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ISSUE 6 2018
A question
Why do consumers like what they like? Sensory analysis aims to answer this question
by evaluating product attributes that impact perception. Kieran Kilcawley, principal
research officer, in the Department of Food Quality and Sensory Science, Teagasc,
explains that scientists at the State agency are combining sensory science and flavour
chemistry to better define sensory attributes that impact on perception
Sensory analysis is the ultimate measure
of product quality and success, according
to Kieran. It comprises a variety of
powerful and sensitive tools to measure
human responses to products and
provides information on likes, dislikes and
specific attribute differences. However,
he says, incorporating flavour chemistry
with sensory science offers even greater
insights, allowing researchers to define
the compounds responsible for those
differences, which, in turn, enables them
to understand how to best manipulate or
optimise key product sensory attributes.
"A descriptive panel is asked to rank at least
12 attributes that best define the product.
We identify the volatile [volatile organic
compounds provide the aroma and impact
flavour] profile of the product using advanced
gas chromatographic mass spectrometry
analysis and then use statistical techniques
to determine which volatiles are contributing
to a particular sensory attribute. Once we
understand the source of the volatile(s)
impacting on perception we can use this
information to direct or control the flavour of
the product."
Smells good
Importantly, Kieran notes, most of what we
taste is defined by what we smell. "You have
olfactory receptors in the olfactory membrane
above the buccal cavity of your mouth and,
when you eat something, volatiles are released
in your mouth and travel to the olfactory
nerve, this is called retronasal olfaction.
This same nerve detects aromatic volatiles
orthonasally when you smell via the nose. So,
a lot of people mistake aroma that is released
in the mouth during chewing as taste. In fact,
approximately 80 per cent of flavour is actually
aroma with only 20 per cent taste."
A flavour of the future
The flavour chemistry facility at Teagasc Food
Research Centre, Moorepark, was established
in 1998 to aid researchers' understanding of
the volatile and non-volatile compounds that
influence the flavour of food and beverages and
to offer support to industry, particularly with
respect to product matching, volatile profiling,
identification of taints of off-flavours and shelf-
life stability, among other topics. "The flavour
chemistry facility is an integral component of
Sensory Food Network Ireland established
in 2015 to bring all the sensory expertise on
the island of Ireland under one umbrella to
promote sensory science, enhance existing
expertise and capability, garner funding,
support industry and provide a platform to
support and train future sensory scientists."
A newly-refurbished flavour chemistry
laboratory recently opened in Teagasc
Food Research Centre Moorepark, funded
by Teagasc with equipment grants from
the Department of Agriculture, Food
and the Marine, Enterprise Ireland and
Science Foundation Ireland (SFI). The
facility is designed to extract, concentrate,
identify and quantify aromatic volatiles in
foods and beverages.
"We have the only comprehensive, two-
dimensional gas chromatography time of flight
mass spectrometry system in Ireland, which
was funded by the SFI, at a cost of 268,455,
in 2017. This new equipment enables us to
identify key volatiles that impact on sensory
perception and to understand how they are
impacted during processing, preparation
and storage. Most of our focus is on volatile
compounds because aroma makes up about
80 per cent of flavour with thousands of
potential compounds involved."
The research group at Moorepark, have
worked primarily on dairy products (milk,
cheese, whey, butter, yoghurt and dairy
powders), but as part of wider internal
and external research collaborations have
investigated the flavour of chocolate, beef (raw
and cooked), lamb, salami, vegetables, truffles,
fruit, cereals, kefir and whiskey, and are
developing databases of volatile compounds
for each product. "We also collaborate with
other national and international groups
in flavour chemistry to evaluate different
extraction techniques and to validate methods
for specific applications."
Research highlights
Kieran provides some of the results from the
ongoing research at Teagasc:
Pasture-based dairy identifiers
"Recently, we identified compounds that
can potentially be used to identify dairy
products produced from pasture-based
feeding systems, some of which directly
impact on sensory perception." This