Bulletin 135, Utilization of Cull Citrus Fruits


should be used, and cold storage if possible, the entire contents
of the bottle to be used soon after opening.
 An oil practically identical with orange oil was obtained
from grapefruit peel, but the yield was very much smaller.
 In connection with the manufacture of oil, the method of
peeling the fruit becomes an important factor. So far as Mr.
McDermott's investigations went, the most practical solution of
the problem seemed to lie in the employment of a number of
boys provided with knives of a special design (see page 23 of
the booklet The Juicy Joys of Florida Fruits" published and
distributed by the Florida Citrus Exchange). In considering
the production of orange oil, attention is called to U. S. Depart-
ment of Agriculture Bulletin No, 399, by Hood and Russell, on
this subject.

 Ill. THE PREPARATION OF ALCOHOL

 Since orange juice contains from 8 to 10 percent of easily
fermentable sugar, it is a good source of alcohol. While it
would probably never pay to use for this purpose fruit which
was fit for human food, still the drops and decayed fruit could
be used for the manufacture of alcohol.
 Several experiments were made on the fermentability of the juice. In
the first experiments about 5 or 10 liters of juice were neutralized with
calcium carbonate, heated in a retort to the boiling point, small amounts oa'
magnesium sulphate and potassium phosphate added, and the juice boiled
rapidly for about fifteen minutes. The juice thus sterilized was cooled to
room- temperatue, inoculated with bakers' yeast at the rate of 20 grams
per liter, and allowed to ferment for from three to six days. The alcohol
was then distilled and about 1 liter of crude spirits was collected from 5
liters of original juice. This crude liquor was then redistilled several times,
using a Glinski distilling column, until a concentration of 94%( by volume
was reached. In several runs the fruit used was badly spoiled, but the yields
were always essentially the same, viz., about 50% of the sugar orig-
inally present. This is as good as is ordinarily obtained in the manufacture
of alcohol. A mixture of orange and grapefruit juices fermented and yielded
alcohol just as well as did either juice separately.
 Further experiment showed that it was not necessary to neutralize the
acid of the juice before fermenting, altho the fermentation process was
somewhat slower than in neutralized juice. The addition of the salts above
referred to is also unnecessary.
 When whole, unpeeled fruit is used for making alcohol it is necessary
to get rid of the oil of the peels since the presence of the oil greatly depresses
fermentation. This, however, is accomplished by the initial boiling to
sterilize the juice before inoculating.