Simultaneous Detection of Multiple Adulterants in Ground Roasted Coffee by ATR-FTIR Spectroscopy and Data Fusion

Reis, Nádia; Botelho, Bruno G.; Franca, Adriana S.; Oliveira, Leandro S.

doi:10.1007/s12161-017-0832-3

Cited by 37 publications

(24 citation statements)

References 27 publications

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“…It provided a measure of how well the model correctly identify samples of a given class [ 20 ]. The reliability rate (RLR) provided an overview of the trueness of the model and its definition was shown in equation 3 [ 12 ].

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Section: Methodsmentioning

confidence: 99%

“…Several analytical methods have been proposed to identify the adulteration of ground roasted coffee, including gas chromatography-mass spectrometry (GC-MS) [ 3 ], high-performance liquid chromatography (HPLC) [ 7 , 8 , 9 ], ultraviolet-visible spectrophotometry (UV-Vis) [ 10 ], ultra-performance liquid chromatography (UPLC) [ 11 ], Fourier-transform infrared spectroscopy (FTIR) [ 12 ] and voltammetric electronic tongue [ 13 ]. The above methods apply either targeted- or non-targeted analysis methods.…”

Section: Introductionmentioning

confidence: 99%

“…The heating/roasting effect of a conventional oven was slow and inhomogeneous. Hence, the roasting time was long—40 min on average for a batch [ 12 , 16 ], while a commercial coffee bean roaster only requires 12–15 min. In order to simulate the commercial roasting method and enhance the representativeness of the sampling, industrial roaster was used in the study.…”

Section: Introductionmentioning

confidence: 99%

“…In order to simulate the commercial roasting method and enhance the representativeness of the sampling, industrial roaster was used in the study. In addition, many chemometric spectroscopy methods for coffee adulteration have been conducted on the powdered form of coffee [ 12 ], or extracted by solvents such as CDCl 3 for nuclear magnetic resonance (NMR) analysis [ 17 ]. However, coffee is normally consumed in liquid form, and hot water is the only solvent.…”

Section: Introductionmentioning

confidence: 99%

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HPLC-Based Chemometric Analysis for Coffee Adulteration

Cheah

Fang

2020

Foods

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Coffee is one of the top ten most adulterated foods. Coffee adulterations are mainly performed by mixing other low-value materials into coffee beans after roasting and grinding, such as spent coffee grounds, maize, soybeans and other grain products. The detection of adulterated coffee by high performance liquid chromatography (HPLC) is recognized as a targeted analytical method, which carbohydrates and other phenolic compounds are usually used as markers. However, the accurate qualitation and quantitation of HPLC analyses are time consuming. This study developed a chemometric analysis or called non-targeted analysis for coffee adulteration. The HPLC chromatograms were obtained by direct injection of liquid coffee into HPLC without sample preparation and the identification of target analytes. The distinction between coffee and adulterated coffee was achieved by statistical method. The HPLC-based chemometric provided more characteristic information (separated compounds) compared to photospectroscopy chemometric which only provide information of functional groups. In this study, green Arabica coffee beans, soybeans and green mung beans were roasted in industrial coffee bean roaster and then ground. Spent coffee ground was dried. Coffee and adulterants were mixed at different ratio before conducting HPLC analysis. Principal component analysis (PCA) toward HPLC data (retention time and peak intensity) was able to separate coffee from adulterated coffee. The detection limit of this method was 5%. Two models were built based on PCA data as well. The first model was used to differentiate coffee sample from adulterated coffee. The second model was designed to identify the specific adulterants mixed in the adulterated coffee. Various parameters such as sensitivity (SE), specificity (SP), reliability rate (RLR), positive likelihood (+LR) and negative likelihood (−LR) were applied to evaluate the performances of the designed models. The results showed that PCA-based models were able to discriminate pure coffee from adulterated sample (coffee beans adulterated with 5%–60% of soybeans, green mung beans or spent coffee grounds). The SE, SP, RLR, +LR and −LR for the first model were 0.875, 0.938, 0.813, 14.1 and 0.133, respectively. In the second model, it can correctly distinguish the adulterated coffee from the pure coffee. However, it had only about a 30% chance to correctly determine the specific adulterant out of three designed adulterants mixed into coffee. The SE, RLR and −LR were 0.333, 0.333 and 0.667, respectively, for the second model. Therefore, HPLC-based chemometric analysis was able to detect coffee adulteration. It was very reliable on the discrimination of coffee from adulterated coffee. However, it may need more work to tell discern which kind adulterant in the adulterated coffee.

