Process
Many fruits and vegetables are prepared for peeling and canning
by exposure to caustic (NaOH). To ensure adequate and consistent
peeling, the concentration of caustic in the treatment bath must be
maintained at an effective strength. At the same time, if the caustic
bath is too strong the fruit or vegetable can be damaged.
The typical process consists of an open tank of caustic heated
to 170–220 °F (76–105 °C) by live steam. The target caustic
concentration can vary from 3 to 15 %. Exposure time for the
product is usually 5 minutes or less, after which the product is placed
on moving grates and washed by high pressure nozzles to remove
entrained caustic.