Untargeted Phenolic Profiling of Pineapple Extracts

The 3 different T. comosus dried extracts (100 mg each one) were dissolved in 2 ml of the corresponding extraction solvents, namely water (TCI), ethanol 70% (TCT), and ethanol 50% (OpTC). After centrifugation (6,000 × g, 10 min, at 4°C), the supernatants were transferred to HPLC vials and supposed to untargeted phenolic profiling through high-resolution mass spectrometry (HRMS) using a Q-Exactive™ Focus Hybrid Quadrupole-Orbitrap Mass Spectrometer (Thermo Scientific, Waltham, MA, United States) coupled to a Vanquish ultra-high-pressure liquid chromatography (UHPLC) pump, equipped with heated electrospray ionization (HESI)-II probe (Thermo Scientific, United States) (Babotă et al., 2022 (link); Nicolescu et al., 2022 (link)). The post-acquisition data filtering was accomplished using MS-DIAL software (version 4.70), while the annotation was achieved via spectral matching against FoodDB and Phenol-Explorer databases. Overall, the mass accuracy (setting a 5-ppm tolerance for m/z values), isotopic pattern, and spectral matching were used to calculate a total identification score, considering the most common HESI + adducts for the chromatographic conditions adopted, thus reaching a level 2 of confidence in annotation.
Semi-quantitative appreciation of each previously annotated phenolic class was made by analyzing representative pure standard compounds under the same conditions: ferulic acid (phenolic acids), quercetin (flavonols), catechin (flavanols), cyanidin (anthocyanins), luteolin (flavones and other flavonoids), resveratrol (stilbenes), and oleuropein (other remaining phenolics). A linear fitting (R² > 0.99) was built and used for quantification, results being expressed as mg equivalents (Eq.)/g lyophilized extract (n = 3).