Sensory Discrimination of Milk Salts, Lactose, Nondialyzable Constituents, and Algin Gum in Milk

A dual-standard, paired-comparison method was used by a trained panel to detect additions to milk of lactose, a milk salt mixture, a concentrate of nondialyzable constituents (NDC, mainly protein), and algin gum. To compare the additives on an equivalent basis, concentrations that could be detected two times out of three, as estimated by interpolation, were used. These values were milk salts, 0.03% in skimmilk (8.5 and 10.0% SNF) and 0.05% in milk with 2.0 and 3.5%, fat; lactose, 0.33%,; and NDC, 2.5% (2.2% protein). Criteria used most frequently to distinguish samples containing the additives were for milk salts, saltiness, tactile properties, and taste (quality unspecified); for lactose, sweetness and aftertaste; and for NDC, richness and tactile properties. In milks to which algin gum was added to increase viscosity, two-thirds correct response was obtained with 1.3 cp difference in whole milks (3.5% fat, and both 8.5 and 10.0%, SNF) and 2.3 cp difference in skimmilk. In comparing milk containing 2.0% fat with milk containing 3.5% fat, increasing the viscosity of the 2.0% milk (by adding gum) to equal that of the 3.5% milk did not influence detection of the difference in concentration of fat. Apparently, viscosity was not an important factor in this discrimination.