Chapter 13: Sour

Sauerkraut 20 g salt per kg (18 to 30 range); brined vegetables 35 to 50 g per kg total; 18 to 22 °C first week then cellar

To check against

doc 93, 114; USDA NCHFP fermented vegetables; Katz, The Art of Fermentation

The verdict

AMENDED

Found

nchfp.uga.edu/how/ferment/recipes/sauerkraut/ (3 tbsp canning salt per 5 lb cabbage, about 2.25 to 2.4 %; ferment at 70 to 75 °F, 21 to 24 °C, 3 to 4 weeks; 60 to 65 °F, 5 to 6 weeks; below 60 °F, 15.5 °C, "kraut may not ferment"); nchfp.uga.edu/how/ferment/general-information-on-fermenti… ("Do not attempt to make sauerkraut or fermented pickles by cutting back on the salt"); nchfp.uga.edu/how/ferment/recipes/dill-pickles/ (brined vegetables about 3.7 % of total weight, see S5)

Note

20 g/kg is slightly under the USDA ratio (about 22 to 24 g/kg) and the 18 g floor is below it; 30 g is fine. 35 to 50 g per kg total for brined vegetables is confirmed. Moving the crock to a 10 to 15 °C cellar after one week is below the USDA's lower fermenting limit (15.5 °C); the traditional warm-start, cool-finish is common but not what the tested guidance says. Katz not opened. Proposed: "Weigh out salt at 22 grams to the kilogram, 25 in a warm kitchen, never less than 20 and never more than 30; keep the crock at 18 to 22 degrees until it tastes clearly sour and has stopped fizzing, two to four weeks, and only then move it to the cellar."

Vinegar must reach 5 % acetic acid to preserve; cider at 5 to 8 % alcohol; "wait two weeks beyond" rule

To check against

doc 89; USDA/NCHFP pickling guidance (≥ 5 % acidity); the two-week rule is the book's own and needs a titration alternative (bench test with baking soda)

The verdict

AMENDED

Found

nchfp.uga.edu/how/pickle/general-information-pickling/gen… ("White distilled and cider vinegars of 5 percent acidity (50 grain) are recommended"; "Do not ... use a vinegar with unknown acidity"); doc 89 (1 % ABV gives roughly 1 % titratable acetic acid on complete oxidation; 10 to 12 °Brix needed for 5 % vinegar)

Note

5 % confirmed. A 5 % cider can at best just reach 5 % acid, so it is marginal; the lower bound should be 6 %. The two-week rule is unsourced and cannot show strength; a titration can. Chemistry (stoichiometry, not a cited source): 1 g baking soda neutralises 0.71 g acetic acid, so 10 ml of 5 % vinegar (0.5 g acid) takes 0.70 g soda; dissolve a weighed 0.70 g in water, add the vinegar 1 ml at a time, and if fizzing is still going at 10 ml the vinegar is under 5 %. Red-cabbage water as indicator makes the endpoint clearer than fizz. Proposed: "Start with cider of 6 to 8 parts alcohol in a hundred; and before you trust a vinegar in a pickle, test it: 10 millilitres of it must use up at least 0.7 grams of baking soda."

Yoghurt: 85 °C 30 min, cool to 42 to 45 °C, 4 to 8 h; hand tests for temperature

To check against

doc 95; replace the 85 °C hand test with a visual cue in draft 2 (safety)

The verdict

AMENDED

Found

doc 95 (85 °C for 30 min or 90 to 95 °C for 10 to 15 min; research PDF, not a confirmation); pubs.nmsu.edu/_e/E216/ (NMSU extension: use a thermometer; temperature control is very important); en.wikipedia.org/wiki/Scalding (route only; attributes to the American Burn Association: scald at 60 °C within 5 s, at 68 °C in 1 s)

Note

Figures 85 °C 30 min, 42 to 45 °C, 4 to 8 h are standard dairy practice but no primary dairy text was opened this pass (tried: Tamime and Robinson and Walstra, not reachable; NCHFP yogurt page, 404; USU and Penn State extension yogurt pages, 404); treat as UNRESOLVED on the numbers. The hand test must go: milk at 85 °C scalds skin in well under a second, and a painful drop is not a way to tell 75 from 95. The 42 to 45 °C finger test (10 s) is safe. Proposed: "Heat a litre of milk until it steams hard, small bubbles stand round the rim and a skin forms, but it does not boil, and keep it there half an hour, stirring; never test it with your skin."

Mould on brine surface: skim if vegetables submerged, brine still safe

To check against

NCHFP; Katz; a food-safety source on surface mould in lacto-ferments

The verdict

AMENDED

Found

nchfp.uga.edu/how/ferment/recipes/dill-pickles/ ("promptly remove surface scum or mold"; "If the pickles become soft, slimy, or develop a disagreeable odor, discard them"); nchfp.uga.edu/how/ferment/general-information-on-fermenti… (surface yeasts and bacteria "feed on the acid thus reducing the concentration"); bfr.bund.de/fragen-und-antworten/thema/schimmelpilze-in-l… (mouldy food should be discarded; exceptions only dry sausage and whole hams); bfr.bund.de/presseinformation/schimmelpilze-und-schimmelp… (BfR 07/2026: mycotoxins heat-stable and may spread through soft, watery foods)

Note

Skimming is supported by USDA for surface growth caught early. "The brine below is still safe, because mould cannot live under the acid" goes beyond any source: surface growth eats the acid, and toxins can diffuse into the brine; BfR advises discarding mouldy watery foods. Proposed: "Skim a small patch of mould as soon as you see it, wipe the rim, and check that everything is under the brine; if the mould is thick, fuzzy, pink or black, or has spread across the surface, or the vegetables are soft, slimy or smell of anything but sour, throw the whole crock out."