VEGETABLE AND FRUIT DEHYDRATION 



25 



used peelers for root products are the abrasive, brine, flame, lye, and 

 retort peelers. Brief discussions of the units are presented below. 



Abrasive peelers. — Abrasive peelers are suitable for processing all 

 root vegetables and are generally divided into two groups, the batch 

 or bucket type and the continuous. The first consists essentially of 

 a cylindrical abrasive-lined drum having a revolving abrasive bottom 

 or floor plate, and is provided with water sprays. A side door facili- 

 tates removal of peeled product. When in operation, the product is 

 dumped into the drum and the revolving floor plate jostles the vege- 

 tables, causing them to be thrown against the sides and bottom until 

 all surfaces are rubbed smooth and the skin removed. The flow of 

 water flushes the finely divided skin through a waste opening in the 

 bottom. Naturally the operation must be continued until all pro- 

 tuberances are ground away if the valleys, eyes, and imperfections are 

 to be removed (fig. 10) . , __ ->^ 



Figuee 10. — Batch-type abrasive peeler. 



The continuous abrasive peeler works on a slightly different prin- 

 ciple (fig. 11). The product passes in a circuitous course among and 

 over the rotating abrasive cylinders. Water sprays flush waste ma- 

 terial away. The rate of feed determines the retention period in a 

 peeler of this type. 



Skill must be exercised in determining the proper degree of abrasive 

 peeling. If the product is retained for a relatively short time, only 

 partial peeling will be accomplished. Excessive retention will result 

 in excessive waste. Since the weight of the product governs the pres- 

 sure at the region of contact, the rate of peeling will vary according 

 to the size and shape of the product. Flattened, pieces which refuse 

 to roll may be entirely ground away. 



If hand peeling is depended upon to finish the semipeeled product, 

 a balance must be struck between the cost of hand peeling and the cost 

 of raw material. As machine peeling is increased, the waste of flesh 

 underneath the skin increases, but the amount of hand peeling required 

 becomes less. 



As previously pointed out, products of different sizes peel at different 

 rates, and if peeling is to be accomplished at maximum efficiency, 

 grading is necessary. Plants operating on potatoes have experienced 

 as low a recovery as 60 percent (40 percent peeling and trimming loss) . 

 At best the peeling and trimming loss with abrasive peelers and hand 

 finishing will be in excess of 20 percent. 



The abrasive peeler is being replaced in a large number of plants 

 by more efficient peeling methods. In general the field in which 

 abrasive peelers are best suited comprises relatively small and inter- 



