STARCH TEST IN FOODS (IODINE TEST)
AIM:
To detect the presence of starch in food items.
APPARATUS:
Test tube, dropper, beaker.
REAGENT:
Iodine solution.
PRINCIPLE:
Iodine reacts with starch to form a blue-black complex.
PROCEDURE:
Add a few drops of iodine solution to the food solution or crushed sample.
Observe for a blue-black coloration.
RESULT:
Presence of starch is confirmed by blue-black color.
Fehling’s Solution
Purpose: Used to detect reducing sugars.
Procedure (Fehling A & B):
Fehling A: Dissolve 69.28 g CuSO₄·5H₂O in 1000 ml distilled water.
Fehling B: Dissolve 346 g Rochelle salt (potassium sodium tartrate) and 100 g NaOH in 1000 ml distilled water.
Use: Mix equal volumes before testing.
FAT CONTENT TEST (SOLVENT EXTRACTION METHOD)
AIM:
To determine the fat content in a food sample.
APPARATUS:
Soxhlet extractor (or simple filter, beaker), drying oven, balance.
REAGENT:
Petroleum ether or hexane.
PRINCIPLE:
Fat is soluble in organic solvents and can be extracted and weighed.
PROCEDURE:
Weigh 5g of dried sample.
Extract fat using ether in a Soxhlet setup or soak in solvent.
Evaporate solvent and weigh the remaining fat.
CALCULATION:
% Fat = (Weight of extracted fat / Weight of sample) × 100
Simulated Saliva Fluid
Purpose: Used for evaluating drug dissolution in the oral cavity.
Procedure:
Dissolve 0.4 g NaCl, 0.4 g KCl, 0.795 g CaCl₂·2H₂O, and 0.69 g NaH₂PO₄·2H₂O in 900 ml distilled water.
Adjust pH to 6.8 with NaOH.
Make up the volume to 1000 ml with distilled water.
Store at room temperature.
Phosphate Buffer (pH 7.4)
Purpose: Used in biological experiments to maintain pH close to physiological conditions.
Procedure:
Dissolve 8.0 g NaCl, 0.2 g KCl, 1.44 g Na₂HPO₄, and 0.24 g KH₂PO₄ in 800 ml distilled water.
Adjust pH to 7.4 using HCl or NaOH.
Make up to 1000 ml with distilled water.
Store at 4°C if not used immediately.
LACTOSE CONTENT TEST (BENEDICT’S TEST)
AIM:
To detect and estimate lactose (a reducing sugar) in milk.
APPARATUS:
Test tubes, water bath, beaker, dropper.
REAGENT:
Benedict’s reagent.
PRINCIPLE:
Lactose is a reducing sugar and reacts with Benedict’s reagent to form a colored precipitate depending on the concentration.
PROCEDURE:
Add 5ml of milk sample to a test tube.
Add 5ml of Benedict’s reagent.
Heat in boiling water bath for 5 minutes.
Observe color change from blue to green, yellow, or brick-red.
CALCULATION:
Compare precipitate color to a standard chart to estimate % lactose.
