Determination of the oxygen-18/oxygen-16 isotope ratios of sugar, citric acid and water from single strength orange juice
✍ Scribed by Gwénaël Houerou; Simon Douglas Kelly; Michael John Dennis
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 70 KB
- Volume
- 13
- Category
- Article
- ISSN
- 0951-4198
No coin nor oath required. For personal study only.
✦ Synopsis
The ratio of the stable isotopes of oxygen ( 18 O/ 16 O) has been measured in the sugar, citric acid and water from authentic single strength orange juices, originating from a number of different countries. The sugars and citric acid were recovered from the juices and their 18 O/ 16 O ratios were determined by pyrolysis/ continuous flow-isotope ratio mass spectrometry (Py/CF-IRMS). The 18 O/ 16 O ratio of the fruit juice water was determined by the carbon dioxide/water equilibration method. The 18 O% values of 45 different sugars ranged from 29.1 to 38.8% and 15 citric acids ranged from 18.9 to 25.4%. The 18 O% values of the water present in the same samples ranged from À2.1 to 7.8%. A correlation was evident between the 18 O% values of the sugar, citric acid and water from the juices. This information can be used to improve the assessment of the authenticity of commercial 'freshly squeezed' orange juices. The detection of the presence of reconstituted orange juice concentrate in 'freshly squeezed' orange juices was improved by 37% using regression analysis of the combined water and sugar 18 O% ratios when compared to the use of 18 O% ratios of fruit juice water alone.