General analytical methods of milk powder final

Detailed analytical procedure of milk powder are explained in this document.

1. General analytical methods of milk powder Procedure-; Preparation of sample of dried milk Determination of moisture of dried milk Determination of fat of dried milk Determination of titratable acidity in dried milk Determination of total carbohydrates in dried milk

2. Preparation of sample of dried milk Make homogeneous either by mixing or shaking alternatively rolling and inverting container. Avoid excessive temperature and humidity when opening sample container to prevent absorption of moisture

3. Determination of moisture in dried milk The sample is dried to constant weight at 102±2ºc and the loss in weight reported as moisture Moisture% by mass =100(m1-m2)/m1-m Where M=mass in gm of the empty dish M1=initial mass in gm of the dish and lid with the material taken for analysis M2=final mass in gm of the dish and lid with the material after drying

4. Determination of fat in dried milk Weigh 1 gm of the sample in a mojonnier flask or suitable extraction flask. Add 10ml of warm(65±5ºc) distilled water. Shake to dissolve the powder. Add 1.25ml of a ammonia in a solution. Shake well and proceed as per Rose Gottlieb method . The sample is treated with ammonia and ethyl alcohol;the former to dissolve the protein and the latter to help precipitate the proteins. Fat is extracted with diethyl ether and petroleum ether. Mixed ethers are evaporated and the residue weighed. Fat%(W/W)=Weight of extracted fat/Weight of milk×100

5. Determination of titratable Acidity in dried milk The method is based on the titration of the sample with sodium hydroxide to phenolphthalin end point and by comparing the colour with colour obtained by mixing rosaniline acetateor cobalt sulphate to known volume of milk sample. Calculate acidity as Lactic acid.(present m/v)if desired. 1ml 0.1 N NaOH =0.0090g Latic acid.

6. Determination of total carbohydrates in dried milk Determine total carbohydrate by difference in infant milk food. Add moisture, fat content and deduct the value from 100 to give carbohydrate content by difference. Total carbohydrate including sucrose,dextrose and dextrins,maltose or lactose percent by weight=100-(A+B). Where A=percent by mass of moisture B=percent of mass of fat

7. DETECTION OF ADULTRANTS IN MILK POWDER

8. DETECTION OF CANE SUGAR IN MILK POWDER MODIFIED SELINWANOFF METHOD- : Principle: -Fructose + Resorcinol in HCL  Red colour Procedure-: Milk + Conc.HCL  Filter---- 1 ml filtered milk serum & 5 ml modified resorcinol-HCL reagent after this withdraw the tube & observe the colour Observe the colour

9. DETECTION OF ADDED UREA IN MILK powder. Procedure-: 5 ml milk+5 ml 1.6% of p- dimethyl amino benzaldehyde (DMAB)  distinct yellow colour observed in milk The control(Normal milk) shows a slight yellow colour due to presence of natural urea.

10. Estimation of Ammonium compound in milk powder. 1.0 ml milk+0.5 ml 2% NaOH+0.5 ml 2% NaOCL+0.5 ml 5% phenol  heat for 20 sec in boiling water bath bluish colour turns deep blue in presence of ammonium sulphate. Development of pink colour shows the sample is freed from ammonia Ammonium sulphate

11. TEST FOR PRESERVATIVE Hehners ’ test(HCHO)-: Procedure 2 ml milk in test tubes 2 ml of 90% H 2 SO 4 traces of Fecl 3 Formaldehyde

12. TEST FOR PRESENCE OF SALICYLIC ACID 50 ml milk+5 ml of dil.HCL+50 ml ether (wash ether layer with water) Evaporate ether Violet colour

13. Test for presence of hydrogen peroxide Milk + conc.Hcl Mix well Drop of HCHO solution 60 c Place Starch iodine paper into solution.

14. Estimation of urea in milk Preparation of standard curve-: Pippete 5ml std solutions into 25ml.Add 5 ml DMAB solutions to each Prepare reagent blank of 5ml buffer and 5ml DMAB solutions. Shake tubes throughly and let stand for 10min. Read at 420 nm PREPARATION OF SAMPLE-: 10 ml of milk sample add 10 ml of tri- chloro acetic(TCA) to ppt the protein and filtered. 5 ml of filtrate + 5ml of DMAB. The optical density of the yellow colour is measured at 420nm. From standard curve the amount of urea in milk is calculated.(70mg per 100ml-700ppm).

15. Determination of chloride content 10 ml milk + 40 ml water Pot.chromate 10drops Titrate with 0.1N AgNO 3 Reddish brown ppt 1 ml of 0.1N AgNO 3 equivalent to 3.55mg of chloride. Indicative of diseased state of animal.

16. Detection of neutralizers in milk Neutralizers( NaOH ,Na 2 co 3 and NaHCO 3 ) are used to neutralize the developed acidity in milk. Rosalic acid method can be used for the detection of presence of these neutralizers in milk. The other method available for detection of neutralizers in milk is through determination of alkalinity of ash. METHOD -:10 ml milk and add equal volume of 95% alcohol in a test tube. Add a few drops of 0.1% alcoholic solution (w/v) rosalic acid. If alkali is present a rose red colour appears whereas pure milk shows only a brownish colour. The limit of detection of method is 0.1% for NaOH,0.1% for Na 2 CO 3 and 0.2% for NaHCO 3.

17. Submitted by-: Sk Aziz uddin M.pharm-2020-22 Pharmaceutical analysis Thank you