite) will do the job...don't forget tp declare this "allergen"in your product.

Yes I have. But the color still changes after a few hours.

Will give it a try. Is there a certain ppm that should be added for avoiding color change?

Try 200ppm should do the job

At what internal temperature did you heat treatment and how long?