Why would a blended salad dressing change its color?

Question

Yesterday evening we had a barbecue and I made a tomato/mozzarella salad. Since I couldn't find my dressing shaker, I used my hand blender (an ESGE M180S, in case it matters).

I got my dressing as usual, dark brown in colour, it was just a bit more smooth than usual, which I expected. A few minutes after pouring it over the salad, the colour went from dark brown to a very very light brown, looking as if I'd used cream in it. The taste stayed the same as usual, but the colour change I thought was weird.

So, why would a blended dressing change its colour while a shaken dressing wouldn't?

Probably the ingredients are important to answer this, so here's what I used:

• Olive & sunflower oil (4 tbsp each)
• Balsamic vinegar (2 tbsp) , malt vinegar (1 tbsp), apple vinegar (1 tbsp)
• Hibiscus syrup (2 tbsp)
• Dried basil (1 tsp)
• Mustard (1 tsp)
• Salt (1 tsp), sugar (1 tsp), freshly ground pepper

Answer

Sounds like some air bubbles were incorporated in the mix and started to resurface (or blend together?).

Generally little air bubbles tend to make a mixture lighter in colour, you can see that, for instance, when you mix sugar and egg yolks.

Now, I'm not sure why did it happen once you poured it on the salad...

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