K-meta rates when bottling

Given some recent post-fermentation infection and oxidation issues in my apple cider and plum wine, I'm thinking of adding k-meta just prior to bottling. I always ferment to dryness, and bottle that way.

Reading several sources, here are the dosing rates I came up with. These bottle-time dosing rates are not to be confused with initial pre-fermentation dosing rates which seem to run 2-4x higher.

• <pH> : <ppm range>, <2/3rds ppm point in range> = <k-meta grams per gallon>
• --- 10ppm keeps lactic acid bacteria (LAB) for malolactic fermentation (MLF) in check ---
• pH 3.2 : 13-21ppm, 18ppm = 0.14 g
• pH 3.3 : 16-26ppm, 23ppm = 0.17 g
• pH 3.4 : 20-32ppm, 28ppm = 0.21 g
• --- 30ppm keeps film yeast sickness in check ---
• pH 3.5 : 25-39ppm, 35ppm = 0.26 g
• pH 3.6 : 31-49ppm, 43ppm = 0.33 g
• pH 3.7 : 39-63ppm, 55ppm = 0.42 g
• pH 3.8 : 49-79ppm, 69ppm = 0.52 g
• --- 75ppm = 0.57 g k-meta = 1 campden tablet ---
• pH 3.9 : 62-98ppm, 86ppm = 0.65 g
• --- 200ppm is a legal limit in many countries ---
• --- 819ppm = 6.2 g k-meta = 1 tsp k-meta ---

Sources

• Accuvin free SO2 test kit, and the pH to SO2 min-max ppm range table included in the kit. I am going with the 2/3rds point on the range given
• http://vinoenology.com/calculators/SO2-addition/
• http://winemaking.jackkeller.net/measures.asp
• The New Cider Maker's Handbook
• Concern - Jack's site is inconsistent on k-meta tsp weights. 1/4tsp = 1.4g, 1 tsp = 6.2g. 4*1.4 != 6.2

Then I pondered how to dose k-meta in say 0.1 g increments without lab equipment. The dosing strategy I came up with is:

• Per Jack: 1 tsp k-meta = 6.2g
• Goal: 1 tsp solution = 0.1g k-meta
• Therefore: add 61 tsp (10.17 ounces) (aka 10 ounce + 1 tsp) of water to 1 tsp k-meta to create ~62 tsp of solution. Each tsp of solution equals 0.1g of k-meta, which equals 12.9 ppm of SO2 per gallon

Sources

• http://winemaking.jackkeller.net/measures.asp
• Concern - Jack's site is inconsistent on k-meta tsp weights. 1/4tsp = 1.4g, 1 tsp = 6.2g. 4*1.4 != 6.2
• Minor concern - 61 tsp water + 1 tsp k-meta is likely less than 62 tsp total. Recall 1 cup sugar + 1 cup water = 1-2/3rd cups solution, because the sugar molecules partially fit between the water molecules

Do my math and dosing rates look reasonable?

I also get the sense that k-sorbate (in addition to k-meta) is only useful if one wants to stop fermentation and leave some sugars. If one is bottling dry, and not priming, k-sorbate should be skipped. Does that sound reasonable?

--SiletzSpey