I had my girlfriends over for a dinner party the other week
and I was experimenting with cocktail recipes.
My all-time favourite cocktail is a Pina Colada, traditionally
made with Malibu coconut rum, coconut cream and pineapple juice. Lacking the
coconut cream I was left with two options:
- Add normal milk instead, or
- Blend with a banana…
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| My concoction... |
Not sure where I got the banana idea from but upon further
thought it seemed like the best option.
So into my trusty blender went the rum, ice, pineapple juice and a
banana. Two minutes later I had a creamy, fruity drink that somewhat resembled
a Pina Colada. Given enough time it did separate out into layers, a juice layer and a foamy layer, but that was
easily rectified with a wee stir.
There is a bar in my town that sells the most
disgusting drink, the aptly named Cement Mixer. You get a shot of Baileys and a shot of lime juice. When the
two mix in your mouth they curdle and you are left to swallow a lumpy mess…
This got me thinking, would milk do the same thing when mixed with the pineapple
juice?Yes, probably, but lets try it anyway.
Milk + pineapple juice = a lumpy mess... Ewwww
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| "Latte 025" by Kagor at the Ukrainian language Wikipedia. https://commons.wikimedia.org/wiki/File:Latte_025.jpg#/media/File:Latte_025.jpg |
But why does this happen? What cause the liquid to lump transition I hear you asking. Well I will tell you.
Milk is made up of protein and fat suspended in a liquid. Milk is slightly acidic, with pH 6.6, it is this acidity that helps it maintain its liquid phases. As milk sours the pH drops and this causes lumps to form in the milk. The same thing happens when we add acid to milk, or in this case pineapple juice, with a pH 3. When an acid is added and the pH of the milk drops the negatively charged micelles, made up of the fat and protein, clump together. These clumps get large enough to see and are called curds.
There may have been some method in my madness when it comes to the banana. Bananas have a pH between 4.5 and 5.2. So when added to the cocktail mix they raise the pH and help prevent curdling!
All that was left to do was to enjoy the fruits of my labour... Drinks all round!!
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| The perils of drink... |
Reference
Food and Foodstuffs - pH Values
Which foods are acidic?
