Towards Oxidatively Stable Emulsions Containing Iron-Loaded Liposomes: The Key Role of Phospholipid-to-Iron Ratio.

To encapsulate soluble iron, liposomes were prepared using unsaturated phospholipids (phosphatidylcholine from egg yolk), leading to high encapsulation efficiencies (82-99%). The iron concentration affected their oxidative stability: at 0.2 and 1 mM ferrous sulfate, the liposomes were stable, whereas at higher concentrations (10 and 48 mM), phospholipid oxidation was considerably higher. When applied in oil-in-water (O/W) emulsions, emulsions with liposomes containing low iron concentrations were much more stable to lipid oxidation than those added with liposomes containing higher iron concentrations, even though the overall iron concentration was similar (0.1 M). Iron-loaded liposomes thus have an antioxidant effect at high phospholipid-to-iron ratio, but act as pro-oxidants when this ratio is too low, most likely as a result of oxidation of the phospholipids themselves. This non-monotonic effect can be of crucial importance in the design of iron-fortified foods.

Lipid Oxidation in Emulsions Fortified with Iron-Loaded Alginate Beads.

The potential use of iron-loaded alginate beads to fortify oil-in-water (O/W) emulsions was studied. Iron-loaded alginate beads with different sizes (0.65, 0.84, 1.5 and 2 mm) were produced by ionic gelation with calcium chloride, leading to 81% encapsulation efficiency (EE) of ferrous sulfate. These beads were added to O/W emulsions to investigate their effect on lipid oxidation. The use of iron-loaded alginate beads inhibited lipid oxidation in emulsions, compared to a control emulsion with the same concentration of free ferrous sulfate in the continuous phase, but did not totally prevent it. Results obtained with scanning electron microscopy and energy dispersive X-ray spectroscopy (EDX) analysis showed that some reactive iron was present at the surface of the beads. Oxidation of the lipid droplets was slightly higher for smaller alginate beads, suggesting that the reaction could be linked to the total bead surface. When covering iron-loaded beads with an extra layer of alginate, lipid oxidation was inhibited, which confirmed the role of reactive surface-bound iron. This study shows that the location of iron within the encapsulates plays a crucial role in the chemical stability of fortified foods and should be taken as a starting point in the design of iron-fortified food products.

Oxidative stability of emulsions fortified with iron: the role of liposomal phospholipids.

BACKGROUND: Interest in supplementing food with iron to counteract dietary deficiencies has been on the rise in recent years. A major challenge is the pro-oxidant activity of soluble iron, which compromises the chemical stability of the enriched food products. This problem could be mitigated by encapsulating iron, to physically keep it separated from oxidizable substrates, such as unsaturated fatty acids. In the present work, the physical and chemical stability of surfactant- or protein-stabilized oil-in-water emulsions fortified with iron was investigated. RESULTS: Iron (ferrous sulfate) was successfully incorporated in liposomes at high encapsulation efficiency (89%). The liposomes obtained were added to emulsions stabilized with either Tween 20 or whey protein isolate (WPI), and its oxidative stability was monitored and compared with emulsions with free iron. Tween 20-stabilized emulsions were more stable against oxidation than WPI-stabilized emulsions, and furthermore lipid oxidation was substantially higher in emulsions containing iron (either free, or encapsulated in liposomes) than in blank emulsions. This shows that liposomal encapsulation did not inhibit the pro-oxidant activity of iron. CONCLUSION: Despite the high encapsulation efficiency of iron in our liposomes, these systems are not suitable to supplement model foods with iron because of the associated deleterious chemical reactivity. This is most probably due to the phospholipids used as encapsulation material being prone to oxidation, which may actively contribute to the oxidative process. These aspects are normally not taken into account but we showed that they are of utmost importance, and should be taken as a starting point in the design of delivery systems. © 2018 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

The effect of gum tragacanth on the rheological properties of salep based ice cream mix.

The influence of concentration (0-0.5%, w/w) of gum tragacanth (GT) on thixotropy, dynamic, and creep-recovery rheological properties of ice cream mixes prepared with milk or water based were investigated. These properties were used to evaluate the viscoelastic behavior and internal structure of ice cream network. The textural properties of ice cream were also evaluated. Thixotropy values of samples were reduced by increasing GT concentration. The dynamic and creep-recovery analyses exhibited that GT addition increased both ice cream elastic and viscous behaviors. The increasing of Burger's model parameters with GT concentration indicated higher resistance network to the stress and more elastic behavior of samples. The applying of Cox-Merz rule is possible by using shift factor (α). GT also led to an increase in Young's modulus and the stickiness of ice creams. The obtained results highlighted the possible application of GT as a valuable member to promote structural properties of ice cream.

Influence of an ultrasonic nozzle in spray-drying and storage on the properties of blueberry powder and microcapsules.

BACKGROUND: Recently, ultrasonic nozzle technology has been applied in spray-drying because of its numerous advantages, including providing more uniform droplets and reducing damage observed in bioactive compounds. In this study, the production of blueberry powders and microcapsules by using an ultrasonic spray nozzle was investigated. Firstly, the important ultrasonic nozzle parameters were optimised by using response surface methodology and compared with a conventional nozzle (control). Secondly, powder and microcapsules obtained at the optimum point were stored at 22 °C and 35 °C at 0.32 water activity (aw ). RESULTS: The optimum conditions were estimated as 125 °C inlet air temperature, 9 W ultrasonic power and 8% feed pump rate. There was significantly difference (P < 0.05) in the total phenolic content and antioxidant power of microcapsules produced by an ultrasonic nozzle and a conventional nozzle. Because the temperature affected the stability of powders negatively, the blueberry powder showed higher losses than microcapsules in the content of bioactive compounds. In addition, the ultrasonic nozzle showed a significantly greater protective effect on physico-chemical properties than did the conventional nozzle. CONCLUSION: Results of the study point that the production of ultrasonic nozzle powders and microcapsules is feasible to use as a functional ingredient in food industry. © 2016 Society of Chemical Industry.