It is estimated that only about 25% of adults and 7% of children consume the currently recommended amounts of vegetables each day and it is thought this could be due to the fact that vegetables are not initially palatable because of bitterness. In July 2018 researchers from different research centres in the USA published the results of their study to assess whether adding very small amounts of sugar or salt to green vegetable purees could lead to a significant reduction in bitterness, thus improving the eating experience. Three different types of green vegetable purees were prepared (broccoli, spinach and kale). In Experiment 1, nine adults tasted the three different purees prepared with different levels of sugar (0%, 0.6%, 1.2%, and 1.8%) or salt (0 and 0.2%), in Experiment 2, 84 adults tasted each vegetable puree prepared with either 0% or 2% sugar and in Experiment 3, 99 adults tasted each vegetable puree prepared with 0%, 1%, or 2% sugar. The results revealed that in Experiments 1 and 2 the addition of small amounts of sugar and salt each reduced the bitterness in all three vegetables without altering other sensory properties (e.g. texture or aroma). However, Experiment 3 showed that adding sugar to the vegetable purees made the vegetable a more pleasurable eating experience.
Bakke AJ et al. Mary Poppins was right: Adding small amounts of sugar or salt reduces the bitterness of vegetables. Appetite. 2018 Jul 1;126:90-101