Our oldest daughter sent us a U-tube that was in a foreign language, Japanese I think. It had me fascinated so when our daughter came up for the weekend we had to try it out to see if it really works. Maybe we didn't have to do it over twelve times but hey, we can now tell you the whole scoop and we got a home-made angel food cake out of the deal.
Miss Doubtful here thought a plastic water bottle's opening was too little so I tried a Naked juice bottle. It sucked up the yolk alright but it immediately fell back on to the plate so our daughter went out to her vehicle to get a water bottle. Amazingly, it worked like a charm. Squeeze the bottle and make contact with the yolk.
Voila, the yolk separates with nary a speck of white. Especially awesome when you are making angel food cake.
And it stays in the bottle unlike the larger mouthed Naked juice bottle.
You can plop the yolk back onto your white and suck it up once more.
The amount of cohesion is impressive. Would this work on store eggs? I don't know since I'm using fresh eggs and the yolks are fresher and have a stronger cohesion. But that isn't a guarantee that every egg will work since we did have one that broke after sucking it up into the bottle.
It is pretty tough to clean out the bottle since it is has such a small opening, so we switched to another bottle. We try and keep a few on hand, though the majority of the time we use reusable containers to haul water in when we travel. They come in handy to give to others, especially when they are leaving and not coming back to our house.