The temporal development of sensory perception of carbonated soft drinks with Stevia

Food industry and governmental efforts are aimed at the reduction of the amount
of dietary sweeteners in our diets. Specific food reformulations replace for
example (part of the) natural sugars by other natural sweeteners such as Stevia
which provides the sweet taste without the calories. Unfortunately, sweet taste
is only one of the criteria for market success of reformulated products.
Another important criterion is that the taste profile over time for sweeteners
is similar to that of natural sugars. Consumers may avoid foods or drinks with
alternative low-caloric sweeteners where the sweet taste appears too quickly or
too slow or lingers for too long oor too short compared to the same product
with a natural high caloric sweetener.

The main objective is to gain insight into the temporal differences between the
perceived sweetness and irritation of carbonated beverages with sucrose and/or
Stevia. More specifically, objectives of part 1 of the study are:
- To assess the overall temporal taste and irritation profiles for carbonated
drinks with different amounts of sucrose and Stevia (part 1a);
- To assess the effect of saliva on the overall temporal taste and irritation
profiles for carbonated drinks with different amounts of sucrose and Stevia
(part 1b).
- To assess the temporal profiles during the on- and off-set phase for
carbonated drinks with different amounts of sucrose and Stevia (part 2).

A single blind, randomized, crossover study.

Commercially available carbonated water will be used that is either undiluted
(100%) or diluted to 50% with plain water (to vary the carbonation level) to
which different amounts of sucrose and Stevia are added (100% sucrose, 70%
sucrose + Stevia, 50% sucrose + Stevia, 30% sucrose + Stevia,100% Stevia).
Plain water from the same source as the carbonated water will be used for the
0% carbonation condition. In total 15 different combinations of carbonation (3)
and sweetener (5) will be tested.

Participants will participate in a total of 12 2-hr sessions (including 3
practice sessions).
In each session of part 1A, participants will take one sip per 15 mins of an
carbonated beverage with either an artificial or a natural sweetener and
records the perceived sweetness and irritation with the technique of
time-intensity. Each recording will take a maximum of five minutes, leaving the
participants with sufficient time to relax between sips. Part 1B is similar to
part 1A, excpet that a Lashley cup will be used to prevent saliva enter the
mouth. The subjects can drink water if she wishes.
In part 2, the subjects will place a small teflon straw (diameter appr. 2 mm)
in their mouth, through which a small continuous flow of liquid is presented to
the tongue using a gustometer. The flow alternates between either water or the
sweetened beverage at different frequencies. Subjects are free to swallow at
will.
Time-intensity recordings and 2-hr sessions are routinely used in sensory
science and do rarely cause discomfort. All test beverages are screened with
regard to their palatability .