Identification of Biochemicals in Pure Form and in Common Foodstuffs

TITLE : IDENTIFICATION OF BIOCHEMICALS IN PURE FORM AND IN COMMON FOODSTUFFS

AIM: THE OBJECTIVE OF THIS EXPIREMENT IS TO PERFORM TESTS ON A VARIETY OF COMMON FOODS TO IDENTIFY THE CHEMICALS THEY
CONTAIN AND TO TEST PURE SAMPLES OF BIOCHEMICALS TO GAIN FAMILIARITY WITH THE COLOUR CHANGES.

RESULTS:
TABLE 1 : BIOCHEMICAL TESTS ON PURIFIED BIOLOGICAL SUBSTANCES

SAMPLE | TEST | OBSERVATION | Glucose | Reducing Sugar | The initial blue colouration of the mixture turns green, then yellowish and finally forms a brick-red precipitate. | Sucrose | Reducing Sugar | As Benedict’s Test | Iodine Solution | Starch | A Blue-Black Colouration | Sudan III | Lipids | A Red-Stained Oil Layer separates on the surface of the water, which remains uncoloured | Biuret Solution | Proteins | Mauve or Purple Colour Slowly Develops |
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Table 2 . Biochemical Tests On Common Foodstuffs

Sample | Proteins | Lipids | Starch | Sugars | Egg white | Turns Purple / +ve | Turns pale orange / -ve | Turn yellow/-ve | -ve /not present in egg white | Sprite | Turns pale orange / -ve | Turns Pale Orange /-ve | Turns an orange-brownish colour / -ve | -ve /not present in sprite | Diet Sprite | Light Blue/ -ve | Turns Pale Orange / -ve | Turns an orange-brownish colour /-ve | +ve/present in diet sprite | Milk | Turns Lilac / +ve | Turns Peach / +ve | Turns Yellow /-ve/not present | +ve/present in milk | Sunflower Seeds | Turns Green/ +ve | Turns Orange/-ve | +ve /Starch is present | +ve/present in sunflower seeds | Corn Starch | Turns Yellow/-ve | Turns Orange/-ve | Turns Puple-+ve/ Starch is present | -ve/ not present in corn starch |

Discussion :
The reducing sugars include all monosaccharides such as glucose and fructose and some disaccharides such as maltose. Benedict’s Test for reducing sugars contains copper sulphate. Reducing sugars reduce souluble blue copper sulphate, containing copper (II) ions (Cu2+) to insoluble red-brown copper