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



good absorption and will permit the use of relatively dilute solutions. 

 This method has a disadvantage in that excess solution will continue 

 to drain from the trays as they are stacked and may lead to variations 

 in sulfite content between the upper and lower trays and, with wood 

 slat trays, to staining unless the trays are new or very carefully 

 cleaned. 



It appears that objections to spraying before or after blanching can 

 be overcome by application during the blanching process. In this 

 way the partially blanched cabbage absorbs the sulfite efficiently and 

 the product is discharged from the blancher with an essentially dry 

 surface, so that no draining from one tray to the next lower results. 



Blanchers and raw stocks of cabbage vary so much that it is impos- 

 sible to give a detailed procedure that can be applied under all condi- 

 tions with equal effectiveness. In general the spray should be located 

 at a point one-third to one-half the length of the blancher from the 

 entrance end. In long blanchers (50 feet or more) best results have 

 been obtained by installing the spray at one-third of the way. In a 

 20-foot blancher best results have been obtained by placing the spray 

 at the midpoint. The best location is apparently critical and should 

 be determined by trial. 



In order to obtain good coverage and uniform results in spite of 

 unavoidable variations in tray loadings, it is necessary to apply the 

 spray at a rate that will result in some run-off. A rate of 5 to 10 gal- 

 lons of solution per 100 pounds of trayed cabbage is recommended. 

 Various types of sprays can be used, such as single or multiple (3 or 4) 

 pipes extending across the blancher at right angles to the direction 

 of belt travel and a few inches above the cabbage, drilled with % 2 - to 

 % 2 -inch holes about 1 inch apart. Still another type consists of a 

 single transverse pipe with the holes so drilled that the jets play 

 against the roof of the blancher and the solution is splattered out 

 rather uniformly over the product. At present it is not known which 

 type is most effective. 



The sulfite solution is conveniently supplied to the sprays from two 

 wood or concrete tanks of such size that each will carry enough for 

 an 8-hour shift. On this basis 3,500-gallon tanks should easily supply 

 a plant with 50 tons of daily capacity. The second tank is used in 

 making up fresh solution to desired strength while the first is in use. 

 Each tank should be equipped with a mixer that will give vigorous 

 stirring without beating air into the solution. The tanks should be 

 set at a level that will supply a minimum head of 12 feet, or if this 

 is not practicable a pressure pump must be provided to deliver the 

 solution to the sprays. 



Control of the sulfite content of the dehydrated product is effected 

 by adjustment of the concentration of the sulfite in solution. For 

 cabbage the required concentration will usually lie within the range 

 of 0.15 to 0.30 percent, calculated in terms of S0 2 , depending upon 

 cabbage variety, blancher, and dehydrator conditions and perhaps 

 other variables. Either the normal sodium sulfite or mixtures with 

 sodium metabisulfite can be used. At present the influence of pH 

 of the applied sulfite solution on product quality is inadequately 

 understood. From the corrosion standpoint it is advisable to use a 

 predominant amount of the normal salt to keep the pH at 7 or above. 

 Moreover, with green varieties of cabbage better color results when 

 the more alkaline solutions are used. However, alkaline sulfite solu- 



