Michigan State University Extension
Preserving Food Safely - 01600611
1. Dark (gray or brown) Pickles Darkness in pickles may be caused by:
Use of ground spices or too much spice.
Packing whole spices in jars with pickles. Whole cloves, allspice, cinnamon should only be used to flavor the pickling liquid.
Corrosion of metal lids.
Minerals in the water, especially iron.
A silver fork is recommended for piercing brined cucumbers to desalt them. While an iron fork should not be used, stainless steel is acceptable.
Darkened pickles are not attractive but they are safe to eat.
2. Blue Garlic Pickle recipes sometimes call for several cloves of raw garlic. Raw garlic contains an active enzyme system that may remain active if jars are sealed without processing (processing is recommended for ALL shelf stable canned goods). Garlic also contains sulfur compounds. In the presence of a little copper, the enzymes may catalyze a reaction between the copper and the sulfur to form copper sulfate, a blue compound. The amount of copper required for this reaction is very low and is frequently found in normal water sources. It is unlikely that any health hazard is involved.
3. Green Garlic If garlic is not fully mature or thoroughly dry, it may turn green. This discoloration is due to a reaction between the acid in the vinegar and the pigment in the garlic. It is harmless.
4. Red Brine Rust often causes red brine. Determine if the water lines had been flushed out shortly before the pickles were made. If so, there is a possibility that water containing a little rust was used for the brine. Store the pickles, undisturbed for a few months; the red color will usually disappear.
5. Pink or Red Dill Pink discoloration in dill is due to a change in the structure of pigment compounds which are normally colorless. It is harmless.
6. Pink of Gray Cauliflower Pink discoloration in cauliflower is due to a change in the structure of pigment compounds which are normally colorless. In the presence of a little iron these pigment compounds may be converted to forms which are gray. Avoid iron contamination during all stages of preparing pickled cauliflower. Pink or gray discoloration may be minimized by blanching the florets for 3 minutes in boiling water containing 2 to 3 tablespoons of lemon juice per gallon. These discolorations are harmless.
7. Dark Pickled Cauliflower, Onions, Pears, etc. Cider vinegar may darken white or light-colored vegetables and fruits. White distilled vinegar is desirable when light color is important. The darkening is harmless.
8. Pink or Dark Sauerkraut Undesirable color, off-odors and soft texture indicate spoilage in sauerkraut. DO NOT USE THE SAUERKRAUT.
9. Dirty Pinkish Gray Sauerkraut Made From Red Cabbage Unless iron contamination is completely avoided (and for all practical purposes this is impossible in the home), sauerkraut made from red cabbage will turn a dirty pinkish gray. The kraut is unattractive but safe to eat provided that there is no evidence of spoilage (e.g. soft texture, off-odors, off-flavors, mold growth).