Effect of Roasting Degree on the Antioxidant Properties of Espresso and Drip Coffee Extracted from Coffea arabica cv. Java

Coffee roasting is the process of applying heat to green coffee beans to bring out flavors through chemical changes. This study aimed to investigate the effect of roasting degree on the antioxidant capacities of espresso and drip coffee extracted from Coffea arabica cv. Java in Laos. Green coffee beans were roasted under four conditions (Light-medium, Medium, Moderately dark, and Very dark), and espresso and drip coffee were extracted. The contents of total phenolics (TP), total flavonoids (TF), and chlorogenic acids (CGA) decreased as the roasting degree increased, whereas the caffeine content increased. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity was lower in the Medium, Moderately dark, and Very dark compared to the Light-medium. The ferric reducing antioxidant power (FRAP) was lower in the Very dark than the Light-medium, Medium, and Moderately dark. Principal component analysis showed that TP, TF, CGA, caffeine, DPPH radical scavenging activity, and FRAP distinguish coffee extracts with various roasting degrees. Therefore, it is concluded that roasting degree is a modifiable factor for the use of coffee as an antioxidant material in the food industry, and TF, TP, CGA, and caffeine contents, DPPH radical scavenging activity and FRAP are good indicators for determining the antioxidant capacity of coffee.

Thermal Coursed Effect of Comprehensive Changes in the Flavor/Taste of Cynanchi wilfordii

This study aims to investigate alterations in volatile compounds and chemical components that may affect the sensory properties of Cynanchi wilfordii roasted at 120 °C and 180 °C for various durations of time (0 to 4 min). For volatile compound profiles, tridecane, tetradecane, and ethyl hexyl ether were detected as major compounds of the sample without roasting. As the roasting temperature increased, the types of volatile compounds increased, whereas the content decreased with an increase in heterocyclic compound generation. The sample roasted at 120 °C for 1 min showed a notably different profile pattern from the other roasted samples. For the sniffing test performed by trained panelists using gas chromatography olfactometry, naphthalene and nonanal, which induce spicy and raw C. wilfordii, respectively, were perceived most intensely throughout all the samples. In the electronic tongue analysis, the sample roasting at 180 °C showed an increased and decreased pattern in umami taste and saltiness, respectively, with increased roasting time. Electronic tongue analysis results showed that the sample roasted at 180 °C for 4 min would have the best sensory preference. Along with the volatile compound profiles, the sample roasted at 120 °C for 1 min had more sourness than the other samples, and would potentially have distinctive sensory characteristics. This study should provide baseline data on variations in the sensory properties and industrial applications of C. wilfordii upon roasting. PRACTICAL APPLICATION: Various applications of food ingredients through changes in sensory characteristics by roasting will provide consumers more options for food selections. Accordingly, this study will be utilized by (1) individuals and food companies who are interested in functional foods, (2) individuals and food industries that seek optimum roasting conditions for proper sensory characteristics of foods, and (3) farmers and crop producers who seek for utilization the applications of Cynanchi wilfordii as a food ingredient.

Discrimination and geographical origin prediction of washed specialty Bourbon coffee from different coffee growing areas in Rwanda by using electronic nose and electronic tongue

The study aimed at discriminating washed specialty Bourbon coffee from major coffee growing areas in Rwanda and evaluating the feasibility of using flavor to predict the geographical origin of Arabica coffees from different origins. Discrimination was achieved by performing a principal component analysis, and a discriminant factorial analysis (DFA) model was used to predict the geographical origin of coffee samples based on their intrinsic flavor. Discrimination results from both e-nose and e-tongue indicated clear grouping of coffee samples from areas within the same geographical sub-regions. A DFA model using e-nose was successful in predicting the geographical origin of coffee samples but not with e-tongue. Therefore, the study demonstrated that aroma could reliably be used to predict the geographical origin of coffee samples from different origins than their taste profile.