Ascorbic acid or vitamin C is a natural antioxidant in fruits and vegetables, but the European Commission permits its use as an additive in juices, jams, dairy products and other foods. The involvement of this substance in the immune response and other biochemical processes such as the formation of collagen and the absorption of iron is well-known.
However, high levels of ascorbic acid can cause diarrhoea and gastrointestinal problems, as a result of which scientists are attempting to determine the content of vitamin C in foods with greater and greater accuracy.
Now, a group of researchers from the Faculty of Pharmacy of the USC has developed a new chromatographic technique (these are used to separate and identify chemical elements) aimed at accurately measuring the ascorbic acid in fruit juices and soft drinks. By applying this method, they have found that the amounts of vitamin C stipulated on the labels of many drinks are not real. In a sample of 17 fruit juices, soft drinks and isotonic drinks, only two correspond to what is indicated on the bottle.
Ana Rodríguez Bernaldo de Quirós is a member of the team which has developed the new technique, whose details have recently been published in the Food Chemistry magazine. "The other drinks contain much higher levels than those specified by the manufacturer because, as has already been indicated in a previous study, the label probably only shows the amount of added ascorbic acid, without taking into account the fruit's natural vitamin C content", she explained to SINC.
Bernaldo de Quirós highlights the greater resolution and sensitivity of the method, by means of which it is possible to detect up to 0.01 milligrams of vitamin C per litre, "thanks to the use of new column chromatography, based on spherical particles of ultra pure silica 3 microns in size".
"Another advantage of the method is its simplicity and speed, as the total time taken to carry out the analyses is no more than six minutes", the researcher remarked.
With the new technique, the valuation of the ascorbic acid in the drinks has revealed some curious data. Of the 17 samples analyzed, the one with the highest vitamin C content was an apple juice (840 mg/l), more than the orange juices (352-739 mg/l). The results for the pineapple and grape juices were 702 mg/l and between 30.2 and 261 mg/l for the soft drinks (orange, lemon and apple).
The researchers also evaluated how the vitamin C content of the orange juices and tea drinks varies while they are on the shelves in the temperature conditions specified by the manufacturer. After six days, the former barely lose 8% of their ascorbic acid while, in the tea drinks, this substance falls by 54% at 4ºC and practically disappears at room temperature.
A. Rodríguez-Bernaldo de Quirós, M. Fernández-Arias, J. López-Hernández. "A screening method for the determination of ascorbic acid in fruit juices and soft drinks". Food Chemistry 116 (2): 509-512, 2009.
SINC | EurekAlert!
TSRI researchers develop new method to 'fingerprint' HIV
29.03.2017 | Scripps Research Institute
Periodic ventilation keeps more pollen out than tilted-open windows
29.03.2017 | Technische Universität München
The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.
To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
29.03.2017 | Materials Sciences
29.03.2017 | Physics and Astronomy
29.03.2017 | Earth Sciences