Found in both cell walls and in space between plant cells. Aid in cementing plant cells
Galacturonic acid (a derivative of galactose) is the basic building block of pectic substances.
Pectin is a pectic molecule common in fruits and is responsible for forming gels in various jams,
jellies and preserves.
Commercially, pectin is produced from apple cores or citrus peel.
E. Vegetable gums/hydrocolloids
Long chain polysaccharides.
Various hexose and pentose sugars are the basic building blocks.
Dissolved in water, they produce a thickening or texture building effect.
Gums can help to retain water, reduce evaporation rates and modify ice crystal formation.
Widely used in the food industry as fat replacers (ice cream, low calorie salad dressings, low fat
Examples of gums/hydrocolloids:
Seaweed extracts: agar, alginate, carrageenan.
Plant seed gums: locust bean gum, guar gum.
Plant exudates: gum arabic (used to stabilize carbonated drinks), gum tragacanth.
Microbial gums: xanthan gum (used for cloud stabilization in orange juice), dextran.
Carboxymethylcellulose, which is used as a bulking agent in low calorie foods and in
Methyl cellulose is used in reformed potato products and in coatings & batters to
reduce oil absorption.
PROCESSED AND FUNCTIONAL CARBOHYDRATES
LEARNING OBJECTIVES: c78
Upon completion of this unit you should be able to do the following:
discuss the process of high carbohydrate foods
explain the process for brewing beer
discuss the use of carbohydrates as functional foods or nutraceuticals
PROCESSING HIGH CARBOHYDRATE FOODS
Wheat, rice and corn are staple foods in different parts of the world. High carbohydrate foods are
often processed into more conventional form:
ground to make cereals and tortillas
processed to make snack foods (e.g. corn chips)
extracted into cornstarch
cornstarch can be hydrolyzed to produce corn syrup (glucose + dextrin)
wheat kernel is composed of bran (outer layer, high in vitamins, minerals and fibre), germ
(the sprouting part high in vitamins and fat) and endosperm (high in carbohydrates)
the bran and germ are removed during milling and the endosperm is made into flour
75% of the wheat produced world-wide is used to