THE CLARIFICATION OF FRUIT JUICES. 23 
the soluble pectin into a colloidal suspension may occur. Whatever 
the nature of the reaction, it is clear that it becomes complete within 
24 hours at temperatures approximating 40° F., and in a shorter 
period at higher temperatures, becoming complete in a few minutes 
when juices are heated to the temperature of pasteurization. Conse- 
quently, if juices are held in the settling tank overnight, or for 24 
’ hours if the temperature is low enough to prevent fermentation, and 
are then decanted, clarified, and bottled, no difficulty due to subse- 
quent clouding of the liquid in the bottles will be encountered. 
EXPEDIENTS TO SHORTEN THE PROCESS. 
Various expedients have been resorted to in the course of the work 
in attempts to increase the ease of filtration or to shorten the process 
by permitting clarification and bottling immediately after pressing. 
Some of these gave negative results and are mentioned only in order 
that they may be avoided by others; some are advantageous if prop- 
erly employed. 
HEATING THE JUICE BEFORE FILTERING. 
Heating the juice prior to filtration has many obvious advantages, 
chief among which are the precipitation of heat-coagulable constitu- 
_ ents and the lowering of the viscosity of the hquid thereby produced. 
Hot filtration, however, is of very definitely hmited applicability 
to fruit juices. It can be advantageously employed only for such 
juices as do not readily lose their characteristic flavors on heating and 
subsequent exposure to the air while hot. Such grape juices as those of 
Concord, Norton, Clinton, Clevener, Early Victor, Worden, Ives, Di- 
ogenes, Moore (Moore’s Harly), Cynthiana, Montefiore, and Niagara 
are not injured in quality or flavor by such treatment, which makes 
possible the usual commercial practice of crushing the grapes and 
heating to 175° F. in kettles prior to pressing. With all of these 
varieties excellent results are obtained by hot filtration. If the grapes 
are heated before pressing, the hot juice is taken directly from the 
press, thoroughly mixed with the earth, and immediately passed 
through the filter. If the grapes are pressed cold, the juice is at once 
heated to 165° to 175° F., mixed with the earth, and filtered. The 
juice obtained from any given variety by pressing cold is, of course, 
quite different from that obtained from heated grapes, but such juices 
are not injuriously affected by subsequent heating and hot filtration. 
This method of treatment can not be employed with apple juice 
or with the more delicately flavored grape juices without considerable 
loss in quality. Juices of such varieties of grapes as Agawam, 
Brighton, Barry, Catawba, Delaware, Diana, Goethe, Elvira, 
Eumelan, Isabella, Lady, Massasoit, Missouri Riesling, } Noah, Salem, 
