Proponents of vacuum blending claim that it improves quality by reducing oxidation. Vacuum blenders are not yet widely available in the US, but it appears that they may be coming soon. I rigged up my own vacuum container for a Vitamix, and in this post I will evaluate just how much of a quality boost you can expect from vacuum blending.
Interested in a pre-built Vacuum blender? Check out my Froothie VAC2 Vacuum Blender Review.
When you cut an apple or avocado and don’t eat it right away, oxidation is what causes it to turn brown. Oxygen from the air reacts with the exposed fruit, and some of the reaction products are brown.
Blender blades cut and smash food countless times, making blends especially prone to oxidation. Blenders can also whip small air bubbles into the blends, which further promote oxidation. If you’ve ever saved some of a smoothie for later, and then it tasted bitter or just not as good, it was likely because of oxidation.
In addition to color and taste, oxidation can also decrease nutritional value. Smoothies with fresh produce are full of phytonutrient antioxidants, which many people believe are beneficial. When antioxidants are exposed to oxygen, they react with it and lose their antioxidant activity (that’s basically the definition of an antioxidant). Vacuum blender companies in Japan and Korea report a difference of several fold, but as far as I can tell, they do not say how long after blending they made those measurements.
The idea of sealing food in a vacuum to retain quality goes back to at least the 1940s. Industrial-grade vacuum mixers have been around since at least the 1930s. However, the idea of applying vacuum to home blenders is relatively recent. Japanese company Tescom released the first home vacuum blender in 2013. That model has a relatively modest 290W motor. Since then, multiple Korean companies have jumped on the bandwagon, and have released more powerful models. They are not yet available in the US, but they may be coming later this year (they’ve been demonstrating at US trade shows).
How it works
The design of a vacuum blender is actually not very different from a traditional blender. The additional component is a vacuum pump that connects to an airtight blending container. The pump sucks air out of the blending container, so that it can blend in a low-oxygen environment. That means it’s possible to adapt just about any blender into a vacuum blender.
One precautionary note about making your own modifications: a non-vacuum blending container was probably not tested for operation under vacuum. Most of them are sturdy enough that I don’t think there should be any problems, but keep in mind that any modifications will void the warranty. In principle the vacuum could also damage the bearing seal or suck grease out of it. I did some vacuum tests with just water in my modified Vitamix container to see if any air or material would come from the bearing seal. I didn’t see anything come from the seal, but I’m not making any guarantees.
A note about vacuum
Not all vacuums are created equal. It is impossible to create a complete vacuum, so every vacuum chamber gets to somewhere on the continuum between slightly below atmospheric pressure, and slightly above complete vacuum. I mention this because the blending results may vary with the amount of vacuum applied. The setup I put together removes ~90% of the air from the container.
I compared a variety of vacuum blends to otherwise identical non-vacuum blends. I blended the vacuum one first to avoid giving the non-vacuum one an unfair disadvantage. If you want to see how I sealed my Vitamix container, check out my separate page on making a DIY Vitamix Vacuum Blender.
Blended apple yields the most dramatic visual difference I’ve seen in vacuum blending. Initially it looks the same, but over the course of a few minutes the non-vacuum blend turns completely brown. This is an equal amount of cored Granny Smith apple and water, blended 60 sec on high right away:
And 5 minutes later (volume went down because of taste tests):
Interestingly, the vacuum blended one stayed green for at least half an hour at room temperature. (The very top layer eventually started to turn brown, but I never saw the full volume turn brown.)
I also blended just tomatoes (40 sec on high):
And peeled Valencia oranges (45 sec on high):
In both the tomato and orange blends, you can see that the non-vacuum blend is lighter, and the vacuum blend is a more vibrant color. This is because of tiny air bubbles mixed in to the non-vacuum blends. I’ve seen this more vibrant color in a variety of other smoothies as well. Unlike the apple blends, the tomato and orange blends did not noticeably change color over time.
There were detectable differences in the taste of all of the above blends. In each case, the vacuum blend tasted fresher and more like the item being blended. It was possible to taste subtle differences right away, and over the course of minutes the differences increased.
I think the best description of the apple blends is the difference between fresh and cooked apple. The non-vacuum blended apple didn’t taste awful, but it it was quite different from the vacuum blend.
The non-vacuum blended tomato lost its tomato flavor, and was bland and unappetizing. The vacuum blended tomato tasted like eating a piece of the tomato.
The orange had the biggest difference in taste. The non-vacuum blended orange turned bitter, while the vacuum blended orange kept its pleasant orange flavor.
I also blended some mixed smoothies, but I did not always notice a difference in flavor. A vacuum-blended pineapple berry smoothie and various ginger and lemon green smoothies tasted the same as their non-vacuum blended counterparts.
