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.

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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.

The effectiveness of grape extracts as food ingredient has been tested in various systems. The objective of this study was to evaluate the efficiency of four concentrations of residues of the wine industry in delaying lipid oxidation in processed chicken meat stored under refrigeration. The development of oxidation during the 14-day storage was evaluated through the thiobarbituric acid reactive substances method (TBAS). The analyses of phenolic compounds and antioxidant activity were performed in grape residue extracts through DPPH (1,1-difenil-2-picrilidrazil) method, lipid peroxidation inhibition and Rancimat. The profile of polyphenols was determined using reversed-phase high-performance liquid chromatography. Isabel grape extract (IGE) and Niagara grape extract (NGE) showed significant content of phenolic compounds. NGE and IGE had high antioxidant activity. The addition of grape extracts significantly increased the oxidative stability of processed and cooked chicken meat during the storage time. The extracts from both grape varieties when applied in concentrations of 40 and 60 mg of GAE, presented results similar to that of Butyl hydroxy toluene (BHT).

In this work the rheological behavior of two varieties of honey were evaluated using a Brookfield viscometer R.V.T in a temperature range of 5-20°C. In order to interpret the experimental results in terms of viscosity, the torque-speed data and scale readings were converted into shear stress-shear rate relations using numerical conversion values proposed by Mitschka. This method offers excellent potential for quality control testing in the food industry. Samples exhibited Newtonian behavior and the temperature effect on the viscosity followed an Arrhenius-type relationship.

Evaluation of nanoparticles obtained from starch is still on a laboratory scale and many challenges need to be overcome up to the industrial scale. In this review, information about the study and development of nanostarches are reported based on a discussion of concepts, production methods, as well as physico-chemical and technological characterization, safety and applications. The usual methods of producing nanostarches (such as acid hydrolysis, enzymatic pretreatment, high pressure homogenization and ultrasound) are discussed in this review, as well as the advancement of applications in the food industry (as in Pickering emulsion, carriers, films and nanocomposite production). Due to the wide variety of data, a protocol for the analysis of starch nanostructures is suggested. However, methods for quantifying starch nanoparticles are based on yield by weight, and no quantification method has yet been presented for processed products. All reports present a promising future for several areas, both in research and industrial applications, as they are considered as open doors to the many challenges on this research area.