Improving Quality of Banked Milk: Utility of Dornic Acid Test

To identify, if Dornic acid test done on human milk bank sample is as effective as doing routine culture, both pre and post pasteurization.

The authors analyzed 477 samples, both pre and post pasteurization. Dornic acid measurement was performed by using N/9 NaOH and titrated to get dornicity of the sample. Senstivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) at different Dornic acid levels were calculated. To find diagnostic power of this study, ROC curve was prepared. Dornic acid for paired pre and post pasteurization were noted and analysed for statistical significance.

A significant growth was seen in 21% (98/477) samples with coagulase negative staphylococci and gram negative organisms being the major contaminants seen prior to pasteurization. In the index study, Dornic acidity ≥4°D had a sensitivity of 98% but very low specificity of just over 10%. However, 8°D had 92% specificity and acceptable sensitivity of 72% in comparison to gold standard microbiological criteria, making it a good test for analyzing the quality of milk before pasteurization.

Dornic acid test at 8°D has a very high specificity with acceptable sensitivity in comparison to dornicity at 4°D. It can be used as a simple method to select better quality of milk sample prior to pasteurization.