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BULLETIN 3 3, PORTO RICO EXPERIMENT STATION 



on the rind. Coloring is greatly retarded by washing the fruit in 

 soapy water, or by running it over the polishing brushes, during 

 which process some of the oil cells in the rind may be ruptured. 



Before it is packed the fruit is soaked in water usually containing 

 some detergent, after which the extraneous matter is removed by 

 brushing machines. The surface of the rind is often covered with 

 various scales and scale-destroying fungi and also with dust and 

 spray residues. This covering when dense is very hard to remove. 

 Of th e many different soaps, emulsions, and soap powders tried at 

 the station for the purpose, a soft soap of the nature of shaving 

 cream when mixed with water to the consistency of lubricating oil 

 was found to give the best result. 



After the fruit is washed and polished it is sized by mechanical 

 sizers and graded by hand according to color and blemishes. For 

 the latter kind of work standards of comparison have been generally 

 agreed upon by the growers, but the agreement is not always ad- 

 hered to. 



Attack by decays such as blue and green molds and stem-end rot, 

 which follow injury to the fruit, may of course be prevented by 

 careful handling of the fruit so as to avoid bruising, by keeping it 

 cooled to a temperature of 40° F., and transferring it directly from 

 the refrigerator to an insulated, refrigerated hold of the steamer. 

 Infection takes place in fruit the rind of which has been torn, 

 especially when the fruit is placed in a hot. moist atmosphere such 

 as prevails in the coloring room or in the hold of a nonrefrigerated 

 steamer. The paper in which the fruit is wrapped inhibits evapora- 

 tion and moisture conditions then favor fungus growth regardless 

 of where the fruit is stored. The fruit should be thoroughly dried 

 to eliminate as much moisture as possible from around the calyx. 

 Fruit which is well dried and kept in dry air is not nearly so likely 

 to decay as is that which is wrapped and packed. However, since 

 wrapping and packing are necessary and since infection is induced 

 by high respiration, the only remaining remedy is refrigeration. By 

 means of refrigeration both respiration and the vitality of the fungus 

 are greatly lessened. 



Infection is likely to take place at any time between picking and 

 refrigeration, and this period should therefore be shortened as much 

 as possible. This matter seems to be understood by growers, and a 

 modern precooling plant has been erected on the steamship wharf 

 in San Juan. After the precooling system is put into practice brown 

 spotting or cold-storage pitting of the rind may become a problem. 

 However, it will not be serious unless the fruit is held at 40° F. or 

 below for some time and can be partly prevented by careful han- 

 dling. Spots always develop on parts of the rind which has been 

 slightly scratched or squeezed. 



SUMMARY 



In a study made of the present practice of citrus growing in Porto 

 Eico the origin of some of the methods now in use are traced and 

 those giving promise of best results are discussed. Operations for 



