232 



TECHNICAL BULLETIN 15 



increases were noted where chopped fruit was used. Likewise greater yields 

 were obtained at 100° than at 88° C. if the sum of either two or three suc- 

 cessive extracts is considered. For two extracts combined an average maxi- 

 mum increase of 15 per cent was noted, whereas for tliree extracts, the maxi- 

 mum was only 7 per cent. Thougii some beneficial effects were gained by 

 extracting at 109°C. as compared with 100°, still these were too slight to be 

 of importance when the difficulties involved in cooking the apple — water mix 

 under steam pressure, are considered. In fact for chopped apples, unless 

 the time of extraction was at least 30 minutes, there was usually no gain in 

 recovery of solids or pectin over the extraction carried on at 100° C. 



The evidence indicates that any temperature above 88° C. is efficacious in 

 bringing into solution the sugars, acid, and pectin of apples, though (jn 

 account of the cost and difficulty of cooking under pressure it is probably 

 not desirable to exceed the boiling temperature. For ordinary purposes 

 100° C. appears to be the most satisfactory extraction temperature though 

 somewhat lower temperatures do not greatly influence the yield of soluble 

 solids, acid or pectin in Baldwin apples. Attention is again called to the 

 greater cloudiness of aU juice samples produced from chopped fruit. This 

 makes for a poorer quality jelly or pectin extract and is distinctly objec- 

 tionable. 



Influence of Extraction Period upon the Composition of Apple Juice. 



Baldwin Apples. Data bearing upon this question have been assembled 

 in Tables 9, 10 and 11 and Charts 1 and 4. 



Chart 4 gives a clear average picture of the influence of period of extrac- 

 tion upon soluble solids and pectin recovered in the juice. For the removal 

 of soluble solids and pectin in one or more extractions the 15-minute cook 

 was practically as efficient as where, in addition to the regular extraction 

 time, a standing period of 10 minutes removed from the source of heat, was 



Chart 4. Influence of the Length of the Extraction Period uison Recovery of Soluble 

 Solids and Pectin in Sliced Baldwin Apples at 100° and 109° C. 



>-70 

 pi 



cc 



%^ 

 o 



'^ 50 



Soluble Solids Pectin 



100°C. 



Soluble Solids Pectin 



109°C. 



*Boiled 15 minutes and allowed to stand 10 minutes. 



