3. stabilizer.pptx

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1. Stabilisers , thickeners and gelling agents

2. Definition stabilisers , thickeners and gelling agents are a group of compounds which play a very important role in the food industry to improve stability, texture, viscosity and make food products firmer ( Feddersen and Thorp 1993)

3. The molecules used as stabilisers , thickeners or gelling agents are macromolecules which, when dissolved or dispersed in aqueous media, are capable of causing an increase in the viscosity or gel formation Most of these compounds are natural from either plant or animal origin ( G´omez-D´ıaz and Navaza 2004).

4. Among the most widely used stabilisers in the food industry are alginates, carrageenans , agar , guar gum, arabic gum, methylcellulose and carboxymethylcellulose . The same molecules are also used in the food industry to perform a variety of roles, for example as emulsifiers or preservatives.

5. Function Stabilisers in foodstuffs prevent food components from separating they also give food a consistent texture. Gelling agents are useful when the consistency of a particular food has to be altered/modified to meet consumer demand.

6. Classification

7. Classification Stabilisers and thickeners may be divided into two main classes: polysaccharides proteins

8. Polysaccharides comprise three main subclasses: non-ionic (neutral), for example hydroxyethylcellulose and dextran ; anionic , for example xanthan , carrageenan, guar gum, alginate and carboxymethylcellulose (Cao et al . 1990 ; Dickinson and Galazka 1991; Samant et al . 1993; Ward-Smith et al . 1994; Dickinson 1996 ); and cationic such as arginine hydrochloride and chitosan (a linear copolymer of D-glucosamine and N-acetyl-D-glucosamine units connected through -(1–4) linkages).

9. Non-ionic (neutral) polysaccharide stabilisers Non-ionic (neutral) polysaccharides such hydroxyethyl cellulose and hydroxypropyl cellulose are widely used as food stabilisers Their mechanism of adsorption involves the formation of steric barriers which are produced when the adsorbed polymer extends its chain to the water phase ( Ain -Ai and Gupta 2008 ). hydroxypropyl cellulose contains both hydrophobicity and hydrophilicity characters

10. Non-ionic (neutral) polysaccharide stabilisers

11. Non-ionic (neutral) polysaccharide stabilisers (b) hydroxyethyl cellulose polymers and (c) hydroxypropyl cellulose polymer (Hansen 1993; Ain -Ai and Gupta 2008)

12. Anionic polysaccharides stabilisers Anionic polysaccharides (e.g. carboxymethyl cellulose, pectin, alginates, carrageenans , guar gums and gelatins) are employed as stabilisers in dairy products in particular (Marshall 1995 ). Their mechanism involves interaction with the positive charges on the surface of foodstuffs such as milk (casein micelles) to stabilise the casein network.

13. Anionic polysaccharides stabilisers

14. Anionic polysaccharides stabilisers

15. Anionic polysaccharides stabilisers

16. Anionic polysaccharides stabilisers

17. Anionic polysaccharides stabilisers

18. Anionic polysaccharides stabilisers

19. Anionic polysaccharides stabilisers

20. Cationic polysaccharide food stabilisers Chitosan is a linear copolymer composed of D-glucosamine and N-acetyl-D-glucosamine units linked by -(1–4) linkages. It is attractive for use as a food additive ( stabiliser ) due to its abundance and chemical properties including its hypocholesterolaemic and hypolipidaemic characteristics ( Nauss et al. 1983; Winterowd and Sandford 1995; Muzzarelli 1996, 1997 ).

21. Cationic polysaccharide food stabilisers Chitosan is also known for its good co-adsorption properties on lipid droplets covered with anionic lipid emulsifiers ( Alamelu and Panduranga Rao 1990; Magdassi et al. 1997) as well as its emulsifying properties (Schulz et al. 1998; Del Blanco et al. 1999). Arginine hydrochloride is another example of a cationic polysaccharide.

22. PROTEIN-BASED FOOD STABILISERS Protein-based stabilisers such as soya proteins are normally used in foods such as burgers or sausages for vegetarians . Soya proteins in these vegetarian food preparations prevent the food from disintegration during cooking Gelatin is one of protein based stabiliser . It is a product of the structural and chemical degradation of collagen derived from animal skin and bones

23. Analysis Methode electrophoresis or immunoassays (e.g. enzyme linked immunoassay or ELISA ) Polarimetry and refractometry Fluorophore -assisted carbohydrate electrophoresis (FACE)

24. Further Thinking Stabilisers , thickeners, gums and gelling agents all play an important role in the processing of fruits such as strawberry and other industrially processed foods, especially the types of foods which do not contain gelatinous compounds or any other stabilising ingredients (e.g. pectin ). These have to be added to maintain their structure as well as their physical properties during the processing period.