 CHOs are aldehyde or ketone alcohols containing carbon, hydrogen and oxygen in which the hydrogen and oxygen are generally in the same ratio as in water.  General formula: Cx(H2O)y; where x=y or x≠y

 Classified into 2 board groups: Sugars & Polysaccharides  Sugars are – Monosaccharides, Disaccharides, trisaccharides, tetrasaccharides and so forth.  Monosaccharides- trios, tetros, pentose, hexose, and others  Sugars are- Crystalline, soluble in water & sweet tasting

 Diose: Hydroxy acetaldehyde  Triose: Glyceraldehyde & Dihydroxyacetone  Tetrose: Erythrose  Pentose: Ribose, Xylose, Arabinose, Ribulose etc  Hexose: Glucose, Fructose, Galactose etc

 most imp. monosaccharides found in plant  first detectable sugar  16 possible aldohexoses and 8 ketohexoses, if consider both alpha and beta form-then 48 isomers  2 occur in free state- D-fructose (Levulose) & D-glucose

 Both found in sweet fruits  Starch on hydrolysis – Glucose  Inulin on hydrolysis – Fructose  Glucose is aldohexose - Polyhydroxy alcohol containing an aldehyde group  Fructose is ketohexose - Polyhydroxy alcohol containing a ketone group

 Glucose generally forms- 6-membered pyranose ring which can be written in two ways-

 Fructose can exist in two cyclic form-  Fructopyranose  Fructofuranose

Sugars that contain aldehyde groups that are oxidised to carboxylic acids are classified as reducing sugars. Common test reagents are : Benedicts reagent (CuSO 4 / citrate) Fehlings reagent (CuSO 4 / tartrate) They are classified as reducing sugars since they reduce the Cu 2+ to Cu + which forms as a red precipitate, copper (I) oxide. Remember that aldehydes (and hence aldoses) are readily oxidised In order for oxidation to occur, the cyclic form must first ring-open to give the reactive aldehyde. So any sugar that contains a hemi-acetal will be a reducing sugar. But glycosides which are acetals are not reducing sugars.

 Ketoses can also be reducing sugars because they can isomerise (a tautomarisation) to aldoses via an enediol:

 Sucrose (α-D-glucopyranosyl-β-D- fructofuranoside) occur abundantly in the free state : glucose and fructose  Maltose-2 molecules of glucose  Lactose- D-glucose & D-galactose

 A mixture of equal parts of glucose and fructose resulting from the hydrolysis of sucrose. It is found naturally in fruits and honey and produced artificially for use in the food industry.

 Plane polarized light, when passed through a sample of pure sucrose solution, is rotated to the right (optical rotation).  As the solution is converted to a mixture of sucrose, fructose and glucose, the amount of rotation is reduced until (in a fully converted solution) the direction of rotation has changed (inverted) from right to left.  C 12 H 22 O 11 (sucrose, specific rotation= +66.5°) + H 2 O (water, no rotation) → C 6 H 12 O 6 (glucose, Specific rotation = +52.7°) + C 6 H 12 O 6 (fructose, Specific rotation = −92°) net: +66.5° converts to −39° Contd……

 Hydrolysis is a chemical reaction in which a molecule breaks down by the addition of water. Hydrolysis of sucrose yields glucose and fructose about 85%, the reaction temperature can be maintained at 50–60 °C (122–140 °F).

 Disaccharide  Saccharum officinarum (Fam. Gramineae)  Beta vulgaris (Fam. Chenopodiaceae)  C12H22O11  Structure:

sugar cane stem crushed between heavy rollers Boiled with lime to neutralize plant acids & to coagulate albumins Juice is filtered & decolorized with sulfur dioxide- concentrated & crystallized residual, dark-colored syrup is molasses

 Syrup  Demulcent  nutrient  bacteriostatic and preservatives  masks disagreeable taste  retard oxidation in certain preparation

 α-D(+)-glucopyranose  grapes and other fruits  controlled enzymatic hydrolysis of starch  purification to obtain crystalline dextrose  99.5% to 100% pure  suitable for parenteral use

 oxidation of dextrose- gluconic acid  Calcium Gluconate  Ferrous gluconate

 nutrient  ingredient in dextrose injection:  alcohol & dextrose inj.  NaCl & dextrose inj.  dopamine HCl & dextrose inj.  lidocaine HCl & dextrose inj.  KCl & dextrose inj.  sweetening agent  substitutes for sucrose in syrups  tablet binders and coating agents

 Fruit sugar  colorless crystals  white crystalline or granular odorless powder  sweet taste  freely soluble in water

 Food for diabetic people  benefit in diabetic acidosis  infant feeding formula  fructose injection  calorie conscious person- half as sweet as glucose