Chocolate Cornstarch Pudding Lab Aim To study the

Chocolate Cornstarch 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 mixtures – Gel: rigid, holds shape of container when unmolded

Pudding - High amylose starches form films: property used to bind other ingredients • Amylopection – highly branched and bushy; no gelling properties • All starches are mixture of amylose and amylopectin • Plants store starches in their seeds, roots and tubers

Starch Granules • Starch stored in plant cells and organized in units called granules: – Microscopic, come in different sizes and shapes depending on the type of starch • Potato: 10 - 100 um • Corn: 5 - 25 um

Factors That Affect Starch 1. 2. 3. 4. 5. Moist Heat → Gelatinization Temperature and Time of Heating Agitation and Stirring p. H Addition of Other Ingredients

Gelatinization • As you heat the starch its granules absorb water and swell → viscosity and thickness increase • After a period of time the granules gelatinize – Get rigid and take shape, resulting in a starch paste

Temperature and Time of Heating • Starch paste prepared most quickly at boiling temp for 1 minute • Granules swell more quickly at high temperature

Agitation and Stirring • Stir 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

p. H • 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