Is there a parotid-salivary reflex response to fat stimulation in humans?

The perception of fats in foods may involve gustatory, olfactory or textural cues. There is contradictory evidence as to whether the orosensory perception of fat is as a basic quality of taste or related to the physical characteristics of fat. A dose-response reflex parotid-salivary secretion has, however, been shown for the accepted basic taste qualities. The aim of this study was to establish whether varying fat concentration in two food types causes an associated dose-response reflex parotid secretion in humans. Parotid salivary flow was recorded using Lashley cups and cannulae connected to an instantaneous flow meter. Gustatory stimuli were achieved using 3 ml of skimmed (0.1% fat), semi-skimmed (1.7% fat) or full (3.6% fat) milk (Sainsbury) or 5 g of extra-light (5% fat), light (16% fat) or original (24% fat) cream cheese (Kraft). No significant differences in salivary flow rate were shown within the milk group (n=10, P=.93) or within the cream-cheese group (n=11, P=.82). Furthermore, no correlation was observed between increasing fat concentration and flow within either the milk (P=.98) or the cream-cheese group (P=.69; Pearson Product Moment Correlation). These results do not support the hypothesis that there is a fat-specific dose-response parotid reflex.