124 MISC. PUBLICATION 5 4 0, U. S. DEPT. OF AGRICULTURE 



double overwrapping of paper with a basic weight of 20 pounds plus 30 pounds 

 of wax per ream. These are packed in solid fiber cartons. 



Type 8. — This is one of the optional soup packages and resembles a cereal 

 container. It consists of an interlining bag of amber glassine with 30 pounds of 

 wax per ream and an outer carton of bending chipboard. The carton is double, 

 overwrapped with paper that has a basic weight of 20 pounds and is coated 

 with 30 pounds of wax per ream. 



Type 9. — In normal times and when hazards are not severe, evaporated apples, 

 dried prunes, apricots, and figs are exported in paper-lined wood boxes containing 

 25 pounds net weight, and dates are shipped in flat boxes containing 15 pounds. 

 Domestic boxes hold 10, 25, and 50 pounds of dried fruits. Uncut fruits, such as 

 prunes, raisins, and apricots, are graded into, various sizes, which are packed 

 separately. Federal packaging specifications are available for most dried fruits. 



Type 10. — Dried fruits are shipped abroad for the armed forces in No. 10 cans, 

 hermetically sealed, and sometimes evacuated. Evaporated or dried apples, apri- 

 cots, pitted dates, figs, peaches, prunes, and raisins are packed at rates varying 

 from 4 pounds per can for evaporated apples to 7 pounds per can for prunes and 

 figs. Six cans are packed in each wood case. 



PACKAGING EQUIPMENT AND METHODS 



After final inspection and culling, dehydrated vegetables and fruits 

 are packaged. If they are to be powdered, a hammer mill will be 

 needed, and also a dehumidifier if the atmospheric humidity in the 

 room is high. Vibrators are often used in packing to produce a higher 

 bulk density. A simple type consists of a low platform, set diamond- 

 shaped with the pivot placed diagonally. Strips along the two back 

 edges form a stop for the cans. Power is supplied by a y s -horsepower 

 motor operating at a few hundred revolutions per minute. An ec- 

 centric is mounted on a low-speed shaft and this is connected to the 

 back corner of the platform by a rod. In another type, a spring- 

 mounted platform is vibrated by a cam in the motor shaft. The vi- 

 brator can be equipped with a weighing scale. Weighing scales 

 should have a 50-pound range, an attachment for indicating the 

 amount over or under, and a tare weight. 



Gassing is required for cabbage or carrots that are to be sold under 

 Government contract (fig. 61). Flavor, color, and vitamins are 

 retained through the elimination of air and its replacement with ni- 

 trogen or carbon dioxide. Vacuum packing is not used because 

 5-gallon cans require a very solid fill if they are to be sealed under 

 vacuum. A maximum limit of 2 percent of oxygen is recommended 

 for sealed, gas-filled containers, and the analysis should be made at 

 least 12 hours after the cans are filled and sealed. Air can be dis- 

 placed to a point at which the oxygen content is below 2 percent by 

 the use of (1) the cylinder-and-meter method, (2) the vacuum- 

 chamber method, or (3) the carbon-dioxide-snow or "dry ice" method. 

 Equipment and methods for the analysis of atmosphere in cans are 

 described on page 157. 



Cylinder-and-Meter Method 



The most common method of removing air has been by the use of gas 

 run from a cylinder through a reducing valve, a rubber tube, and a 

 metal purge tube thrust to the bottom of the can. The amount of 

 gas is controlled by the pressure setting of the reducing valve, the 

 duration of the gas flow, and the occasional testing of the gas at the 

 top of the can with a burning match. If the match goes out, the can 

 is considered to be sufficiently low in oxygen content. While this 



