Simplified sialometer for continuous weight monitoring of salivary secretion

Relation between saliva flow and flavor release from chewing gum

The objective of this study was to investigate whether or not parotid saliva flow is a significant determinant of flavor release from chewing gum. Cherry-flavored gum with 3 concentrations of citric acid (0.5, 1, and 2%) acting as a sialagogue was evaluated for sweetness and cherry flavor in duplicate by 13 subjects, using a computerized system for simultaneous time-intensity (TI) measurements and unilateral collection of parotid saliva. With increased acidity in the gum, maximum intensity of, and area under, the cherry flavor curve increased (p < 0.001), whereas total duration of sweetness decreased (p < 0.05). Large interindividual differences were found for parotid saliva flow in response to chewing gum. Mean unilateral parotid saliva flows in response to stimulation with water and gum with 0.5, 1, and 2% citric acid were 0.07, 0.30, 0.36, and 0.44 g/min, respectively. There was a significant positive correlation between saliva flow and time to reach maximum intensity of sweetness (p < 0.05) and of cherry flavor (p < 0.01), with "high-flow" subjects taking longer to reach maximum intensity than "low-flow" subjects for both attributes. We conclude that parotid saliva flow may affect the rate of flavor release, but not how much nor for how long flavor is released.

Interaction of salivary flow with temporal perception of sweetness, sourness, and fruitiness

To explore the effect of salivary flow on perception of sweetness, sourness and fruitiness, 19 subjects continuously recorded perceived intensity from ingestion, through expectoration to extinction of the sensation, for each attribute in solutions sweetened with three levels of aspartame or sucrose at three levels of citric acid. Unilateral parotid flow was collected in response to the solutions at the medium acid level and used to assign subjects to low, medium and high-flow groups. For all three attributes, although the low-flow subjects reached maximum intensity later than high-flow, no significant difference in any time-intensity parameter for any attribute was found among salivary flow groups. No difference in salivary flow was elicited by equi-sweet solutions of aspartame or sucrose. Maximum intensity of sourness and salivary flow rate decreased as the level of sweeteners was raised (at a constant acid concentration) suggesting that salivary flow is mediated by cognitively processed taste response and not only the concentration of stimuli.

Temporal gustatory and salivary responses to capsaicin upon repeated stimulation

Repeated oral stimulation with solutions of 2 ppm capsaicin increased time to maximum intensity, but yielded a decrease in sequential mouth-burn intensity due to a rising minimum irritation rating between stimuli. Two response patterns were observed: for 18 subjects mouth-burn increased, while 14 subjects showed depression upon repeated stimulation. Because of across-subject variability, there was little correlation between parotid salivary response and perceived sensory responses. Capsaicin-stimulated salivary flow was significantly higher than flow stimulated by distilled water in 9 high-flow subjects, but not in 14 low-flow subjects. Oral adaptation to capsaicin may attenuate parotid salivary response, although eaters and noneaters of chili peppers did not differ significantly in their perception of mouth-burn or in salivary flow.

Human saliva and taste responses to acids varying in anions, titratable acidity, and pH

Twenty subjects recorded perceived sourness of solutions of citric + fumaric and of citric + tartaric acids, at pH 3.5 and titratable acidity (TiA) of 4.0 g/l on a moving chart, while parotid saliva flow was recorded via a sialometer . Sourness intensity and flow were greater when citric was the minor acid than when it was dominant. Subjects varied widely in calculated volume of saliva reservoir, but not flow rate (time to 2/3 reservoir vol.). In tartaric-fumaric acid mixtures varying in pH (3.0-3.75) at a constant TiA of 4.0 g/l, and varying in TiA (3.7-4.6 g/l) at a constant pH of 3.5, sourness intensity and parotid flow increased with acidity and decreased with pH. However, eight subjects with a high flow (HF = 1.2 +/- 0.28 g/2 min) and nine subjects with a low flow (LF = 0.43 +/- 0.11 g/2 min) differed widely: (a) In response to variation in stimulus pH and TiA, HF demonstrated marked alteration in flow, but little change in sourness ; LF responded at a lower absolute level, but showed marked changes in sourness and little change in flow; (b) Salivary pH was higher and Na+ was three times greater for the HF than for the LF subjects; and (c) Salivary Ca++ showed a direct relationship with flow and pH among the HF, but an inverse relationship for the LF subjects.

Parotid and whole-mouth secretion in response to viewing, handling, and sniffing food

There was no significant change in flow rates of parotid saliva in nineteen of twenty subjects while they viewed photographs of lemons, or in fourteen of twenty subjects while they cut lemons in a glove box. Neither parotid nor whole-mouth secretion changed from baseline when subjects viewed fresh lemons and lemonade presented in a plastic box. Further, no significant changes in whole-mouth secretion rates were observed when subjects viewed photographs of two appetizing foods, or of fresh doughnuts in a plastic box, even though subjects knew they could eat the doughnuts after the experiment. In most cases, sniffing of the lemons or of the doughnuts resulted in increased flow rates. Subjects demonstrated large differences in their patterns of affective responses to full-strength and diluted lemon juice, which were independent of salivary flow. In the absence of olfactory or tactile stimulations, few subjects altered parotid or whole-mouth secretion rates in response to viewing food or photographs of food. A reevaluation of findings on 'psychic' stimulation of saliva may be in order to ascertain the role of olfactory, tactile, and even trigeminal clues in salivary response to food stimuli.