PRODUCTION OF SIRUP FROM SWEET POTATOES. 15 
and all decaying potatoes were removed. Very little decay, only 
from 1 to 2 per cent, was originally present, and this was almost 
entirely eliminated as the result of the inspection given. 
Pale distillers' malt of high diastatic power was employed. The 
kieselguhr which served as a filter aid was of California origin. 
Before being added to the mixing tank it was ignited at a low red 
heat in cast-iron pans in the fire box of the boiler. 
Labor. 
The labor force at the experimental plant, which was entirely 
adequate, consisted of one mechanic and two laborers. A run of 
crude sirup was usually made on two consecutive days. The next 
two days were then required for the finishing of the sirup. Thus in 
four 10-hour days approximately 140 gallons of finished sirup was 
produced. By running the apparatus at full capacity approximately 
200 gallons of sirup could have been produced, or an average of 50 
gallons a day. The mechanic received 40 cents an hour and the two 
laborers each 20 cents an hour. 
The authors acted as the supervising force in directing the opera- 
tions. In commercial practice a plant superintendent would be 
necessary. 
Method of Manufacture. 
A flow diagram of the method of manufacturing sweet-potato 
sirup (Fig. 11) shows the steps in the operation and the points at 
which steam and water were used. It also shows how the different 
materials were handled and at what points they were put into the 
operation. 
WASHING THE POTATOES. 
The sweet potatoes were given a visual inspection at the storehouse 
and all those showing signs of rot were rejected. As the potatoes 
were inspected they were placed in bushel crates. Upon the comple- 
tion of the inspection each batch of potatoes was hauled in an auto 
truck from the storehouse to the washer. 
The washed potatoes were placed in bushel crates. The action of 
the washer wore off the ends of the potatoes, thus effectively remov- 
ing the withered ends, a possible source of off flavor. 
The potatoes were weighed on the platform scales, four crates at a 
time, and were then carried to the mash tank. Approximately 50 
bushels of potatoes to a run or batch were used. 
-MASHING. 
The potatoes were leveled in the tank and the tank covers were 
closed. Live steam was then admitted at such a rate that gentle 
streams of vapor passed out between the upper edge of the tank 
and the covers. The condensate was allowed to drain off as fast as 
it formed through the gate valve, which was opened slightly for 
this purpose. This treatment removed from the outer portions of 
the potatoes certain extractives which if retained impart a dull green 
color and an off taste to the sirup. 7 One and one-half hours' steam 
7 Previous laboratory work (Chemical Age, 89 (1921) : 1511 had shown that the loss 
Of sweet-potato solids in the condensed water is very small. 
