Stripping out the flavor

I've read here that fermenting to complete dryness can "strip out the flavors".

I've been told by the local brewing shop that champagne yeasts are especially aggressive, and can "strip out the flavors".

So that brings me to a question. As things approach dryness, is it the lack of sugars that makes us perceive fewer flavors, or is the yeast in fact forever stripping out stuff from the cider that reduces flavor, and even back-sweetening can't recover the lost stuff? Maybe for lack of sugar, the yeasts start attacking other stuff?

For 3 seasons, I've fermented to utter dryness of 0.992-0.996 and bottled. At serving time, I back-sweeten with table sugar. Now I'm wondering if I need to halt the fermentation to save the flavorful stuff.

As an aside - the local shop seemed to suggest the popularity of champagne has less to do with great flavors, and more to do with how reliable (i.e. idiot proof) they are. Reactions?

--SiletzSpey

The most important factor is how much flavour is in the juice to start with. If you are using supermarket juice there isn't much flavour to begin with so when the sweetness goes there isn't much left. If you use tree-ripened cider fruit there is plenty of flavour so even when fully dry it will still taste great. people with poor quality juice like to blame the yeast when their cider turns out crap. the quality of the juice is much more important than the yeast. I have used champagne and other yeasts, if you have good fruit you won't notice very much difference between yeasts. The big advantage of EC1118 is that it is cheap and reliable.

True that the juice you start with is the biggest factor. But different yeasts also affect the flavor. Ale yeasts tend to leave more fruitiness than wine or champagne yeasts. Alcohol content also has a big effect. Lots of sugar = high ABV and you get apple wine not cider. Temperature and ferment speed (nutrient content) also have an effect. My best ciders are winter batches fermented slowly at 65° with ale yeast.

Several points can be made here.
1. Fermentation does not strip flavor although some fermentation practices might.
2. I very much agree, flavor comes from the fruit itself. The richer the apple blend and the more it was prepared for hard cider rather than apple juice (the pH, the tannic quality, the sugar content of the fruit) the richer the flavor of the bottled cider.
3. If you use an aggressive yeast (like EC 1118) then you blow off much of the flavor. If you ferment at higher rather than lower temperatures with any yeast you destroy the volatile flavor molecules. EC1118 has its uses - to restart a stalled fermentation or perhaps to ferment in a bottle to make a wine sparkling. Personally, I cannot think of any other reason to touch that yeast.
5. Best yeast for cider (IMO) is 71B, a wine yeast but a yeast that metabolizes malic acid (where malic is the dominant acid found in apples). D47 is also good as is QA 23) There are others too.
6. Many folk confuse the flavor of apples with the sweetness of the fruit. Remove the sweetness (through fermentation) and if the flavor was thin, then the flavor is gone. Again, most eating apples are as far as cider is concerned pretty flavorless and have virtually no tannins. They may be "sweet" but they lack real flavor.
7. Backsweetening to a gravity of about 1.000 - 1.010 will help to bring out the apple flavor. There is always a need for balance between ABV and flavor and acidity (TA, not pH) (and mouthfeel). That means (IMO) you may need/want to stabilize the cider and then add back some sugar (from concentrated apple juice perhaps - and by "concentrated" I mean use the same orchard pressed apple mix that you are using for the cider but freeze it and then collect the first 1/3 that you slowly thaw. That 1/3 will contain about twice the concentration of the sugar and twice the intensity of flavor).

A fast turbulent ferment will strip out some flavour, though I don't think the flavour compounds in cider are all that volatile. The speed of fermentation depends a lot on temperature and nitrogen in the apples. Low nitrogen apples ferment a lot slower. Some wine yeasts will produce fruity esters like awri350. there is a bit of a movement away from 'tricking up" wine with this sort of yeast, but they are popular for cider. These yeasts are often quite expensive and only available in big quantities.
71B is quite popular, you can also get rid of malic acid with a MLF culture. In cool areas you don't get natural malolactic so a dry cider will taste pretty sour with the malic acid. I like dry cider but not unless it has gone through MLF. With a sweet cider the malic acid isn't so sour.