Gums and Pectin

1
Gums and Pectin

• FCS 3120
• M. Burns

2
Vegetable gums

• Complex polysaccharide used widely by food
  industry as thickeners, stabilizers, and gelling
  agents
• Fat replacers new use
• Three categories

3
Vegetable gums

• Natural
• True exudates (gum arabic)
• Seed or root gums (carob, guar gum)
• Seaweed extracts (carageenan, agar)
• Modified
• Chemical derivative of starch
• Methylcellulose, xanthan

4
Vegetable gums

• Synthetic
• Totally produced in lab
• Vinyl polymers, acsylic polymers
• Most are natural or modified.

5
Pectic Substances

• Protopectin
• Parent substance, relatively insoluble with no
  gel-forming power
• Pectin or pectinic acid
• Soluble form needed for gel formation
• Pectic acid
• Formed from pectin by enzymes that hydrolyze a
  methyl ester group from the pectin molecule no
  gelling power

6
Jelly Preparation Principles

• Ingredients
• Pectin
• Jelmeter
• Acid
• Sugar
• Water ingredient (fruit juice)

7
Jelly Evaluation of quality

• Characteristic color
• Clear or at least translucent
• Gelled, ie retains shape when removed from mold
• Tender texture, easily cut with spoon

8
Factors influencing gel formation

• Kind and ripeness of fruit
• Underripe
• Overripe
• pH necessary for gel formation
• 3.2 (2.8-3.4) is optimal
• Degree of methoxylation of pectin

9
Methoxylation

• High methoxyl pectin
• Pectins are colloidally dispersed in water
• Slows gelation leading to clearer jellies and
  jams that hold the fruit in place

10
Methoxylation

• Low methoxyl pectin
• Gelation brought about by addition of dilavent
  ion, such as Ca
• Advantage can gel with little to no sugar