From: Common milk adulteration and their detection techniques
Adulterant | Procedure | Observation | Limit of detection (v/v) (R. Sharma, Rajput, Barui, & N., 2012) | References |
---|---|---|---|---|
Sugar | Take 5Â mL milk sample in a test tube. Add 1Â mL conc. HCl and 0.1Â g resorcinol solution. Place the test tube in water bath for 5Â min. | Appearance of red color indicates he presence of added sugar. | 0.2% (w/v) | (Sharma et al. 2012); (Kamthania et al. 2014); (Arvind Singh et al. 2012) |
Starch | Take 3Â mL sample in a test tube. After boiling it thoroughly, cool it to room temperature. Add 1 drop of 1% iodine solution. | Appearance of blue color indicates he presence of starch. | 0.02% (w/v) | (Sharma et al. 2012); (Arvind Singh et al. 2012), (Kumar et al. 1998) |
Glucose | Take 1Â ml of milk sample in a test tube. Add 1Â ml of modified Barfoed's reagent. Heat the mixture for exact 3Â min in a boiling water bath. Rapidly cool under tap water. | Immediate appearance of deep blue color indicates the presence of glucose. | 0.1% (w/v) | (Sharma et al. 2011) |
Add one ml of phosphomolybdic acid reagent to the turbid solution. | ||||
Common salt | Take 5Â ml of milk sample into a test tube. Add 1Â ml of 0.1Â N silver nitrate solution. Mix the content thoroughly and add 0.5Â ml of 10% potassium chromate solution. | Appearance of yellow color indicates the presence of added salts, whereas, brick red color indicates the milk free from added salt. | 0.02% (w/v) | (Sharma et al. 2012) |
Buffalo milk | Dilute the milk 1/10. Put a drop of diluted milk on the centre of a glass slide. Now place a drops of Hansa test serum (duly preserved) on the drop of milk and mix together with a glass rod or clean tooth pick. | Curdy particles develop within half a minute in milk containing buffalo milk. | Â |