Sensory perception of acidulants at equal weight and equal sourness concentrations

M. Kinnear* & H.L. de Kock

Dept. of Food Science, University of Pretoria, Pretoria 0002, South Africa

 marise.kinnearup.ac.za

The most commonly added acid in beverages, especially juice-based ones, is citric acid. Claims have been made that other acidulants e.g. malic acid, fumaric acid and tartaric acid or combinations of these, may potentially provide superior sensory properties in beverage applications.  Fruitaric acid is a commercially available blend of malic, fumaric and tartaric acids. Malic, fumaric and tartaric acids added at equal weight is perceived to be more sour compared to citric acid.

Equi-sourness levels of malic, fumaric and tartaric acids compared to 0.2% w/v citric acid in deionised water were determined using paired comparison tests incorporating 5 to7 concentrations of each acid.  Equi-sourness was defined as that concentration at which 50% of responses of a trained panel (n=12) indicated it to be more sour than citric acid.  The perceived equi-sourness concentrations compared to 0.2% citric acid were 0.14% for malic acid, 0.101% for fumaric acid, 0.121% for tartaric acid and 0.108% for fruitaric acid.

A different sensory panel, trained to use labelled magnitude scaling (LMS), used this method to verify the equi-sourness results.  Significant panellist effects were found, reflecting the lack of standardisation of the panel. Using LMS no significant difference in sourness intensity were found between malic, fumaric, tartaric and fruitaric acids when compared to citric acid at equi-sourness concentrations.  At equal weight fumaric and fruitaric acids were found to be significantly more sour (p<0.05) compared to citric acid. Contrary to expectations the difference between malic and citric acids at equal weight was not significant (p=0.06).  The panel also did not find a significant difference between citric and tartaric acid at equal weight (p>0.05). This may be because apart from sourness, acidulants also differ in duration and mouthfeel properties.  Malic acid is known to have a slow build up but lingering sour taste. Tartaric acid has a sharp initial impact without the lingering effect.

Key words: acidulants, equi-sourness, sour, labelled magnitude scaling