Viscosity and flavour perception: Why is starch different from hydrocolloids?

The effect of viscosity on perceived flavour was investigated in savoury basil flavoured warm systems with intermediate viscosities (from 80 to 480 mPa s at 50 s−1). Three types of starches (wheat, waxy maize and a physically modified waxy maize) were compared to another hydrocolloid, hydroxypropylmethyl cellulose (HPMC). When evaluated by a trained panel using magnitude estimation, it was found that for HPMC thickened products a considerable decrease in perception was detected for both flavour and saltiness with increasing viscosity. When the system was thickened with different starches it was found that viscosity induced flavour and taste suppression was very much smaller than for HPMC. When comparing starches at comparable viscosity perceived flavour was higher in the modified waxy maize and wheat starches that maintained granular integrity in the pastes compared with the waxy maize starch where the granules had clearly disintegrated. It is hypothesised that both flavour perception and mouthfeel can be related to the efficiency of mixing of the thickened solutions with water. Polymeric as opposed to granular solution structures mix less efficiently as a result of entanglements between chains leading to different mouthfeel attributes and reduced release of tastants to the receptors.