Guys, thanks for the clarifications. A few followup questions:
- Would the potassium sorbate typically only be used at the initial dosing after fermentation is complete even though the potassium metasulfite may be used multiple times?
- Should I gently stir the crushed metabisulfite into the carboy before bottling or just drop it in? i.e. What is the correct balance between getting the metabisulfite mixed in vs. concerns of aeration/oxidation.
- Does the metabisulfite affect the flavor of the mead after repeated dosings?
- My wife is allergic to sulfites. Are there any other options for my future batches of mead?
A, yes. That's correct, but you use both on the first occassion, then as the sulphites dissipate, add more every second racking just to keep the levels to a point where they prevent the problems.
B, Yes, just crush a campden tablet and gently stir it in, so there's not splashing action. If you're not actually doing anything else with the batch, you can just drop the tablet in as it will dissolve over a day or so.
C, Yes, metabisulphite can affect the flavour if used in too higher concentrations. But the point of using it only to the recommended levels as mentioned above means that it's just at a maintenance level i.e. 1 campden tablet will give approx 50 ppm per gallon, I understand that the most sensitive tastes will only notice if it's above 100 ppm - the racking action in between additions is where it dissipates.
D, Allergies can be a pain. Yet sulphites are used in many, many foodstuffs, so it would depend on the level of sensitivity that your wife has to sulphites. The obvious answer is careful production, and using levels of honey whereby you eventually make them strong enough to exceed the tolerance of the yeast - the step feeding process is about the easiest and most hassle free i.e. if you know that a yeast is capable of 16% ABV (I'll use the example of my favourite yeast for traditionals, D21 which is tolerant to that level). So 16% ABV equates to a drop of 118 points. To make a batch that has a starting gravity of 1.118 might, feasibly stress the yeast with all the sugars added up front, so you just make a batch with an SG of say 1.100, get it fermenting, test to monitor where the gravity gets too, then when it's at something in the 1.030 to 1.050 area, you just add enough honey to bring the gravity up by 18 points and it can then be left to ferment dry - presuming dry at 1.000 - if the yeast likes it's environment it might exceed that a bit and get down below 1.000 - either way, you can then back sweeten to your desired level as the yeast won't be capable of refermentation, and just clear it and finish the process in the usual way.
The point of stabilising a batch is to prevent any further fermentation when there's still fermentable sugars available and the yeast has capacity to ferment left. Even the clearest mead will have yeast cells present, unless it's been "sterile" filtered, with a filter gauged at about the 0.25 to 0.40 micron area (and most don't have access to such fine filtration).
If the yeast can't ferment any further then that part is unnecessary. Plus a stringent hygiene regime with all your kit, bottles, siphoning pipes etc, should, theoretically, reduce the chance of infections by spoilage organisms. Any that did get in would, as with the occasional bottle of wine, just be bad luck.