Cheese Whey Detection in Frozen Desserts

Conventional analyses and high pressure liquid chromatography were used to detect sweet-type cheese whey replacement for nonfat milk solids in ice milk mixes at substitutions below and above the allowable 25%. Sweet whey replacement was monitored by noting abnormally high lactic acid and lactose, lower protein (using Kjeldahl nitrogen and dye binding), high lactose to protein ratios, and small but distinctive amounts of glycomacropeptide as determined by its solubility characteristics (soluble in 12% trichloroacetic acid but precipitated by phosphotungstic acid) and sialic acid content. The following compositional characteristics of ice milk would be suspect in sweet whey adulteration above 25% replacement: lactic acid (lactate) above .05%, lactose to protein ratio above 2.1, and glycomacropeptide precipitate, (per 100g mix) having a dry weight above 55mg, and sialic acid content above 5.2 μ moles.