The market of freshly consumed salads is increasing rapidly, due to the consumer perception of healthiness, their ease to use, and the constant recommendations by many health authorities for a consumption of at least 5 portions of fruit and vegetables by day. Vitamin C, including ascorbic acid (AA) and dehydroascorbic acid (DHA), has many biological activities in the human body. The content of vitamin C in fruits and vegetables can be influenced by various factors such as genotypic differences, preharvest climatic conditions and cultural practices, maturity and harvesting methods, and postharvest handling procedures (1). Moreover, owing to the lability of vitamin C, the foodstuff content in this compound is frequently used as an indicator of quality and freshness. The determination of vitamin C in freshly consumed salads has therefore a double target: to assess the nutritional value for human vitamin C intake, and to act as a marker of product quality. Many analytical methods, based on different techniques, are reported in the literature for the quantitative determination of vitamin C, but HPLC has demonstrated to be the most reliable (2). The extraction procedure required in vegetables is usually quite time and solvent consuming, involving two or three extraction steps to achieve good recoveries, due mainly to the complexity of the matrix, often with strong cellular walls that encage the analytes. In the present study the application of HPLC to the determination of AA and DHA levels in some freshly consumed salads is described. The method was applied to six varieties of commonly consumed salads: three were vegetables with a soft texture (rocket, red oak leaf, and baby lettuce), the remaining had an harder texture (escarole, continental and romaine lettuce). In order to optimize and to make easier the overall procedure we have introduced some modifications both in the sample pretreatment operations, by the use of an ultrasonic bath, and in the chromatographic determination, with an aqueous mobile phase, achieving good recoveries (> 90%) and repeatability. Therefore the method demonstrated to be suitable for routine analysis. The vitamin C content observed was in the following order : rocket > continental > red oak leaf > baby lettuce > escarole > romaine lettuce.
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|Titolo:||Simplified analytical method for the determination of ascorbic and dehydroascorbic acids in freshly consumed salads.|
|Data di pubblicazione:||2013|
|Appartiene alla tipologia:||04d Abstract in atti di convegno|