CONCORD GRAPE JUICE. 



although low temperatures during heating are very desirable for at- 

 taining quality, higher temperatures give a better dissolution of the 

 fruit and a better yield of juice. As is evident from what has just 

 been said, it is not possible to fix a definite temperature for the heat- 

 ing process. The temperature, however, should be between 135° 

 and 150° F. The time required for heating is simply the time nec- 

 essary to heat to the desired temperature. 



By the heating of the crushed fruit the skins are drawn upon for 

 color and body. A cold-pressed juice lacks the body and color of 

 the hot-pressed juice, so this may be said to be the character-forming 

 step. The effect of heating upon the chemical composition of the 

 pressed juice may be seen by a comparison of the data given in Table 

 3, which shows the chemical composition of juices pressed from the 

 heated and unheated fruit. 



To obtain the cold-pressed juice a well-mixed sample of the pulp 

 from the stemmer was pressed by hand through several thicknesses 

 of cheesecloth and filtered through cotton. This gave the sample 

 mentioned in Table 3 under the heading "Before heating." The 

 same batch of pulp was again sampled after it had been heated to 

 1 50° F. in the cooker and the juice expressed in the same manner. This 

 gave the sample in Table 3 under the heading "After heating." 



Table 4 summarizes the results given in Table 3, and shows the 

 increases in the various ingredients caused by heating the pulp. 



Table 3. — Chemical composition of hot and cold pressed Concord grape juices. 



Ex- 

 peri- 

 ment. 



Juice pressed 

 before or 



after 

 heating. 



Solids, 



per 

 100 cc. 



Sugar 

 as in- 

 vert 

 before 

 inver- 

 sion, 

 per 

 100 cc. 



Non- 

 sugar 

 solids, 



per 

 100 cc. 



Total 

 acid 

 as 

 tar- 

 taric, 

 per 

 100 cc. 



Total 

 tar- 

 taric 

 acid, 

 free 

 and 

 com- 

 bined, 



per 

 100 cc. 



Ash, 



per 



100 cc. 



Alka- 

 linity 

 of solu- 

 ble ash, 

 N/10 

 acid, 

 per 

 100 cc. 



Alka- 

 linity 

 of in- 

 soluble 



ash, 

 N/10 

 acid, 



per 

 100 cc. 



Free 

 tar- 

 taric 

 acid, 

 per 

 100 cc. 



Cream 



of 

 tartar, 



per 

 100 cc. 



Gms. 



Gms. 



Gms. 



Gms. 



Gms. 



Gms. 



Cc. 



Cc. 



Gms. 



Gms. 



17.20 



14.36 



2.84 



0.78 



0.63 



0.26 



30.0 



3.0 



0.14 



0.56 



17.83 



14.58 



3.25 



1.12 



1.04 



.46 



55.8 



4.8 



.13 



1.05 



16.33 



13.88 



2.45 



.74 



.63 



.27 



33.2 



2.8 



.09 



.62 



17.25 



13.62 



3.63 



1.01 



.97 



.43 



52.4 



4.0 



.12 



.99 



16.10 



13.74 



2.36 



.84 



.61 



.20 



22.4 



3.6 



.22 



.42 



17.17 



13.74 



3.43 



1.16 



1.01 



.33 



49.2 



4.4 



.21 



.93 



16.57 



14.32 



2.25 



.75 



.55 



.22 



25.2 



2.S 



.13 



.47 



18.50 



15.12 



3.38 



1.10 



.98 



.39 



44.0 



4.0 



.26 



.83 



15.66 



13.38 



2.28 



.80 



.65 



.22 



24.4 



2.6 



.24 



.46 



16.44 



13.29 



3.15 



1.07 



.96 



.33 



38.0 



3.8 



.33 



.71 



16.28 



13.91 



2.37 



.79 



.57 



.23 



26.0 



3.6 



.13 



.49 



17.41 



13.83 



3.58 



1.09 



.94 



.37 



41.2 



4.4 



.26 



.77 



Tan- 

 nin 

 and 

 color- 

 ing 

 mat- 

 ter, 

 per 

 100 cc. 



/Before . 

 \ After.. 



/Before. 

 \ After.. 



o I/Before. 

 6 !\After... 



. '/Before. 

 4 \ After... 



c (/Before. 

 s ,\ After.. 



ft /Before. 

 b \After.. 



Gms. 

 0.08 

 .24 



.07 

 .19 



.06 

 .20 



