Easily Prepare Your Own Acid-Base Indicator from Red Cabagges
Don't you mean pink cabbage? No, I mean blue cabbage. Wait, now it's pink again! As you can see, your little angel might just discover that this stuff is cool enough to eat!
1.Red cabbage contains a cornucopia of healthy chemicals but don't bother telling that to a toddler. They will be much more interested in the groovy molecules called anthocyanins that change colour in acid or alkaline solutions.
2. If you're boiling red cabbage for a recipe, save the juice and allow to cool. If you're making coleslaw, finely chop the discarded outer leaves and soak them in a bowl of hot water. When the purple water is cool, pour through a sieve, and you're good to go.
3. Grab an egg, baking soda (or sodium bicarbonate), white vinegar and lemon juice. You can try any other ingredients you like but these will work well.
4. Fill two clear plastic cups or glasses with water and pour some of red cabbage juice into each. The first cup is for the experiments. The second cup will remind you what colour the first one was before you added the other ingredients.
5. Separate the eggwhite from the yolk. Now pour the eggwhite into the red cabbage solution, stir and watch it change from purple to a beautiful shade of blue. You've just discovered that eggwhite is alkaline.
6. Next, pour in a teaspoon or so of white vinegar and the solution will change from blue to bright pink.
7. To make the solution turn blue again, add a teaspoon of baking soda and stir (or you could add more eggwhite).
8. To turn pink again, add a teaspoon of lemon juice (or more white vinegar, or tartaric acid). You can keep changing the colour back and forth as long as you like. When you're finished experimenting, pour the contents on a garden bed and your plants will all say "yum, yum".
What's going on?
The amazing stuff that makes red cabbage juice change colour belongs to a family of plant chemicals called anthocyanins. Nearly all terrestrial plants produce anthocyanins which are part of a subset of a larger family of plant chemicals flavonoids. Flavonoids have a huge variety of functions in plants but the most visible is their role as pigments to attract animal pollinators.
Anthocyanins are responsible for many of the beautiful red, purple and blue colour of flowers such as pansies, and also cause the leaves of deciduous plants to change colour when autumn comes.
Beetroot and other plants including carnations and cacti, get their pretty colours from a different family of chemicals called betalains, which don't change colour like anthocyanins. Interestingly, anthocyanins and betalains are never found in the same plant but that's another story.
The colour of anthocyanins changes with pH from a yellowy green in very alkaline solutions, to a blue-ish purple in neutral solutions, to bright pink in acidic solutions.
The colour of the red cabbage and many flowers depends on the soils they grew in. Alkaline soils produce bluer cabbages and flowers while acidic soils result in a more red outcome. If you purchase a blue-ish cabbage but prefer to eat more red ones, just add a few drops of vinegar to the boiling water and voila! Your blue cabbage turns red.
Apart from their groovy colour changing properties, anthocyanins are also known to be powerful antioxidants. But while you'll find millions of articles about the health benefits of eating foods that contain them, research suggests that anthocyanins are poorly preserved after eating and only a small fraction make it from your stomach into your blood and eventually into cells. The good news is that, like all vegetables, red cabbage contains a venerable cornucopia of other amazing, health promoting chemicals so there's still plenty of good reasons to get stuck in.
Another thing that does seem clear is that, like so many other naturally occurring plant chemicals, anthocyanins probably only provide health benefits when they are consumed in combination with all the other amazing substances found in whole plants. And most importantly, taking any of these substance individually as a supplement probably won't do you much good so, like your grandmother always said, the best thing is to eat a wide and varied diet of fresh food.
But grandma's advice on how to get those fresh vegetables down a toddler's throat might not have been quite so helpful. Nearly every kid has their nemesis vegetable and researchers have found much better mealtime strategies than simply forcing a child to sit at the table until they've had "at least one bite!"
For instance, one study by Columbia University nutritionists showed that, rather than sending kids out of the kitchen, getting them to help with the cooking has amazing results.
Over 600 kindergarten to year-six kids took part in nutrition lessons but the ones who cooked their own food ate more of it in the cafeteria and even asked for seconds. Kids who chopped radishes, famous for their child repelling properties, suddenly loved them in salads. Amazing!
Restricting access to "yummy" food and rewarding kids for eating healthy foods also seems to backfire perfectly. If you want some nifty tips, this brilliant summary of parental influence on eating behaviour is packed with fascinating examples that suggest the biggest problem with healthy eating is the completely counterintuitive way kids react to just about everything you do. Bless 'em!
I have no idea if playing around with the colour changing properties of red cabbage will make it any more palatable for a toddler because there's still the problem of it smelling remarkably like a fart. Still, it's worth a shot and I would love to hear from anyone who gives it a go.
From: abc.net.au
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