Debunking ultrasonic steeping

[Old Greybeard]

There seems to be a lot of controversy concerning the use of heated and unheated Ultrasonic Cleaners [UC] for the steeping of DIY juice. I haven't managed to perform a blind scientific test yet with real life juice scenarios as I don't have enough available kit, but I hope to do this soon once I stock up on more plastic bottles and hardware etc.

Having worked with ultrasonics extensively over a number of years, I was disappointed to see the following video online.



While the creator has made a valiant attempt to debunk the efficacy of UC baths when it comes to the mixing and steeping of ejuice solutions, his test is based, as far as I can tell, on a false premise. For ultrasonics to work effectively in this scenario, the transducer has to be effectively coupled to the liquid in the container. Normally this is via water, as hydrogen dioxide [Water to you and me] is an extremely good conductor of sound waves. Five times as good as air, in fact. However, if you are to use a flexible plastic bottle, this will have the effect of attenuating the waves hitting the ejuice. While some of the waves may pass through the material, the soft plastic will act as a shock absorber. A simple test will prove this, flick a glass jar and a standard ejuice bottle with your fingernail, and the glass is clearly a lot harder. While I am not a molecular scientist or chemist, my hypothesis is the harder the material of the container holding the ejuice, the more effective the "mixing" process will be. As far as I am concerned, the jury is still out on rigid plastic bottles as I was not able to test any, but I suspect that as they are generally injection moulded, and are molecularly different from glass, they may show a slight improvement in conductivity over their softer cousins.

I decided to conduct a test with the following parameters:

• A PG and water soluble powdered food colouring mix would be steeped in a glass container, semi-submerged in an unheated UC for 1 hour
• The food colouring would not require heat to dissolve and be proven to dissolve quickly and effectively in water with a minimum of stirring
• A control glass container would be left at the same temperature for the same time
• At the end of the experiment the results would be compared, and both containers swirled rapidly [like a brandy or wine glass to release the aroma] to reveal any sediment remaining
• The UC would be rated at 50W @ 40Khz. The 100W heating element would not deployed

The results [In photo order]

1. Food colouring added to the jar destined for the UC. Note the trails where the powder has dissolved while gravity has pulled the powder to the bottom
2. The jar in the running UC. Due to the air in the jar, I couldn't submerge it or rest it on its base, but 5 seconds in you can see the food colouring beginning to dissolve
3. 10 seconds in and I think we can work out what the results will be like
4. The control 60 seconds in
5. The UC test after 60 minutes
6. Both containers after 60 minutes. Due to the nature of the UC, the surrounding water was warmer than the control, as the bath heats up during operation even with the built in heating element turned off. IIRC, the temperature of the water bath was 40C versus an ambient temperature of 22C. This temperature disparity can be effectively ignored due to points 4&5 above - the water in the UC would have not risen much above ambient at this point
7. Top view of the UC container. Some scum has developed on the surface [as had on the control]. This may be down to any detergent used to wash both items not being properly rinsed off, or something in the food colouring or the PG.
8. Swirl test of the UC jar - no sediment. The shadows are in the background, not the jar.
9. Swirl test of the control, big lump of sediment

Conclusions

1. Using a UC bath at room temperature effectively dissolved the powdered food colouring over the control
2. Due to the construction of UC's, unless they are cooled it is impossible to make a like for like comparison due to the inherent rise in bath temperature. In theory, a miniscule rise in temperature will also incur in any shaken test fluid. Heat will inevitably create Brownian motion in the solution, and will assist the dissolving of any matter. This is proven science, the results demonstrated in points 3&4 above prove however that while heat will have an effect, the ultrasound is also assisting in combining the colouring
3. This is not an exact like for like test against the video above, rather it is a demonstration of the efficiency of ultrasound in dissolving PG soluble matter in PG using a glass container. A closer comparison would be achieved by using a] Plastic and glass containers b] a mixture of VG/PG+ dissolved colouring. If requested, I'll be happy to conduct this, but it will have to wait until I have some additional spares and to be honest it will have to be on a smaller scale as I don't want to waste any more ingredients. Personally, I believe the results will be identical, plastic will fail and glass will prove to be more efficient. The only question will be down to the viscosity of the fluids when mixed. My hypothesis is that a magnetic stirrer will be more efficient, followed by UC glass, then UC plastic.

 

[untar]

While interesting, it's still not a test for steeping. Steeping isn't equal to just mixing. If that was the case then people wouldn't wait a few weeks for their juice to steep and just strap it to their washing machine or something.
Steeping means the taste changes, to verify if that's the case you need to taste, UC liquid vs non-UC (preferably also a 2 week old batch of non-UC set up earlier to compare to the UC steeping). You'll also need to use flavors that need longer steeping like more complex dessert or tobacco flavors, a plain mango or apple will probably be done after just shaking the bottle for a minute.

Good point about the glass containers though, I think many are missing that.

 

[Eskie]

Good stuff. It does leave open the issue of the viscosity of VG, which is usually the big problem when mixing. Honestly, IME, anacdotal as it is, a hot water bath for 20 minutes (decreasing the viscosity of the final juice at higher temp) followed by vigorous shaking mixes things up just fine. Letting it sit open to allow any alcohol to evaporate off if any of your flavors contain it, and it should be pretty much there. I know some desserts and tobaccos benefit from sitting around to steep, but I've always wondered if that's just a matter of regular shaking adding more air (bubbles) just results in oxidation of some of the flavors, which might be where the advantage of "steeping" occurs.