For the apple and tomato blends above I weighed them to make sure the amount was the same. Particularly with the tomato, you can see that the vacuum blend is a smaller volume, and that’s because of air bubbles mixed into the non-vacuum blends.
I also took a photo of one of my foamiest recipes, this spicy green juice:
There was a noticeable difference in consistency between vacuum and non-vacuum blends, but I think it was mainly due to the air bubbles in non-vacuum blends. However, the non-vacuum blended apple did seem noticeably pulpier.
If you leave a non-vacuum blend for a while, it can start to separate. I believe this is primarily caused by air bubbles sticking to bits of fiber and slowly rising. Vacuum blending prevents separation. Here’s a photo of the tomato blends after 25 minutes:
The first takeaway from these tests is, yes, vacuum blending can have a real impact on improving blends. That said, I don’t think that we need to start vacuum blending everything. It has the biggest impact if you are not consuming the blends right away.
There are other ways you can reduce oxidation:
- Temperature: add ice or frozen ingredients to keep blends cold
- Time: minimize blending time, and consume right away
- pH: lowering pH with acids greatly slows enzymatic oxidation1 (adding lemon or lime is the most common way of doing this)
- Antioxidant: add extra antioxidant (most common is vitamin C)
- Avoid oranges if it won’t be consumed right away
- Bubble removal trick
Here is the spicy green juice from above after using the bubble removal trick:The non-vacuum blended one still has some tiny bubbles, but it is possible to get rid of most of the foam.
There are also a few disadvantages to vacuum blending:
- Extra time: pumping out the container takes at least 30–90 seconds.
- Less convenient to adjust recipes on the fly
- Can’t use tamper
This is a big topic, and I haven’t been able to cover all of it here. If there are aspects that you are still wondering about, please let me know, and I can either expand this post or make a new one.
1. Plants contain enzymes that can greatly speed up oxidation reactions. The most common is polyphenol oxidase (PPO). PPO activity is much lower at acidic pH values. PPO also causes polymerization reactions, which may be responsible for the pulpier texture of the non-vacuum blended apple.
What great information.
I am surprised no one has started a chain wth these blenders and charging a premium for their unique smoothie.
I made my own set-up following the instructions in the accompanying post. I’m enjoying the process. It’s really quite fascinating. And I really love the product.
Your review of vacuum blending is interesting. The objective is to eliminate oxygen from the blend to preserve color and taste for a longer period of time. That triggered another thought in my own head. Why not use the anti-oxidant Vitamin C (ascorbic acid)? Canners use it all the time for exactly the same purpose. You can buy ascorbic acid at most supermarkets in the canning section or you can simply drop a couple of vitamin C tablets into the blender. I don’t know if it works but it can’t hurt to try.
The fact that most of the foods I blend have some to a lot of Vit C, is why I don’t see much difference in the color and hopefully the nutritional quality of the smoothies I make….
Other than B12, Algae Oil & Vitamin D, I try and stay away from supplements to do what food can do better especially something like Vitamin C.
I wrote about non-vacuum methods of reducing oxidation in the discussion section above. And I’ve done the test with Vitamin C and blended apples: they don’t turn brown with added Vitamin C.
1. Any thoughts on using cold carbonated water/ice as a base? Does CO2 oxidize nutrients less than O2? I occasionally blend mint or basil into carbonated water, or I make very concentrated green smoothies and add carbonated water into them afterwards. Note: high powered carbonated blending could lead to a messy explosion.
2. I don’t have photos, but I’ve noticed that adding a tbs of coconut oil dramatically prolongs the vibrant color of my smoothies. My theory is that a layer of fat between the blades and the vulnerable compounds might prevent oxidation.
1. I’m not sure about CO2. I have wondered about it, but haven’t found any authoritative information about how it affects foods, other than that it will acidify them a bit. And I haven’t done any tests. CO2 should oxidize things less than O2, but I think it might still react with some nutrients.
I wouldn’t think that adding the carbonated water after blending would help prevent oxidation, because you would already have mixed in air bubbles that have oxygen. Blending with carbonated water might help a bit. My idea was a bit more extreme: adding a bit of dry ice to the container to displace the oxygen gas. With dry ice you could really flush out any remaining air (and it’s convenient that CO2 is denser than air).
2. I’ve encountered adding a bit of oil to cut down on the formation of foam. Having less foam will make it look more vibrant because the air bubbles scatter light and make things look lighter. And then having fewer air bubbles trapped will also cut down on oxidation. (I don’t think that oil would particularly coat the blades, and oxidation doesn’t occur exclusively at the blades—it happens anywhere there are air bubbles, which is everywhere in a high-speed blender.)
