PURPOSE: α-L-aspartyl-L-phenylalanine methyl ester is added to food products mainly consisting of vegetables with strong grassy smell, in a certain amount to reduce their grassy smell and improve the taste.

CONSTITUTION: α-L-aspartyl-L-phenylalanine methyl ester is added to food products made from vegetables with strong grassy smell such as tomato juice, vegetable juice or green juice so that its concentration finally becomes 0.0005W 0.02wt%. Resultingly, the grassy smell of the vegetables are weakened. The process can be applied to any food products which need masking their grassy smell, preferably to tomato, celery, carrot, green pepper, cucumber, cabbage, lettuce, green peas, broadbean, onion, spinach, aloe or Chrysanthemum coronarium.