Florida A-gricult'ral Experiment Statiou


 After it was discovered that discoloration of the juice could
be prevented by replacing the air with a non-oxidizing gas, it
was thought that the same result might be accomplished by
sealing the juice in a vacuum. Laboratory experiments, using
small glass sealing bottles, indicated that this was the case.
Afterward a small apparatus was arranged by means of which
samples of juice could be sealed in vacuum in ordinary glass
containers. A number of jars of orange juice were sealed in
this way and for the most part they kept quite well.
 Altho the work thus far reported showed clearly that the discoloration
uf citrus fruit juice could be prevented by excluding oxys'en, it still failed
to show the exact cause and nature of the discoloration. In order to throw
further li'ht on this question many other experiments were carried out.
Various combinations of orange juice and orange-juice constituents were
prepared in different ways and treated by different methods. The effects ol
a large number, of chemicals and artificial preservatives were investigated.
Hydrogen peroxide in considerable quanttities did not entirely prevent dis-
coloration or fermentation. Sodium benzoate (0.1', ) preserved the jinia:
quite well; some fermentation occurred. however. Salicylic acid ,,.l',
produced sterilization but did not preserve the color. The same was true i,
chloroform and formic acid. Formaldehyde I 0.1';) preserved both sterility
and color, but is, of course, objectionable. Toluene. acetone, and thymol all
failed to prevent darkening. Hydrofluoric acid and sulphur dioxide 1;oth
preserved the juice quite well, altho darkening' was not entirely prevented.
Increasiing- the amount of citric acid did not have any effect; neutralizini-
the acid did seem to prevent darkening' in some cases, iut juice rendered.
alkaline darkened rapidly.
 Considering' all of the evidence available it seems quite probable that thI
darikeniinL is the result of autoxidation, possibly as the result of some enzitme
action, in sterile solution, of some normal constituent of the orange juice.
 A few experiments were made in an attempt to discover a method ol'
cold sterilization other than by using chemical antiseptics. The methods
tried consisted of treatment of the juice with ultra-violet light and with a
weak electric current. Neither of these methods, however, gave satisfactory
results.
 (R) THE (CON)CNT'IR'ATED .11 I1CE
 Experiments were next undertaken along the line of con-
centrating the juice. In general there are two methods for
accomplishing this, by vacuum evaporation and by freezing out
the water. Mr. McDermott's work was confined to the evap-
oration method.
 After preliminary trials with various types of vessels some
experiments were made in the laboratory of the J. P. Devine
Co., at Buffalo, N. Y. Here it was found that using a vacuum
of 27.5 to 28 inches and a temperature of only 50WC., in a
steam-jacketed copper pan, as much as 3.5 gallons of juice to