Researchers at Virginia Tech in the US have assessed how different concentrations of iron and water ‘hardness’ can affect the taste of sweetened drinks.
Aili Wang and her colleagues dissolved five natural and artificial sweeteners – sucrose, honey, sucralose, saccharin, and acesulfame potassium (ace-K) – into four synthetic waters with varying levels of iron – from soft water with no iron to very hard water containing three milligrams per litre.
A group of 25 staff and students were then asked to try the drinks and rank how sweet and/or metallic they tasted. They were also asked how some of the drinks made them feel, selecting terms from 43 ‘emotional’ options.
The impact of water chemistry on taste perception of sweetened synthetic waters was “varied”, they concluded.
But what struck them was that the mineral concentrations in moderate and hard waters “can amplify the sweet perception through taste interaction”. A high concentration of iron and water hardness “significantly increased” the sweetness of sucrose, honey and ace-K, they noted.
'Bored' and 'disgusted'
This finding “may be applied to reduce the use [and thus cost] of sweeteners in production,” they added in a paper published in the journal Food Quality and Preference.
They also found that the addition of sucrose in very hard water can reduce the metallic/bitter taste of ferrous ions, which in turn “significantly increased” its liking rate amongst the panel.
Indeed, the emotional response of panelists reinforces this finding, since ‘bored’ and ‘disgusted’ were unique terms for very hard water, while mild was a unique term for sweetened very hard water.
The high sweet intensity of ace-K (200 times sweeter than sucrose) and saccharin (300 to 400 times sweeter than sucrose) make them economical sugar substitutes in sweetened drinks, but there can be a metallic aftertaste. Using water with a high level of metal ions could mask this without decreasing sweetness perception, the researchers suggested.
They added that ace-K, saccharin, and sucralose may be suitable calorie-free sweeteners for beverages with bitter/metallic metal ions, but this was not yet proven in acceptance tests.
Source: Food Quality and Preference
Published online ahead of print, doi.org/10.1016/j.foodqual.2016.06.016
“Effect of iron on taste perception and emotional response of sweetened beverage under different water conditions.”
Authors: Aili Wang et al.