The DPPH assay is one of the most commonly employed methods for measuring antioxidant activity. Even though this method is considered very simple and efficient, it does present various limitations which make it complicated to perform. The range of linearity between the DPPH inhibition percentage and sample concentration has been studied with a view to simplifying the method for characterising samples of wine origin. It has been concluded that all the samples are linear in a range of inhibition below 40%, which allows the analysis to be simplified. A new parameter more appropriate for the simplification, the EC20, has been proposed to express the assay results. Additionally, the reaction time was analysed with the object of avoiding the need for kinetic studies in the method. The simplifications considered offer a more functional method, without significant errors, which could be used for routine analysis.
The forecast f o r the year 2000 indicates a need to produce 164Experiments were conducted to measure the influence of the main variables in protein extraction (concentration, temperature, time, solid/liquid ratio and pH). Sodium hydroxide, sodium chloride and magnesium chloride aqueous solutions (of different ionic strength) and de-ionised water were used as extracting solvents.The results are reported in Table 1. In general, the most efficient extracting solution was aqueous NaOH. The water-extracted protein amounts were higher than those in salt solutions, as observed by Castriotta and Canella (1978) in Italian grapeseeds. Table 1 clearly shows that increasing ionic strength reduces the protein extractability, which is considerably lower in MgCl, solutions than in NaCl solutions. In addition, it seems that concentrations above 0
In this paper, we describe the study and characterization of the lipids from lees of Sherry wine, one of the main byproducts from the wine-making industry in the Jerez/Xeres/Sherry denomination of the origin zone in Jerez de la Frontera, Spain. The lipid content, extractability, classification, fatty acid composition, and its main chemical characteristics have been determined in order to evaluate their potential use as a food or food additive.
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