20 BULLETIN 1367, U. S. DEPARTMENT OF AGRICULTURE 
tons the fruit should be colored at a lower temperature, between 70° 
and 80° F., with a slightly lower humidity, about 85 per cent, which 
will keep the fruit from appreciable shrinkage and still insure the 
retention of the buttons. The same holds true for oranges. If it 
is desired to retain the buttons the fruit should be colored slowly 
and at a.temperature of about 70° to 80° F.; if a fruit is known to be 
liable to stem-end rot and it is desired to remove the buttons it can 
be accomplished by coloring it at a higher temperature and with 
a high humidity. At a temperature of 70° to 80° F. and a humidity 
of 85 per cent, it will require about three days to bring Parson 
Brown oranges showing some color when placed in the room to 
nearly full color, whereas at high temperatures the same results can 
be obtained in a somewhat shorter time. In these recommendations 
it must be remembered that the time element is not exact, as much 
depends upon the condition of the fruit when placed in the room. ° 
If the fruit shows no yellow color on the surface, it takes consid- 
erably longer to bring it to a full golden yellow than if the yellow 
color shows through the green on the fruit. Late Valencias are some- 
what harder to color than grapefruit or early varieties of oranges, 
and in our experiments it has been found that it requires about 70 
to 96 hours to color this fruit if the temperature is held around 90° 
F. with a humidity of about 85 per cent. Removing the buttons 
from Florida fruit is to be recommended in most cases, as there 
seems to be no doubt that this treatment will considerably reduce the 
occurrence of stem-end rot in transit or on the market. Produce 
dealers may raise some objection to this practice, because fruit with 
the buttons removed is regarded as “ drops,” fruit which has fallen 
from the tree, the shipping of which is, of course, not practiced to 
any extent. But if it is shown that fruit is less liable to decay with 
the buttons removed, the trade will: adjust itself to these conditions. 
In the coloring of oranges with gas, it is important that the 
burners of the stove be so arranged that they give off a large quan- 
tity of gas with as little heat as possible. Two burners, properly 
regulated, should furnish enough gas for the coloring of a carload 
of fruit. Care should be exercised to see that the humidity is as 
nearly constant as possible, and various methods of humidifying the 
room can be used, as, for example, sprinkling the floor of the color- 
ing room with water, dropping water into the intake of the fan, or 
forcing the gas through a humidifier. Very good results were ob- 
tained in these experiments by simply dropping the water into the 
intake of the fan. One very important consideration is that the 
temperature of the room should not be allowed to go above 90° F., as | 
there would then be danger of injury to the fruit. Low temperatures 
can be obtained more easily in insulated houses with the gas-generat- 
ing apparatus in a separate building at some distance from the house, 
conducting the gas through buried pipes to the coloring room. If 
precautions are taken to keep the proper temperature and humidity 
and to supply the right kind of gas to the coloring room, no difficulty 
should be experienced in successfully coloring oranges, tangerines, 
or grapefruit. - : 
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