The objective of this work was to study the influence of two postharvest processing methods on the biochemical composition and sensory analysis of a Colombian specialty coffee. For this purpose, coffee beans (Coffea arabica) of the Castillo variety were collected and processed using the wet and semi-dry methods, and the drying process was conducted in a sun drier prototype with a plastic parabolic cover, with a maximum drying air temperature of 50 °C; green coffee beans were managed according to the official Specialty Coffee Association cupping protocol and roasted to a medium and dark degree. Physicochemical determinations (pH, color, titratable acidity, caffeine content, and chlorogenic acid quantification) in green coffee and roasted coffee beans were performed; the sensory analysis was performed by a panel of trained tasters. The wet and semi-dry processing methods resulted in differences in color parameters, pH values, and caffeine content. However, the titratable acidity, chlorogenic acid, and sensory evaluation did not have any difference; therefore, the type of coffee processing method used is not relevant to the final chemical properties of the roasted coffee (i.e., the Castillo variety) evaluated in this study; the coffee cup score is also not affected, and the post-fermentation washing process can be dispensed with.
Defects in coffee affect the sensory quality of finished drink. To avoid this, defective beans are usually removed after threshing, as, once the green beans have been roasted, it becomes difficult to identify the defects. Procedures have been developed to evaluate coffee samples using infrared spectroscopy to detect such defects. As such, this study evaluated infrared spectra and sensory attributes of 39 coffee samples in: commercial ground and instant coffees, medium and high roast quality coffees, and defects present in the coffee. The sensory analysis was performed by 10 judges, semi-trained by a Q-grader, and eleven attributes were assessed using a semi-structured hedonic scale. The spectra obtained from the coffee samples were processed by mean centering, normalization (probabilistic quotient normalization), area normalization, first derivative and second derivative, later followed by principal component analyses. The sensory results showed differences in the evaluated attributes, differentiating between the samples of high quality medium roasted coffee from the other samples. After processing IR spectra of the samples by area normalization, PCA results exhibited four different groups: a) medium, high roasted quality coffee, with broken and chipped defects; b) commercial ground coffee and defects of sour, insect damaged, and faded; c) black defects, and d) instant coffee. Using the chemical descriptors obtained from the infrared spectra, it was possible to separate between high quality, commercial and instant coffee.
Currently, the use of coffee pulp to prepare infusions is being studied based on its antioxidant properties. The objective of this study was to evaluate the effect of drying temperature on the chemical properties of dehydrated coffee pulp to characterize the coffee pulp beverage in single-dose capsules physically and sensorially after being subjected to three thermal treatments (CT, natural drying; T50, oven drying at 50°C; T60, oven drying at 60°C). Chemical characterization of the dehydrated pulp was performed using Fourier transform infrared spectroscopy analysis (ATR-FTIR) and liquid chromatography (HPLC). Next, physical and sensorial characterization of the beverage was performed to determine the soluble solids (SS), pH, titratable acidity, and color. On the other hand, this beverage was evaluated sensorially. Principal component analysis was performed on the data from the FTIR spectral ranges of 1,800-650 cm-1. Physicochemical and sensory results were analyzed using ANOVA. The chemical, physical, and sensory behavioral results allowed the identification of T60 as a viable processing treatment.
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