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…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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HPLC-Based Chemometric Analysis for Coffee Adulteration

Cheah

Fang

2020

Foods

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“…In order to enhance the coffee production chain, coffee produced in certain regions (that is, country of origin labelling, protected designation of origin, and protected geographical indication) has specific sensory properties that consumers are willing to acquire even if the product has a premium price (Reis, Botelho, Franca, & Oliveira, ). Because the consumer is willing to pay for quality, certification allows consumers to relate the unique characteristics of coffee to its producing region.…”

Section: Introductionmentioning

confidence: 99%

Chemometric Authentication of Brazilian Coffees Based on Chemical Profiling

Monteiro

Santos

Rodionova

et al. 2019

Journal of Food Science

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In this work, different chemometric tools were compared to classify n = 26 conventional (CONV) and n = 19 organic (ORG) coffees from the main Brazilian producing regions based on the chemical composition, physicochemical properties, and antioxidant activity. Principal component analysis separated ORG and CONV coffees but the distinction among the producing regions of Brazilian coffee was not possible. Partial least squares discriminant analysis classified all ORG and CONV coffees in the external validation. Similarly, linear discriminant analysis was able to discriminate 100% and 81% of ORG and CONV coffees in the external validation, respectively, in which total phenolic content (TPC), ferric reducing antioxidant activity, and caffeic acid were the main discriminant variables. Overall 100% of samples from Paraná, Minas Gerais, and blended samples were correctly classified, where TPC, flavonoids, inhibition of lipid peroxidation, caffeic acid, pH, and soluble solids were the main discriminant variables. Support vector machines classified 95% ORG and 88% CONV, 100% Coffea arabica, and 88% and 78% coffees produced in São Paulo and Minas Gerais. k‐Nearest neighbors was effective in distinguishing 100% CONV, 89% ORG, 100% coffees from São Paulo, and 100% C. arabica coffees. Overall, HPLC data and simple physicochemical parameters allied to chemometrics were effective in authenticating the cultivation system and the botanical origin of Brazilian coffees. Practical Application Coffee adulteration is a serious problem in the food chain as some fraudsters replace coffee powder by other cheaper products. In the case of organic coffee, this scenario is even worse as still there is not a universal method to differentiate conventionally grown coffee from its organic counterpart. In addition, Brazilian coffee is produced in different regions and the commercial value varies. Therefore, we analyzed some physicochemical, chemical, and antioxidant properties of Brazilian coffees from distinct origins and classified the samples using chemometrics. Our approach seems to be interesting for quality control purposes.

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Front-face synchronous fluorescence spectroscopy: a rapid and non-destructive authentication method for Arabica coffee adulterated with maize and soybean flours

Xie

Tan

2022

J Consum Prot Food Saf

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This article describes a novel front-face synchronous fluorescence spectroscopy (FFSFS) method for the fast and non-invasive authentication of ground roasted Arabica coffee adulterated with roasted maize and soybean flours. The detection was based on the different composition of fluorescent Maillard reaction products and caffeine in roasted coffee and cereal flours. For each roasted maize or soybean adulterant flour (5–40 wt%), principal component analysis coupled with linear discriminant analysis (PCA–LDA) was used for qualitative discrimination. Quantitative prediction models were constructed based on the combination of unfolded total synchronous fluorescence spectra and partial least square regression (PLSR), followed by fivefold cross-validation and external validation. The PLSR models produced suitable results, with the determination coefficient of prediction ( R p 2 ) > 0.9, root mean square error of prediction (RMSEP) < 5%, relative error of prediction (REP) < 25% and residual predictive deviation (RPD) > 3. The limits of detection (LOD) were both 10% for roasted maize and soybean flours. Most relative errors for the prediction of simulated blind samples were between -30% and + 30%. The benefits of this strategy are simplicity, rapidity, and non-destructive detection. However, owing to the high similarity between roasted coffee and roasted cereal flours and the influence of the roasting degree on fluorescent Maillard reaction products, its application is limited to the preliminary screening of roasted coffee with the same roasting degree, adulterated with relatively large amounts of roasted cereal flours which are roasted to analogous color to the coffee. Supplementary Information The online version contains supplementary material available at 10.1007/s00003-022-01396-8.

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Simultaneous Detection of Multiple Adulterants in Ground Roasted Coffee by ATR-FTIR Spectroscopy and Data Fusion

Cited by 37 publications

References 27 publications

HPLC-Based Chemometric Analysis for Coffee Adulteration

HPLC-Based Chemometric Analysis for Coffee Adulteration

Chemometric Authentication of Brazilian Coffees Based on Chemical Profiling

Front-face synchronous fluorescence spectroscopy: a rapid and non-destructive authentication method for Arabica coffee adulterated with maize and soybean flours

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