COMMEECIAL CANNING OF FOODS. 65 



can not be kept in the open ■uithout shrinkage and can not be marketed like white 

 potatoes; therefore cannino; is used to extend the season throughout the year. There 

 are two varieties canned, the yellow or Jersey type, grown extensively in New Jersey, 

 Delaware, Maryland, and Vii-ginia, and the whiter or southern type, grown in the 

 South. The former is preferred in most markets, owing, in part, to the better appear- 

 ance, the color being a clean yellow. The southern type is sweeter but inclined to 

 turn a rather dark, dead color and to become slightly watery. 



When the potatoes are received at the factory they are graded roughly for size, 

 those more than 1} inches in diameter being placed in separate boxes so that they 

 may be given a heaA'ier cooking without overcooking the smaller ones. They are next 

 washed, after which they are placed in crates, the layers not being more than 6 inches 

 deep. The crates are then run into retorts and the potatoes given a steaming at 240° F. 

 for from 9 to 12 minutes, depending upon their size and the length of time they have 

 been out off the ground. The object is twofold, to heat the skins so that they will 

 come off easily and to partially cook the potato before it enters the can. A quick, high 

 heat applied for a short time A^dll loosen the skin much better than a low temperature 

 applied for a longer time. The peeling is done as soon as possible after the potatoes 

 are taken out of the retorts, and, if the work has been well done, the peel is slipped 

 off by squeezing between the fingers and not by cutting or scraping. The fresher the 

 , potatoes are from the ground the less steaming will be required, and also the less waste. 

 Potatoes held for several weeks or allowed to dry in the air will show double the waste 

 of those freshly dug. Peeling is also done by the lye process, such as is used for 

 peaches, and is successful on the freshly dug product. In addition to the spraying 

 they are \dgorously brushed by revolving brushes, but there is always need for some 

 hand trimming. The skin is also removed by means of the abrading machines used 

 for white potatoes; these potatoes need hand trimming, as the machine does not 

 rub in the creases and depressions. After preparation by lye or machine the potatoes 

 are given a preliminary cooking to soften them before being packed in the can. 



The potatoes are rushed from the peelers to the filling tables so that they may be 

 placed in the cans while still warm. Little attention is paid in filling to layering 

 the potatoes in the cans, the object being to fill closely and then heap on a sufficient 

 amount so that, when pres.sed down, the interstices will be filled. They are packed 

 either wet or dry, the latter method being preferred. Some packers in putting up a 

 "solid pack" add about an ounce of water to the can so that sufiicient steam will be 

 generated to prevent oxidation or darkening. The addition of any water is unneces- 

 sary, and, a.s sf)on as packers learn how to handle this product, it is probable that 

 the practice will cease. The filling should be strictly by weight, as that is the only 

 method of securing a uniform fill. 



As soon a.s poasible after filling, the potatoes should be given a thorough exhaust. 

 The usual steaming for 3 minutes is insufficient, as the outside only is heated and the 

 inside may be nearly cold. Cans examined in coming from the exhausts may show 

 a temperature of 135° F. on the outside and top and only 70° or 80° in the center. 

 As the heat penetrate.s the potato very slowly, a second heating in the retort or from 

 12 V) 18 minulo.s in the exhaust box is not unreasonable. If well heated the cans are 

 not likely to bf; overfilled, a.s the expansion will be such as to cause a part to bo thrown 

 out before cap[)iiig. If the right quantity has been weighed into the can and th<! lid 

 lightly crimped on before exhausting, the contents will expand to fill all intersficcis. 

 The packers know that the ran must, be well filled to preserve the clear bright yellow 

 color, but if the exhau.sting is imperfect springers or flippers are almost certain to 

 roHult. The bane of a slack-filled can is darkening of color and of the overfilled can 

 in the Hpringer, the cfjrrection of both being proper weight and exhaust. The sealing is 

 done in the usual way, the general practice being to process for 3 hours at boiling heat 

 for No. 3 cans. Sterilization may also be securc^d by |)nK(!HHing at 2d0° F. for 70 niiii- 

 79258°— Bull, mi—lfj 5 



