Physicochemical characterization, determination of total concentration and estimation of bioaccessible fraction of elements in fruit functional flours

The total concentrations and the bioaccessible fractions of macro, micro, and potentially toxic trace elements in fruit functional flours were evaluated using inductively coupled plasma techniques (ICP OES and ICP-MS). Fruit flours from açaí, apple, blackberry, coconut, green banana, strawberry, orange, passion fruit and grape were submitted to microwave-assisted and in vitro digestion methods, and As, Ba, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Mo, Ni, P, Pb, S, Se, V and Zn were determined. Samples were also analyzed to determine physicochemical parameters. Granulometries and moisture were generally smaller than 500 µm and 15%, respectively. pH was in the 3.2–6.2 range, and titratable acidities were usually lower than 3%. High protein (133–174 g kg -1 ) and fat (105–192 g kg -1 ) contents were found for grape and coconut flours, while ashes up to 7.5% were observed for passion fruit flour. Total concentrations determined by ICP OES (mg kg -1 ) were in the 312 – 5199 (Ca), 167 – 2774 (Mg), 1512 – 26868 (K), 262 – 4912 (P), 121 – 1705 (S), 7.9 – 134 (Fe), 4.4 – 100.5 (Mn) and 4 – 42 (Zn). For ICP-MS concentrations were lower than the LOQ for As, Cd, Se and V, and situated between 0.39–1.41 (Cr); 0.73–96.04 (Cu); 0.35–3.09 (Ni); 0.34–0.68 (Mo); 0.41–47.82 (Ba); and 0.18– 0.36 (Pb) mg kg -1 . Accuracies were checked by analyzing a certified reference material and spiked samples from in vitro digestates, with good recoveries and adequate precision often obtained. Bioaccessible fractions were between 14.5–93.6 % (Ca), 9.7–94.5% (Mg), 7.9–83.2% (Mn), and 6.3–138% (Zn), 9.1–115% (Cr), 15.9–62% (Cu), 2.66–66% (Mo), 0.5–4.47% (Ni) and 7–77.3% (Ba). K, P, and S were not determined due to high blank values, and As, Cd, Pb, Se, and V were lower than the LOQ.