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 tuber s

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: um Corn: um

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 → 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

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