Turn your crops into condiments and seasonings Part 6.2:
Peeling methods of ginger
P
eeling involves removing the skin, peel or other outer protective layers from fresh produce using manual or mechanical devices. Before further processing the ginger rhizomes are peeled. Peeling basic information: Almost all fruits and vegetables that are processed for dehydration in piece or fluid form must be peeled. Current peeling methods may be divided into steam peeling, knife peeling, abrasion peeling, lye peeling and flame peeling, and each of these peeling methods have characteristic advantages. Abrasion peelers: Although there are many types of peelers, one such type is used to remove the peel from root-type crops by abrasion. In this peeling the food product is tumbled and thrown against surfaces that have been coated with abrasive, while a spray of water washes away the loosened materials. Abrasion peeling may be used to good advantage, but must be properly operated and controlled for best results. Abrasion peelers have a lower water consumption than other peeling methods and are also very effective as a means of removing peel that has been previously loosened by chemical or heat pre-treatment. For this reason they are frequently installed in lines following flame, steam or lye peelers.
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Lye peeling: In peeling methods that involve the use of hot lye solutions, the following factors must be taken into consideration: a. control of the lye penetration for proper peel removal, b. provision against safety hazards, c. protection against corrosion, d. disposal of spend lye, e. removal of all lye from the peeled products, f. treatment of some products with diluted acid after lye peeling in order to prevent discolouration, g. provision for lye storage and makeup facilities The principle variables involved in lye peeling are: a. immersion time in the lye bath, b. temperature and concentration of the lye solution, c. the commodity characteristics such as type, variety, maturity and storage history The original lye-peeling methods used boiling or near-boiling lye solutions in concentrations just high enough to be effective. However, there are many advantages to using lower treatment temperatures: a. deep cooking of the outer tissue is reduced or eliminated, yields are higher and ‘heat rings’ are avoided,
b. heat losses and evaporation from the lye bath are reduced, c. hazards of boiling, splashing, leaking, overflowing and dripping are reduced Lye peeling is suitable for almost all root vegetables, as well as some fruit, and may be performed in batch-type or continuous operations. Batch peeling is mostly used in relatively small operations and is performed by dipping baskets of the food product in a hot lye bath for a predetermined time and then washing off the loosened peel and the residual lye. Continuous lye peeling equipment can be used with any scale of operation. The rotary peeler consists of a perforated steel drum fitted with internal vanes that form pockets, rotating partially submerged in hot caustic solution. The drum itself is enclosed within a concentric shell in order to keep the food product confined while the drum rotates. The food product enters he drum pockets from an overhead or side chute, moves with the drum through the lye solution, and is then carried upward to the discharge chute. A steam coil in the tank keeps the lye solution hot, or alternatively the lye solution is circulated through an external heat exchanger. The drapertype continuous peeler is made up of a long, narrow tank equipped with a metal wire-mesh belt, which conveys
ProAgri Zambia 59
