Eating is a big part of Korean culture. They love food here so and Koreans really love to express how whatever they are eating tastes. So it is important to know how to describe the food you are eating.
First off for “delicious”. In the graphic above, we showed you the standard/low formal way to say it. If you want to be more formal, you can use “맛있습니다” (ma-shi-sseum-ni-da). You can also apply the same ending for not delicious and say “맛없읍니다” (mat-eop-sseum-ni-da), but it would probably be rude considering you are using a very formal tone which is used with people older than you.