8 
BULLETIN 47, HAWAII EXPERIMENT STATION. 
Table 7 shows that with increasing proportions of water the pectin 
number decreases but the total pectin extracted increases. The 
percentage of acidity decreases in all the guava fruit except the 
Kailua guava, and the total acid extracted increases. The addition 
of over 5 pounds of water to 5 pounds of fruit would doubtless in- 
crease the total extraction, but the juice would be diluted to such 
an extent that prolonged boiling would be required to produce a 
jelly. When the cost of fruit is an important item it might be ad- 
visable to use a greater proportion of water than at other times, but 
even then a reboiling of the pulp, as is shown in the following para- 
graph, would be preferable. 
SECOND EXTRACTION OF GUAVA JUICE. 
The guava pulp remaining after the juice is drained off is often 
thrown away. Guava butter can be made from the pulp, but it is 
never as much in demand as guava jelly. The jelly factories have 
heretofore treated a large part of the pulp as waste. 
To determine whether a second cooking would produce a juice 
sufficiently rich in pectin and acid to make jelly, the pulp which 
remained after the first juice had been boiled for an hour and then 
drained was reb oiled with water for 30 minutes and allowed to drain 
overnight in a cheesecloth bag. A third cooking produced a muddy, 
dark-colored juice which was not adapted to jelly making. Table 8 
gives the composition of the juices of the first and second boilings of 
two lots of guavas. 
Table 8. — Composition of jh vices from guavas which v.ere boiled once and twice, respectively. 
Juice 
No. 
Source of juice. 
Drained 
juice. 
Brix. 
.reading. 
Pectin 
No. 
Acidity 
(as 
HoS0 4 ). 
Total 
pectin 
ex- 
tracted. 1 
Total acid 
extracted 
(as 
H2SO4). 
A 
B 
c 
D 
5 pounds of fresh Kailua guava.. 
Pulp from AX1100 centimeters 
water 
5 pounds of fresh Kailua guava.. 
Pulp from CX1335 centimeters 
water 
Cubic 
centi- 
meters. 
1,100 
828 
890 
1,150 
Degrees. 
5.2 
9.2 
6.6 
1h 
7 
Per cent. 
0.97 
.64 
1.04 
.66 
Grains. 
12.5 
S. 4 
11.1 
12.2 
Grams. 
10.67 
5.30 
9.26 
7.59 
1 Pectin number x0.15lxcubic centimeters drained juice divided by 100. 
Table 8 shows that juice resulting from the second extraction 
contains almost as much pectin, but not nearly so high a proportion 
of acidity, as does the juice of the first extraction. 
A comparison of the total pectin and the total acid contents of 
A and B with those of C and D shows that the second extraction 
contains practically as much total pectin and acid as does the first 
extraction when the latter is very concentrated, as in C; and that the 
total extraction in the second boiling is appreciably less when the 
juice of the first extraction is sufficiently dilute, as in A. 
Jellies of good quality were made from juices of the second ex- 
traction. As a rule they were darker in tfolor than those of the first 
extraction and did not possess as strong a guava flavor. Jelly having 
as high a sugar ratio as the juices of the first extraction can be made 
when sufficient acid is added to the juice of the second extraction. 
Second-extraction guava juice is now being used by the various jelly 
companies of Hawaii to meet the demand for a low-priced pure fruit 
jelly. The only cost involved in producing jelly from the second- 
extraction juice lies in the additional 30 minutes required for boiling. 
