Composição centesimal, perfil de ácidos graxos e efeitos da digestão in vitro sobre o teor de minerais, compostos fenólicos e atividade antioxidante de polpas comerciais de açaí (Euterpe oleracea Mart.) roxo e branco

Abstract

Açaí (Euterpe oleracea) is a palm native to the Brazilian Amazon, characterized by the presence of globular, rounded, fibrous and greenish (white-açaí) or purple (purple-açaí) drupe clusters, when it is ripe. Frequently it fruits are used to obtain pulps, which can be commercially classified in coarse, medium and fine according to the total solids content. In this context, the objective was to evaluate the centesimal composition; the profile of fatty acids (FA) and their contributions to reach the dietary references of essential FA ingestion; the mineral content, total phenolic compounds (TPC), and antioxidant capacity before and after in vitro gastrointestinal digestion of commercial purple-açaí (coarse-PAC, mediumPAM, and fine-PAF), and white-açaí (coarse-WAC). To evaluate centesimal composition the samples were submitted to analysis of moisture, total solids, ashes, lipids, proteins and carbohydrates. The FA analysis was performed by gas chromatography with flame ionization detector. The minerals analysis was performed by ICP-OES, TPC and the antioxidant capacity by the FRAP, ABTS and DPPH methods by UV-Vis spectrometry. The samples were submitted to in vitro gastrointestinal digestion, comprised in the gastric and intestinal phases. All the results were submitted to analysis of variance and Tukey's test at 5% of significance, except FA. As for the composition, the moisture contents varied from 82.74-92.00g/100g and total solids, from 7.97-17.26g/100g, however only the PAF sample differed from the others, with respectively 92.00 and 7.97g/100g. The ashes content differed in all the samples (0.420.94g/100g). In relation to lipids, the PAC sample (10.67g/100g) had the highest content and the PAF (2.94g/100g), the lowest. Protein and carbohydrate levels varied between 1.211.62g/100g and 2.88-5.24g/100g, respectively. Regarding the FA profile, there was predominance of unsaturated, especially monounsaturated as oleic (56.80-59.50%) in the samples. As regards to the contribution of polyunsaturated FA to the achievement of the essential FA recommendations, the PAC sample is again highlighted with contributions of at least 17.71% for linoleic AF and 12.06% for alpha-linolenic AF respectively for portions of consumption. The TPC content differed in all samples, with PAC (583.79mgAGE/100g) being the highest content, however, the PAM sample had the highest bioaccessibility (32.27%). The PAC sample presented higher antioxidant capacity in the FRAP tests (74.34μM ferrous sulphate/g) and ABTS (55,05μM Trolox/g). Only in the DPPH no differences were found between the PAC (1,986.66 EC50) and PAM (2,408.88 EC50) samples. All samples showed a decrease in antioxidant capacity after in vitro gastrointestinal digestion. Regarding the FRAP, the reduction was observed in the PAC sample (80.52%). In the ABTS, the largest reduction was in the PAM (73.79%). As for DPPH, the PAM sample (13,711.40 EC50) presented a smaller reduction in antioxidant capacity. In all samples K was the mineral in highest proportion (721.90mg/100g PAC), followed by Ca (349.92mg/100g PAM) and Mg (169.51mg/100g PAM). However, Ca had the highest bioaccessible fraction, followed by Mg and Mn, with the highest bioaccessible fractions observed in WAC samples (90.30, 74.30 and 64.52%, respectively).