Download
carbohydrates n.
Skip this Video
Loading SlideShow in 5 Seconds..
CARBOHYDRATES PowerPoint Presentation
Download Presentation
CARBOHYDRATES

CARBOHYDRATES

208 Views Download Presentation
Download Presentation

CARBOHYDRATES

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. CARBOHYDRATES SUGARS, STARCHES, PECTINS, AND OTHER CARBOHYDRATES

  2. CHARACTERISTICS • Organic compounds • Carbon, Hydrogen, Oxygen • Simple or complex • Source of energy or fiber • Important food CHOs - Sugars, dextrins, starches, celluloses, hemicellulose, pectins, gums

  3. FUNCTIONS • SWEETENERS • THICKENERS • STABILIZERS • GELLING AGENTS • FAT REPLACERS

  4. MONOSACCHARIDES • SIMPLE SUGARS • MOST COMMON - 5 OR 6 CARBON

  5. GLUCOSE • Dextrose • Naturally present in fruit • Basic unit for starches • Less sweet than fructose • Used in food industry because of water holding properties and ability to control crystals • Food for yeast

  6. FRUCTOSE • Levulose • Part of sucrose • Sweetest of all sugars • In many fruits • Very soluble • Not easily crystallized • Glucose isomerase to change glucose to fructose

  7. GALACTOSE • Part of lactose – milk sugar • Basic unit of pectic substances • Building block of many vegetable gums

  8. COMMON MONOSACCHARIDES

  9. DISACCHARIDES • Two monosaccharides • Glycosidic bonds-readily hydrolyzed by heat, acid, enzymes

  10. SUCROSE • Table sugar • From sugar cane or sugar beet • Glucose + fructose • Invert sugar important in controlling crystallization • Most common disaccharide

  11. MALTOSE • Glucose + glucose • Product of starch breakdown • Corn syrup • Flavoring and coloring agent in beer, candies, shakes

  12. LACTOSE • Glucose + galactose • Milk sugar • Extracted from solutions of whey • Not broken down or fermented by yeast • Does not react in batter leavened with baking soda or baking powder • Available for Maillard reaction so added to bakery products for browning

  13. DISACCHARIDES

  14. PROPERTIES OF SUGAR

  15. SOLUBILITY • Solution in foods • Varying degrees of solubility for monosaccharides and disaccahrides • As temperature increases  greater the amount of sugar that dissolves • Slow heating increases the solubility • As concentration increases  boiling point increases • Each gram molecular weight of sucrose increases boiling point 0.940F (0.520C) • Can use temperature to determine sucrose concentration

  16. SATURATION • Unsaturated – small amount of sugar in water, can hold more sugar • Saturated – no more sugar can be dissolved • Supersaturated – holds more than what is usually soluble at a certain temperature • Supersaturation – heat to high temperature and cool slowly

  17. CRYSTALLIZATION • Cool supersaturated solution • Formation of closely packed molecules from the solidification of dispersed elements in a precise orderly structure • Arranged around a nuclei • Size of crystal depends on rate of formation of nuclei and rate of growth • Crystals form too soon  only a few  crystals too large, continue to grow, candy grainy

  18. MELTING POINT/HEAT DECOMPOSITION • Apply dry heat  sugars melt to liquid state • Sucrose melts and forms liquid that turns brown • Carmelization – nonenzymatic browning, flavors food • Noncrystalline

  19. HYGROSCOPICITY • Ability to absorb moisture • Responsible for lumpiness (sugar) • Decreases staling in bread • Gives stickiness for high moisture characteristics to foods • Fructose most hygroscopic

  20. INVERT SUGAR • Acid hydrolysis of disaccharide sucrose • Heat increases hydrolysis • Glucose and fructose in equal amounts (equimolar) • Resists cyrstallization and retains moisture • Add cream of tartar, vinegar, molasses (acids) • Enzyme hydrolysis with invertase

  21. TYPES OF SUGARS CRYSTALLINE AND NON-CRYSTALLINE

  22. GRANULATED SUGAR • Crystalline – table sugar • Sugar cane or sugar beet • Affects texture of baked goods • Improves body and texture of ice cream • Fermented by yeast • Retards growth of microorganisms • Raw sugar banned by FDA • Turbinado –raw sugar separated in centrifuge, washed with steam • Retailed as fine or extra fine

  23. POWDERED SUGAR • Pulverized granulated sugar • Add cornstarch to prevent caking • X designates fineness

  24. BROWN SUGARS • From cane sugar – late stages of refining • Crystals of sugar coated with molasses • Contains invert sugar • Sold in grades • More refined  lighter color, less flavor, lower grade – for baking – less flavor • Higher, darker grades more flavorful and suitable for cooking strong flavored foods

  25. CORN SYRUP • Acid and high temperatures to hydrolyze corn starch • Varying degrees of sugars • High fructose corn syrup (HFCS) from high glucose corn syrup – use enzyme glucose isomerase • Significant use in food industry

