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IV%20Starch%20Gelatinization%2009[1] - CHEMISTRY OF FOOD...

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CHEMISTRY OF FOOD AND BIOPROCESSED MATERIALS Laboratory IV . Starch Solubility and Gelatinization: Effects of Modifications OBJECTIVES 1. Understand the concept of viscosity based on molecular phase volume 2. Be able to relate changes in clarity, viscosity and birefringence 3. See the differences between different starches 4. Understand hydrogen bonding SAFETYALERT!!!! Use hot hand™ when handling hot beakers Becareful with HOT plates DO NOT let the thermometer touch the bottom of the beaker - hold it! DO NOT use the thermometer as a stirring spatula PROCEDURE I. Starch Samples Set 1 Melojel - Normal corn starch Purity NCS – Modified corn starch Flojel 65 – Modified corn starch Set 2 Amioca – Waxy corn starch Instant Clearjel – Pregelatinized, modified waxy corn starch Colflo 67 – Modified waxy corn starch II. Treatments Each group of 2 analyzes a NORMAL and a MODIFIED starch (two starches per group of two). Each group of 4 compares the data for all three starches in a set (i.e., each group of 4 is responsible for set #1 or set #2). III. Experimental 1. Prepare a starch slurry by slowly adding 15 g of starch to 300 ml of water (use warm water with pre-gelatinized). Add starch in approximately 5 g amounts while mixing. 2. Place approximately 25 ml into a 50 ml beaker (unheated control). 3. Heat the remaining solution, stirring occasionally. During heating record the temperature corresponding to a sudden increase in clarity (T clarity
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