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

Abstract

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).

Recent Research Advancements of Coffee Quality Detection: Targeted Analyses vs. Nontargeted Fingerprinting and Related Issues

“…NIR has been applied to detect relevant quality issues about cofee, including determining diferent geographical origins of cofee, varieties, degrees of roasting, and adulterants [128]. Buratti et al [98] analyzed the spectral and morphological data of raw cofee, ground cofee, and cofee beverage by NIR, electronic nose, and electronic tongue coupled with PCA.…”

Metabolomics-Based Approach for Coffee Beverage Improvement in the Context of Processing, Brewing Methods, and Quality Attributes

“…Moreover, the detection of multiple adulterants, including corn, barley, soybean, rice, and even coffee husks and robusta coffee by NIR in roasted and ground arabica coffee was possible, derived from different geographic origins. The developed method was able to detect adulterants in concentrations ≥10% [ 111 ]. In addition, mid-infrared (MIR) Fourier transform spectroscopy (FT-MIR) coupled with chemometrics showed its identifying and quantifying power for arabica coffee adulterants (e.g., 1–30% of corn, barley, soy, oat, rice and coffee husks).…”

Coffee Origin Determination Based on Analytical and Nondestructive Approaches –A Systematic Literature Review

“…The studies listed in Table 5 used NIR for numerous purposes, e.g., differentiation of modern and traditional coffee cultivars from Brazil [5], regional classification of Brazilian coffee samples [115], origin determination of coffee from Cuba, Ethiopia, Indonesia (Bali, Java, and Sumatra), Tanzania, and Yemen [8] comparison between South American and Asian coffee [68], and to detect impurities (Corn, Rice, Barley, Soybeans, Coffee husks) in Arabica roasted coffee samples as well as to separate South and Central American coffee samples [69]. All the above studies used >100 total samples.…”