Sensory perception of double emulsions

The food industry, seen as a major contributor for providing processed foods
which overconsumption is linked to an increase in obesity, aims to tackle this
problem by reducing the energy density of high caloric food. Especially fat
delivers high caloric value per gram of food (9kcal/g), compared to
carbohydrates and proteins (4 kcal/g).
The use of water-in-oil-in-water (w1/o/w2) double emulsions offers a potential
approach for the reduction of oil content in food products (Muschiolik, 2007).
In literature, it is assumed that sensory perception (fattiness, creaminess,
thickness, etc.) of double emulsions is the same as of normal oil-in-water
(o/w) emulsions (Jiménez-Colmenero, 2013). Two studies have been reported so
far (Malone, Appelqvist, & Norton, 2003) (Lad, Hewson, & Wolf, 2012). However,
their research hypotheses were different from ours and therefore their
experimental setups did not match the requirements for the hypothesis we aim to
test. Additionally, results about achieved fat reductions, as far as reported,
are questionable, since accurate methods and appropriate stabilization
mechanisms only recently developed. We can conclude that until this moment, no
research has yet been published to prove that the sensory perception of
fat-reduced double emulsions is comparable of that of non-reformulated full-fat
emulsions.
We want to perform the present research with model emulsions that are similar
to real food products by having similar oil contents to prove the principle
that stable fat-reduced double emulsions are indeed able to provide the same
taste and mouthfeel as full-fat emulsions.
With these two non-invasive sensory studies, we therefore aim to test the
hypothesis that various double emulsions have similar sensorial properties than
their full-fat counterparts. The effect of different fat reduction levels will
also be explored. The results of the presented studies will therefore be a
milestone in the implementation of double emulsions as potential fat replacers
in several food product categories. Reducing oil content in food products while
maintaining sensory perception is a challenge for the food industry, and has
great potential for social and health impact.

Primary Objective
To investigate the sensory perception (taste and mouthfeel) of various double
emulsions differing in fat reduction level and/or original oil content, in
comparison to non-reformulated oil-in-water emulsions by means of two sensory
methods differing in the level of training of the participants and duration of
the research.

Secondary Objective
To validate the recently developed sensory method RATA (rate-all-that-apply),
characterized by its short duration and use of untrained panellists, on its
applicability to be used for food products with very similar taste and
mouthfeel properties, in comparison to the classical descriptive analysis for
which a trained sensory panel is required.

Study 1:
The CanYouFeelIt study is an observational study on taste and mouthfeel of
various double emulsions differing in fat reduction and original oil content,
with three phases, i.e. screening, training and sensory evaluation. The study
will be performed in the Axis building 118 at Wageningen University, and at the
Restaurant of the Future at Wageningen University.
After the recruitment and prior to the training and sensory evaluation
sessions, there will be a 2-hour screening session (Phase I) during which we
will select participants based on their performance in a sensory test and group
discussion.
During the training session (Phase II) participants need to commit and involve
in two 60-minutes training sessions a week for approximately eight weeks (until
sufficiently trained). The usual panel performance of the panellists is also
discussed with the panellists and monitored throughout the training phase.
At the sensory evaluation sessions (Phase III), trained panelists also need to
involve in two sessions a week for three weeks. Each session will approximately
take 60 minutes. During these sessions, various double emulsions differing in
fat reduction level and/or original oil content will be evaluated on their
taste and mouthfeel in comparison to non-reformulated oil-in-water emulsions.

Study 2:
The WOW! study is an observational study on taste and mouthfeel of various
double emulsions differing in fat reduction and original oil content, with two
phases, i.e. training and sensory evaluation sessions. The study will be held
in the sensory testing rooms at the Restaurant of the Future (WUR).
After the recruitment there will be a 90-minutes training session (Phase I)
during which participants will be made familiar to our test products, the
sensory attributes to be used in this study, and the use of a scale.
At the sensory evaluation sessions (Phase II), panelists need to involve in two
sessions a week for one and a half weeks. Each session will approximately take
60 minutes. During the first two sensory evaluation sessions, various double
emulsions differing in fat reduction level and/or original oil content will be
evaluated on their taste and mouthfeel in comparison to non-reformulated
oil-in-water emulsions by using the Rate-All-That-Apply method (RATA). During
the third sensory evaluation session, samples will be evaluated in pairs on a
selection of sensory attributes with regard to which of the two samples is
perceived higher in these selected attributes.
Due to logistical and organizational reasons, participants will be split up in
two groups (Group A and group B) depending on their availability. That means
that not all participants will start on the same day with the research. The
order of sessions will be the same for each participant.

The food sensory descriptive test is non-therapeutic to the participants. In
addition, all test products only contain food grade ingredients, and the daily
intake of emulsifier E476 per session per subject does not exceed the
acceptable daily intake for participants with a body weight of >55kg. All test
products are prepared in a food grade environment, and their storage conditions
will follow food safety rules, strictly complying to HACCP. We do not foresee
any risks of participating in this research.
Regarding time investment, participants of the WOW! study will come, apart from
the information session (30 minutes), to one training session (60 minutes) and
three sensory evaluation sessions (60 minutes each). These four sessions will
be held within two weeks.
Participants of the CanYouFeelIt study will come, apart from the information
session (30 minutes), to 16 training sessions (60 minutes each) and six sensory
evaluation sessions (60 minutes each). These 22 sessions will be held from
November 2014 until February 2015 with two sessions per week, including a
Christmas break.

Both studies are non-therapeutic to the participants. The risk associated with
participation is negligible and compared to other studies the burden of the
WOW! study can be considered low. The burden of the CanYouFeelIt study can be
considered moderate, since participants have to come two times per week over 12
weeks, and have to work in a team.