We developed a simple
microtechnique to measure
lipids in milk by UV
spectrophotometry. This technique
is based upon the property of fatty acids to absorb UV light proportional to their concentration. Samples of powdered or fluid milk (30 or 60 muL) were added to 3 mL of analytic grade
ethanol and stored
at -20 degrees C for at least 1 h. This procedure
precipitates proteins and
hydrophobic peptides that interfere with UV measurement. Sample
absorbances are then measured at 208 nm in an UV-Vis
spectrophotometer. This technique correlated very well against Milko-Scan, a device that measures milk fat by IR
spectroscopy, with an r(2) >0.982. Accuracy and precision, evaluated by recovery and replicate assays, are also very acceptable. This method is suitable as a fast, cost-effective alternative screening
method to estimate milk fat content in small samples without prior
lipid extraction.