By Harold McGee
While some fruits and vegetables are fermented alone in tightly covered pits or jars, most are either dry-salted or brined to help draw water, sugars, and other nutrients out of the plant tissues, and to provide a liquid to cover the food and limit its exposure to oxygen. The characteristics of the pickle depend on the salt concentration and the fermentation temperature, which determine which microbes dominate and the substances they produce. Low salt concentrations and temperatures favor Leuconostoc mesenteroides, which generates a mild but complex mixture of acids, alcohol, and aroma compounds; higher temperatures favor Lactobacillus plantarum, which produces lactic acid almost exclusively. Many pickles undergo a microbial succession, with Leuconostoc dominating early and then giving way to Lactobacillus as the acidity rises. Some Asian pickles are made not by spontaneous lactic fermentations, but by the addition of another fermented “starter” material, the by-products of producing wine or miso or soy sauce. Japanese nukazuke are unique in employing rice bran, whose abundant B vitamins end up enriching the pickled daikon and other vegetables.