Jabuticaba (Plinia spp.) peel flours: characterization, correlation between antioxidant content and dietary fiber, and development of prediction models based on FTIR data

Jabuticaba´s peel has been shown to contain high amounts of antioxidants and other bioactive compounds. These peels could be used for the preparation of flours, as a strategy for their conservation. Thus, the objectives of this study were to investigate the composition of flours obtained from jabuticaba peels both in terms of conventional techniques and infrared spectroscopy (FTIR) and to verify the feasibility of developing prediction models based on FTIR data. Twentyeight flours (JPF) were produced by drying, milling and sifting the peels of different jabuticabas samples. Evaluated parameters were: nutritional composition, soluble solids and pH, insoluble (IDF) and soluble dietary fiber (SDF), anthocyanins and other extractable phenolics (EP) (Folin-Ciocalteu), nonextractable proanthocyanidins (NEPA) and total carotenoids. FTIR data were used for construction of compounds prediction models by Partial Least Squares Regression (PLS). Evaluation of the prepared flours showed high variability in composition, with IDF ranging from 26.99 to 46.33 g/100g; SDF from 4.41 to 9.27 g/100g; EP from 8.90 to 16.49 g GAE/100g; NEPA from 842.88 to 1889.06 mg/100 g; anthocyanins from 344.00 to 1304.52 mg/100 g and carotenoids from 1925.2 to 4296.41 µg/100 g. Principal component analysis (PCA) of the data indicated that the main separation of the samples occurred in association to the ripeness of the fruits. Moderate correlation values were observed between the amounts of anthocyanins and insoluble fibers (r = 0.45) and also between the levels of EP and NEPA (r = 0.44). These correlations indicate that the absorption of the compounds must occur by different strategies and that the JPF can be very beneficial for modulation of the colonic microbiota. Four PLS models were constructed. The best model predictions were obtained for the EP contents, followed by anthocyanins, SDF and IDF. Results show that FTIR and chemometrics can be used to quantify compounds in JPF.