I have been waiting for the right vacuum blender to come on the marked, and … I’m still shopping. Meanwhile – this post was fabulous – thanks!!
Which is better to vacuum after or before blending? I thought I bought a vacuum before blending. But it turns out it’s a vacuum after blending blender I got.
Vacuuming before blending should prevent more oxidation. Whether you’d be able to tell a difference depends on what you’re blending.
How about Argon gas used to preserve wine?
Couple of puffs before blending to displace O2.
No oxidation. Thoughts?
I haven’t tried, but I suspect that it would work. You could test it with those little gas dispensers that are sold for wine. If you were doing it regularly, I would expect that you’d want to get a bigger gas cylinder. I’d also guess that nitrogen would work as well as argon, and it’s cheaper.
Many thanks for sharing this post with us, very informative!
I do smoothies everyday and have a normal blender. I have also a vacuum sealer for food. I’m considering to buy vacuum sealed jar and pump out the air after the blending. How would the results compare to a blender with vacuum function?
Alternative to the jars is to buy a new vacuum blender (which means ~ 400USD instead of ~50USD). Wondering if the higher costs are really worth it)
HI, thank you for the info, I’ve been using the BioChef Carafe that fits the Vitamix blender base and it works awesome!
One can save some money by just buying the BPA Carafe without the pump that costs the most by using a wide rubber sink stopper (I just poked a hole on the top of it and it fits the round indent on the lid) with the Food Saver vacuum hose. It works great! I then use those glass handle jars from the dollar store combined with the silicone rings from Amazon and use the electrical tape over pinhole method of sealing the jars. They last for about two days with no issue and tastes great 🙂
I don’t know. I’ve been tempted to buy a vacuum blender but there are so many confusing reviews out there. The same reviewers will say one thing in one video review and quite the opposite in another. Don’t know if vacuum blending is worth the high price of a Kuvings or a Dynapro. I was toying with purchasing the Biochef for the Vitamix until I saw a negative review. In a nutshell, the reviewer talked about poor quality blades, finicky vacuum and non-existing customer service.
The Vitamix is a great machine. I’ve made great smoothies with it. I also have a Kuvings juicer. Likewise, another great machine. Today, however, I tried making the Kuvings frozen banana, avocado and milk smoothie recipe using the smoothie screen. To that , you would add vanilla, cocoa powder and cinnamon after the initial blend. Disaster!!!. The initial ingredients didn’t blend well. So never mind adding the secondary ingredients. I decided to make the smoothie in the Vitamix adding all ingredients and used the vortex technique to eliminate bubbles and GREAT SUCCESS! Moral of the story; use the juicers for juicing and blenders for smoothies.
However still intrigued about vacuum juicing and if you have any updates, your input will be appreciated.
I enjoyed your articles/notes about vacuum blending. It’s something I hadn’t thought of, which surprises me. I like to “tinker” with things and use them in non-standard ways. For instance, did you know you can use a hammer to remove a thumbnail. OK, that’s true, I’ve done it, but it’s not recommended. In fact, I’ll boldly say DON’T do it.
So, back to the subject at blend, adding CO2 or dry ice would not oxidize in the way that most would think of, but it would infuse CO2 into the liquid and probably change the flavor. Think of “flat” water vs. carbonated water. Adding a small amount of dry ice seems a quick and effective way to do this. Handle the dry ice carefully, it can freeze your skin. Quickly. Use tongs to handle the dry ice pieces.
I also wondered if purging with nitrogen might result in a similar effect as vacuum blending. A rig to add N2 gas to a blender would be easier to make than a vacuum attachment although a lot of the equipment used for the modification would be similar. I would expect that oxidation would be reduced a lot, or maybe non-extant.
But you would still have bubbles in the blend. These would be nitrogen bubbles, so in themselves would not contribute to oxidation. The bubbles would likely be smaller than atmospheric or CO2 blending. Either O2 or CO2 can form bonds with the water molecules in the stuff you are blending, whereas nitrogen cannot. You can also get nitrogen infused water or “nitro” coffee drinks. Need I mention Guinness brewing. Didn’t think so, but you can look them up.
So, my short predictions (some of which have already been verified by earlier contributors) are that:
1) Nitrogen purge blending will result in little or no oxidation, similar to what is seen in vacuum blending.
2) Nitrogen purge blending will still result in bubbles in the blend, but these will be smaller and will not add to oxidation.
3) CO2 purge blending will result in bubbles, these bubbles will effect the taste of the product. I would also expect little or no oxidation in the final product depending on how thoroughly you purge your blender container.
4) Is it really worth the effort. Your call, I’ve made my decision.
5) Most people will not have bothered to read this far into my missive, that’s OK.