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Effect of time and temperature on vitamin C stability in horticultural extracts. UHPLC-PDA vs iodometric titration as analytical methods

Spínola, Vítor, Mendes, Berta, Câmara, José S., Castilho, Paula C.
Lebensmittel-Wissenschaft + [i.e. und] Technologie 2013 v.50 no.2 pp. 489-495
ascorbic acid, cherimoyas, dehydroascorbic acid, foods, fruits, high performance liquid chromatography, horticulture, papayas, passion fruits, sweet peppers, temperature, titration, Portugal
Several fruits and vegetables from Madeira Island (Portugal) were evaluated by two analytical methods for their total vitamin C content (l-ascorbic acid, l-AA and dehydroascorbic acid, DHAA). DHAA was determined indirectly with DL-1,4-dithiotreitol (DTT) applied as a pre-column reductant. Ultra high performance liquid chromatography coupled to photodiode array (UHPLC-PDA) determinations were compared with l-AA content obtained by a classic iodometric titration method. The stability of vitamin C in horticultural extracts stored at different temperatures was also investigated. Red peppers represented the better source of vitamin C followed by green peppers and papayas. Passion fruits and cherimoyas were the analyzed foodstuffs with lowest vitamin C content. Both analytical methods were suitable for l-AA analysis in various food commodities, the UHPLC-PDA technique being preferred due to its advantages of selectivity, speed and accuracy. The degradation study showed that horticultural extracts were stable at least 24 h at 4 °C and during 4 weeks when stored at −80 °C.