Abstract
The relative sourness of malic, citric, tartaric, and lactic acids was determined in two ways: by using the acids to change total titratable acidity by 0.1% or to change pH to 3.30. A trained laboratory panel used a ranking procedure to compare the sourness at the same titratable acidity. The order of sourness was malic> tartaric>citric>lactic. At the same pH the order was malic>lactic>citric>tartaric. All of the differences were statistically significant. Malic thus appears to be the most "sour" of the acids tasted.
The tasters varied markedly in ability to rank sourness—some tasters were nearly twice as efficient as others (as measured by deviation in ranking duplicate samples). Differences of 0.05 pH unit for the four acids were easily detected by the panel. These differences in pH were accompanied by differences in titratable acidity of 0.02 to 0.05%. When titratable acidity was changed 0.02, 0.03, 0.04, and 0.05, the differences in pH were 0.03, 0.035, 0.042, and 0.093. The panel was generally able to rank the samples, except tartaric acid, in order of sourness. Malic changed the pH less than the other acids. In these studies, both pH and percent titratable acidity appeared to be important in determining sensory response to sourness.
- Copyright 1965 by the American Society for Enology and Viticulture
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