Al'PLK JUICE EXTRACTION FOR JEI.LY 233 



allowed. A sliylit gain in aiiiouiit of pectin extracted was found, but tliis 

 was of little significance particularly wlien two or more extractions were 

 considered. 



It is interesting to note tliat one 30-niinute extraction was not ecjuivaleiit 

 by any Ineans to two IS-niinute extractions. At all tiiree temperatures used, 

 there was an average increase of less than 10 per cent in sohil)le solids, 

 pectin, or acid in the 30-minute as compared to the single lo-minute extrac- 

 tions. Two successive 15-niinute extractions yielded from 50 to 90 per cent 

 more soluble solids, pectin and malic acid than a single 30-minute extraction. 

 Of course other considerations enter here such as a greater volume of liquid 

 to evaporate when two 15-niinute extractions are made instead of one 30- 

 minute period, doubled labor in handling the two extracts and a small loss 

 of time. The cost of fuel is practically the same and, all things considered, 

 the data indicate that two short extractions were much more efficient and 

 economical than a single long one. 



Although a slight gain in both total solids and pectin was observed in the 

 60-minute extract, it was far too long to be practical. Furthermore the in- 

 creased amounts of solids obtained did not repay for the huge fuel consump- 

 tion, time, and loss in jelly quality. This latter point is very important and 

 in almost every case where apples were extracted for as long as 60 miimtes, 

 a serious loss in jelly quality was observed. The long-continued boiling 

 hydrolyzed the pectin and reduced its activity. Usually apples could be 

 boiled 15 minutes without great apparent injury to the pectin or jelly qual- 

 ity though after 30 minutes boiling this was very apparent. A decrease in 

 both jelly yield and jelly strength in juices boiled for 30 minutes showed 

 that even in that short heating period, some pectin decomposition occurred. 



Other Varieties. As regards apple varieties other than Baldwins, the same 

 conclusions hold. A comparison of the data in Tables 10 and 11 (15-and 30- 

 minute extractions respectively) shows very little difference in the amounts of 

 soluble solids obtained. Pectin recovery was slightly greater in the 30-min- 

 ute extraction period, though the increase was not significant. Since con- 

 siderably more evaporation loss occurred during a 30-minute extraction period 

 than during a 15-minute period, the volume in the former case was consid- 

 erably less. It was also more difficult to separate the liquid from the pulp 

 where the amount of liquid was small. There was a tendency toward mushi- 

 ness as the period of extraction increased and this physical condition of the 

 fruit pulp interfered somewhat with the removal of juice from it, that is the 

 pulp retained a higher percentage of the extractives. The data indicate quite 

 clearly that under the conditions of the experiment two 15-minute extrac- 

 tion periods with the ratio of fruit to water 3:2 to 3:3 were best for juice 

 extraction from the common varieties of the apple. It is possible that a 

 shorter period than this is desirable, but none was studied in this experiment. 

 By this procedure from 65 to 85 per cent of the total soluble solids, accord- 

 ing to the ratio of apple to water used and the temperature, and from 50 to 

 70 per cent of the pectin present in the apple can l)e utilized. Under the 

 average conditions of jelly manufacture a third extraction would be un- 

 economical. 

 Influence of Added Acid upon the Composition of the Juice. 



Tartaric acid was added directly to the sliced or chopped api)les in quan- 

 tities sufficient to produce theoretically acidities of 0.2, 0.4, and 0.8 per cent 

 tartaric acid in the apple-water mixture. This was in addition to the natural 



