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Blender companies state that a blender for smoothies should have speeds of at least 30000 rpm. They argue that only at 30000 rpm are cells of fruits and vegetables sheared enough to maximize nutrition and ease of digestion. Would blending at lower speeds, such as 20000 rpm, be sufficient? |
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I'm guessing that what they mean by 'maximize nutrition' for digestion is that they are assuming that the cells are broken open. This would make the co-factors we call vitamins, protein and sugars freely available to the digestive system and more easily absorbed. I think it is a marketing literature claim, though the blender may have some valid advantages... details below. Stainless steel waring blenders used to be typical pieces of lab equipment which could be used to homogenize tissue to extract proteins or DNA from tissue. These blenders would typically run from 10k-30k rpm. The web search for 'cell lysis blender' gives lots of examples of prepping DNA from plants at these speeds, but they don't complain for speeds towards the lower end of the range. A reputable looking example in my short search: This paper for tomato fruit cell wall preparations doesn't even give a speed the blender might have run at. Cell lysis in the literature is not precise - the cell toughness, the strength of the tissue around it and other such factors all come into play. Putting woody stems into your blender and those cells won't really get opened up at all. Also in the cell literature cell lysis buffers may have detergents or other chemicals (the reference above is done in 50% ethanol) to weaken the cell walls. Not exactly what you'd want to use if you were making a health drink. In experiments they have to contend with oxidation that happens when the cells are broken open with all the air whipping through the mixture. This is one reason you don't see blenders in labs to much anymore - hydraulic presses, sonicators, and bead beaters have taken their place - they have less aeration in the mixture and also deliver more power so that they can break open yeast and bacteria, which blenders really can't. So there will be some vegetables where the cell walls won't break open and all the nutrients won't be so easily accessible. It must help to be running at the top end of the range, but there will always be some vegetables which won't be broken open. For most things like bananas and apples it sounds like you'll get similar benefit with other blenders too. Just have to think about how much more are you paying for that extra 10k of rpm I guess. Is there a benefit to breaking open the cells and letting all the nutrients (as well as cell waste) break out into solution? It might give you a quick pulse of nutrition when you drink, but I'm pretty sure all the cells of a piece of fruit or vegetable will be pretty much broken down and extracted by the end. On the other hand, it sounds like it will save the digestive system some work... So there's that question too. |
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