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2. Pectin characterization
Characterization of resulted pectin is done by testing moisture content, ash content, equivalent weight, methoxyl content, galacturonic acid content, and degree of esterification.
a. Moisture content AOAC 1995
Moisture content of the samples was determined by drying milled samples ~1 g for 24 hours at 105±0.5 ⁰C to a constant mass. Analyzes were done in triplicates for statistical purposes. The
analysis was done for determination of initial moisture content of fresh bamboo shoots and the drying curve. The average moisture content in dry basis, expressed in percents, was calculated
using the following equation: w =
m − m m
× where: m
1
= mass of samples before drying m
2
= mass of samples after drying
b. Ash content AOAC 1995
Crucible with lid was dried in an oven at 105
o
C for 15 minutes and then cooled in a desiccator and weighed. A total of 3-4 grams of sample was put into the crucible. Next, sample was heated
over the burner flame until it smokes fade away. Then, sample was ashed in the electric furnace at a temperature 400-600
o
C for 4-6 hours or until sample became white ash. Then sample was cooled in a desiccator and then weighed. The calculation of ash content can be expressed as the
percent. Ash content =
mass of ash mass of sample ×
c. Equivalent weight EW Ranganna 1977
Pectic substance was weighed 0.5 grams into a 250 mL conical flask and then moistened with 5 mL ethanol. Sodium chloride 1 gram added to sharpen the end point and then 100 mL of carbon
dioxide-free distilled water and 6 drops of phenol red indicator was added. Make sure that all the pectic substance had dissolved and that no lumps were retained on the sides of the flask. Titration
was done slowly to avoid possible deesterification with 0.1 N NaOH until the color of the indicator changed from yellow to pink pH 7.5, the color change should persist for at least 30
sec. The neutralized solution could be used for methoxyl determination. Equivalent weight =
mass of samples x mL of alkali x Normality of alkali
d. Methoxyl content Ranganna 1977
To the neutral solution titrated for equivalent weight, containing 0.5 grams of pectic substance, was added 25 mL of 0.25 N sodium hydroxide and then shook thoroughly and allowed to stand
for 30 min at room temperature in a stoppered flask. Add 25 mL of 0.25 N HCl or an amount equivalent to the based added and titrated with 0.1 N NaOH to the same end point as before. 3.1
value is derived from molecular weight of methoxyl. Methoxyl content =
mL of alkali x Normality of alkali x 3. mass of sample
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e. Galacturonic content Rungrodnimitchaia 2011
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