Discrimination of Prunus domestica L. fruit extracts by FTIR-PCA coupled technique

Dina Gligor (Pane), Cristina Liliana Birau, Christine Alexandra Lucan (Banciu), Alina Ciobanu (Sibu), Iulia D. Stefan,  Nicoleta Gabriela Hadaruga, Daniel Ioan Hadaruga

Volume 29, Issue 1;
Pages: 1-8; 2023
ISSN: 2069-0053 (print), Agroprint;
ISSN (online): 2068-9551

Plums (Prunus domestica L.) are valuable fruits due to their high content of antioxidants, including anthocyanins and anthocyanidins. However, the polyphenol compositions significantly differ for plum varieties. The goal of this study was the evaluation of the similarity/dissimilarity of dry extracts of plum pulp samples from different varieties growing and/or commercialized in Romania, including “Bistrita”, “Stanley”, “Renclod”, “President” and “Vinete Romanesti”, using the Fourier-transform infrared spectroscopy-principal component analysis (FTIR-PCA) coupled technique. The extracts were obtained from fresh pulp, using ethanol, room temperature, and intermittent stirring for 48 h. Extracts were filtered and dried at moderate temperature in the dark. The dry extract was subjected to FTIR analysis and both wavenumber and intensity of the FTIR specific bands were processed using PCA analysis. The band corresponding to the stretching vibration of the C=O group (flavonoids and organic acids) was identified in all extracts at 1713-1717 cm^-1, as well as the those related to the stretching vibrations of the CC aromatic and pyrane skeletons, ν^sk_(arC#C) and ν^sk_pyr, at 1630-1637 and 1233-1258 cm^-1, respectively. Valuable discriminations between plum extract samples obtained from different varieties have been obtained by FTIR-PCA analysis of all wavenumber and intensity parameters. “Bistriţa” samples were grouped in the left side of the PC1 and the other plum samples in the right of this scores plot. Also, other plum varieties were well sub-classified, especially based on the stretching vibrations of the pyrane skeleton and for the carbonyl groups in antioxidant compounds (intensities for the positive side and wavenumbers for the negative side) for the first principal component. The CH and CO bending vibrations or the stretching vibration of the benzene skeleton (wavenumbers or intensities) were important for the positive and negative side of the second principal component, respectively. Moreover, the samples obtained from particular orchards (i.e., “Bistrita” varieties) were clearly discriminated from the other plum varieties, revealing the quality of these autochthonous fruit varieties.