Module 5.1.1: Starch

• Starch


  The most abundant substance found in nature, a carbohydrate consisting of polymers of glucose joined together by glycosidic linkages
• Hydrolysis of starch


  Enzymes called amylases break down the glycosidic linkages
• Starch in human diet


  The main source of carbohydrate
• Starch synthesis


  Made by plants through photosynthesis, stored in roots, seeds, fruits, and stems
• Glycogen


  Highly branched carbohydrate stored in animals
• Starch granules


  • Exhibit birefringence due to highly organized structure, microscopic in size, differ in size and shape among starches from various sources
• Amylose


  Straight chain polymer of glucose, responsible for gelling characteristics of cooked and cooled starch mixtures
• Amylopectin


  Branched chain glucose polymer, responsible for thickening property of starch
• Differences between amylose and amylopectin

  • Number of glucose molecules
  • Chemical configuration
  • Molecular weight
  • Solubility in water
• Amylose and amylopectin content in different starches

  • Waxy rice
  • Waxy corn
  • Ordinary rice
  • Sweet potato
  • Tapioca
  • Wheat
  • Ordinary corn
  • Sago
  • Amylomaize
• Iodine test for starch


  Amylose forms blue-black color, amylopectin forms purple-red color
• Uses of starch in food products

  • Thickening agent
  • Gelling agent
  • Edible film - protective coating
  • Structural
  • Binding and filling
  • Coating
  • Coloring (dextrinization)