Lj | py Dl/Citrus ,TE PI AMr wr UNITED STATES DEPART^NT OF AGRICULTURE Z WAR!) Bureau of Entomology and Plant Quarantine Washington, D. G. B. E. P. Q. 506. J~' U> SUGGESTIONS ON TREATING CITRUS FRUITS 3Y kSTHODS PRESCRIBED IN CIRCULAR B. E. P. Q, 505 Circular B. E. P. Q. 505, which provides for the shipment of oranges and grapefruit from Puerto Rico to the mainland on the oasis of heat or cold treatments, makes no specifications as to methods or equipment required. 1. Heat treatment Available information with respect to the high-temperature treatment clearly indicates that by the application of dry heat the required tempera- ture, cannot he reached without injury to the fruit. Experience has also shown that temperatures much above 110° F. may have injurious effect on the fruit. It is important therefore that the temperature he held very close to 110° F. and that it at no time exceeds 11?° F. In successful treatments live steam as the source of heat was applied in such a manner as to secure a uniform distribution of steam-heated air introduced into the treating chamber so that it did not discnarge directly on the fruit. Uniform and gradual heating of the fruit to the required temoeratures was found necessary for the best results. A good method is to increase tit air temperature with the fruit temperature, gradually raising 0« F. as the fruit temperature rises. In treating rooms Properly equipped and operated commercial quantities of fruit can be heated to .he nrescrib-d temperature of 110° F. in not more than S hours, and this fruit fempTrature maintained for the required period by using air at a temperature not exceeding 110° F. and at a relative humidity of 100 percent. After treatment the fruit should be well cooled before being packed. If fruit is to be colored by the use of gas, this should be done prior to treatment. Wax or paraffin should not be used on fruit either before or after treatment. 2. Cold tr-atment. In cuccessful treatments employing low temperature, experience has shown naisati factory cooling can be accomplished in_ cold storage chambers onlTwhen the chambers are provided with adequate refrigeration and Positive, uniform circulation of the refrigerated air. In cold-storage rooms properly ^ped and operated it is possible to cool the fruit to the required tem- perature and maintain this temperature with variations of 2 F. oi lea*. Attention is called to the fact that Puero K^trato^Kl^r^ shipment to the mainland under the provisions of circular B *. P. q. W tinted under supervision of a plant quarantine inspector of the Department of l^fcSturf in pfanls approved "for the purpose by the Bureau of Entomology and Plant Quarantine. ^ A> gm^oNG ( Chi ef , Bureau of Entomology and Plant Quarantine. 3 1262 09312 1720