eChapter Name: Tests to Maintain Quality of Dairy Products
9789390083725
eBook Name: QUALITY ASSESSMENT OF MILK & MILK PRODUCTS
by D.K.Thompkinson
The growing chemicalization of milk presents a great challenge to the dairy industry. A number of chemical compounds get entry into milk, intentionally or un-intentionally, through their direct or indirect usage for crop, animal; or dairy husbandry practices, as environmental contamination. Several of these contaminants may be naturally present on grazing grass or use as pesticides for green fodder or they may get entry through use of compounded animal feeds. These eventually get excreted into milk as residues and pose problems to food safety. The risk of health hazards arises from veterinary drugs, residual pesticides, heavy metals, detergents and micotoxins etc. It is therefore, become necessary to detect these contaminants in order to make food safe for human consumption.
Detection of Aflatoxin M 1 in Milk
Material requirements : Glass column(30 cm x 1 cm), Silica gel (63-200 µg particle size), volumetric flasks, beakers, micro pipette, HPLC equipment fitted with C 18 column(25 cm x 4.6 mm) and fluorescence detector.
Reagents: Sodium chloride solution (400g in 1000ml water), acetonitrile/water mixture (25:75), sodium sulphsate, chloroform, toluene/acetic acid mixture (9:1), acetonitrile/diethyle ether/hexane mixture (1:3:6), chloroform/acetone mixture (8:2), n-hexane and aflatoxin standard ampule.
Preparation of stock solution : Transfer contents from 2.5ml or 0.5ml ampoule, quantitatively, to 25ml or 50ml volumetric flask respectively. Rinse ampoule with small quantities of chloroform and collect rinsing into flask. Makeup the volume with chloroform, mix well and store at 5º C or below. These solutions will contain 1 µg per ml aflatoxin M1.
Working solution : Transfer 0.5ml of stock solution to a 10ml conical flask. Evaporate contents to dryness using inert gas. Dissolve residue in 10ml of acetonitrile/water mixture. Prepare series of dilutions containing 0.0025, 0.005, 0.01 and 0.025 µg/ml aflatoxin. Similarly treat 5ml of stock solution to give a concentration of 0.5 µg/ml.