22 
BULLETIN 47, HAWAII EXPERIMENT STATION. 
NOTES OX JELLY MAKING FROM THE POHA. 
It was found rather difficult' to produce a poha jelly having the 
proper consistency. This is due to the fact that the resultant 
product becomes entirely too firm and tough when the jelly is 
allowed to cook until a test, suitable for guava jelly, is obtained. 
A very soft jelly test must be used to produce a good, tender con- 
sistency. 
Owing to its very high sugar content, poha jelly has a tendency 
to crystallize. If trie jelly is covered with paraffin, or hermetically 
capped, crystallization can usually be prevented. 
CONSISTENCY OF JELLIES AS AFFECTED BY THE PHYSICAL PROPERTIES 
OF PECTIN. 
A fruit jelly is essentially a colloidal gel, throughout which sugar 
and acid cause a uniform precipitation of the pectin. The character 
of the resultant gel depends primarily upon the physical properties 
of the pectin. Extensive studies have been made of the occurrence, 
extraction, and chemical composition of pectins. 20 Little mention, 
however, has been made of the difference in their physical properties, 
which, from the standpoint of jelly making, is of very great importance. 
Observations on the physical difference in the alcohol precipitate 
of the four fruit juiced (grape, roselle, guava, and poha) studied by 
the writer show that the properties of jellies are closely related to 
the physical properties of their pectins. 
Table 28 shows the relation existing between the physical prop- 
erties of pectins and the resultant jellies. 
Table 28. — Relation of the physical properties of pectins to the resultant jellies. 
Fruit. 
Pectin. 
Jelly. 
Grape 
Roselle 
Guava 
Poha 
Very weak pectin; very short fibers: pectin 
mass easily broken apart. 
Weak pectin; short fibers; pectin mass easily 
broken apart. 
Strong pectin; long fibers; pectin mass spongy 
and tenacious. 
Very strong pectin; very long, dense fibers: 
pectin mass tough and stringy. 
Tendency to weep; easily destroyed by over- 
heating; low sugar content: tender - ; lacks 
body. 
Tender; lacks body. 
Dense; plenty of body; tough, if overcooked. 
Verv dense jelly; plenty of body; very tough, 
if 'overcooked; high sugar content. 
Table 28 indicates that there is a gradation of the physical prop- 
erties of the pectin and jelly from grape through, to, and including 
that from poha. The pectin gradually increases in length of fibers 
and tenacity from the gelatinous grape , pectin to the dense, tough 
poha pectin. The jellies increase in body and density from the 
tender grape jelly of low sugar content to the tough poha jelly of 
high sugar content. It seems, therefore, that the physical character 
of the pectin is an important factor in determining the consistency 
of jelly. 
APPLICATION OF THE GUAVA PECTIN TABLE TO OTHER FRUIT JUICES. 
Reference of the pectin numbers of roselle, grape, and poha juices 
to the guava-pectin table shows that the maximum sugar ratio for 
the roselle and grape juice is too high by one-fourth and that the 
20 U. S. Dept. Agr., Bur. Chem. Bui. 94 (1905), pp. 67-89. 
