Applications of Machine Olfaction - The Electronic Nose Artificial Olfaction Technology - page 208

(f) Cocoa beans quality assessment:
Olunloyo et al. designed and developed a prototype E-nose sensor for moni-
toring the quality of cocoa beans. They employed in this work a sensing element
manufactured by Figaro TGS (Figaro website: www.figaro.com ) gas sensor, which
includes a Tin Oxide (SnO 2 ) semiconductor, with low conductivity in clean air.
The compounds dependable for the cocoa aroma are methylpyrazines, which are
nitrogen heterocyclic substances, known as volatile compounds in the aroma of
five types of roasted and unroasted (raw) cocoa beans as isovaleraldehyde, iso-
butyraldehyde, propionaldehyde, methyl alcohol, acetaldehyde, methyl acetate, n-
butyraldehyde, and diacetyl. They used PCA method for baseline correction of
data and normalization of data [ 11 ].
(g) Honey Characterization:
Honeys can be distinguished according to their botanical origin on the basis of
volatile compound outlines obtained by E-nose. The differences caused by the
honey types (obtained differences originating from the geographic samples of
honey) were counteracted by Frane et al. [ 12 ]
(h) Aroma Detection of Coffee:
Schedule analysis is frequently performed on coffee aromatic extracts to
evaluate the effectiveness of the extraction methods used in interpretation in a
quality of coffee aroma. A good extraction method is expected to provide an
extract with sensory characteristics very close to the aroma of ground coffee beans
prior to extraction.
(i) Quality of Tea:
There are around 700 volatile organic compounds (VOCs) in black tea and
Linalool, Geraniol, Trans2-hexen-1-ol, and Methyl Salicylate which are present in
reasonably high concentrations; these concentrations increase the good quality of
black tea. As there are quite a large number of volatile compounds present in tea, a
sensor array, comprising a group of sensors, is the best option for assessment of tea
quality [ 13 ].
(j) Wine Fermentation:
Fermentation in wine is the process whereby yeast transforms sugar into carbon
dioxide and ethyl alcohol (ethanol). The proposed E-nose (Wi-Nose) was suc-
cessfully designed to examine the fermentation stages in wine. With the help of
neural networks, 100 % accuracy is possible to be realized. The product quality is
maximum consumer satisfaction, which is better than the competition, and can be
marketed optimally at a price slightly lower than the competitor price [ 14 ].