Salad dressing- does it go bad fast if it is creamed in a blender?

Question

I made a salad dressing with these ingredents:

• 1 cup olive oil
• 1/2 cup Tahini
• 1/4 cup apple cider vinegar
• 1/4 cup soy sauce
• 1 Juice of a lemon
• 4 garlic cloves
• 6 basil leaves
• 1 handful of parsley
• 2 green onion

Then blended it all to a creamy finish.

Does it go bad fast if it is creamed in a blender?

If so, can it be placed in the freezer?

Answer 1

All the blender does is emulsify the mixture--it has no effect on how long it will keep before the dressing begins to spoil or go off.

Normally, oil and water do not like to mix. The oil will coalesce into droplets, then rise to the top due to buoyancy, so that you will have a layer of oil above the water-based liquids. Blending the mixture will break up the oil droplets into very small droplets. These take much longer to coalesce together, so you have a creamy dressing for a time.

Over time, the oil can coalesce and separate back out. If this happens, assuming the ingredients have not spoiled, you can always remix or re-blend the mixture--it s not a safety issue.

I suggest storing your dressing in the refrigerator, where it will be good for several days, probably up to a week, although the oil may separate out.

You can freeze it, but this is likely to encourage the emulsion to break.

Note: I have not discussed emulsifiers like lecithin from egg yolks or mustard which help keep oil-water emulsions stable, because I don't see any in this recipe.

Answer 2

The existing answer by SAJ14SAJ addresses the food safety concerns really well. Blending won't change those.

But as for taste, it may change earlier. The point is that your blender will introduce more oxygen into the mixture. And even though you have no good physical emulsifiers like mustard, the ingredients are heterogenous enough to act as not-so-good physical emulsifiers, trapping a bit of extra oxygen. This oxygen will alter the taste of the oils.

I cannot predict how large a difference it will make within the typical shelf life of the dressing. It is possible that you won't be able to taste the difference between a previously blended and a freshly blended dressing after a day or two in the fridge. But theoretically, it can have an effect, so if you are unsure, you should test it next time and see if you can taste it.