Phenolics in cereals, fruits and vegetables: Occurrence, extraction and analysis

Phenolic composition and antioxidant properties of Pleurotus ostreatus and Pleurotus eryngii enriched with selenium and zinc

“…The results were higher than those obtained by Yang et al [46], but similar to Oke and Aslim [47]. Other studies demonstrated that the yield mainly depends on polarity of the solvent [6,47,48]. The Folin-Ciocalteu method is a colorimetric method commonly used to determine the total phenolic content [7,47].…”

Influence of extraction conditions on antioxidant properties of passion fruit (Passiflora edulis) peel

“…The decrease in the scavenging activity after 60 min extraction time could be explained by the Fick's second law of diffusion, where fi nal equilibrium among the solute concentrations in the solid matrix and in solvent was estimated to be achieved after 1-2 h of extraction duration [Silva et al 2007]. Longer extraction time might increase the oxidation of phenolic compounds, thus contributing to lower DPPH radical scavenging activity [Naczk and Shahidi 2006]. The use of different extraction times to extract phenolic compounds may be due to the varying degrees of phenolic polymerization, solubility of phenolics and interaction between phenolic compounds and sample extract [Silva et al 2007], where the fi nal equilibrium between solvent and solid diffusion was attained exactly at an optimum extraction point [Lee et al 1986].…”

“…It was reported that an increase in temperature favoured extraction, increased bond dissociation energy of phenolic compounds, as well as enhanced solubility and diffusion coeffi cients of the compounds [Spigno et al 2007]. On the contrary, a high extraction temperature (>40°C) will cause some loss of organic solvent through evaporation, and also degradation of bioactive compounds [Naczk and Shahidi 2006]. Taking into consideration from the industrial point of view, higher extraction temperature (>30°C) increase the usage of organic solvent and electrical cost, selection of 30°C would be the most appropriate extraction temperature for the passion fruit peel to maximize the extraction yield and minimize degradation of antioxidants at high temperature.…”

“…Extraction parameters such as type of solvent, solvent concentration, extraction temperature, extraction time, and solvent-to-solid ratio are the major consideration for enhancement of extraction effi ciency to obtain optimal amount of bioactive compounds in the extract [Pinelo et al 2005, Naczk and Shahidi 2006, Spigno et al 2007. Different drying methods used have also been reported to affect the antioxidant activity of fruits and vegetables [Choi et al 2006, Chantaro et al 2008, Kuljarachanan et al 2009, Suvarnakuta et al 2011.…”

Influence of sonication treatments and extraction solvents on the phenolics and antioxidants in star fruits

“…These features makes it possible for the solvent like methanol to easily diffuse into the pores of the plant materials (plant cell) and leach-out the bioactive compounds (like that of antioxidants) *Values are the means of three independent replicates ± standard deviation (S.D.). Means in the same column with different superscripts letters denotes significant differences from each other at p<0.05 1 Percentage inhibition of DPPH radicals by samples (100 μg/mL); 2 mM ferric reduction to ferrous/g extract (FRAP, Ferric Reducing Antioxidant Power); 3 mg ascorbic acid equivalent antioxidant activity/g extract; 4 mg gallic acid equivalent/g extract; 5 mg catechin equivalent/g extract; 6 mg catechin equivalent/g extract more effectively (Hemwimol et al 2006;Naczk and Shahidi 2006). Whereas, the decrease in some of the parameters after the extended time duration (at 45 and 60 min) might be attributed to the lower concentration gradient of the solvent, prolonged interval of sonication as well as to the probable degradation that could have occurred due to the generation of free radicals, mainly the highly reactive hydroxyl radicals.…”