(269a) A Product Engineering Approach: Diffusion and Performance of Fragranced Products | AIChE

(269a) A Product Engineering Approach: Diffusion and Performance of Fragranced Products

Authors 

Rodrigues, A. E., LSRE - Laboratory of Separation and Reaction Engineering - Associate Laboratory LSRE/LCM



Product
Engineering Approach for the Design of High Performance Fragranced
Products

Miguel A. Teixeira and Alirio E.
Rodrigues*

LSRE -- Laboratory
of Separation and Reaction Engineering, Associate Laboratory, Dept.
of Chemical Engineering, Faculty of Engineering of University of
Porto

Rua
Dr. Roberto Frias, 4200-465 Porto, Portugal

Abstract

Chemical Product
Engineering has emerged over the last decade as a new paradigm on
Chemical Engineering.
1,
2

In fact, this is an answer to a global change in the chemical
industry economy: in the past driven by technological expansion for
the large production of commodities, towards a market-driven
production of high added-value, specialty and performance products as
happens today.
2,
3

The relevance of introducing perception, and namely consumer
perception, in the design of chemical products has been recently
highlighted as an important step for product design. Among the
different types of perception, those related to chemical perception
(chemosensory) and namely taste and olfaction are still difficult to
work with. This is due to the complexity of the process of olfaction
at the biochemical level.

Fragrances are
presented in countless products we deal with everyday like perfumes,
shampoos and soaps among many others. In fact, more than
three-quarters of toiletries and household products contain a
fragrance in its composition. However, the design of fragranced
products is still a combination of art, technology, and some
scientific knowledge, although the former predominates at the
industry.
4,
5

In order to reduce
subjectivity and empiricism in this field, we have developed an
integrated theoretical model to assess the performance of fragrances
considering the release and diffusion processes together with the
predicted odor intensity over time and distance from the source. In
order to achieve that goal, our model combines different scientific
fields: Thermodynamics, Transport Phenomena, and Psychophysics into a
common product - fragrances. This approach is within Product Design
or Engineering, which in this case is applied to Perfume Engineering
as shown in Figure 1.

Figure
1 - Our vision of what is Perfume Engineering: the integration of
concepts from different fields (Thermodynamics, Transport Phenomena,
and Psychophysics) in order to improve the design and development of
new perfumed products.
4

Within this line of
though, we can simplify fragranced products to a mixture of
N
fragrance raw materials diluted in a suitable matrix (a liquid
solvent, a water/oil emulsion among others) at some concentration
which can be sprayed on the skin or the clothes by the customers.
After application of the product, the process of perception proceeds
as follows:
i)
fragrances start to evaporate at different rates depending on their
physicochemical properties and those of the mixture and, then,
ii)
they diffuse through the surrounding air until reaching the nostrils
of consumers or other people around; and, finally,
iii)
fragrance molecules will eventually reach the human nose and above
some concentration (known as the odor threshold) they will be
detected and recognized with a specific intensity and character.
Thus, our approach for Perfume Engineering combines knowledge from
Chemical Engineering (Thermodynamics and Transport Phenomena) which
can describe steps
i)
and
ii),
together with models from Psychophysics for step
iii)
as shown in Figure 2.
6-9

Figure
2 -- Schematic representation of our odor model for the perception
of fragranced products.

Overall, our model
will allow predicting and mapping the perceived odor elicited from
any mixture of fragrance ingredients, thus reducing significantly the
number of trial and error experiments which are expensive and time
consuming for the Flavor & Fragrance industry.

In this work, we
present a theoretical approach and experimental validation of our
model for the step of fragrance diffusion together with the
assessment of product performance using similar properties to assess
it as the industry (like impact, tenacity, diffusion and volume
parameters).
9
In this way, concentration profiles were experimentally measured in a
diffusion tube, similar to the Stefan tube, and predicted with a
model for pure fragrance chemicals, binary, quaternary, and
multi-component (up to 11 chemicals) mixtures. A very good agreement
between our purely predictive model and experimental concentration
data was observed. Fragrance concentrations in air were then
converted into odor intensities using models from psychophysics,
making it possible to evaluate the evolution of the odor with time
and distance using a performance plot. Accordingly, the performance
of these mixtures was modeled and experimentally validated, which
constitutes a landmark for fragrance design.

It was observed
that the performance of a fragrance depends on the intrinsic
properties of its constituents, but also on their molecular
interactions in the liquid solution. Thus, the evaporation rate of
each fragrance remains a function of mixture's initial composition
(xi),
molecular interactions (activity coefficient,
i),
and
temperature (
T)
but it is simultaneously dependent on the physicochemical and
psychological properties of each fragrance chemical (diffusivity,
saturated vapor pressure, molecular weight, ODT, and power law
exponent). Another important conclusion to draw from this work is
that it is possible to measure and predict the performance of a
perfumed product using perfumery terminology and a theoretical model
to assess the perceived odor over time and distance from the source.
Finally, it is expected that this work might contribute to reduce the
time needed for the design of perfumes and fragranced products in the
pre-formulation step and the reduction of the consumption of raw
materials. Altogether, that will contribute to decrease production
costs.

References

1. Cussler, E. C.; Moggridge, G. D., Chemical
Product Design
. Cambridge University
Press: Cambridge, 2001.

2. Wesselingh, J. A.; Kiil, S.; Vigild, M. E.,
Design & development of biological,
chemical, food and pharmaceutical products
.
Wiley: Chichester, U.K., 2007.

3. Cussler, E. L.; Wagner, A.; Marchal-Heussler,
L., Designing Chemical Products Requires More Knowledge of
Perception. AIChE Journal 2010, 56, (2),
283-288.

4. Teixeira, M. A.; Rodriguez, O.; Gomes, P.; Mata, V.; Rodrigues,
A., Perfume Engineering: Design, Performance & Classification.
Elsevier: Oxford, UK, 2013.

5. Sell, C. S., On the unpredictability of odor.
Angewandte Chemie-International Edition
2006,
45, (38), 6254-6261.

6. Teixeira, M. A.; Rodriguez, O.; Mata, V. G.;
Rodrigues, A. E., The Diffusion of Perfume Mixtures and Odor
Performance. Chemical Engineering
Science
2009,
64, 2570-2589.

7. Teixeira, M. A.; Rodriguez, O.; Mata, V. G.; Rodrigues, A. E.,
Perfumery Quaternary Diagrams for Engineering Perfumes. AIChE
Journal
2009,
55, (8), 2171-2185.

8. Teixeira, M. A.; Rodriguez, O.; Mota, F. L.;
Macedo, E. A.; Rodrigues, A. E., Evaluation of group-contribution
methods to predict VLE and odor intensity of fragrances. Industrial
& Engineering Chemistry Research
2011,
50, 9390--9402.

9. Teixeira, M. A.; Rodriguez, O.; Rodrigues, A.
E., Diffusion and Performance of Fragranced Products: Prediction and
Validation. AIChE Journal 2013,
(accepted).

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