Thursday, August 07, 2014

Blackberries (or are they blackcurrants?)

One of my favourite foods is the blackberry - or is it the blackcurrant? They look completely different in their native forms, but in the shop they look the same.

When I was living in London during the 70s, I frequently made apple and blackcurrant crumble (I'm not sure how I would buy the black whatevers, fresh or canned). The colour of this tasty dish was purple. One day, someone added cream to the crumble and the colour instantly changed to sky blue. Regurgitating a lecture which I had heard that week in biochemistry, I was able to inform the diners that the colour depends on the light absorbing properties of double bonds within the phenolic flavonoid phytochemicals of the berries. The arrangement of these double bonds is dependent somewhat on pH (acidity); adding cream raises the pH of the mixture which causes the double bonds to rearrange which causes the crumble to change colour. I'm sure that this small dollop of information improved their appreciation of the crumble - or maybe it was the cream that they enjoyed.

Over the summer of 1978, after having completed my degree but before emigrating to Israel, I worked in the laboratory of a public analyst when someone brought in several punnets of blackcurrants. The full story can be read here.

My access to blackberries/currants has been virtually nil for the past thirty five years, but I've recently discovered a way of buying them. A few months ago, I related how I bought stinging nettle tea at a health shop; I didn't mention that I also bought a few hundred grams of blackberries. Ever since, I have been enjoying a spoonful of them every morning with my yoghurt. This morning I remembered to see what the nutritional benefits of eating them are; according to this site (edited slightly):
  • As in other kinds of bush berries, blackberries are packed with numerous plant nutrients such as vitamins, minerals, anti-oxidants and dietary fibers that are essential for optimum health.
  • The berries are very low in calories. 100 g provide just 43 calories. Nonetheless, they are rich in soluble and insoluble fiber (100 g whole berries consist of 5.3 g or 14% RDA of fiber). Xylitol, a low-calorie sugar substitute which is absorbed more slowly than glucose inside the gut, thus not causing rapid fluctuations in blood sugar levels, is found in the fiber.
  • Blackberries are composed of significantly high amounts of phenolic flavonoid phytochemicals such as anthocyanins, ellagic acid, tannin, quercetin, gallic acid, cyanidins, pelargonidins, catechins, kaempferol and salicylic acid. Scientific studies show that these antioxidant compounds may have potential health benefits against cancer, aging, inflammation, and neurological diseases.
  • Fresh berries are an excellent source of vitamin-C (100 g of berries contain 23 mg or 35% of RDA), which is a powerful natural antioxidant. Consumption of fruits rich in vitamin C helps develop resistance against infectious agents, counter inflammation, and scavenge harmful free radicals from the human body.
  • They contain adequate levels of vitamin A, vitamin E, and vitamin K (16% of RDA/100 g) and in addition; they are rich in much other health promoting flavonoid poly-phenolic antioxidants such as lutein, zea-xanthin, and ß-carotene in small amounts. Altogether, these compounds help act as protective scavengers against oxygen-derived free radicals and reactive oxygen species (ROS) that play a role in aging and various disease processes.
  • Blackberries have an ORAC value (oxygen radical absorbance capacity, a measure of anti-oxidant strength) of about 5347µmol TE per 100 grams.
  • Further, blackberries contain a good amount of minerals like potassium, manganese, copper, and magnesium. Copper is required in the bone metabolism as well as in production of white and red blood cells.
  • They contain moderate levels of B-complex group of vitamins, containing very good amounts of pyridoxine, niacin, pantothenic acid, riboflavin, and folic acid. These vitamins are acting as cofactors helping the body metabolize carbohydrates, proteins, and fats.
But (and this is a very big BUT), recent research has shown that the berries should not be consumed with milk (and presumably with milk products such as yoghurt). This means that I shall now move my blackberry consumption to a milk-free hour - probably lunchtime.

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