The Diversity of Green Bean Biochemical Compounds in Robusta Coffee (Coffea canephora Pierre ex A. Froehner) as Evaluated by Near Infrared Spectroscopy | Chapter 07 | Advances and Trends in Agricultural Sciences Vol. 3
Aims:
This study characterized biochemical compound variability that influence green
bean quality in C. canephora as a basis for identifying heterogeneous genotypes
for use in crop improvement because genetic erosion aided by climate change
effects is gradually threatening the cultivation of Ugandan Robusta coffee
(Coffea canephora) local races.
Study Design: Four hundred and fifty
four accessions from twenty four districts were analyzed with Near Infra Red
Spectroscopy (NIRS) for six biochemical compounds using calibrations developed
at CIRAD, France.
Place and Duration of Study: This
work was conducted at the National Coffee Resources Research Institute
(NaCORRI), Uganda between January 2007 and December 2013.
Methodology: Spectrometer Nirsystem
6500 Foss- (Denmark) machine and Software ISI NIRS 2 version 4.11 (Infra Soft
International, Port Matilda, USA) were used to analyze ground samples in
diffuse reflectance from 400 nm to 2500 nm (2 nm steps) and predictive models
were used to quantify the biochemical contents in the green beans. Data was
analyzed with XLSTAT version 2011.2.05 (Addinsoft), Paris, France.
Results: Chlorogenic acid and fat
concentrations of 13.26 and 13.19% dry matter respectively reported in this
study were much higher than 5.88 and 9.0% dry matter respectively reported
earlier. Caffeine concentrations were positively significantly correlated with
cholorogenic acid but negatively significantly correlated with trigonelline,
sucrose, fat and dry matter contents. Caffeine and chlorogenic acid
concentrations increased with age whereas trigonelline declined as trees aged.
Chlorogenic acid and trigonelline concentrations were at their lowest levels in
elevations of between 1000- 1200 metres above sea level and like fat and dry
matter concentrations, the compounds were at their highest levels in higher
elevations of about 1500 metres above sea level. Local landraces, ‘’nganda’’
and ‘’erecta’’ had higher concentrations of chlorogenic acid, sucrose and
caffeine than improved, hybrid and commercial types.
Conclusions: Ugandan C. canephora
caffeine content was lower than that of West-African Robusta coffee but higher
than that of Arabica coffee. Four distinct diversity groups derived from the
six biochemical compounds represented the major organoleptic categories. The
results reported here will be useful in defining the desirable cup qualities of
Robusta coffee as demanded by world markets.
Author(s) Details
Prof. Kahiu Ngugi
Department of Plant Sciences
and Crop Protection, Faculty of Agriculture, College of Agriculture and
Veterinary Sciences, University of Nairobi, P.O.Box 30197-00100, Nairobi,
Kenya.
Pauline Aluka
National Agricultural
Research Organization (NARO), National Coffee Resources Research, Institute
(NaCORI), P.O.Box 185, Mukono, Uganda.
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