Summary Food ingredient Functionality - food polysaccharides

Food polysaccharides
• Introduction
- Carbohydrates are




- Structure carbohydrates




- Classification carbohydrates




- Roles of carbohydrates in food products
o Sweetener: sugar
o Humectant: lowers water activity
o Energy supplier: glucose, saccharose, starch
o Texture: cell wall, thickeners, gelling agents
o Colour: browning reactions
- Question
o Which of the following structures is not a carbohydrate?




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,• Polysaccharides – classification
- Polysaccharide: high DP
o DP = Degree of Polymerization




- Classification of polysaccharides: based on structure




o Example of a branched heteroglycan




- Classification of
polysaccharides: based on
biological function (cell wall)




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, - Question
o Is starch a homoglycan or a heteroglycan?
o Is starch branched or linear?
o Are all glycosidic linkages the same in starch? Explain




• Polysaccharides functional properties
- Polysaccharide can thicken or gel
- Viscosity: resistance to flow
o Factors influencing viscosity
▪ Conformation of monosaccharide unit – α or β
▪ Branching pattern – e.g. many or few branches
▪ Degree of Polymerization (DP) - # of monomeric units
▪ Presence of charged groups – e.g. uronic acid
- Conformation of unit: α or β




- Branching pattern: many or few




- Degree of Polymerization (DP): number
of monomeric units



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, - Presence of charged groups: e.g. uronic acid




- Formation of a gel
o Gel = 3D-network which can retain water/liquid




- Question
o Which molecule will give a higher viscosity and why?




• Starch
- Sources of starch & starch granules
o Important energy source in human food
o Some starches are not degradable by human: act as fiber

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