flavor enhancer
US /ˈfleɪ.vər ɪnˌhæn.sər/
UK /ˈfleɪ.vər ɪnˌhæn.sər/

1.
a substance added to food to improve its taste or aroma
:
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Monosodium glutamate (MSG) is a common flavor enhancer.
•
Many processed foods contain artificial flavor enhancers.