Chocolate Pudding Lab

Aim: To study the effects of cornstarch in the preparation of a simple pudding

Pudding• A starch thickened

desert

– A starch is a polysaccharide made up of 2 fractions: amylose and amylopectin

• Amylose – linear molecule and gives gelling characteristics to cooked and cooled starch mixers

• Amylopection – highly branched and bushy; no gelling properties

Starch Gradules

• Stored in plant cells• Come in different

sizes and shapes depending on the type of starch– Potato: 10 - 100 um– Corn: 5 - 25 um

Potato Starch

Factors That Affect Starch

1. Moist Heat → Gelatinization

2. Temperature and Time of Heating

3. Agitation and Stirring

4. pH

5. Addition of Other Ingredients

Gelatinization

• As you heat the starch its granules absorb water and swell → increased viscosity and thickness

• After a period of time the granules gelatinize –

gets rigid and takes shape

Temperature and Time of Heating

• Starch paste is quickly prepared by boiling it for 1 minute – granules swell at high

temperatures

Agitation and Stirring

• Stir in the early stages of cooking with uniform consistency for a smooth product

• If agitation is too intense → rupture of granules and decreased viscosity

Other Ingredients

• Sugar – raises temperature at

which a starch gelatinizes

→ delays swelling of starch granules decreasing thickness of paste

– It competes with the starch for water

pH

• High acidity causes fragmentation of granules– Decreases the

thickening power

Other Ingredients

• Protein and Fat: – coat the starch

which delays swelling and lowers rate of viscosity development