I 



APPLE JUICE EXTRACTION FOR .IKI.LY 2:U 



weight of a finished apple jolly is sugar, and the weight of roncentraled juice 

 and the percentage of solul)le solids in it are known, the finishing point of 

 the jelly is readily determined by the simple ex])edient of weighing the sugar- 

 juice mixture from time to tune until the calculated yield of jelly is reached. 

 For <;xample in Table 14, it is shown that an average of 20 ounces of jelly 

 per pound of apples may be expected where the ratio of fruit to extraction 

 water is 3 to 3 by weight and the combined first and second I5-niinute ex- 

 tractions are utilized. Then if 3 pounds of fruit are taken, the yield of 

 sugar in 90 ounces of unconcentrated juice containing 5 per cent soluble solids 

 (Table 2) is approximately 90X-05 or 4.5 ounces of sugar in the juice. This 

 figure is not absolutely correct because only about 76.5 per cent of the solids 

 in extracted apple juice is sugar (Table 5), but this correction is unnecessary 

 for ordinary work. Since 3 pounds of apples are used, 3X20 or 60 ounces of 

 jelly should result. This jelly nmst contain 60X0.675 or 40.5 ounces of sugar. 

 Therefore 40.5 — 4.5 or 36 ounces of sugar must be added to the juice which 

 is then concentrated until the weight of jelly in the pan is exactly 60 ounces. 

 This is the finishing point of the jelly. The writer has used this method of 

 preparing samples of experimental jellies and jams in numerous cases. In 

 general, the results obtained by the procedure just outlined, usually approxi- 

 mate those obtained by the sheeting test as made by an experienced jelly 

 maker. 



The temperature test was useful but could not be relied upon in all cases 

 if used by itself. The refractometer test was found to be of particular value 

 in following the evaporation of water in a jelly mixture. The results checked 

 those obtained by occasional weighings. 



For a discussion of the role of sugar, acids, and salts in pectin jellies ref- 

 erence shoidd be made to the series of bulletins issued by Tarr, Myers and 

 Baker of the Delaware Agricultural Experiment Station. In many cases 

 their results are applicable as well, to fruit jellies. These fundamental con- 

 tributions on the chemical and physical factors influencing jelly formation 

 are very important and, when properly utilized by jelly manufacturers, should 

 enable them to produce economically standardized products of high quality. 



ACKNOWLEDGMENT 



The writer is deeply indebted to I'rofessor AV. W. Chenoweth, who original- 

 ly proposed this investigation, for his sustained interest in the project and 

 for many timely suggestions freely given during its entire progress, and to 

 Mr. Francis P. GritSths who assisted in the final phases of the laboratory 

 work. 



SUMMARY AND CONCLUSIONS 



Baldwin apples showed but slight yearly variation in composition of fruit, 

 juice or yield of jelly. Red Siberian Crab, King David, Red Astrachan, 

 Winesap and Mcintosh were the most suitable varieties for jelly manufacture. 



A study of juice extraction by heat showed: 



1. Two short (15 minute) successive extractions were usually desirable to 

 obtain an optimum yield of juice containing sufficient pectin and acid to 

 give satisfactory yields of high quality jelly. 



2. When only one extraction of the fruit was made, there was a serious 

 loss in jelly yield. This was found to be due largely to the difficulty of ex- 

 tracting pectin. 



