Scientific Study

Background: Ground pistachio nut is prone to be adulterated because of its high economic value and wide usage area. Green pea is known as the main adulterant in the frauds of pistachio nuts. Present study developed a new, rapid, reliable and low-cost methodology by using a portable Raman spectrometer in combination with chemometrics for detection of green pea in pistachio nuts. Results: Three different methods of Raman spectroscopy-based chemometrics analyses were developed for the determination of green pea adulteration in pistachio nuts. The first method involved the development of hierarchical cluster analysis (HCA) and principal component analysis (PCA) by which authentic pistachio nuts were differentiated from green pea and green pea-adulterated samples. The best classification pattern was observed in the adulteration range of 20-80% (w/w). In addition to classification methods, partial least squares (PLS) and genetic algorithm- based inverse least squares (GILS) were also used to develop multivariate calibration models in order to quantitatively determine the degree of green pea adulteration in grounded pistachio nuts. The spectral range of 1790-283 cm-1 was used in the case of multivariate data analysis. Green pea adulteration level of 5-80% (w/w) was successfully identified by PLS and GILS. The correlation coefficient of determination (R2 ) was determined as 0.91 and 0.94 for the PLS and GILS analyses, respectively. Conclusion: Raman spectrometer combined with chemometrics has a high capability with regard to the detection of adulteration in pistachio nuts, combined with low cost, great reliability, high accuracy, rapidity of analysis and minimum amounts of sample preparation.