Affiliations: Nutrition Department, Cardenal Herrera-CEU University,
Valencia, Spain | Centro de Salud Moncada, Sevei Valenciá Salut,
Valencia, Spain | Physiology, Pharmacology and Toxicology Department,
Cardenal Herrera-CEU University, Valencia, Spain
Note: [] Address for correspondence: Dr. Francisco Javier Romero Gómez,
Universidad Cardenal Herrera-CEU, Avda. Seminario s/n, 46113 Moncada, Valencia,
Spain. Tel.: +34 961369000; Fax: +34 961369013; E-mail: jromero@uch.ceu.es
Abstract: Available lysine content is an indicator of protein quality and
nutritional value of milk. Many studies have examined the effects of
extraction, treatment and storage of human milk upon its components, though no
references are found regarding the possible changes in milk quality as defined
by its content in essential amino acids such as lysine. The present study
investigates the available lysine content in human milk and the variations in
lysine resulting from milk manipulation as follows: (a) Cold storage
(refrigeration at 4°C for 48 hours, and frozen for 15
days at −20°C); (b) Thermal
treatment under conditions of low (Holder)(63°C/30
minutes) and high pasteurization (75°C/15 seconds).
The results obtained show a decrease in milk lysine concentration after storage
in both refrigerated and frozen samples. Pasteurization causes a highly
significant loss of available lysine. The lysine losses were greater on
applying low pasteurization versus the more gentle conditions of high
pasteurization. Conclusions: While manipulation through cold storage or thermal
treatment does not affect the protein content of human milk, its protein
quality is modified. When human milk must be subjected to hygienization, it is
preferable to apply high temperature treatment (75°C,
15 seconds) than habitual pasteurization (63°C, 30
minutes).
Keywords: Lysine, human milk, pasteurization, refrigeration, freezing
Journal: BioFactors, vol. 26, no. 1, pp. 71-79, 2006
