According to Stephen Beckett in The Science of Chocolate, there are six crystal structures that cocoa butter can take. There are various labels used to describe these forms and Beta 6 is actually a combination of two of them - Beta 1 and Form VI.
Forms V and VI are the most stable, however, Form V is the one that is achievable by the normal tempering process:
Form VI is in fact more stable, but under normal conditions is only formed by a solid to solid transformation and not directly from liquod cocoa butter. This means that chocolate with fat in Form V will, after a period of months or sometimes even years, start to bloom. This is because some of the cocoa butter is still liquid, even at room temperature, and energy is given out as the fat is transforming to the lower energy state. This combination of effects pushes some of the fat between the solid particles on on to the surface.
The Science of Chocolate is a great book. I can't recommend it more highly as a solid reference to the technical aspects of chocolate making and working with chocolate. Click on the image below to order the book from Amazon.
I've used Mycryo a few times for tempering chocolate, and it does work, but I think that it is harder to use than seeding using either chunks or callets because the seed has the thermal mass to help cool the chocolate down. That said, I find it incredibly useful as a substitute for solid cocoa butter since it is a powder and is therefore easier to mix with other ingredients. I use it to mix with powdered colors to make "Paint". I can use it as a binder and mix it with other dry ingredients and then melt everything together. And when I first started using it, Mycryo was actually cheaper then bulk cocoa butter (that may not be true anymore).
Meh, I have Mycro and use it, but it is very expensive compared to bulk cocoa butter. There's no magic to Mycro, all it is, is cocoa buter heated to around 48 C and then sprayed on to a frozen roller, then scraped off. The extremes between the two temperatures "shocks" mycro into pure beta 6 crystals.
I think the prescribed amount is 1%, (1 gram auf every kilogram) melted couveture, but the couveture must be around 35 C.
I still get in the (cheaper) Kessko cocoa butter in the 5 kg pails, but of course it is like cement in a bucket. What I do is throw the whole bucket into a warm oven overnight (around 30-35 C) and then pour the melted butter into cling-film lined trays about 1/2" (2-3 cm) thick. When cold I coarsely chop this in the food processor and use it to thin out couveture or to mix with fat-soluble colours for molding chocolates. This is NOT a substirute for Mycryo as it has no beta 6 crystals, but it is in an easily dispensable form.
One of the best uses of Mycryo is dredging chicken breasts that need to be held for some time before they are baked or fried off for service. The crystals are real stable and because it is solid, it doesn't run all over the place like an oil would. Plus it's real stable at high temperatures (doesn't burn all that easily) and imparts a slightly nutty taste.
You're right: Mycryo is not a substitute for cocoa butter. If I only need to thin couverture, I use bulk cocoa butter; however, for tempering I sometimes use the Mycryo esp. if I don't have a lot of seed chocolate on hand.
I wasn't always a big fan of Mycryo. In pastry school, we used it once and I thought the results were not as good as using one of the more traditional methods of tempering. Since I've started using it more in a professional environment, I think it's an excellent product and definitely has its place.
I have used Mycryo Powder from CB and Beta 6 from AUI Imports.
Personally I like the Beta 6 a little better. Its a little more tempermental
but the results are amazing. A little better shine and it holds a little better.
Hope this helps.
Is there a taste difference? Can you tell a difference in the product with the beta crystals? Sounds interesting. Nothing more has been developed in this vein, has there? It's been years since some of the articles I have read online. Any more input?