Thermophysical properties of parchment coffee: New Colombian varieties

Abstract

The thermophysical properties of coffee have a special partaking during the drying process since a material‐depending heat and mass transfer occurs between the bean and the drying air. Conditional to the thermophysical properties of the parchment coffee, the drying can be more or less efficient, affecting the final quality and seed safety. Several coffee varieties have been studied; however, the National Coffee Research Center of Colombia has developed new highly productive coffee varieties resistant to different diseases: Cenicafé 1 and Castillo®. Nevertheless, the thermophysical properties of these specific varieties were not yet investigated; moreover, the availability of information related to these properties of different coffee varieties in the literature is relatively scarce. Thus, this study targeted to determine the parchment coffee thermophysical properties of these new varieties at five different moisture contents % (wb): 53%, 42%, 32%, 22% and 11%, using optimized techniques and methods to ensure high accuracy and exactness. It was found that the new varieties have larger, heavier, and denser beans; it was also seen that the bulk thermal conductivity and the bulk‐specific heat are higher in these varieties than in the older ones. It was also revealed that the length, width, thickness, and surface area did not change as the moisture was removed, whereas the bulk density, kernel density, mass, bulk‐specific heat, and bulk thermal conductivity decreased as the moisture was reduced. Displaying better thermophysical properties will improve the drying and roasting processes; hence, a better final product can be expected from these varieties. Practical applications Knowing the thermal and physical properties of these new varieties will allow the growers and coffee processing facilities to predict, simulate and control different post‐harvesting processes such as pulping, fermentation, drying, storing, and roasting. Also, the already developed mathematical models to estimate coffee drying times can be updated, improving the accuracy of the predictions, bed porosities, mass, and heat transfer in order to safeguard the innocuousness of the product.

Characterization of Fermentations with Controlled Temperature with Three Varieties of Coffee (Coffea arabica L.)

“…In addition to the high diversity in coffee after processing using the wet method, the diversity varies between farms and regions [41,42]; however, characteristics did not vary among varieties maybe because they were produced in one place. The largest populations of mesophilic microorganisms require an optimal temperature to ensure and accelerate fermentation, which would be the case of those carried out at 30 • C. On the contrary, fermentations at low temperatures indicate that the processes can develop without problems, maintaining stable and reliable control [39], as in fermentations at 15 • C. The Castillo and Cenicafé1 varieties have different sizes, densities and thermal properties related to the humidity of the coffee [43], which could also affect the fermentation behavior. Some of these differences were observed with the Cenicafé1 and Tabi varieties, which had more beans of a larger size than did the Castillo variety (Table 4), a finding that could be related to the fact that this variety had the greatest descriptive changes in coffee drink scores.…”

“…Given the diffusion of compounds that occurs from the mucilage to the endosperm, this is facilitated by the water content of the coffee in this state and the size of the bean [44]. The Castillo variety has a lower surface area and bulk and real density values than those for the Cenicafé1 variety [43]. Despite the fact that fermentation under the same conditions ended at similar times and that there was no significant difference in quality, differences in attributes were perceived, being more noticeable for Castillo.…”

Physical, Sensorial, and Physicochemical Characteristics of Arabica Coffee Dried under Two Solar Brightness Conditions

“…Different levels of crop elevation do not influence changes in this variable [41]. This variable can vary widely; therefore, differences in real density can be detected, for which measurements are made bean by bean [42]. Regarding size, most of the beans from the two climatic zones were greater than 18 mesh, indicating the characteristics of the variety used in the study.…”

Peaberry shape and size influence on different coffee postharvest processes

“…The initial moisture content of the samples was attained by gravimetric principles on a standalone sample from both peaberry and standard grain, taken previously from the original wet mass. Also, the general moisture removal was tracked by following the same gravimetric relation using Equation (1) (Corrêa et al, 2010; Duque‐Dussán, Sanz‐Uribe, Dussán‐Lubert, et al, 2023). where m f stands for the final mass of the sample, m i represents the initial mass value, while M i and M f denote the initial and final moisture content values in % (wb) respectively.…”

“…The initial moisture content of the samples was attained by gravimetric principles on a standalone sample from both peaberry and standard grain, taken previously from the original wet mass. Also, the general moisture removal was tracked by following the same gravimetric relation using Equation (1) (Corrêa et al, 2010;Duque-Dussán, Sanz-Uribe, Dussán-Lubert, et al, 2023).…”