Florida Agricultural Experiment Station


 IV. THE PRODUCTION OF CITRIC ACID
 It does not seem probable that oranges or grapefruit can
successfully compete with lemons and limes as sources of citric
acid. However, it is known that certain Penicillium-like molds
of the genus Citromiyces possess the ability to convert sugar
into citric acid when grown under proper conditions. In fact,
it appears that this process was at one time actually used in
Europe for the commercial production of citric acid.
 In view of this it seemed possible that the Citronices organisms might
be grown in orange juice with a consequent increase of the acid content.
Experiment proved this to be the case and some work was undertaken along
the lines of (1) hastening the rate of growth and production of acid; and
(2) treating the medium so as to prevent the invasion of foreign organisms.
The work along the first branch was quite unproductive of results; no salts
or other agents were found which could markedly increase the rate of
growth. Along the second line some success was obtained; it was found 7hat
the Citromyc'.cs molds will grow in a medium containing 6', of sea-salt, u f-
ficient to inhibit the growth of most bacteria and many molds.
 It cannot be said that this offers more than a mere possi-
bility from the commercial standpoint and it seems far better
to allow the production of citric acid from natural sources to
be restricted to those regions where lemons and limes are raised.
It should be stated, however, that in the event of the manufac-
ture of alcohol from waste juices, the spent beer from the still
might be worked up for the recovery of the citric acid originally
present in the fruit juice.

 V. UTILIZATION OF THE WASTE PULP, SEEDS AND PEEL
 No experimental work along this line is reported by Mr.
McDermott, but from theoretical considerations he concluded
that the refuse might have considerable value as a fertilizer or
as a stock food.
 MR. McDERMOTT'S CONCLUSIONS
 1. It is possible to preserve orange juice for at least
eighteen months, and probably indefinitely, by pasteurization in
the absence of air (oxygen).
 2. The juice may be concentrated to about twenty percent
of its original volume by vacuum evaporation, after proper clar-
ification, the concentrated product flavored with orange extract,
and packed and preserved in the same way as the fresh juice.
 3. The same facts as represented in 1 and 2 and true for
the juice of the grapefruit.