Determination of vitamin C in tropical fruits: a comparative evaluation of methods

Auteur(s) :
Forbes-Hernandez TY., Lobo MG., González-Paramás AM.
Date :
Juin, 2006
Source(s) :
Food chemistry. #96:4 p654-664
Adresse :
Addresses: Gonzalez M (reprint author), Inst Canario Invest Agr, Plant Physiol Lab, Dept Trop Fruits, Apdo 60, San Cristobal la Laguna 38200 Spain Inst Canario Invest Agr, Plant Physiol Lab, Dept Trop Fruits, San Cristobal la Laguna 38200 Spain E-mail Addresses:

Sommaire de l'article

Two analytical methods for extracting vitamin C (L-ascorbic and L-dehydroascorbic acids) in tropical fruits [banana, papaya, mango (at three maturity stages) and pineapple] were evaluated. These methods used ion-pair liquid chromatography (LC) for detecting ascorbic acid, but differed in the preparation of the sample (extraction with 3% metaphosphoric acid -8% acetic acid or 0.1% oxalic acid). Results were validated by comparison with ascorbic acid content obtained by the AOACs official titrimetric method, by performing a recovery study and by the determination of within-day repeatability and inter-day reproducibility. There were differences in the efficiency of vitamin C extraction related to the fruit matrix and especially to the maturity stage in climacteric fruits. The LC-extraction method using 3% metaphosphoric acid -8% acetic acid shows high mean recoveries (99 +/- 6%) for all matrices assayed, while the LC-extraction method with 0.1% oxalic acid proved to be unacceptable in some cases (unripe, half ripe and ripe banana and ripe mango) obtaining mean recoveries of 39.9 +/- 9.1% and 72 +/- 13% for banana and mango, respectively. The detection limit achieved with the metaphosphoric acid-acetic acid LC-extraction method for ascorbic acid (0.1 mg/l) allowed the determination of this vitamin in fruits analysed with good precision (5.94-12.8%), making its use as a routine analysis method perfectly valid. Recommendations about storage temperature, methods of thawing L-ascorbic acid extracts and the addition of antioxidants to extracts were made.

Source : Pubmed