Whitehall Memorial High School Whitehall, WI Starches By Scott McConnell High School Life Science Instructor And by Delaine Stendahl
What is a starch?
According to Webster s Dictionary: an odorless tasteless white substance occurring widely in plant tissue and obtained chiefly from cereals and potatoes. It is a polysaccharide that functions as a carbohydrate store and is an important constituent of the human diet.
Chemical Structure of Starch 1. Starch is a polysaccharide, which is a large number of glucose molecules chemically bonded together. 2. Because it is composed of sugar, it is classified as a carbohydrate. 3. Synthesized in plants, starch is stored energy for the plant when the plant is NOT undergoing photosynthesis.
Let take a break and just hold hands!
Two types of Starch Molecules: 1. Amylose long straight strands that tend to break down very quickly. 2. Amylopectin strands that contain many branches, which break down more gradually.
Tastes good What makes starches so popular as an ingredient in foods? Substantial supply of sugar for a given mass Very shelf stable Creates a viscous (thick) texture
How large are starch molecules?
Osmosis and Diffusion Lab Here is a lab in progress Step 1: Step 2: Step 3: Step 4: Step 5: Step 6: stir Step 7: Step 8: Step 9: Step 10: Step 11: Step 12: Cut a 15cm long section of the dialysis tubing. Place the section of tubing in water for 3 minutes. Remove the tubing from the water and tie one ends of tubing with the string or rubber band Rub the untied end between your fingers to expose the opening in the tube. In a 400ml beaker make a 15% sucrose (C 12 H 22 O 11 ) solution (15 grams of sucrose and 85 grams of water) Measure 5 grams of cornstarch (repeating linked C 12 H 22 O 11 ) and add it to your 15% sucrose solution and Measure 15mL of your starch/sucrose solution into the funnel which will nearly fill up your dialysis tubing. Tie opening of the dialysis bag with string or rubber band, leaving a 1.0 cm gap for the bag to expand. Pour 300 ml of water into a 400mL beaker then pour 10.0 ml of IKI (Lugol s solution) into the water. Determine the mass of the tubing and sucrose solution and record it along with the time on the data sheet. Since each group will be given a different amount of time the sucrose bag should be submerged, set a timer Remove the dialysis tubing from the IKI solution and test both solutions with the glucose test strips
Corn Starch Water IKI Holes in the Dialysis Tubing Glucose < < < <
Determining the presence of starch in liquids STARCH TEST FOR LIQUIDS TEST LIQUID HYPOTHESIS TEST RESULTS present (+) not present (-) present (+) not present (-) 1. Water 2. Cornstarch 3. Corn Syrup 4. Corn Oil 5. Milk 6. Propel
Youtubes on Starch Labs for You to Try Testing for Starches in Food Food Starch Tests Why does iodine turn starch blue?
What foods contain a high concentration of starch?
Determining the presence of starch in Foods FOOD Hypothesis Result from Iodine Banana Shredded Cheese Potatoes Macaroni Peanut Butter Apples Beef Eggs Cheetos Corn
How does this relate to food preparation?
https://www.youtube.com/watch?v=oiguyvmhqm4
What is Amylase? How is starch digested and absorbed?
Amylase is an enzyme, found chiefly in saliva and pancreatic fluid, that converts starch and glycogen into simple sugars.
Amylase vs Starch Lab Step 1 - Fill graduated cylinder with 5 ml of Sta-Flo liquid starch and pour into a labeled test tube (S1) Step 2 - Add 10 ml of water to the liquid starch test tube Step 3 - Fill the graduated cylinder with 5 ml of Sta-Flo liquid starch and pour into a second labeled test tube (S + A1) Step 4 - Add 3 ml of 5% amylase solution, or collect 3 ml of saliva to substitute for the amylase. Step 5 - Place both test tubes into a water bath of boiling water and boil for 5 minutes. Step 6 - Extract equal amounts of each test tube after the 5 minute boiling period and place into separate wells of a white muffin container. Step 7 - Add 4 drops of IKI (iodine) to each well and observe differences.
What s up with Gluten?
Gluten is a general name for the proteins found in wheat, rye, barley and triticale a cross between wheat and rye. Gluten helps foods maintain their shape, acting as a glue holding food together. Gluten is a sticky protein found in wheat. The prevalence of wheat and wheat products, especially processed and refined varieties, have led to a greater percentage of the population developing gluten intolerance or an allergy to gluten. According to the National Institute of Diabetes, Digestive and Kidney Diseases (NIDDK), celiac disease affects 1 in 133 people in the US. Having a first-degree relative with the disease increases the rate of celiac disease to 1 in 22. Around the globe, 1 in 200 people have celiac disease and because of its genetic component, it s likely that the incidence of the disease will continue to climb as it is passed down through the generations. That is, unless something is done to change the diet in the family tree. Celiac disease exists in higher rates in cultures that eat a lot of wheat: the Italian culture for instance. It s been climbing in America due to the high proportion of wheat gluten in a multitude of our food products, supplements and health and beauty products. In celiac disease, gluten causes an immune reaction that targets the intestinal villi. These finger-like projections are responsible for nutrient absorption. The damage flattens the villi over time so malnutrition is a serious result of celiac disease.
What is Resistant Starch?
Resistant starch is digested differently to other starches. It passes through the small intestine undigested similar to soluble fiber. It makes its way to the colon where it is then fermented by microbes that produce byproducts called short chain fatty acids. These unique fatty acids feed healthy gut bacteria, along with playing important roles in lipid, glucose, and cholesterol metabolism. Very little energy is extracted from resistant starch, which results in minimal impact on blood glucose levels. Resistant starch has been shown to improve insulin sensitivity, increase satiety/fullness, increase calories burned and improve colon health by reducing inflammation in the colon, thereby helping reduce/prevent cancer. Resistant starches are often destroyed in cooking, so most foods need to be eaten in their raw form or cooked, then cooled.
Resources: Study.com study.com/academy/plans/teacher.html Diffusion/Osmosis Lab https://www.youtube.com/watch?v=hxzfu2lbfga Resistant Starch https://diabetesmealplans.com/10562/starch-and-diabetes/ Gluten https://draxe.com/whats-the-deal-with-gluten/ Scott McConnell - mcconnells@whitehallsd.k12.wi.us