Background: Magnesium is a micronutrient which plays an important role in a wide range of fundamental cellular reactions. Deficiency of magnesium leads to serious biochemical and symptomatic changes. The present study was carried out to establish the influence of magnesium lactate fortification on the physico- chemical, microbiological and rheological properties of fat-free yogurt manufactured using different starters.
Methods: In this study, yogurts were produced from fat-free milk, standardized with skimmed milk powder to 6% protein content, and then divided into two parts. One part was left without supplementa- tion as a control and in the second part, magnesium L-lactate hydrate was added in the amount of 317.30 mg 100 g–1, which was equal to 35 mg of Mg2+ 100 g–1 of milk. Both mixtures were blended, pasteurized at 85°C for 30 minutes, cooled to 45°C and then divided into three parts, inoculated with: (1) YC-X11 yogurt cul- ture, (2) YF-L811 yogurt culture and (3) VITAL yogurt culture supplemented with probiotics (Lactobacillus acidophilus, Bifidobacterium lactis) respectively. Fermentation was performed at 43°C and the final yogurts were cooled to 5°C. After 24 hours of cold storage, the pH values, titratable acidity, syneresis, color, texture profile, viscosity, sensory analysis and microbiology of the yogurts were analyzed.
Results: The results showed that addition of magnesium lactate significantly reduced syneresis and increased the hardness of fat-free yogurts. There was no impact on the viability of starter bacteria in the yogurts after 24 hours of refrigerated storage.
Conclusions: Magnesium lactate showed good potential for the fortification of dairy foods, according to physicochemical data. Further research is needed regarding the influence of storage time and to establish whether the observed effects are largely due to the magnesium cation or lactate anion.
Keywords: magnesium; minerals; quality; starter culture; yogurt.