Effect of Prolonged Fermentations of Coffee Mucilage with Different Stages of Maturity on the Quality and Chemical Composition of the Bean

Abstract

The sensory quality of coffee begins in the plant tree, where the characteristics of the fruits define the composition of the chemical precursors, which can be preserved or transformed in stages such as mucilage fermentation, and are the basis for the beverage attributes. This study evaluated three degrees of maturity and their comportment in fermentation under two temperatures and two-time extensions, establishing their sensory and chemical characteristics through analytical techniques such as liquid and gas chromatography. The effect of the prolongation time was evidenced for oxalic, quinic, citric acids, glucose, and fructose in two of the three degrees of maturity evaluated. The interaction of the process conditions increased the content of fructose and glucose in one of the states, being more evident at 20 °C. The treatments associated with the most advanced stage of maturity and with higher temperature decreased the scores of five sensory attributes and the fructose content increased by 48.50% and the glucose content increased by 47.31%. Advanced stages of maturity preserve quality standards, but their performance can be differential in postharvest processes, especially in those that are beyond the standards, such as those involving prolongations in different processes such as fermentation.

Content of Acidic Compounds in the Bean of Coffea arabica L., Produced in the Department of Cesar (Colombia), and Its Relationship with the Sensorial Attribute of Acidity

“…The data are presented as the average and standard deviation obtained by each acid group for each of the evaluated harvests: phosphoric acid, organic acids and chlorogenic acids. For OAs (Table 2), in general, citric acid (12.1 ± 1.6 g kg −1 ), quinic acid (6 ± 0.8 g kg −1 ), malic acid (4.4 ± 0.8 g kg −1 ) and acetic acid (4 ± 3 g kg −1 ) were the predominant acids; these data were within the average values reported for C. arabica grown in Colombia [15,30].…”

“…As observed descriptively, the variability of acetic acid does not remain consistent from one harvest to another. This change could be associated with post-harvest practices carried out by coffee growers in the wet process [15,49,50]. However, it was not the focus of this study to control these factors, and therefore, it is not possible to precisely determine the causes of the variability.…”

“…The quality of Colombian coffee is the result of the cultivation of varieties of the Arabica species, in combination with environmental (soil and climate) factors associated with the geography and location of Colombia; agronomic practices during the stages of sowing, fertilization, and the integrated management of pests, diseases and weeds [4][5][6][7][8]; and harvesting mainly ripe fruits and implementing wet processing [9][10][11][12][13]. The wet process to obtain washed coffee has more processing stages than does the dry process used to obtain natural coffee or the semidry process used to obtain honey type coffee; each of these processes yields beverages with sensory attributes differentiated by fragrance and aroma, acidity and body [14][15][16].…”

“…Wet processing, which is carried out by the majority of Colombian coffee growers, begins with the harvest of ripe fruits [15,[17][18][19]. Then, pulping, considered the first stage of transformation, involves removal of the peel from the fruit [20] and the elimination of mucilage from coffee [21][22][23][24]; mucilage is the hydrogel that covers the shelled bean and, in combination with yeasts and bacteria present in the environment and in the equipment, leads to the natural occurrence of fermentation at room temperature [15,25]. After the spontaneous fermentation stage [26], the coffee is washed, followed by the drying process until it reaches a moisture content between 10-12% [27][28][29].…”

“…From a sensory perspective, certain groups of acids are considered constituents of coffee beans that directly affect beverage quality; these acids constitute 11% of the total bean mass, and they are flavor precursors for other coffee quality descriptors. Two groups of acids have been identified in coffee beans: organic acids (OAs), such as citric, malic, quinic, acetic, lactic, succinic and oxalic acids [15,30,33,[35][36][37], and chlorogenic acids (ACGs), grouped as caffeoylquinic acids (5-CQA, 4-CQA and 3-CQA), feruloylquinic acids (5-FQA, 4-FQA and 3-FQA) and dicaffeoylquinic acids (3,4-diCQA; 3,5-diCQA and 4,5-diCQA) [32,[38][39][40][41]. Among other acids present in coffee beans, inorganic acids such as phosphoric acid (H 3 PO 4 ) have been identified [42].…”