CITRUS PECTIN “i oe 
jellying power. Barker (3) states that pectin must be present in , 
quantities of 0.5 per cent or more to give a good cider apple jelly. 
Tarr (48) found a direct relation between jelly formation and active 
acidity of hydrogen-ion concentration, which can not be correlated 
with total acidity. The minimum hydrogen-ion concentration at 
which jelly formation occurred was pH 3.46. 
By the standard test used throughout this work for determining 
the jellying quality of the citric acid pectins obtained (p. 5), it was 
found that 0.20 per cent pectin in the finished product gave a good 
jelly in one instance and 0.25 per cent in several other instances. In 
order to determine the variations in citric acid and sugar that could 
be used with the better grades of pectin, a large number of tests were 
made by this standard-jelly test. 
Six pectins of high-jellying quality were obtained from three lots 
of lemon peel as felis: No. 1, from peel No. 1, by extracting for 
45 minutes at 98° C. in 0.1 per cent acid solution; No. 2, from peel 
No. 1, by extracting for 15 minutes at 98° C. in 0.1 per cent acid 
solution; No. 3, from peel No. 1, by extracting for 4 hours at 70° C. 
in 0.1 per cent acid solution; No. 4, from peel No. 2, by extracting 
for 30 minutes at 98° C. in 0.1 per cent acidsolution; No. 5, from peel 
No. 3, by extracting for 45 minutes at 98° C. in 0.1 per cent acid 
solution; No. 6, from peel No. 3, by extracting two samples twice 
for 45 minutes, one in 0.1 per cent acid solution and the other in 0.5 
per cent acid solution, and then combining the two. The pectins 
were precipitated from solution twice with alcohol, washed, dried, 
and ground. 
The effect of using varying quantities of citric acid with 0.26 per 
cent of pectin 1, 2, 3, and 4 was tested. The results are shown in 
Table 15. All of the percentages are based on the finished jelly. 
A good jelly was obtained with as little as 0.045 per cent of acid. 
The 0.5 per cent acid jelly was considered the best tasting and enough 
of the sucrose (about 65 per cent) was inverted to prevent crystalli- 
zation. 
TaBLe 15.—Effect of variation of acid on consistency of jelly (pectin and sucrose 
nearly constant) 
{| 
Citric | Consistency of | 
i jelly 
= = Citric | Consistency of 
Sample No. aid Sample No. Se - le 
Pectin 1 Per cent Pectin 2: Per cent 
2 La ee Ses 0 Sirup. | oe My ae eee Pe eae 0.027 | Sirup. 
2,4, Dos Bake SS eae . 020 Do. CA Re ee 035 Do. 
eee eee ey EY I .040 | Barely jellied ee at Pol als 1S ee BE 039 Do 
th see .045 | Good jelly. pion et Se are . 046 Do. 
5 A aes SE ee . 052 Do. Be SASS PLAS .048 | Good jelly. 
(iia as . 080 | Do. res eer ee aes 049 Do. 
ite ere SF . 100 | Do. Pectin 3: 
mepoee Att tere t . 200 Do. Rb aR OP ei ey .020 | Sirup. 
eae See . 300 Do. Fees i ye SS .046 | Fair jelly. 
aca 2 . 400 Do. 5 al ed Se ae .073 | Good jelly. 
| eye ee eee . 500 Do. Pectin 4: 
Mee Seen FN ae . 600 | Do. te ad gre Se ara .020 | Sirup. 
RS eae eae ae . 750 | Do. BEF. STILT . 043 Do. 
Cans ee Sees . 900 | Do. ot SO Si stp es: . 046 Do. 
| AE Se eS Dee. 1, 300 | Do. oA SL yg Bk .056 | Fair jelly. 
2 ae 1. 800 | Do. ee ee ae .065 | Good jelly. 
iv) 2 OS See ee Peas | 2. 500 | Do LT ee 073 | Do. 
