Estudo de desempenho de metodologia para determinação rápida e simultânea de acidez titulável e proteína em leite humano

Abstract

Human milk (HM) is the most appropriate food for newborns, especially preterm and low birth weight infants, due to its unique nutritional and immunological composition. In human milk banks (HMBs), quality control of donated HM is essential to ensure sanitary safety and appropriate nutritional allocation for infants. However, although routine analyses are performed during milk screening, the quantification of total protein is not yet part of HMB routine practice, due to the complexity, time requirements, cost, and laboratory infrastructure associated with reference methods such as the Kjeldahl method. In this context, the present study aimed to evaluate the performance of a rapid analytical methodology for the simultaneous determination of titratable acidity and total protein in HM, applicable to HMB routine. For this purpose, the formaldehyde (Sørensen) method adapted for HM, as described by Quirino (2022), was used, with miniaturization of the technique and integration into Dornic acidity analysis. Initially, 196 HM samples were analyzed in duplicate using both the adapted formaldehyde method and the Kjeldahl method, resulting in a statistically significant linear regression model (p < 0.05), enabling the prediction of protein content (%) based on the volume of Dornic solution consumed after formaldehyde addition. Subsequently, the methodology was adjusted to HMB operational conditions, using materials and procedures compatible with routine practice, and applied to 78 HM samples, also in duplicate, with simultaneous comparison to the Kjeldahl method to assess applicability and agreement. The results demonstrated that the adapted method showed analytical feasibility and potential for incorporation into HMB routine, as it allows rapid, simple, and low-cost estimation of total protein content without additional sample consumption, representing a promising alternative to improve screening and nutritional allocation of donated HM.