THE CLARIFICATION OF FRUIT JUICES. 25 



Experiments with grapefruit juice were made at three periods in 

 the life of the fruit, employing portions of the same lot of fruit. 

 The first samples of juice were made on receipt of the fruit from the 

 growers on November 9, the second on February 21, after the fruit 

 had been in cold storage for 104 days, and the third on May 2, when 

 the fruit had been in cold storage 174 days. The last lot of fruit had 

 reached the limit of its life in storage and was in bad condition; 

 pressing was difficult and the juice contained large quantities of pulp 

 with a reduced yield, but clarification involved no difficulties. The 

 treatment given the three lots was identical and the results were 

 equally satisfactory; hence, an outline of one experiment only will 

 be given. 



The fruit was peeled, freed from adhering rag as completely as 

 possible, passed through an apple grater, and pressed with a com- 

 mercial hydraulic press. The juice was placed in deep containers 

 and allowed to stand 18 hours for sedimentation to occur, after which 

 it was decanted from the sediment. A portion was bottled and pas- 

 teurized, to serve for comparative purposes, and the remainder di- 

 vided into portions of 10 gallons each. One of these was mixed with 

 diatomaceous earth and at once passed through layers of earth sup- 

 ported on cloths in the disk filter press used in experiments with ap- 

 ple juice. The filtration was rather slow, but the product was en- 

 tirely clear when bottled and pasteurized. The second lot was di- 

 vided into two parts, one of which was mixed with earth, heated in 

 an open vessel to 168° F., and filtered through freshly prepared earth 

 filter plates in the same filter. This filtered more rapidly than the 

 first lot, was equally clear, and showed no alteration in flavor. For 

 purposes of comparison the remaining portion was heated to 168° F. 

 without the addition of earth and filtered while hot through a closely 

 packed pulp filter. As the filtrate was turbid and opaque, it was 

 passed six times through the filter in an unsuccessful effort to im- 

 prove its appearance. All the lots were then bottled and pasteurized 

 in a hot- water tank at 168° F. for 30 minutes. Quart bottles of the 

 untreated juice threw down a heavy precipitate upon standing and 

 remained densely opaque after eight months' standing in a labora- 

 tory room. The juice filtered repeatedly through pulp while hot 

 deposited a less heavy but considerable precipitate and held in sus- 

 pension sufficient quantities of material to make the solution per- 

 manently opaque and tawny yellow in color. The juices filtered with 

 the addition of diatomaceous earth, with or without subsequent heat- 

 ing prior to filtering, remained after eight months perfectly trans- 

 parent and without a trace of precipitate, with a color suggesting 

 that of olive oil and with a flavor indistinguishable from that of the 

 untreated juice. It is consequently possible to shorten the process 



