Powder milk formulas, sealed in their original packaging, were stored at different temperatures in order to accelerate their eventual oxidation and to have information about the shelf life of these products more quickly. The samples were extracted with aqueous trichloroacetic acid, and MDA was quantified on the basis of the third derivative absorption spectrum of the pink MDA/TBA adduct. The stability of infant milk formulas was evaluated trough the detection of MDA with the thiobarbituric acid (TBA) test, which is the simplest and fastest method available. On this basis, the aim of this study was the evaluation of the stability of infant milk formulas, supplemented with PUFAs, under different storage conditions. MDA is, in fact, the most important secondary product of autoxidation, and it is usually used as an indicator of the lipid peroxidation process, both for its early appearance and the high sensitivity of the analytical methods available. ![]() ![]() Among the different parameters that could be used for monitoring the autoxidation process, to our knowledge, one of the preferred is based on malondialdehyde (MDA) detection, because it allows evaluating the oxidation status of foods in the initial phase of autoxidation. For these reasons, it is very important to monitor the modification of some oxidation parameters during the storage of milk powder under different conditions, in order to get more insight into their shelf life. Therefore, the high temperatures required by some steps of the manufacturing process, such as spray-drying, may catalyze the autoxidation process. In fact, infant milk formulas are particularly prone to autoxidation, because of their chemical composition, as they are made of 33% fats and are very rich in polyunsaturated fatty acids. For all of these reasons, it is of primary importance to manufacture infant formulas using mild technological processes, low temperature, appropriate packaging and a modified nitrogen atmosphere, in order to protect these products from oxidative decomposition. Deterioration of lipid-rich foods starts with the initial formation of peroxides, unstable and reactive primary products, which breakdown into a mixture of off-flavored and potentially toxic, mutagen and carcinogenic secondary products (mainly aldehydes and ketones) with the consequent loss of the nutritional value of the food. ![]() Fatty acids with three or more unsaturations represent a class of molecules that can rapidly evolve into unpleasant and toxic by-products. The main stability problem of all fat-/oil-containing foods is related to the autoxidation process, which is more pronounced when the lipid fraction is sizable, and it gets worse if the composition is changed toward a more unsaturated mixture. Newborns are highly exposed to the toxic effects of the degradation products of PUFAs, because of the immaturity of their enzymatic systems and detoxification organs, their low body weight and, above all, because no other options are available for them, other than infant milk formulas. However, due to their low chemical stability, the addition of PUFAs to foodstuffs may represent a problem for their shelf life and, consequently, for consumers’ safety, especially when they are designed for infants. In particular, they are supplemented during the manufacturing process with polyunsaturated fatty acids (PUFAs), such as linoleic (LA 18:2n-6), α-linolenic (ALA, 18:3n-3), arachidonic (ARA, 20:4n-6) and docosahexaenoic acid (DHA, 22:6n-3), as they are considered important for the proper neural and cognitive development of newborns, in general, and premature babies, specifically. Īccording to the Italian and international laws and GMP requirements, powdered milk formulas are obtained by deep modification of cow milk, with the final aim of simulating breast milk as much as possible. Due to the complex nature of infant milk formulas and the stability of some of their components, great care has to be taken in all steps of their formulation, handling and storage. Infant milk formulas represent the only food for non-breast-fed infants and premature babies, playing a very important nutritional role, since they represent the only way for providing newborns with all of the nutrients they need for healthy growth.
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