How Does LC/MS Compare to UV in Coffee Authentication and Determination of Antioxidant Effects? Brazilian and Middle Eastern Coffee as Case Studies

Coffee is a popular beverage owing to its unique flavor and diverse health benefits. The current study aimed at investigating the antioxidant activity, in relation to the phytochemical composition, of authenticated Brazilian green and roasted Coffea arabica and C. robusta, along with 15 commercial specimens collected from the Middle East. Ultra-high-performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-ESI–HRMS) and UV spectrometry were employed for profiling and fingerprinting, respectively. With the aid of global natural product social molecular networking (GNPS), a total of 88 peaks were annotated as belonging to different chemical classes, of which 11 metabolites are reported for the first time in coffee seeds. Moreover, chemometric tools showed comparable results between both platforms, with more advantages for UV in the annotation of roasting products, suggesting that UV can serve as a discriminative tool. Additionally, antioxidant assays coupled with the UHPLC-ESI–HRMS dataset using partial least-squares discriminant analysis (PLS-DA) demonstrated that caffeoylquinic acid and caffeine were potential antioxidant markers in unroasted coffee versus dicaffeoyl quinolactone and melanoidins in roasted coffee. The study presents a multiplex metabolomics approach to the quality control of coffee, one of the most consumed beverages.

Effects of different ingredients on antioxidant and oxidant status of brewed roasted coffee

It was aimed to evaluate the effects of different ingredi-ents on total antioxidant sta-tus (TAS) and total oxidant status (TOS) of the brewed Brazil mild roasted coffee. Sugar, sucralose, butter, co-conut-oil, animal and plant-based milk types were add-ed and milk types&sweeteners were combined separately. TAS and TOS were measured and oxidative stress indice (OSI) was calculated. TAS value of coffee with whole milk was the highest among all coffee types. TOS values of coffee with soy milk, with soy milk+sugar and soy milk+sucralose were lower than all other coffee types. When compared to OSI val-ues, coffee with soy milk, with soy milk+sugar and soy milk+sucralose had the lowest OSI values among all coffee types. Moreover, ad-dition of coconut-oil to cof-fee samples increased the TOS and OSI values of cof-fees. While the TOS and OSI of the sugar and su-cralose addition were found higher in comparison to plain coffee; TOS and OSI of the sucralose addition was lower than those sugar combinations. In conclu-sion, the OSI of the coffee may change depending on the alterations of chemical structures and nutritional matrices by the added in-gredients. The addition of soy milk or sucralose in-stead of sugar or whole cow milk instead of oil-based ingredients could be a promising strategy of reduc-ing the oxidative capacity.

Ochratoxin A and 2′R-Ochratoxin A in Selected Foodstuffs and Dietary Risk Assessment

The aim of this study was to estimate the contamination of grain coffee, roasted coffee, instant coffee, and cocoa purchased in local markets with ochratoxin A (OTA) and its isomerization product 2′R-ochratoxin A (2′R-OTA), and to assess risk of dietary exposure to the mycotoxins. OTA and 2′R-OTA content was determined using the HPLC chromatography with immunoaffinity columns dedicated to OTA. OTA levels found in all the tested samples were below the maximum limits specified in the European Commission Regulation EC 1881/2006. Average OTA concentrations calculated for positive samples of grain coffee/roasted coffee/instant coffee/cocoa were 0.94/0.79/3.00/0.95 µg/kg, with the concentration ranges: 0.57–1.97/0.44–2.29/0.40–5.15/0.48–1.97 µg/kg, respectively. Average 2′R-OTA concentrations calculated for positive samples of roasted coffee/instant coffee were 0.90/1.48 µg/kg, with concentration ranges: 0.40–1.26/1.00–2.12 µg/kg, respectively. In turn, diastereomer was not found in any of the tested cocoa samples. Daily intake of both mycotoxins with coffee/cocoa would be below the TDI value even if the consumed coffee/cocoa were contaminated with OTA/2′R-OTA at the highest levels found in this study. Up to now only a few papers on both OTA and 2′R-OTA in roasted food products are available in the literature, and this is the first study in Poland.

