hey bud, sorry didnt relise cider was in here.......
You said Wyeast 4766 yeast but u also said depends what final product your after.
What changes do different yeast make at the final result??
OK.. that's a hard one and probably deserves a thread all on its own.
Pretty much any yeast will ferment a cider out dry. Even a yeast with a low attenuation will still finish dry in a cider as the yeast attenuation is a measure of how well it will ferment complex sugars. Any yeast will eat right through the simple sugars in apple juice regardless of its stated attenuation. The exception would be something like a sweet cider yeast which essentially has a very low alcohol tolerance and will poison its self before it finishes fermenting. I find them a bit hit and miss though.
Mostly, different yeasts will enhance or decrease the fruit flavours and may add some esters and other flavours of their own. Making things even more difficult, different apples have different flavours/aromas that will be enhanced/decreased differently by different yeasts.
I tend to use 4766 as it leaves a lot of good fruit flavour and doesn't strip anything out. It also doesn't seem to add much flavour so you end up with something that tastes like apples. I don't want any beery esters as this is for the missus and she doesn't like that. I press my own juice though so I can ensure I have good flavoured juice. Some shop bought juice is pretty bland - very little acid, not much character. In juices like this the 4766 can leave the cider a bit thin and tasteless. A juice like that might benefit from an ale yeast (S04/S05 seem to be popular) as that will add some esters and give you more flavour. The esters might clash with the apple flavour though so you don't want too many. A belgian yeast probably wouldn't work so well. Even some of the English ale yeasts might be a bit too estery. If you have a very perfumy apple and want to preserve that, you need something that doesn't ferment too quickly. I have heard of lager yeasts being used successfully for that.
For me though, because I can control my juice I find the 4766 gives a good result. I don't tend to use nutrient and I ferment a bit colder than recommended. The reason for this is that I want a dry cider but not bone dry so I want the yeast to finish a little earlier than they otherwise would. By starving them of nutrients (actually apple juice has quite a bit of yeast nutrient naturally so its not really starvation.. its more like a mild diet) and stressing them with cold I am trying to get a slightly premature end to fermentation. Its a fine line though. Its really easy to end up with a stuck fermentation and something really sweet or for the yeast to just finish dry anyway.
You can also play tricks like keeving (letting the juice sit for a few days underneath a cap of foam) which reduces the amount of nutrient available and gives you a sweeter cider. That's next year's experiment.
Welcome to the wonderful world of cider.
Cheers
Dave
