“Once liking for a specific vegetable flavour has been developed via these strategies, added sweeteners could be reduced or eliminated once innate aversions and/or neophobia have dissipated,” write the US scientists in Appetite Journal.
“If this approach were to be successful, one might imagine bitter vegetables could be introduced with very small amounts of added sweeteners, either nutritive or non-nutritive, to increase initial acceptance, thereby facilitating mere exposure and positive flavour-flavour learning."
They found that adding sugar to green vegetables results in “significant reductions in bitterness and increases in both sweetness and palatability without altering other sensory properties”.
Importantly, these changes can occur with “very small” amounts of the added ingredient, they say.
In the first part of the experiment, the researchers prepared three different green vegetable purees of broccoli, spinach and kale were prepared with different levels of sugar (0%, 0.6%, 1.2%, and 1.8%) or salt (0 and 0.2%) and asked nine adults to give detailed descriptive analysis.
In the second leg of the experiment, a larger group of 84 adults tasted vegetable purees containing no sugar or a 2% addition and evaluated them for bitterness. Finally, in the third experiment, each puree was prepared with 0, 1 or 2% sugar and rated for liking by 99 adults.
The first two experiments showed that addition of small amounts of sugar and salt each reduced the bitterness (and increased sweetness and saltiness) from all three vegetables without altering other sensory properties, such as the texture or aroma, while the third experiment showed that adding sugar increased hedonic liking.
However, the scientists noted that participants in the study who were parents had "mixed attitudes" about the idea of adding sugar to foods for infants and toddlers, and that the present data may not fully translate to behaviour in children.
“[…] Infants and toddlers are also not merely small adults,” they note. “For example, children have higher taste pore density compared to adults, perceive foods differently compared to adults, and prefer different foods compared to adults.”
They therefore call for more research to determine if such minimal additions can increase vegetable intake for children.
Source: Appetite Journal
“Mary Poppins was right: Adding small amounts of sugar or salt reduces the bitterness of vegetables”
Available online ahead of print, doi.org/10.1016/j.appet.2018.03.015
Authors: Alyssa J. Bakke, Cody A. Stubbs, Elliott H. McDowell, Kameron J. Moding, Susan L. Johnson, John E. Hayes