Let's face it, juice sitting around darkens. That's a chemical reaction, not a mixing phenomenon.

I will say the observation about soft plastic versus glass is a good one for UC use.

 

[Old Greybeard]

While interesting, it's still not a test for steeping. Steeping isn't equal to just mixing. If that was the case then people wouldn't wait a few weeks for their juice to steep and just strap it to their washing machine or something.
Steeping means the taste changes, to verify if that's the case you need to taste, UC liquid vs non-UC (preferably also a 2 week old batch of non-UC set up earlier to compare to the UC steeping). You'll also need to use flavors that need longer steeping like more complex dessert or tobacco flavors, a plain mango or apple will probably be done after just shaking the bottle for a minute.

Good point about the glass containers though, I think many are missing that.

Completely agree @untar, I think there is a lot at play here around steeping, not just the mixing itself:

• Time
• Temperature
• Evaporation
• Viscosity / suspension / solubility
• Air flow
• Pressure [e.g. French press]
• Light / UV exposure
• Container permeability
• Oxidation
• Using a seed mixture [e.g. like a yeast base in bread making]
• Etc ...

What got me was the whole plastic/glass thing, it just didn't click with my experience.

 

[tailland]

Ultrasonic mixers do exist, so why wouldn't this work at least when done right? It's a different question alltogether whether the steeping can be accellerated by this as well.

By all means, make a test. And if you like, make a video of it. Many people will want to see this.

(BTW rhe real question here is: Why does "Old Greybeard" have women's hands, as seen in the 2nd to last image?)

 

[untar]

I've always wondered if that's just a matter of regular shaking

Trust me, I've fabricobbled a rig that shakes the living sh out of a juice bottle and it doesn't steep the liquid at all. Even after 6h of continuous rattling. Once it's mixed, it's mixed, can't mix it more.

I can only suggest to try the UC steep with a juice that needs longer to develop certain flavor notes. Eg a lemon tart flavor usually takes at least a 4-5 days to shine. It's vapable before but not tasting as good as it can.

 

[untar]

Why does "Old Greyboard" have women's hands, as seen in the 2nd to last image?

He's a left handed guitarist or there's some terrible Scottish secret we're better off not knowing

 

[Letitia]

Appreciate the effort to show those that didn’t realize that UC is near worthless with plastic. I'm still in the mix it and let time do its thing camp.

 

[Cynophobe]

He's a left handed guitarist or there's some terrible Scottish secret we're better off not knowing

Blame the banjo and dishwashing liquid methinks.

 

[Old Greybeard]

Let's face it, juice sitting around darkens. That's a chemical reaction, not a mixing phenomenon.

Agreed. I've noticed it with a 10ml batch I put together 2 days ago, it is already noticeably darker.

Trust me, I've fabricobbled a rig that shakes the living sh out of a juice bottle and it doesn't steep the liquid at all.

Tell me more @untar, I'm curious how you put hat together.

BTW rhe real question here is: Why does "Old Greybeard" have women's hands, as seen in the 2nd to last image?

Nothing sinister @tailland, just genetics and delicate fingers. I like long thumbnails as they great for flicking catches open, pulling insulation off wires, scraping off labels etc. My keratin levels are such that I've actually busted nail clippers in the past. Even hairdressers hate me as I have such tough hair.

 

[tailland]

so that's how it is... how uninspiring

 

[Letitia]

Now I wants my pillow again. Dog looks more comfy.

 

[untar]

Tell me more @untar, I'm curious how you put hat together.

It's basically just the motor of a broken cord drill, a disk with a drive shaft and a metal box on a few springs.
It does make some noise.

 

[untar]

so that's how it is... how uninspiring

Nice, it's that japanese dog from the shiny thread

 

[Old Greybeard]

There is no way after @Eskie mentioned VG that I was going to be able to go to bed and and actually sleep without tossing and turning and thinking about fluid dynamics and viscosity.

1. LTR - PG mix with red water soluble powdered food colouring, VG in hard plastic bottle, VG in glass bottle. The glass has a thick glass bottom, so will cause some distortion in the images. Don't have a soft plastic bottle.
2. Containers with PG/FC mix floating on top of VG.
3. 10 seconds after bath batch insertion. I think we can see where this is going.
4. After 10 minutes. Batch temperature climbed from 18C to 30C

Conclusions

1. A UC bath will mix VG/PG in a very short period, I would say seconds rather than minutes
2. Hard plastic conducts ultrasound as effectively as glass
3. What the original researcher achieved was either by using a non-VG soluble mix or it was indeed the soft plastic bottles. I'll leave you to make your own conclusions as I don't have the kit to prove definitively.

 

[untar]

Well, you proved at the very least that the guy in the video didn't know what he was doing

 

[Old Greybeard]

Well, you proved at the very least that the guy in the video didn't know what he was doing

Thanks @untar, being methodical and pedantic [bordering on OCD] has it's uses sometimes .

 

[Cynophobe]

Gots me thinking....I'm going to start my own line selling sterile containers chock full of top notch patience.
As a freebie I'll throw in a random box of hopelessness and my brand new, 'untouched by human hands' ziplock satchel of high grade despair. 'Metric time' coming soon!
Form an orderly rabble folks!

 

[tailland]

Q: What happens if heated up VG cools down again? Does it acquire its original viscosity?

 

[untar]

Does it acquire its original viscosity?

I heated it to 80°C a few times during my tobacco flavor extraction experiments, went back to its natural goopyness.