COLORING CITRUS FRUIT IN FLORIDA 19 
standpoint. It has been shown in numerous instances that this 
coloring does not appreciably affect the chemical composition of 
the pulp or edible portion of the fruit. It is therefore important 
that only fruit which is palatable and attractive as an article of 
food should be colored. It is of course well known that a yellow 
or orange color is not necessarily associated with maturity in citrus 
fruits, and that many varieties under certain climatic conditions 
usually reach their best eating quality when their rind is still green 
in color. 
From the fact that the fruit does not change appreciably in chemi- 
cal composition during coloring, it is evident that it should have 
reached such a stage of development that it will pass the test for 
maturity provided by Food Inspection Decision No. 182 of the 
United States Department of Agriculture, 1921. In grapefruit “ the 
‘juice of the mature fruit contains not less than seven (7) parts of 
soluble solids to each part of acid calculated as citric acid without 
water of crystallization,” and for oranges “the juice of the mature 
fruit contains not less than eight (8) parts of soluble solids to each 
part of acid calculated as citric acid without water of crystalliza- 
tion.” 
The coloring of fruit which does not meet these requirements may 
be interpreted as an attempt to conceal inferiority and makes such 
fruit liable to seizure if shipped in interstate commerce without 
being specifically labeled. Careful observance of this regulation is 
very important from a marketing standpoint, as flooding the mar- 
ket with immature fruit may result in a decided reaction on the 
part of consumers against all citrus fruit from Florida. There is a 
legitimate field for the application of this coloring process in Florida 
to fruits which from a combination of varietal characteristics with 
climatic conditions do not assume the orange or yellow color com- 
monly associated with the ripe orange or grapefruit in the minds of 
the consuming public, but may remain green in color long after 
they have reached their best eating quality. If coloring is con- 
fined to these cases where it can be legitimately used it will be of 
considerable benefit in marketing, as it makes the fruit much more 
attractive and desirable in appearance, and by removing scale, makes 
it cleaner and easier to grade carefully. 
In the experimental work which formed the basis for this bulle- 
tin, it was found that grapefruit and oranges could readily be col- 
ored by the gas formed by the incomplete combustion of kerosene in 
oil stoves, by the exhaust from internal combustion engines, or by 
ethylene. Grapefruit colors more readily than oranges, and the 
early oranges, such as Parson Brown, seem to assume the character- 
istic golden-yellow color with less treatment than do the Valencias 
in the spring. In this work it was found possible to color grapefruit 
which showed sufficient yellow color through the green to be char- 
acterized as 10 to 20 per cent colored in 18 to 36 hours. Oranges be- 
ginning to show color required from 48 to 72 hours for the early 
fruit. It has been shown that during coloring the removal of the but- 
tons, or short ends of stem left on the fruit when it is harvested, very 
_ much reduces the decay from stem-end rot and can be accomplished 
_ with grapefruit by maintaining a temperature around 90° F. with a 
high humidity (85 to 90 per cent). If it is desired to retain the but- 
apie 
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