Chemical analysis and NIR spectroscopy in the determination of the origin, variety and roast time of Mexican coffee.

Coffee is a product whose quality and price are associated with its geographical, genetic and processing origin; therefore, the development of analytical techniques to authenticate the above mentioned is important to avoid adulteration. The objective of this study was to compare conventional analytical methods with NIR technology for the authentication of roasted and ground coffee samples from different producing regions in Mexico (origins) and different varieties. A second objective was to determine, under the same processing conditions, if roasting times can be differentiated by using this technology. A total of 120 samples of roasted and ground commercial coffee were obtained from the states of Chiapas, Oaxaca, Tabasco and Veracruz in Mexico, 30 locally available samples per state. Samples from Veracruz included three different varieties, grown on the same farm and processed under the same conditions. One of these varieties was selected to evaluate the chemical composition of samples roasted at 185 °C using four different roasting times (15, 17, 19 and 21 min). Samples from different producing regions showed significant differences (P < 0.05) in fat content (from 7.45 ± 0.42% in Tabasco to 18.40 ± 2.95% in Chiapas), which was associated with the altitude of coffee plantations (Pearson's r = 0.96). The results indicate that NIR technology generates sufficient useful information to authenticate roasted and ground coffee from different geographical origins in Mexico and different varieties from the same coffee plantation, with similar results to those obtained by conventional analytical methods.

On the soil-bean-cup relationships in Coffea arabica L.

BACKGROUND: The relationships between soil and coffee beans variables were evaluated and then the influence of bean composition on cup quality attributes was computed by means of relation studies. A total of 139 coffee and soil samples were collected directly from the same number of coffee plantations in Chiapas, Mexico. RESULTS: In the elemental composition, only phosphorus, potassium, calcium, and copper in coffee beans had a significant (P < 0.05) relationship with the content of the same elements in soil. The level of macro- and microelements in the coffee bean affected some of the cup quality attributes, but variables such as texture, titratable acidity, and pH of water in soil had a major influence on those attributes. Caffeine, trigonelline, and 5-caffeoylquinic acid in green coffee beans also had a significant influence (P < 0.05) on the sensory attributes of the beverage. CONCLUSION: The elemental composition of soil and coffee beans was important in explaining the cup quality attributes, but the most important variables influencing the sensory quality of coffee were altitude of plantations and moisture of coffee beans. © 2020 Society of Chemical Industry.