Bitter taste of unsaturated free fatty acids in emulsions: contribution to the off-flavour of soybean lecithins

The contribution of (poly-) unsaturated free fatty acids (FFAs) to the bitterness of soybean lecithins was investigated by an analytical-chemical and by a sensory approach. Standardized, hydrolyzed, deoiled, and fractionated soybean lecithins were characterized by taste profiles and their yields of FFA were quantified. Threshold tests revealed the polyunsaturated free linoleic acid (cis-9, cis-12-octadecadienoic acid) and free linolenic acid (cis-9, cis-12, cis-15-octadecatrienoic acid) as the FFAs with the lowest bitter taste thresholds in emulsion and the highest impact on the off-taste problems of soybean lecithins and their applications. These results were confirmed by sensory model mixtures. Furthermore, the relationship between FFAs and the perceived bitterness in dependency on the emulsion and the intensity of FFA bitterness in correlation to the FFA concentration were investigated.