Laser light Scattering for Investigation of Particle size Dependency of Quality and Flavor of Coffee
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Date
2012-06
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Addis Ababa University
Abstract
In Ethiopia, the methods of co ee variety and standard identi cation is often through
traditional inspection and previous experience which is subjective and non e cient with
the basis of attributes of color, size, shape and
avor, frequently examined by human
inspectors. In this research, e cient and objective discrimination of co ee varieties and
quality determination method is developed by investigating particle size dependency of
quality and
avor of co ee using Laser light scattering technique. Particle size determi-
nation for ve types of co ee samples (Unwashed Harar-4, Washed Lekempti-2, Washed
Sidamo-2, Washed Yirgache ee-2 and Washed Limu-2) were performed after determina-
tion of their optical properties with three phases of experiments. The results show that,
all tested samples has high scattering coe cient in the forward direction as compared
to their negligible absorption coe cient. And their scattering coe cient has direct rela-
tion with their particle size as well as their quality and
avor, the larger the scattering
coe cient is the nest the particle size and the highest the quality with good
avor. Ac-
cordingly, Washed Yirgache ee-2 has highest scattering coe cient and nest particle size
with succession of others. In line with this, using liquid-liquid ca eine extraction method
the participation of ca eine on scattering was tested for Unwashed Harar-4 Co ee sample.
And the result show that, ca eine has its own comparable e ect on scattering. In general
the obtained results were in excellent agreement with those obtained using traditional
cup-test and other known methods. Thus, since the developed method have wider eco-
nomic and scienti c applications, even for other turbid mediums, light scattering method
is the most preferable for classi cation of co ee quality standards
Key Words: Co ee, Standard, Airy Disk, Airy Pattern, Extraction, Scattering
Optical Properties, Particle Size
Description
Keywords
Coffee; Standard; Airy Disk; Airy Pattern; Extraction; Scattering Optical Properties; Particle Size