6 
BULLETIN 47, HAWAII EXPERIMENT STATION. 
high in all instances for jelly making. The superiority for jelly making 
of guavas from the leeward side over those from the windward slopes 
is undoubtedly due to the high acidity of the former. 
The variations due to seasons are not outstanding, but copious 
rainfall during the winter months increases the percentage of water 
and decreases the pectin content in the guava. t 
Variations due to varietal differences. — Thompson 8 gives analyses 
of six different varieties of guavas in Hawaii, one of which, the straw- 
berry guava, was found to contain more acid than the other varieties, 
although it is less acid to the taste. The only guava which grows in 
sufficient quantity to be of practical importance for jelly making is 
the common guava, but for the sake of comparison the juices of three 
other varieties of guavas were tested. The results of the test are 
given in Table 4. 
Table 4. — Compisition of juices from different varieties of guava. 
Moisture 
in 
guava. 
Drained 
juice. 
Juice. 
Variety. 
Brix 
reading. 
Sucrose. 
Reducing 
sugars. 
Pectin 
No. 
Acidity 
(asH;S0 4 ). 
Sweet guava l 
Per cent. 
87.1 
84.6 
Cubic 
centimeters. 
1,100 
1,190 
1.160 
1,200 
Degrees. 
5.8 
10.5 
Per cent. 
0.22 
Per cent. 
4.66 
5* 
7 
Ik 
6$ 
Per cent. 
0.31 
1.65 
White guava l 
10.3 
7.8 
1.99 
Common guava 1 
87.5 
1.04 
4.18 
1.16 
i Psidium guayava. 
2 P. cattle ianum. 
It is apparent from Table 4 that all of the varieties of guava tested 
contain sufficient pectin for jelly making, and that all, with the 
exception of the sweet guava, have sufficient acid for jelly making. 
Variations due to individual differences in the same variety. — The 
fruit from five guava bushes was kept in separate containers and their 
juices were compared. The bushes apparently were all of the com- 
mon guava variety and grew in the same locality. The fruits selected 
from them were as near the same degree of ripeness as it was possible 
to select them. Table 5 gives the composition of the juices of the 
fruits from five trees. 
Table 5. — Composition of guava juices from the fruits of five trees growing in the same 
locality. 
No. of 
juice. 
Drained 
juice. 
Brix 
reading. 
Pectin 
No. 
Acidity 
(as 
H2SO4). 
No. of 
juice. 
Drained 
juice. 
Brix 
reading. 
Pectin 
No. 
Acidity 
(as 
H2SO4). 
1 
2 
Cubic 
centi- 
meters. 
1,040 
1,050 
Degrees. 
9.9 
9.2 
8.4 
7* 
Per cent. 
2.19 
1.16 
4 
5 
Cubic 
centi- 
meters. 
1 , 235 
1,100 
Degrees. 
8.4 
8.0 
8 
n 
Per cent. 
2.06 
.73 
3 
1,240 
7J 
1.09 
Table 5 shows striking variation in the acidity of the fruits, but 
uniformity in pectin content. 
Individual variations have but little effect where the fruit is picked 
in ton lots. Variations in acidity would probably be rather large 
where the fruit is gathered from only a few bushes. Uniformity in 
acidity results when the fruits are picked from a large number of 
bushes. 
* Hawaii Sta. Rpt. 1914, pp. 64, 67. 
