Pectin
DE equation
(esterified D-galacturonic acid residues/total number of D-galacturonic acid residues) x 100
Protopectinase
Pectic enzyme that turns insoluble protopectins into pectins that are colloidal and soluble
Normal pectin gel
pH: 2.8-3.4 Sugar concentration: 65% (w/w) Pectic concentration: ~1% (w/w_ Temperature 104.5 degrees celsius --> cooling
The higher the DP..
the higher the MW of the polymer
1 unit of pectin = ___ units of sugar
65
Low methoxyl pectin (LMP) DE
< 50%
High methoxyl pectin (HMP) DE
> 50%
Pectin
>75% methylated mature plant material
Low methoxyl pectin gels
- No acid or sugar required - Pectin: 0.5-1.0% (w/w) - Calcium is required (to form electrostatic bridge btw pectin molecules) - pH 3.2-4.0 (do not want pH too acidic bc competition between H ions and calcium will arise)
Sugar for normal pectin gel
- Required to gel - Contributes to flavor - Preservative
Acid for normal pectin gel
- required to gel - contributes to flavor
Pectinic acid
0-75% methylated mature plant material
Temperature needed for a normal pectic gel to gel
104.5 C
Commercial pectin
Can be liquid or powdered Source: mostly lemon or lime peel
Main chain of pectin
D-galacturonic acid
How to modify pectin
De-esterification (w/ dilute acid or base) De-polymerication (w/dilute acid and high temp)
Pectin definition
Methyl ester of polygalacturonic acid (alpha 1-4 linked galacturonic acid. Some azrabinanas and galactans are also included in this definition
Pectin
Present in plant middle lamella and primary cell wall (cement cells together) Soluble dietary fiber Spreadable gels in food
Degree of polymerization (DP)
The number of D-galacturonic acid residues per molecule
Degree of esterification (DE)
The number of carboxyl groups esterified compared to the total number of carboxyl group, expressed as a percent (%)
Pectin grade
amount of sugar, by weight, required per unit weight of pectin to prepare a normal jelly
More pectin means..
harder more crunchy
When pectin is complexed with Calcium it becomes
insoluble
How does sugar act as a preservative in a normal pectin gel
microbes cannot grow due to high osmotic pressure in jelly
Pectic acid
~0% methylated overripe, less methyl group, mushy plant material
Protopectin
~100% methylated immature, most methyl groups, firmest immature plant material, insoluble in water