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2nd lec chemical tests for meat differentiation
- 1. Chemical Tests for Differentiation of Meat Meat Hygiene and Public Health Dr. M. Wasim Usmani Dept. of Pathology, FVS-UAF
- 2. Methods for Glycogen Test EXTRACT GLYCOGEN FROM SAMPLE DECOMPOSITION OF FIBERS PRECIPITATION OF PROTEINS BOILING WATER POTASSIUM HYDROXIDE (KOH)
- 3. Brautigam and Edelmannโs Method โข Meat โข Distilled Water โข Burner โข Nitric acid โข Filter โข Saturated Aqueous Solution โข Iodine โข Iodine:KI:Water (2:4:100) โข Beakers โข Pipettes
- 4. Brautigam and Edelmannโs Method โข 50 grams of finely divided meat โข 200cc of water and boil for 30 mints โข Cooling (lowering temperature) โข Dilute nitric acid added to broth โข Precipitate protein โข Decolorize โข Filter the broth โข Portion of filtrate treated with freshly prepared aqueous solution โข Not to be mixed with broth โข Only form a layer above broth
- 5. Brautigam and Edelmannโs Method โข Glycogen presence โข Wine colored ring โข Disappears on heating & Reappears on cooling โข If color is not apparent clearly, โข Heat chopped meat on water bath with KOH solution (3% of wt f flesh) โข Fiber decomposed & broth become concentrated โข Treated with NHO3 โข Precipitate protein โข Filtered & treated with iodine
- 6. Brautigam and Edelmannโs Method Applied only on horse flesh Detect as little as 5% of horse flesh in a mixture Dextrins derived from starch also give the same colouration
- 7. Bastienโs Method โข 20 grams sausage โข Water โข Burner โข Filter โข Aqueous solution โข Iodine โข Iodine:KI:Water (1:2:100) โข Pipettes โข Beakers โข Dropper
- 8. Bastienโs Method โข 20 grams of finely divided sausage โข Add 100cc water โข Boiling for 30 to 60 mints โข Reduced the volume of liquid to about 30cc โข Cooling (lowering temperature) โข Filter the broth โข 10cc of broth treated โข 2 or 3 drops of iodine/solution of iodine
- 9. Bastienโs Method โข Fugitive reddish-violet color โข Starch โข Acetic acid is added โข Capable of detecting 5% of horse flesh in the presence of starch
- 10. Landwehrโs Method โข 20 grams sausage โข Water โข Burner โข Zinc acetate โข Ferric chloride โข Sodium hydroxide (Conc.) โข Acetic acid (Conc.) โข HCl โข Alcohol โข Pipettes โข Beakers
- 11. Landwehrโs Method Preparation of broth 20 grams of finely divided sausage Add 100cc of water Boil for 30 to 60 mints Reduce volume to 30cc Add Zinc acetate Neutralize & free from albuminous substances, Filter Heat the filtrate on water bath with ferric chloride
- 12. Landwehrโs Method โข Add conc. solution of NaOH โข Iron precipitation โข Filter the precipitate rapidly โข Wash with hot water โข Dissolve precipitate in conc. Acetic acid โข Add HCl in cold solution โข Yellow coloration โข Pour solution in alcohol โข Collect, wash & dry flocculent ppt. of glycogen
- 13. Niebelโs Method โข Converts whole carbohydrates into dextrose โข Determines total amount of reducing substances โข Fehlingโs solutions Glycogen has undergone decomposition
- 14. Niebelโs Method โข No horse flesh โข Dextrose not more than 0.7% โข Horse flesh โข Dextrose will be about 1.18 to 3.7% Total amount of carbohydrates exceeds 1%