Spoilage of the top layers of vegetables fermented in brine is sure to
occur unless the scum which forms on the surface is frequently removed.
This scum is made up of wild yeasts, molds, and bacteria, which, if
allowed to remain, attack and break down the vegetables beneath. They
may also weaken the acidity of the brine, in which way they may cause
spoilage. The fact that the top layers have spoiled, does not necessarily
mean, however, that all in the container are spoiled. The molds and other
organisms which cause the spoilage do not quickly get down to the lower
layers. The part found in good condition often may be saved by carefully
removing the spoiled part from the top, adding a little fresh brine, and
pouring hot paraffin over the surface.