Human Milk Composition and Preservation: Evaluation of High-pressure Processing as a Nonthermal Pasteurization Technology.

Human milk is seen not only as a food, but as a functional and dynamic biologic system. It provides nutrients, bioactive components, and immune factors, promoting adequate and healthy growth of newborn infants. When mothers cannot supply their children, donated breast milk is the nutrition recommended by the World Health Organization, as it is a better alternative than infant formula. However, because of the manner in which donor milk is handled in human milk banks (HMB) many of the properties ascribed to mother's own milk are diminished or destroyed. The major process responsible for these losses is Holder pasteurization. High-pressure processing (HPP) is a novel nonthermal pasteurization technology that is being increasingly applied in food industries worldwide, primarily as an alternative to thermal treatment. This is due to its capacity to inactivate microorganisms while preserving both nutritional and bioactive components of foods. This review describes human milk composition and preservation, and critically discusses HMB importance and practices, highlighting HPP as a potential nonthermal pasteurization technology for human milk preservation. HPP technology is described and the few currently existing studies of its effects in human milk are presented.

Effect of thermal pasteurisation and high-pressure processing on immunoglobulin content and lysozyme and lactoperoxidase activity in human colostrum.

Human milk, and particularly human colostrum, is the gold standard for newborn nourishment. Colostrum contains the highest concentration of immune factors, being the most potent immune booster known to science. In this work, we investigated Holder pasteurisation and high-pressure processing (HPP) effects on colostral IgA, IgM, IgG, lysozyme and lactoperoxidase. The amount of Igs was significantly decreased after Holder pasteurisation (20%, 51% and 23% for IgA, IgM and IgG, respectively), but fully preserved after HPP at 200 and 400 MPa. HPP at 600 MPa for 2.5 min resulted in the maintenance of IgA and losses of IgM and IgG (21% for both). The pressure treatments at 600 MPa for 15 and 30 min led to similar or higher losses than pasteurisation. D-values (min) for Igs ranged from 4941 to 452 at 400 MPa and from 235 to 40 at 600 MPa. Lysozyme activity was lost after pasteurisation (decreased 44%) and maintained after HPP. Lactoperoxidase activity was not detected. As far as the authors are aware, this is the first study evaluating HPP effects on human colostrum.

Design of ionic liquids for lipase purification.

Aqueous two-phase systems (ATPS) are considered as efficient downstream processing techniques in the production and purification of enzymes, since they can be considered harmless to biomolecules due to their high water content and due to the possibility of maintaining a neutral pH value in the medium. A recent type of alternative ATPS is based on hydrophilic ionic liquids (ILs) and salting-out inducing salts. The aim of this work was to study the lipase (Candida antarctica lipase B - CaLB) partitioning in several ATPS composed of ionic liquids (ILs) and inorganic salts, and to identify the best IL for the enzyme purification. For that purpose a wide range of IL cations and anions, and some of their combinations were studied. For each system the enzyme partitioning between the two phases was measured and the purification factors and enzyme recoveries were determined. The results indicate that the lipase maximum purification and recovery were obtained for cations with a C(8) side alkyl chain, the [N(CN)(2)] anion and ILs belonging to the pyridinium family. However, the highest purification parameters were observed for 1-methyl-3-octylimidazolium chloride [C(8)mim]Cl, suggesting that the IL extraction capability does not result from a cumulative character of the individual characteristics of ILs. The results indicate that the IL based ATPS have an improved performance in the lipase purification and recovery.