Effect of content of acetaldehyde and diacetyl on the flavor of yogurt

In this paper,the content of acetaldehyde and diacetyl were determinated by using iodine titration and the o-phenylenediamine colorimetric in fermented milk.And the test showed that both methods were simple,stable and reproducible.The milk added different concentrations of exogenous acetaldehyde and diacetyl were tasted.The results showed that acetaldehyde was refreshing aroma,diacetyl can bring cream flavor.The thresholds of those were 5mg/L.When the content more than 30mg/L,the yogurt will produce an unpleasant flavor.The yogurt had coordinated flavor when the ratio of aldehyde and diacetyl was 2.5.The study provided a more objective reference for the evaluation of yogurt flavor.