Is the fast invalidated by tasting food?
Tasting food does not invalidate the fast, if a person does not swallow it. But you should not do it unless there is a need for it; and in this situation, if any of it enters the stomach without your intending it, then your fast in not invalidated.
Shaykh Muhammad bin Saalih al-`Uthaymeen
Fatawa Arkaanul-Islaam, Vol.2, p.667