Buelltin 135, Utilization of C'll Citrus Fruits


cause. At the same time it is quite possible to go to the other
extreme, especially when the plant is just getting started, and
attempt to manufacture a greater vaNriety of products than can
be successfully handled.
 AMr. ?McDermott's investigations fall naturally under four
main heads. They are:
 L The Preservation of the Juice:
 (A) In its natural concentration;
 (B) Concentrated;
 (C) Dry.
 II. The Preparation of Oil from the Peel:
 Extraction, expression, and distillation.
 III. The Preparation of Alcohol.
 IV. The Preparation of Citric Acid.
 The work done on these various problems will be taken up
in order.
 1. PRESERVATION OF THE JUICE
 4A) 'Il'HE .III<CE I;N TITS X 1 t i l ( CONCENT'l'IiATION
 It has long been known that the preservation of orange juice
 in a permanent and palatable form is a difficult proposition. A
 great many fruit juices can be preserved by simple pasteuriza-
 tion at low temperature, but this is not sufficient for orange
 juice. Orange juice which was pasteurized, at either high or
 low temperature, usually kept only a few weeks before it turned
 dark in color and acquired an offensively acrid taste, and where
 high temperature was used there was the additional disadvan-
 tage of an unpleasant cooked taste. Since this cooked taste
 could be avoided by using less heat, the problem resolved itself
 into finding the cause and means of prevention of the discolora-
 tion.
 At first heat resisting micro-organisms were suspected and
 many experiments were made to isolate and identify them.
 Bouillon and gelatin media were inoculated with juice which had
 darkened after pasteurization and also with juice immediately after pas-
 teurization. As a general rule 'rowths were not obtained with specimens
 of juice which has been heated to GOC. or above; in one or two isolated
 cases, bouillon cultures showed the presence of the species of wild yeast
 a strain of Willian anomala-which grows regularly on untreated orange
 juice and which is responsible for the development of the perfume-like "
 odor which is noticed about orange juice after it stands some hours with-
 out treatment. The organism was constantly present upon oranges and
 was probably always present in the air of the room, to some extent, and
 its appearance thus in isolated cultures was most probably due to acci-
 dental infection.