I have been taking a small banana smoothie to have for lunch at work along with some other whole fruit pieces.
For a while i was having frozen banana, plums and water in a smoothie which seemed to taste fine - the colour would always change to a dark brown but apart from that the taste seemed ok.
However the past couple of days i have been having just frozen banana and water in the smoothie and by the time i eat it at lunch it tastes different and not very nice at all.
Does this happen to other people? is there something wrong with my bananas? How do i stop this from happening?
When I blend it for more then 15-20 secs sometimes it tastes weird. Sometimes when I mix it with other fruits, even if they combine, it also tastes funny. I never tried the frozen banana thing because frozen bananas oxidize so fast and they turn into something kinda gross after that.
Bananas are very sensitive to oxidation. It's oxidation that darkens the smoothie and gives it that metallic taste. Blending for a longer time or at a higher setting will lead to more oxidation. High-powered blenders create a vortex that draws in too much air during blending. You have to avoid vortex formation in your blender by using a pulse blending technique. In my experience blenders with sharp blades (Vitamix etc.) are better for this sort of low-speed/pulse blending than those with dull blades (Blendtec). It's easier to minimise vortex formation if you blend larger volumes. Alternatively, use a handheld stick blender which doesn't create a vortex at all. If using a stick blender, choose a long-handled model with a closed-cup head and make sure to blend in a tall container, and to keep the head of the blender submerged whilst blending.
Also, blend any other ingredients to a smooth consistency before adding the bananas. Bananas always require the least time to blend. It's important to use ripe bananas - the riper the bananas you use, the less blending they'll require, and less blending means less oxidation. Ideally use as little added water as possible, keeping the consistency as thick as you can tolerate. Try to avoid adding tap water if you've got a faucet aerator installed. If you're having problems with froth formation (which can happen if you add dates or greens, or if the smoothie is too thin) then add some fat as a surfactant - flax seed, avocado, nut butter etc. or a few drops of hemp or flax oil. Froth traps air in the smoothie which will gradually oxidise it.
For best results, blend in the same container you'll be drinking from to avoid exposing the smoothie to the air as you pour it between containers. Make sure the container is filled to the brim before you put the lid on so there's no air pocket sitting above the smoothie. If necessary you can add a bit of water after blending to achieve this. And yeah, the lid has to be airtight if you're storing it for a few hours, wide-mouth mason jars with rubber seals are best. You can use a wide-bore glass straw (from Glass Dharma or Strawesome) with a drinking lid (EcoJarz or similar) to drink straight from the mason jar at work. Using a glass container may also help to preserve the taste.
Finally, don't use frozen bananas if you're gonna be storing the smoothie. Bananas darken and turn slimy as they defrost. If you use frozen bananas in a smoothie, you have to drink it within about 20mins to avoid discolouration. Try adding ice or other frozen fruits (berries and mangos freeze well) instead to keep the smoothie cold as you transport it. Then make sure to refrigerate the smoothie when you get to your workplace.
Hope that helps! If you're careful you can keep a banana smoothie bright and tasty for 24hrs+. I've also heard that using pre-boiled, distilled, or RO water can help avoid oxidation, but not tried it yet.
Oh, and adding citrus, particularly lime or lemon juice, will help avoid oxidation too, but it's not good food combining and you might not like the taste.
very helpful reply, thankyou!
Thanks for all this information Nathan! There is a lot of stuff here that i never knew about bananas!
I never knew that it is not good to over blend bananas - i have defiantly been doing this.
I will give these tips a try and see if it improves my banana smoothies :)
BTW, I've been experimenting with adding ascorbic and citric acid to prevent browning and ascorbic acid (vitamin C powder) has a noticeable effect. The necessary dose seems to be ~1g AA per litre of pure banana smoothie.
interesting, thanks! i will give this a try :)
HI - I agree with Nathan on this one...I've been amazed at how awful a banana smoothie can taste if I over blend...let us know if you figure it out, I'm curious !
wow, that never occurred to me, i'll give it a shot!
+1 Nathan also fill cup to the brim and seal over with cling film then put lid on loose this should stop any air getting in....
Ya gotta eat those ban ban smoothies quick after you make em. Otherwise it oxidizes and breaks down and seperates into brown mucky yuck, and tastes unpleasant. If you can't blend em at work, just carry em in, peel em and eat em!! I second Nathan's comments regarding the pulsing and the vortex. Punch the pulse button to the rythm of your favorite song! You'll have creamy yellow smoothies. But still, ya gotta drink it quick!! :P