  26. MOLASSES AND SORGHUM • By-product of sugar production from sugar cane • Mineral content varies • Bitterness increases as refinement continues – blackstrap molasses • Treacle – dark fluid left after sugar cane is processed • Sorghum – from cane sorghum, similar to molasses

  27. MAPLE SYRUP AND HONEY • Maple syrup from sap of mature maple trees • Water evaporated, organic acids cause flavor • Honey flavors according to flower nectars • USDA has standards for grades of honey

  28. ALTERNATIVE SWEETENERS • Non-nutritive – high intensity sweeteners • Approved saccharin, aspartame, acesulfame-K, sucralose, neotame • Except for sucralose not enough bulk to substitute in recipes • Cyclamates – banned • Sugar alcohols - polyols– improve bulk, mouthfeel, and texture

  29. SUGAR COOKERY CANDIES

  30. CRYSTALLINE CANDIES • Generally soft • Smooth, creamy with tiny crystals that cannot be detected with the tongue • Fondant and fudge • Use interfering agent to prevent early crystallization • Must concentrate solution-test temperature to determine concentration • Complete solution of crystalline sugar

  31. INTERFERING AGENT • Interfere with size or rate of crystal growth • Contribute to viscosity of syrup and elevate the boiling point • Examples – milk, butter, cream, eggs, chocolate, cocoa, proteins, fats, dextrins, invert sugar, corn syrup

  32. NON-CRYSTALLINE CANDIES • Amorphous • No definite crystalline pattern • Cook to very high temperature • Adding large amounts of interfering agent • Combination of methods • Hard – brittles, high temperature, low moisture • Chewy – caramels, high interfering agent • Aerated – marshmallows, air trapped in protein foams and interfering agent

  33. POLYSACCHARIDES • Complex carbohydrate polymers • Properties depend on sugar units, glycosidic linkage and degree of branching • Starches, Pectins, Gums most important • Hydrocolloids – water loving colloidal substances

  34. STARCH • Plant polysaccharide - linked glucose monomers • GRANULES - formed in cells, grow by adding on layers • Long-chain glucose polymers • Insoluble in water • Form temporary suspension

  35. SOURCES • Characteristic of finished food depends on starch source • Seeds, roots and tubers • Cereal grains - wheat, corn, rice, oats • Roots and tubers - potatoes, arrowroot, cassava

  36. STRUCTURE AMYLOSE AND AMYLOPECTIN

  37. AMYLOSE • Straight chain or linear fraction • 1/4 of all starch • Thousands of glucose units • Forms thick gels-hold shape when molded, rigid

  38. AMYLOPECTIN • Highly branched • 3/4 of starches • Thickens but does not gel • Proportion of amylose:amylopectin influences cooking qualities and keeping characteristics of finished food product

  39. AMYLOPECTIN

  40. STARCH CHARACTERISTICS • Ability to absorb water limited • In uncooked stage is insoluble in cold water - forms temporary suspension because polymer is too large • Doesn’t change boiling point or freezing point of liquid • Reversible

  41. EFFECTS OF HEAT

  42. DRY HEAT • Heating - increases uptake of water • Dextrinization • Color and flavor changes • Reduced thickening power • Nonenzymatic browning • Dry flour browned

  43. MOIST HEAT • Complete absorption as heat increases - permanent swelling, irreversible • Sol - as starch continues to come out of granules • Viscosity-thickness, thinness of liquid • Translucency increases during heating

  44. GELATINIZATION • Sum of changes in first stages of moist heating of starch granules • Gelatinized granules = opaque, fragile, ordered structure disrupted • Temperature of gelatinization differs for each starch • Short chains of amylose come out of the granules • Irreversible changes

  45. CONTINUED HEATING • Gelatinization requires addition of heat • Cooking develops flavor • Pasting occurs • Granules swell • Granules of starch swell independently

  46. PASTE CHARACTERISTICS • Concentration of starch affects consistency • Clear thickened gel made from root starches or waxy versions of starches • Cloudy gels from cereal starches

  47. FACTORS AFFECTING GELATINIZATION

  48. ACID • Fragments (hydrolyzes) starch molecule = thinner hot paste and less firm product • Hydrolysis = less hydration of starch • Add acid after gelatinization and after starch has cooked • Applicable - lemon juice, vinegar, tomatoes

  49. AGITATION • Over-stirring causes granules to burst, empty bound water = gel will thin • Creates more uniform mixture

  50. OTHER FACTORS • FAT AND PROTEIN- coats (adsorbs) to surface of granule = delays hydration Fat in pie crust to prevent clumping • SUGAR - competes for liquid = delays absorption by granule = thinner mixture Elevates temperature for gelatinization • ENZYMES - hydrolyze starch molecules