THE CLARIFICATION OF FRUIT JUICES. 8 
chemistry. It is known that the specific flavor of a fruit juice is 
determined in part by the ratio borne by one of the colloids (tannin) 
to the acid and sugar content and in part by very imperfectly known 
and complex constituents which are probably in the colloidal condi- 
tion. While many of the pigments which give juices their color are 
crystalline substances, others are either colloids or closely associated 
with colloids. In order that a juice may be clarified without reducing 
its value as a beverage, these constituents must remain unaltered by 
the treatment, which must at the same time completely remove from 
the liquid other colloids, including pectins, gums, complex carbo- 
hydrates, and nitrogenous bodies. The methods which may be em- 
ployed to make such a separation are greatly restricted by the condi- 
tions, and the preservation of desirable constituents is more difficult 
than the removal of the undesirable ones. This is especially the case 
in devising methods which the small producer without special equip- 
ment can use, 
For these reasons, the literature dealing, both from the theoretical 
and from the practical point of view, with the clarification of such 
colloidal solutions as are encountered in brewing, wine making, and 
sugar manufacture was examined for suggestions as to possible lines 
of attack, and considerable time was spent in determining the appli- 
eability to the problem in hand of methods used in these industries. 
No attempt to review this enormous literature will be made, but it 
may be of interest to state the unsatisfactory or negative results ob- 
tained in attempts to utilize some of these methods before describing 
the method found most effective. 
METHODS OF CLARIFICATION GENERALLY EMPLOYED. 
The methods of clarification employed by wine makers and brewers 
and in sugar manufacture may be grouped broadly into three classes: 
(1) Those in which the colloid is destroyed by the use of enzyms; 
(2) those which bring about by chemical treatment the formation 
of a precipitate which “envelops” and carries down suspended ma- 
terial; and (3) those in which the colloid is removed by adsorption 
upon insoluble, chemically inert adsorbing agents. 
CLARIFICATION BY MEANS OF ENZYMS. 
The Wallerstein (10, 27, 28, 29)* process for the prevention of the 
development of cloudiness, or “ haze,” in bottled beer when placed 
upon ice prior to serving is an instance of the first treatment. Ac- 
cording to the results of Brown’s extended investigations (4), the ap- 
pearance of “ haze” under such conditions is due to the presence in 
‘Serial numbers (italic) in parentheses refer to ‘ Literature cited’’ at the end of 
this bulletin. 
