食品化学教学课件电子教案全套课件一.pptx

CARBOHYDRATES Carbohydrate - polyhydroxy aldehyde, ketones and their derivatives.Functions - structure material storage material for carbon and energy. CONCEPTS OF ISOMERS Two or more different compounds which contain the same number and types of atoms and the same molecular weights.?Projection formula (spatial arrangement to represent 3-dimensional structure): D-glyceraldehyde (hydroxy group at the highest numbered asymmetric carbon atom is written to the right): L-glyceraldehyde (hydroxy group at the highest numbered asymmetric carbon atom is written to the left):D-Erythrose is the mirror image of L-Erythrose. Glyceraldehydes: Model compounds of monosaccharides D-Glyceraldehyde L-Glyceraldehyde D-Erythrose L-Threose POLARIMETER Dextrorotatory -plane polarized light rotated to clockwise (or to the right)Levoratatory - plane polarized light rotated to counterclockwise. FISHER PROJECTION FORM Anomeric Carbon --- The carbon atom which is involved in hemiacetal or acetal formation. Anomers: Stereoisomers formed when ring is formed (a, b). a is same side with ring HAWORTH PROJECTION FORMULAS FOR SUGARS a - D - Glucopyranose HOCOCH2OHCHHOHHCOHCHHCOHHOOHCHHCOHCHHHOHCCH2OHOCCOCH2OHCHHOHHCOHCHHCOHOHCOCH2OHOHCHHOHHCOHCHOHHCOHOHCHHCOHCHHHOHCCH2OHOC-D-Glucofuranose (0.5%)aa-D-Glucopyranose (35%)-D-Glucofuranose (0.5%)bb-D-Glucopyranose (0.5%)Aldehydo-D-glucose (0.03%)HAWORTH PROJECTION FORMULAS FOR SUGARS MONOSACCHARIDE Hexoses1. Glucose (dextrose) --- rotate the polarized light to the right. Most common monosaccharide.Commercially from starch.Cereal roots, legumes, animal tissue, and liver.?Mutarotation --- The optical changes of glucose in water solution to constant value a20D = +520??a - D - glucose - D - glucose - b - D - glucose a20D = 113 a20D = 52 a20D = = 19 At equilibrium = 35% of a - form and 65% of b - form. Glucose (dextrose) 2. Galactose --- Component of lactose (milk sugar) a-D-G