Determination of Dornic acidity as a method to select donor milk in a milk bank.
BACKGROUND
Dornic acidity may be an indirect measurement of milk's bacteria content and its quality. There are no uniform criteria among different human milk banks on milk acceptance criteria. The main aim of this study is to report the correlation between Dornic acidity and bacterial growth in donor milk in order to validate the Dornic acidity value as an adequate method to select milk prior to its pasteurization.


METHODS
From 105 pools, 4-mL samples of human milk were collected. Dornic acidity measurement and culture in blood and McConkey's agar cultures were performed. Based on Dornic acidity degrees, we classified milk into three quality categories: top quality (acidity <4°D), intermediate (acidity between 4°D and 7°D), and milk unsuitable to be consumed (acidity ≥ 8°D). Spearman's correlation coefficient was used to perform statistical analysis.


RESULTS
Seventy percent of the samples had Dornic acidity under 4°D, and 88% had a value under 8°D. A weak positive correlation was observed between the bacterial growth in milk and Dornic acidity. The overall discrimination performance of Dornic acidity was higher for predicting growth of Gram-negative organisms. In milk with Dornic acidity of ≥ 4°D, such a measurement has a sensitivity of 100% for detecting all the samples with bacterial growth with Gram-negative bacteria of over 10(5) colony-forming units/mL.


CONCLUSIONS
The correlation between Dornic acidity and bacterial growth in donor milk is weak but positive. The measurement of Dornic acidity could be considered as a simple and economical method to select milk to pasteurize in a human milk bank based in quality and safety criteria.
Department of Neonatology, Hospital 12 de Octubre, Madrid, Spain. sara.vazquezroman@gmail.com
Sara
S
Vázquez-Román
Nadia Raquel
NR
Garcia-Lara
Diana
D
Escuder-Vieco
Fernando
F
Chaves-Sánchez
Javier
J
De la Cruz-Bertolo
Carmen Rosa
CR
Pallas-Alonso
D001420:Bacteria, Aerobic / Q000254:growth & development; D015169:Colony Count, Microbial; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D019344:Lactic Acid / Q000032:analysis*; D017784:Milk Banks / Q000706:statistics & numerical data; D008895:Milk, Human / Q000737:chemistry / Q000382:microbiology*; D061352:Pasteurization / Q000379:methods; D011247:Pregnancy; D014019:Tissue Donors
D019344:Lactic Acid