Carbohydrates Simple, Complex, Sugars, “-ose” Carbohydrates Are organic compounds and the body’s main source of energy Carbon + hydrogen + oxygen Our sources of carbohydrates are plants, fruits, vegetables, grains Photosynthesis Chlorophyll + sunlight = glucose Plants use carbon dioxide and water and sunlight to create glucose and oxygen We eat the glucose, and breathe the oxygen and release carbon dioxide and water vapor Chlorophyll is the green pigment in plants Glucose is the basic sugar molecule from which all other CHOs are built A plant can convert glucose into other sugars, starches and fibers The Simplest Carbohydrates The simplest carbohydrates are the sugars They are a natural part of many foods They have a sweet taste can be extracted from plants and used to sweeten candy, pop and baked goods Simple carbohydrates exist in their pure form as crystalline solids Eating too many simple sugars can lead to health problems Sugars are also called SACCHARIDES CHO= Sugars + Starches + Fibers Simple Sugar Molecule has 6 C, 12 H and 6 O It is a six sided ring (more stable form) containing a hydroxyl group (combination of hydrogen and oxygen containing one atom of each (OH) The “-” is a chemical bond that attaches the group Linear vs ring glucose Types of Simple Sugars There are two types of simple sugars: Monosaccharide Disaccharides The three examples of monosaccharides are glucose (buuilding blocks for all other sugars) fructose (fruits and tree sap) and galactose (usually bonded to something else…some are found in milk products) disaccharides Are made from 2 monosaccharides bonded together Three examples of disaccharides are sucrose (table sugar), lactose in milk (glucose and galactose stuck together) and maltose (commonly found in cereals…2 glucose molecules) ALL carbohydrates (whether simple or complex) are broken down into monosaccharides when digested Sucrose- table sugar Lactose (milk products) Maltose (cereals) 4 Properties of Sugar While sugars have the same chemical formula, they differ as to how they are positioned in the molecule ring The four properties are sweetness, caramelization, solubility, and crystalization Property 1- SWEETNESS Some sugars are sweeter than others Order of sweetness: fructose, sucrose, glucose, galactose, maltose and lactose The sweetness depends on concentration, consistency, temperature, and pH level, and how the molecules fit at the taste bud sites Sugar in Processed Food ½ cup of canned corn: 3 tsp 12 oz cola: 8 tsp 1 tbsp ketchup: 1 tsp 1 small yogurt: 7 tsp 2 oz chocolate: 8 tsp Property 2- Caramelization This is the browning reaction that can occur with any kind of sugar when heated. Sugars differ at what temperature this occurs As sugar is heated, water leaves the molecule. At high temperatures the molecule remnants join to form larger molecules with a higher concentration of carbon, which creates the distinctive caramel color Property 3: Solubility The ability of sugar to dissolve in water mirrors their sweetness Order of solubility: fructose (most soluble), sucrose, glucose, galactose, maltose and lactose Solubility is affected by water temperature (heat increases it) Supersaturation: solution that holds more dissolved solute than it would normally hold at that temperature Property 4: Crystallization This is beneficial in candy making Water evaporates increasing the amount of sugar when you are boiling the sugar solution at high temperatures. When it reaches a certain temperature, crystallization occurs. Crystals separate from solution each in a unique pattern of molecules The size of the crystals depends on how many particles are present and how quickly crystals grow around them A larger # of particles = smaller crystals Rapidly growing crystals = smaller Size also depends on the type of sugar (sucrose = large crystals and glucose and fructose = relatively small) Sucrose (left) and Fructose crystals The Complex Carbohydrates: Starches and Fibres Starches: plant foods, taste rather bland, stored in granular form Fibre: gives plants their structure (cellulose, pectins, gums, bran- which is the most concentrated form of fibre) There are also peas, lentils, corn, potatoes, dry beans, grain products (such as rice, pasta and breads) Polysaccharides Complex CHOs are polysaccharides or large molecules made of many simple glucose units Polysaccharides are made of chemically linked monosaccharides (there may be 10…there may be 10,000) A polysaccharide is an example of a polymer…which is a large molecule formed when small molecules of the same kind chain together together Starches Are literally plant food They are to plants what glycogen is to people RESERVE ENERGY Starches are stored in granular form mostly in seeds and roots While they are made of chains of sugar molecules they taste bland because of the type of glucose they are made of (alpa-D-glucose) Starches have 2 structures A) amylose (in this form of starch the molecules are linear, the are long and narrow like a line B) amylopectin (in this form molecules have multiple branches like veins in a leaf- typically more abundant than amylose) Most starches found in foods have both forms but in differing proportions Amylose vs. amylopectin Another view… Starches Starches are really important in food preparation as thickening agents and stabilizers Fiber Is not digested by the body It is what gives plants their structure The main plant fiber in foods in cellulose which is a polymer made of alpha-D-glucose Other edible fibers include hemicellulose, pectins, and algal polysaccharides Fiber, continued Fiber absorbs water helping to transport food through the intestines Fiber is found in whole grains, fresh fruits and vegetables dried fruits and nuts In order to digest fiber we need the enzyme cellulase. We can not synthesize this enzyme in our digestive tracts so we cant digest fiber, but ti does add bulk to our diet to help us feel full and also helps us to clean our intestines Pectins Are water soluble CHOs that occur naturally in many ripe fruits and vegetables. They produce a gelatine-like substance used to thicken jellies. They are also used in food as emulsifiers and stabilizers in the food industry. They are very easily oxidated becoming dark. This is why apples, pears and other fruits quickly brown after you cut them.