EDIBLE CANNA IN HAWAII 
Comparison of viscosity of edible carina starch and other starches 
15 
Starch 
Viscosity (Saybolt) at 80° C « 
solution 
Edible 
canna 
Potato 
Corn 
Cassava 
Per cent 
Min. Sec. 
Min. Sec. 
Min. Sec. 
Min. Sec. 
0.5 
... 31 
... 33 
... 30 ... 28 
1.0 
... 33 
... 41 
... 32 ... 32 
1.5 
... 38 
1 29 
... 36 ... 35 
2.0 1 10 
3 24 
... 42 ! ... 48 
2.5 2 19 
9 ... 
... 54 1 .. 
3. 7 15 
21 ... 
1 35 1 46 
3. 5 20 15 
6 45 3 13 
4.0 
13 40 4 57 
4.5 

24 32 7 27 
• Twenty-eight seconds are required to run 
viscosimeter. 
i cubic centimeters of distilled water at 80° C. through the 
From the above table it is apparent that potato starch possesses a 
greater viscosity than do either of the other two starches. Canna 
starch is, however, greatly superior to either corn starch or cassava 
starch in this respect. It was observed that the viscosity of potato 
starch is reduced by agitation more easily than is that of canna 
starch. This is true, especially in concentrations of about 2 per 
cent, where the viscosity begins to rise abruptly with small incre- 
ments of starch. 
GELLING STRENGTH 
Hot starch solutions, which were prepared like those used in the 
viscosity tests, were pouied into test tubes one-half inch in diameter 
and allowed to cool for one hour. The tubes were then inverted. 
The minimum concentration necessary to keep the mass from run- 
ning down the side of the inverted tube was termed its "gelling 
strength." 
The gelling strength of edible canna starch, potato starch, corn 
starch, and cassava starch was found to be 3.75, 3.25, 4, and 6.25 per 
cent, respectively. Examinations of the four starches at the concen- 
trations noted above showed, however, that while the corn starch 
and the cassava starch formed a definite gel structure, which re- 
tained its shape when shaken out of the tube, the other two starches 
remained as nydrosols or possibly as plastic gels having sufficiently 
high viscosity to prevent their running down the side of the tube. 
USES 
Both the foliage and the tubers of the edible canna make excellent 
feed for dairy cows, and the tubers when cooked are fairly good for 
pigs. The small, immature tubers when cooked resemble white pota- 
toes in taste and consistency, but soon become too fibrous to be 
palatable. The tubers are little used for human consumption in 
Hawaii. 
The starch would seem to have considerable value as a food and 
for industrial uses. A very pure product can be prepared by simply 
shredding the tubers, mixing the pulp with water and passing the 
whole through a perforated screen, and finally, by separating the 
fecula or amylaceous matter from the fibrous substance by sedimenta- 
tion. Owing to its extraordinarily large granules, the starch settles 
in a few minutes and very little time and expense is required to free 
