Florida Agricultural Experiment Station


 Series N: Jan. 8, 1912.-Juice was heated to 60C. in an open vessel
in a current of CO2, cooled to 10C. in this gas, bottled in it, and pasteurized
at 600C. for 30 minutes. This series kept very well.
 Series S: Jan. 19, 1912.-Juice was first warmed to 55'C. and cooled to
10C. in a hydrogen stream, in bottles. Pasteurized for 30 minutes at 60"C.
The specimens kept quite well, altho darkened slightly. Taste rather better
than with CO, specimens.
 Series U and V: Feb. 8 and 9, 1912.-These two series contained juice
of the same lot of oranges, but in series U all air was replaced by CO2, while
series V received no gas treatment. Both sets were pasteurized at 63 to
65C. for one hour on each of two successive days. Series U kept all right
while Series V began to darken 13 days after pasteurization and later de-
veloped the full discoloration characteristic of juice pasteurized in air.
 Series W: Feb. 27, 1912.-Juice was saturated with CO0, but was
pasteurized (at 70 to 75C.) in bottles from which the residual air had not
been displaced. Darkening was complete in a month.
 The specimens of preserved juice were not kept under any
special conditions of light or temperature, but they retained
their appearance and taste unimpaired for over 18 months and
gave every indication of being permanent. When large bottles
of juice were pasteurized it was found best to heat for the full
30 minutes.
 While most of the work was done on orange juice, it was
found that grapefruit juice was subject to the same sort of
discoloration and change of flavor and that the same measures
could be used to prevent it.
 Some study was also made of the flavor of juice expressed
from whole, unpeeled fruit, using a press which crushed the
peels considerably. The presence of a certain amount of flavor-
ing from the peel adds greatly to the pleasant taste of orange
juice. It was found that the most desirable flavor was obtained
by leaving about one-tenth of the oranges unpeeled. In the
case of grapefruit, however, it is necessary to peel all of the
fruit on account of the bitter glucosides contained in the peel.
 One difficulty in all of the work with citrus fruit juice arose
from the fact that whenever the juice came in contact with iron
it attacked the metal and acquired a bad taste from it. Ex-
periment showed that tin, copper, bronze, brass, nickel, and
even silver were attacked with a similar result. Solid aluminum
proved to be the most satisfactory metal to use for pans and
other apparatus for which it is mechanically suitable. Altho it
too is acted upon by the juice to some extent, it is tasteless and
harmless in the small quantities which dissolve. Glass, por-
celain, and enameled ware are also suitable for use in handling
citrus fruit juices.