How to get rid of Garlic taste in tomato sauce

I can give you the Italian answer - first of all, normally we don't use tomato paste to make sauce, but rather to add a tomato "kick" to recipes. Tomato paste is simply tomato puree that has been cooked down to a high degree of concentration.

A basic tomato sauce is made by

1. making a soffritto with onion, carrot and celery (plus other flavors)
2. adding tomato puree, or "pelati", more rarely fresh tomato
3. cooking the sauce down until the taste and thickness is what you want

If you want to use paste instead of puree, the third step has to be omitted or greatly reduced in duration. Keep in mind that tomato paste has its own taste, and that taste will remain in the final sauce.

A few things can cause tomato sauces to become bitter:

• Overcooked spices. Both basil and oregano can become bitter with long simmers. Add them near the end of the process.
• Under-ripe tomatos. Store bought tomatoes are often picked green and ripened in the store. These tomatoes make less sweet sauces (which may be contributing).
• Cooking in an aluminium pan. Aluminium reacts with the acid in the tomatoes and adds an off-putting flavour.
• Seeds/skin in the sauce. Both seeds and skins can be bitter.

You can improve a bitter sauce by adding a small amount of baking soda (or salt), and something sweet (but not too much).