Are there differences in the different types of yeasts? Does one yield slightly differently?
I know many people say that they can be used interchangeably but why are there two types if there isn't a difference?
Are there any differences in reactions that you can see when cooking different foods? E.g. rising rates, rising ratios, taste, freezing reactions, lifetime, etc…
I've already seen the following:
active dry yeast vs instant yeast
How to convert a recipe calling for active dry yeast into rapid rise yeast?
and was hoping for more insight.
Best Answer
There are indeed many 'kinds' of yeast (same species, separate strains). If you check out your local brewing supply house you can find yeasts that have many different properties, mostly centering around flavor (or lack of flavor) and heartiness (level of alcohol attained before the yeast dies off).
When it comes to bread making, while you could use any of the specialty brewing yeasts (different from brewer's yeast aka 'nutritional yeast' which would NOT be suitable for bread making as it is 'dead') there are a few varieties, the two most common of which you have already struck on, active & instant. In addition there is a third, less common, 'live' yeast. The primary difference being the size of the 'granules'. Active yeast is larger and you need to 'proof' it before use (mix with water and sugar) where Instant yeast is finer and can be added directly to your dry ingredients when making bread. Live yeast comes in a large piece, which you break off a portion, crumble and then proof, much like active yeast). Similarly, rising rates for 'instant' are faster (as the name implies) and a second rise is not necessary with the instant yeast.
As for the other factors you ask about (lifetime, freezing, etc.) while there may well be difference between the various yeasts in these categories I've never found them significant or documented and are probably more related to taking care of your yeast (storing in a cool place with little or no air/circulation) than the strain of yeast.