Production, chemical composition, and quality of Arabic coffee subjected to copper doses

Herminia Emilia Prieto Martinez,José Soares De Lacerda,Jaime Barros Da Silva Filho,Adriene Woods Pedrosa,Paulo Roberto Cecon,Junia Maria Clemente,Ricardo Henrique Silva Santos

doi:10.1590/s0100-204x2018000400006

Abstract

Abstract: The objective of this work was to evaluate the effect of copper on the chemical composition of coffee beans and on the quality of the beverage, relating both of them to the Cu leaf contents in coffee (Coffea arabica) plants. Coffee plants were grown in a hydroponic system containing 0.2, 0.4, 0.8, 1.6, and 3.2 μmol L-1 Cu until fruit setting. Coffee bean production was evaluated, and, after the cherries were dried, the following characteristics were determined: leaf Cu content; total titratable acidity; color index; electrical conductivity; leached K; polyphenol oxidase (PPO) activity; concentrations of caffeine, trigonelline, organic acids, total phenols, chlorogenic acids (3-CQA, 4-CQA, and 5-CQA), sucrose, glucose, arabinose, mannose, and galactose; and sensory quality of roasted beans. Cu increased bean yield, PPO activity, and the concentrations of organic acids, 3-CQA, sucrose, and arabinose. Total titratable acidity, total phenols, 4-CQA, and 5-CQA were reduced with increasing Cu doses. Leaf contents related to the maximum and minimum values of desirable and undesirable quality attributes ranged from 5.6 to 11.4 mg kg-1 Cu, respectively. Copper affects the production and chemical composition of coffee beans, and the attributes related to quality are maximized in plants with low leaf contents of the nutrient.

Highlights

The characteristic coffee flavor derived from the bean is directly related to edaphoclimatic conditions, cultivars, soil or leaf fertilization, and post-harvest processing, which includes drying, storage, roasting, grinding, and packaging
The chemical composition, and qualitative and quantitative variations of coffee beans were investigated according to species (Monteiro & Farah, 2012), cultivar (Kitzberger et al, 2013), and to processing, growing environment, and management (Ribeiro et al, 2016)
The activity of the polyphenol oxidase enzyme in raw beans has been used as a biochemical indicator of beverage quality, since the best quality coffees show a greater activity of this enzyme and have a higher color index (Carvalho et al, 1994; Mazzafera et al, 2002; Silva et al, 2009)

Summary

Introduction

The characteristic coffee flavor derived from the bean is directly related to edaphoclimatic conditions, cultivars, soil or leaf fertilization, and post-harvest processing, which includes drying, storage, roasting, grinding, and packaging. Several chemical constituents of the bean, such as aroma, flavor, acidity, body, astringency, and residual taste, among others, are responsible for the characteristics of the beverage, and their proportion or combinations will define its quality (Buffo & Reineccius, 2008). Among the chemical components of the raw coffee beans, chlorogenic acids, caffeine, trigonelline, phenols, and sucrose are closely related to the sensory quality of the beverage and are used in its classification (Farah et al, 2006). The activity of the polyphenol oxidase enzyme in raw beans has been used as a biochemical indicator of beverage quality, since the best quality coffees show a greater activity of this enzyme and have a higher color index (Carvalho et al, 1994; Mazzafera et al, 2002; Silva et al, 2009)

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