Transcript Document
Note Tour of Atlantic Superstore in Sydney River Lecture 21- 27 February 2015 Carbohydrates Carbohydrates Definition -hydrate of carbon -hydrate means water -carbon is an element Carbohydrates Definition -literally a carbohydrate then is a hydrate of carbon -remember water is H2O -thus they contain carbon, hydrogen and oxygen -contain 1 oxygen atom and one carbon atom for every two hydrogens -thus overall formula is CH2O Source -plants take carbon dioxide from air, water from the soil and energy from the sun to make carbohydrates Types -simple, complex -Types of Carbohydrate -Simple -defined by the way sugar units are linked together -sugar units are called saccharides -a sugar unit is 6 carbons (frequently) Types of Carbohydrate -Simple -simple includes monosaccharides and disaccharides -monosaccharides are one sugar unit -eg glucose (blood sugar) and fructose (fruits and vegetables) -disaccharides are two sugar units -eg sucrose (table sugar) and lactose (milk sugar) and maltose ( occurs when the body digests starch) mono- and disaccharides give varying degree of sweetness to foods Complex -Oligosaccharides -3-10 sugar units linked together -dried beans, peas contain the 2 most common oligosaccharides Complex -Oligosaccharides -body cannot not break down these two most common oligosaccharides on its own so it requires bacterial enzymes that make these 2 oligosaccharides into gas -this explains why one gets gas after eating beans and peas Complex Polysaccharides -more than 10 sugar units linked together -some are straight chains -other are branched chains Polysaccharides -the way that the sugars units are linked to one another dictates whether the body can digest polysaccharides -we can digest starch but not dietary fibre - some dietary fibre can be digested by some bacteria in the large intestine -in the process of such bacterial digestion gas is made Polysaccharides -plants store sugars as starch -starch comes in two forms -amylose and amylopectin Polysaccharides -when we eat plants we eat starch (eg bread or potatoes) -animals store sugars as glycogen -when an animal is slaughtered glycogen is broken down as part of the death process down so we eat only trivial amounts of glycogen or no glycogen at all Polysaccharides -dietary fibre provides structure to plant cell walls -all types of plants have dietary fibre including fruits, vegetables, legumes and whole grains Polysaccharides -fibres include -cellulose (long straight chains) -pectins (found especially in fruits) -pectins mixed with acid give firmness to jellies and jams -gums- used in ice cream to thicken it Polysaccharides -fibres are classified as water soluble and water insoluble -this means that they dissolve in water (water soluble) or that they do not dissolve in water (water insoluble) -pectins and gums dissolve in water (water soluble) -cellulose does not dissolve in water (water insoluble) Polysaccharides -foods rich in soluble fibre fruits- apples, oranges, cranberries vegetables-asparagus, broccoli,carrots nuts and seeds-pecans, peanuts, walnuts legumes-most legumes grains-oat bran, oatmeal Polysaccharides -foods rich in insoluble fibre fruits- apples, bananas, cherries vegetables-sprouts, broccoli, red cabbage nuts and seeds-almonds, sesame seeds, walnuts legumes-most legumes grains-brown rice, whole wheat breads Digestion- breaking down foods and their nutrients in digestive tract -eg carbohydrates Absorption- moving nutrients across intestinal wall -eg carbohydrates Transport-moving nutrients around in body -eg carbohydrates