Near-Infrared Spectroscopy Applied to the Detection of Multiple Adulterants in Roasted and Ground Arabica Coffee

Roasted coffee has been the target of increasingly complex adulterations. Sensitive, non-destructive, rapid and multicomponent techniques for their detection are sought after. This work proposes the detection of several common adulterants (corn, barley, soybean, rice, coffee husks and robusta coffee) in roasted ground arabica coffee (from different geographic regions), combining near-infrared (NIR) spectroscopy and chemometrics (Principal Component Analysis—PCA). Adulterated samples were composed of one to six adulterants, ranging from 0.25 to 80% (w/w). The results showed that NIR spectroscopy was able to discriminate pure arabica coffee samples from adulterated ones (for all the concentrations tested), including robusta coffees or coffee husks, and independently of being single or multiple adulterations. The identification of the adulterant in the sample was only feasible for single or double adulterations and in concentrations ≥10%. NIR spectroscopy also showed potential for the geographical discrimination of arabica coffees (South and Central America).

Phenotyping Green and Roasted Beans of Nicaraguan Coffea Arabica Varieties Processed with Different Post-Harvest Practices

Metabolomics techniques have already been used to characterize two of the most common coffee species, C. arabica and C. canephora, but no studies have focused on the characterization of green and roasted coffee varieties of a certain species. We aim to provide, using NMR-based metabolomics, detailed and comprehensive information regarding the compositional differences of seven coffee varieties (C. arabica) of green and roasted coffee bean batches from Nicaragua. We also evaluate how different varieties react to the same post-harvest procedures such as fermentation time, type of drying and roasting. The study characterises the metabolomic profile of seven different Arabica varieties (Bourbon-typica) enabling us also to assess the possible use of an NMR spectra of bean aqueous extracts to recognize different farms, even from the same geographical area (Nueva Segovia). Here, we also evaluated the effect of post-harvest procedures such as fermentation time and type of drying on green and roasted coffee, suggesting that post-harvest procedures can be responsible for different flavours. This study provides proof of concept for the ability of NMR to phenotype coffee, helping to authenticate and optimise the best way of processing coffee.

Quantification of Caffeine and Chlorogenic Acid in Green and Roasted Coffee Samples Using HPLC-DAD and Evaluation of the Effect of Degree of Roasting on Their Levels

Chlorogenic acid and caffeine are among the important components in coffee beans, determining the taste and aroma. In addition, phenols and antioxidants content possess vital health values. The main aim of this study is to determine the levels of caffeine and chlorogenic acid in several coffee samples of different origins and degrees of roasting. The coffee samples were extracted using hot water. The levels of caffeine and chlorogenic acid were quantified using high-performance liquid chromatography (HPLC) equipped with a diode array detector, a reverse phase system, and an ODS column (C18). Total phenol and antioxidant contents were previously determined for the same samples. The results showed that the highest content of caffeine was found in the medium roasted coffee (203.63 mg/L), and the highest content of chlorogenic acid content was found in the green coffee (543.23 mg/L). The results demonstrated a negative correlation between the chlorogenic acid levels with the degree of roasting, while it showed a positive correlation between the caffeine levels with the degree of roasting till a certain point where the levels dropped in the dark roasted coffee. The origin of coffee samples did not show any effect on any of the measured variables. Antioxidant effects of coffee samples were largely determined by chlorogenic acid content.

Detection roasting level of Lintong coffee beans by using euclidean distance

Coffee roasting is the process by which raw coffee beans (green beans) are roasted until they reach a certain roast level. In general, the roast level of roasted coffee beans is divided into 3 levels, namely the roast level of light, medium and dark. One way to find out the roast level of roasted coffee beans is to see the color change of the coffee beans. However, it is very difficult to know the exact color conditions of each roast level of roasted coffee beans and this can be overcome by build an automatic coffee roasting equipment. In this research, an automatic coffee roaster was done with a system that is able to control the roasting temperature and stirring of coffee beans. This tool can also monitor the change in color of the coffee beans during the roasting process. The system that has been implemented can detect color changes and classify the level of dark roast of roasted coffee beans using the Euclidean distance algorithm. The Euclidean distance give a threshold to classified the roast level. The system accuracy for predicting coffee beans color at the level of dark roast is 90% and 80% for overall.