Phenolic compounds are secondary metabolites widely found in fruits, mostly represented by flavonoids and phenolic acids. The growing interest in these substances is mainly because of their antioxidant potential and the association between their consumption and the prevention of some diseases. The health benefits of these phytochemicals are directly linked to a regular intake and their bioavailability. Studies have shown the importance of the regular consumption of fruits, especially for preventing diseases associated with oxidative stress. In the present review, the most recent articles dealing with polyphenols in fruits are reviewed, focusing on their occurrence, main methods of extraction, quantification and antioxidant assays. In addition, the health benefits and bioaccessibility ⁄ bioavailability of phenolic compounds in fruits are addressed.

The recovery of phenolic compounds of Eugenia pyriformis using different solvents was investigated in this study. The compounds were identified and quantified by reverse-phase high-performance liquid chromatography coupled with ultraviolet-visible diode-array detector (RP-HPLC-DAD/UV-vis). Absolute methanol was the most effective extraction agent of phenolic acids and flavonols (588.31 mg/Kg) from Eugenia pyriformis, although similar results (p ≤ 0.05) were observed using methanol/water (1:1 ratio). Our results clearly showed that higher contents of phenolic compounds were not obtained either with the most or the least polar solvents used. Several phenolic compounds were identified in the samples whereas gallic acid and quercetin were the major compounds recovered.

In this study, the antioxidant capability, total phenolic content and antimicrobial activity of ethanolic extracts of seven fruits from the Brazilian Atlantic Forest were evaluated. The conditions for the extraction of crude phenolics from the fruits were determined using an experimental factorial design. Total phenolic content, 1,1-diphenyl-2-picrylhydrazyl radical (DPPH • ) scavenging activity and b-carotene-linoleic acid couple oxidation assays were used to evaluate the antioxidant properties of the extracts. In addition, antimicrobial activity was screened using two Gram-negative bacteria (Escherichia coli and Klebsiella pneumoniae) and one Gram-positive bacterium (Staphylococcus aureus). All native fruits assayed in this study have high potential as natural antioxidant sources. Among the seven fruits evaluated, Jabuticaba and Uvaia had the highest antioxidant activity in the DPPH • and of b-carotene-linoleic acid coupled oxidation assays. In the biological assay, K. pneumoniae was the most sensitive microorganism to the fruit extracts, and the Jabuticaba extract had a slight inhibitory effect against this Gram-positive bacterium.

No abstract

The effects of acid treatments (HCl or organic acids) and drying processes (oven or sun) on the physico‐chemical and functional properties of cassava starch have been studied. The objective was to obtain modified starches with expansion properties similar to those of sun dried fermented cassava starch (polvilho azedo) as produced by an empirical process. Expansion was evaluated using a baking test. Independent of the drying method, organic acid‐hydrolysed cassava starch presented the same X‐ray diffraction patterns (changes from C to A) and similar intrinsic viscosity values. SEM observations showed no differences between granule surfaces of sun dried and oven dried samples. However sun dried organic acid‐hydrolysed starches presented lower paste consistency values at 30°C when compared with oven dried ones. HCl‐modified cassava starches were oven or sun dried, giving biscuits with low specific volumes (2·5–3·1 ml g−1). Similar behaviour was obtained using oven dried organic acid modified cassava starches. When submitted to sun drying, organic acid modified starches showed great improvements in biscuit expansion (5–10 ml g−1). The highest average specific volumes were obtained using lactic acid modified starches. © 1998 SCI.