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