Magdalena Wirkowska

An assessment of various powdered baby formulas by conventional methods (DSC) or FT-IR spectroscopy

Milk components are assumed to be uniformly distributed in a concentrate whilst it is being dried. During milk powder production, these components are redistributed in the drying droplets and the powder surface composition is significantly different from that of the bulk of it. The objective of this article was to analyze and compare phase transitions of powdered baby formulas as well as to make a study of their FT-IR spectra. Food powders of different composition were tested by a differential scanning calorimeter (DSC, TA Instruments Q 200) with a normal pressure cell and a System 2000 spectrophotometer. Significant differences were observed in the shape of curves of the mixtures and the agglomerates. The observed phase transitions in powders depended on fat content. Characteristic peaks of melting lactose were observed in the curves of the powdered baby formulas. The IR spectra proved to be useful in determining adulteration of baby formulas. Both methods were complimentary during a thorough evaluation of these food powders.

Oxidative stability and triacylglycerols structure of lipid fraction from cookies for infants

The aim of this research was to analyse the quality of the lipid fraction extracted from commercially available cookies intended for infants. The composition, fatty acid distribution and oxidative stability of fats, interpreted as the resistance of fats against autooxidation, were studied. In addition, the kinetic parameters of the oxidation process, such as activation energies (Ea), pre-exponential factors (Z) and reaction rate constants (k) for fat oxidation under the differential scanning calorimetry tests conditions were calculated using the Ozawa–Flynn–Wall method and the Arrhenius equation. The distribution of fatty acids in the tested cookies is similar to that present in most of infant formulas, but differs significantly from that in human milk. Based on the results obtained, high oxidative stability of tested fats can be observed. The Ea values ranged from 86.22 to 116.13 kJ/mol; Z from 1.95 × 109 to 1.05 × 1013; and k values ranged from 5.70 × 10− 4 min− 1 at 100°C to 2.12 × 10− 1 min− 1 at 170°C.

The influence of trehalose–maltodextrin and lactose–maltodextrin matrices on thermal and sorption properties of spray-dried β-lactoglobulin–vitamin D3 complexes

In the study, the effect of lactose–maltodextrin and trehalose–maltodextrin matrices on the glass transition temperatures and moisture sorption characteristics of spray-dried β-lactoglobulin–vitamin D3 complexes was investigated. Incorporation of sugars into complexes can influence the thermal properties and moisture sorption characteristics of powders. The glass transition temperature as an important physiochemical parameter that determines the processing conditions, product quality and stability of the final product was studied with the use of modulated differential scanning calorimetry method. Moisture sorption isotherms, water activity and moisture content as parameters related to sorption properties, were also investigated. Additionally, particle size, wettability and insolubility index were studied to characterise newly synthesized products. For the samples tested, two well-separated glass transitions were found. The dominant effect of maltodextrin on the glass transition temperatures was observed. An increase in the percentage of maltodextrin added resulted in increasing Tg value of studied complexes. At low water activity all powdered complexes showed typical sorption behaviour of food systems. Trehalose as a carbohydrate component of powdered complexes, in comparison to lactose, delayed the occurrence of crystallization.