Identification of adulterants in açaí pulp samples using laser-induced fluorescence spectroscopy combined with linear discriminant analysis (LDA) method: A demonstration of the potential applicability of the technique

Açaí (Euterpe oleracea Mart.), a fruit from the açaí tree, is very common in the Amazon biome and is considered a food of high nutritional value. The growing increase in the production and consumption of açaí pulp, including abroad, has led to greater product quality control. Laser-induced fluorescence spectroscopy (LIF) combined with Linear Discriminant Analysis (LDA) was used in this study to differentiate adulterants in açaí samples. All the samples were produced using commercial frozen pure açaí pulp. One pure açai sample was used as standard, and three samples with the addition of specific adulterants: (i) maize starch, (ii) wheat flour and (iii) ice cream stabilizer was made for three different concentrations. After obtaining the fluorescence spectra, the Principal Component Analysis (PCA) was performed, and the clustering of the samples was analyzed. Finally, using the first five principal components (PCs) as input, the LDA method was applied as a dimensionality reduction technique in order to obtain a better discernment of the samples. The best performance of the method to discriminate the samples was achieved in samples with a 6% concentration of adulterants.