Nowadays, coffee and cocoa have broad applications in the food and pharmaceutical industries due to their organoleptic and nutraceutical properties, which have turned them into products of great commercial demand. Consequently, these products are susceptible to fraud and adulteration, especially those sold at high prices, such as saffron, vanilla, and turmeric. This situation represents a major problem for industries and consumers’ health. Implementing analytical techniques, i.e., Fourier transform mid-infrared (FT-MIR) spectroscopy coupled with multivariate analysis, can ensure the authenticity and quality of these products since these provide unique information on food matrices.
Spectral Range (cm−1) | Sampling Technique | Algorithm | Purpose of the Analysis | Reference |
---|---|---|---|---|
Arabica coffee variety Kona typica | ||||
1900–800 | ZnSe ATR | PCR PLS |
Detection and quantification of adulteration of coffee grown in Kona, Hawaii, with coffee from another region. | [19] |
Brazilian coffee | ||||
3600–2820 1800–784 1900–800 |
DRIFT |
Spectral Range (cm−1) | Sampling Technique | Algorithm | Purpose of the Analysis | Reference | |||||
---|---|---|---|---|---|---|---|---|---|
Chocolate | |||||||||
3600–2800 1800–500 |
ATR cell | PCA PLS |
Determination of cocoa solids content in chocolates. | [42] | |||||
PCA | |||||||||
1800–700 | Diamond ATR | PLS | Quantification and prediction of antioxidant capacity and catechin concentration in chocolate. | [43] | PLS-DA | Discrimination of decaffeinated coffee and classification according to roasting degree. | [20] | ||
Chocolate and fermented cocoa beans | KBr pellets | RBF (ANN) | Coffee classification by geographic and genotypic origin. | [21] | |||||
4400–600 | ZnSe ATR | PLS | Green Arabica coffee | ||||||
Prediction of antioxidant capacity and total phenolic content. | [ | 44 | ] | ||||||
Cocoa bean shells | 4000–700 | ZnSe ATR DRIFT |
PCA, LDA HCA |
Discrimination of immature coffee (defective) and mature coffee (non-defective). | [22] | ||||
4000–500 | Ge ATR | PCA PLS-DA |
Identification of systematic patterns related to the geographical origin of the samples. | [45] | 4000–700 | KBr pellets ZnSe ATR, DRIFT |
PCA HCA |
Discrimination of defective and non-defective coffee using three different sampling techniques. | [23] |
3600–600 | DRIFT | PCA, LDA |
Discrimination of defective and non-defective roasted coffee. | [24] | |||||
1800–800 | KBr pellets | SVM | Geographical classification of different coffee genotypes. | [25] | |||||
4000-600 2920–2850 1745 |
ZnSe ATR | PCA | Discrimination of coffee beans according to their origin (Brazil, Colombia, Ethiopia, Kenya, and Yemen). | [26] | |||||
3000–900 | ZnSe ATR | PLS | Prediction of quality scores given by cuppers for coffee beverage samples. | [27] | |||||
Roasted Arabica coffee | |||||||||
3200–700 | DRIFT | PCA LDA |
Discrimination between roasted coffee, corn, coffee husk, coffee-corn, and coffee-husk blends. | [28] | |||||
3200–700 | DRIFT | PCA LDA |
Discrimination between roasted coffee, coffee husks, coffee grounds, corn, barley, and coffee-adulterant blends. | [29] | |||||
3200–700 | DRIFT | PLS | Prediction of adulteration levels of roasted coffee with different adulterants (pure and blended). | [30] | |||||
4000–700 | ZnSe ATR | PLS | Simultaneous quantification of four adulterants (coffee husk, coffee grounds, barley, and corn) in roasted coffee. | [31] | |||||
4000–525 | Diamond ATR | PCA PLS |
Detection and quantification of adulteration of roasted coffee with corn. | [32] | |||||
3200–700 4000–600 |
DRIFT ZnSe ATR |
PLS-DA HM DF |
Discrimination between roasted coffee and adulterated coffee using two sampling techniques and merging data. | [33] | |||||
ZnSe ATR | PCA PLS-DA |
Classification of cup quality of coffee with different roasting degrees. | [34] | ||||||
3500–2800 1800–800 |
Diamond ATR | SIMCA PCR PLS1, PLS2 |
Identification and quantification of adulterated coffee with coffee husks, corn, barley, soybeans, oats, and rice. | [35] | |||||
Arabica and Robusta coffee | |||||||||
4000–600 2000–1500 3000–2750 |
ZnSe ATR | PLS | Quantification of Robusta coffee content in blends with Arabica coffee. | [36] | |||||
1800–800 | ATR | PCA PLS-DA |
Comparison of three spectroscopic techniques (1H-NMR, NIR, and MIR) for the discrimination of coffee by species and origin. | [37] | |||||
Commercial coffee capsules | |||||||||
3000–600 | ZnSe ATR | PCA PLS-DA |
Discrimination of espresso coffee according to sensory characteristics. | [38] |