Wednesday, August 11, 2010

Blueberries - last longer - but have less nutrition

The strong "mustard" type taste/effect that wassbi, horse radish and of course mustard is called by the chemical   Allyl isothiocyanate. This chemical can be manufactured in a lab or processed mustard seeds. Its a natural insecticide, bactericide and nematocide (anti parasites). Therefore it is sometimes used in food processing as a preservative. It has been shown to extend the life of strawberries, blackberries, raspberries and blueberries.

A study investigated the effects of using allyl isothiocyanate on the antioxidant properties of blueberries. What they found was this compound reduced the level of antioxidants when compared to stored grapes without this chemical (both were stored at 10 degree C). In fact a large number of anti oxidants were reduced including:
  • Superoxide dismutase (SOD
  • Guaiacol peroxidase (G-POD) 
  • Glutathione reductase (GR)
  • Glutathione-peroxidase (GSH-POD)
  • Acorbate (AsA)
  • Ascorbate peroxidase (AsA-POD) 
  • Dehydroascorbate reductase (DHAR)
  • Monodehydroascorbate reductase (MDAR
  • Gutathione (GSH).  
  • A range of phenolic acids 
  • A range of anthocyanins
So to put it bluntly this chemical although it is "natural" destroys the goodness in blueberries. The studies conclusion was:
The results from this study indicate that AITC does not promote antioxidant property or scavenge constitutive reactive oxygen species (ROS), but maintain blueberry fruit quality through other mechanisms.
So just because something is natural doesn't make it better. The good news is that this preservative treatment is not yet used commercially. What is really disturbing is that they could use this preservative treatment and we wouldn't now!

Reference: Shiow Y. Wang and Chi-Tsun Chen. Effect of allyl isothiocyanate on antioxidant enzyme activities, flavonoids and post-harvest fruit quality of blueberries (Vaccinium corymbosum L., cv. Duke).
Food Chemistry Volume 122, Issue 4, 15 October 2010, Pages 1153-1158

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