vegetable raw materials. This improves the appearance and taste of the final product. During peeling, peeling losses need to be minimised by removing as little of the underlying food as possible but still achieving a clean peeled surface.
|Field of application|
|Techniques, methods and equipment|
|a) Steam peeling|
|b) Knife peeling|
|c) Abrasion peeling|
|d) Caustic peeling|
|e) Flame peeling|
Peeling is applied on an industrial scale to fruits, vegetables, roots, tubers and potatoes.
pressure vessel and exposed to high-pressure steam (180-200°C). In the case of tomatoes, the temperature may be lower (120-130°C). The high temperature causes a rapid heating and cooking of the surface layer (within 15-30 s). The pressure is then instantly released, which causes flashing-off of the cooked skin.
The continuous steam peeler is a pipe with a screw inside. The steam is fed direct into the pipe (generally at lower pressure than the batch process) and the product is heated during the residence time (adjustable). Most of the peeled material is discharged with the steam. Any remaining traces are sprayed off with water.
fruit suffers little damage.
water sprays. A new development in caustic peeling is dry caustic peeling. The material is dipped in a 10 % sodium hydroxide solution. The softened skin is then removed by rubber discs or rollers. A drawback of caustic peeling is that it causes decolourisation of the product.