Tank Blancher – Vegetables, Blanching, Water-based
Industry: Fruit and Vegetable Preserving and Specialty Food Mfg (NAICS 3114)
Process Brief: Fruits and vegetables are scalded or briefly boiled prior to canning or freezing.
Energy source: Hot water
Energy Intensity: 400-500 Btu/lb of fruit or vegetable
Blanching is the rapid heating of fruits or vegetables to stop the enzyme action that causes deterioration of flavor, texture, and nutrients. Batch blanchers are stainless steel tanks in which the product is added to hot water. The product is blanched for the desired time and is removed from the tank in a sieve and is cooled. Tank blanchers are uncommon at modern food processing facilities where they have been replaced by more efficient, continuous technologies. The water in the tank is heated by the addition of steam to the tank. Unlike tubular or screw conveyor blanchers, tank blanchers are not amenable to automatic operation.
Tank blanchers are less efficient than other technologies with only 25%-30% of the energy actually transmitted to the product. The loss of uncondensed steam accounts for the inefficiency of tank blanchers because much of the injected steam is vented before it is completely condensed in the tank water. Because food blanching requires fairly specific temperature and retention times, measures to optimize the retention of steam energy in the tank are limited.