VEGETABLE AND FRUIT DEHYDRATION 35 



mg from the cutter to the blancher. This operation is usually ac- 

 complished by means of cold-water sprays over the conveyor leading 

 from the cutter. 



None of the cutting equipment mentioned above is suitable for pro- 

 ducing a riced product. Hieing equipment is usually one of three 

 types : namely, rotary, screw, or plunger. The essential action of each 

 consists of mashing the product and extruding it through perforations 

 of suitable size, not exceeding three-sixteenths inch in diameter. 



For ricing, the product is first thoroughly cooked, and best results 

 are usually obtained if the operation is carried out while the product 

 is still hot. If the product becomes cool, it may become pasty or 

 gummy, which will make it difficult to obtain a uniform spread on the 

 drying trays. * 



In the preparation of material for ricing, the precooking can be 

 carried out on the sliced, whole, halved, or quartered product. The 

 procedure using slices is probably best from the standpoint of prac- 

 tical operation and labor saving, since slicing can be accomplished 

 mechanically while halving or quartering is accomplished by hand 

 labor. Furthermore, slices can be cooked throughout, without over- 

 cooking the surface. Cooking the whole, halved, or quartered ma- 

 terial has the disadvantage of longer cooking time and additional 

 labor of size grading. It has an advantage over the use of slices in 

 that better retention of water-soluble material is obtained, since less 

 surface area is exposed to leaching action and oxidation. When 

 potatoes were sliced three-sixteenths of an inch and blanched in steam 

 for 4 minutes, the loss of ascorbic acid was 68.4 percent ; when they 

 were quartered and blanched in steam for 20 minutes the loss of as- 

 corbic acid was 23.5 percent. The cut product intended for ricing 

 can be precooked by means of flowing steam, boiling water, or steam 

 under pressure in a retort. Cooking in flowing steam or by steam 

 under pressure is preferred over the water cooking method since water 

 cooking may lead to excessive loss of water-soluble nutritive materials 

 from the product. 



Cooking in flowing steam can be accomplished by one of two meth- 

 ods. The first method consists of spreading the material on trays 

 and placing them in a cabinet or a retort into which live steam is 

 allowed to escape for the time required to thoroughly cook the mate- 

 rial. The second method consists of passing the prepared material 

 on a belt through a continuous steam blancher, as described for slices 

 or cubes. In this case, however, the retention time may be somewhat 

 longer than required in ordinary blanching in order to effect thorough 

 cooking. For the cooking of whole, halved, or quartered pieces the 

 cabinet or retort method is the most satisfactory, since the retention 

 time is so great as to make it impossible to handle a large volume 

 of material by the continuous method. Cooking with steam under 

 pressure has the advantage of shortening the retention time for 

 thorough cooking, and is especially useful for cooking whole, halved, 

 or quartered material. 



Regardless of the method, the cooking time will vary with a num- 

 ber of factors, such as type of vegetable, variety, maturity, and qual- 

 ity, size of pieces, rate of loading, temperature of the cooker, and 

 uniformity of heat distribution in the cooker. Because of these fac- 

 tors each operator must determine the cooking time by trial, the 

 criterion of adequate cooking being the production of a product 



