During the project it is intended to create iron-loaded microencapsulation systems (single, double emulsions and oleogels) for food the use of which will help to reduce iron deficiency in the human body. Different technologies will be used for the manufacturing of these systems (emulsification and oleogelation). The rheological properties, pH, gel-forming properties of the different interphase-stabilizing biopolymer solutions, as well as the texture of the prepared oleogels, water absorption properties and deformation behaviour will be investigated. Encapsulation efficiency of iron as well as it diffusion from the microencapsulation systems to the environment is of great importance. The iron content in these systems will correspond to the recommended amount per day. It is important not only to enrich the systems with iron, but also to eliminate the unacceptable taste of this trace element as well as prevent oxidation products formation. That is why the selected thermodynamically most stable emulsions and oleogels will be used in specific animal products in assessing the residual metal flavour intensity.
Project funding:
KTU Research and Innovation Fund
Project results:
1. Double emulsions with encapsulated iron were produced and characterized. It was found that the stability of the obtained systems depended on the concentration of the emulsifier used, on the concentration of ferrous sulfate used for encapsulation and on the position of ferrous sulfate in the composition of the double emulsions. In particular, increasing the whey protein concentration increased the stability of the double emulsions and this was attributed to the higher amount of biopolymer that was used to stabilize the oil/water interphase. It was also found that increasing the concentration of encapsulated ferrous sulfate from 0.06 to 0.60% decreased the size of the oil particles and this was attributed to the formation of a more stable system.
It was determined that the emulsions in which iron was encapsulated in the internal and external phases had the lowest iron encapsulation efficiency (52.12%), the lowest viscosity (0.865 Pa•sn), the largest particle size (74.41 – 86.64 ?m) and the lowest stability during the entire storage period. Meanwhile, emulsions in which iron was encapsulated only in the internal water phase were very stable and successfully retained iron in their structure immediately after preparation and during storage (>90%).
2. For the first time, oleogels with encapsulated iron have been produced. Stable systems with desired properties (oil and water release, morphology, viscoelastic properties, and iron encapsulation efficiency) were obtained only in systems stabilized with high amounts of wax (10 and 15%). It is also innovative that no additional emulsifiers were used to stabilize the water contained in the oleogel. And iron was immobilized in the composition of oleogels only because of the stable structure of the three-dimensional network consisting of crystal aggregates, stabilized by van der Waals forces. When investigating the influence of the type of wax on the properties of oleogels, it was found that oleogels stabilized with beeswax were characterized by higher stability, elastic modulus (G’) values ??and iron encapsulation efficiency (~100%).
3. Iron, which was encapsulated in the composition of the manufactured systems, is known as a catalyst for oxidative processes. For this reason, the oxidative stability of the most stable double emulsions and oleogels was evaluated by determining the formation of primary oxidation products (peroxides). It was found that oleogels stabilized with beeswax showed the highest oxidative stability, which also showed the highest hardness. The obtained result is based on the fact that the dense structure of the wax crystal network reduces the outward diffusion of iron ions and at the same time reduces the potential interaction of pro-oxidants with the oil.
With the already mentioned most stable systems, model meat systems were made, in which emulsions and oleogels are used as a substitute for fats of animal origin. Compared to beef or pork, chicken naturally contains a relatively low amount of iron, which is why this meat raw material was chosen for the production of meat systems. It was determined that the total thermal losses increased when replacing animal fats with oleogels or emulsions (from 44.16 to 47.05 – 49.40%) with an additive. The relationship between total thermal losses and hardness was also established.
The sample with the highest hardness (0.155 N) also had the highest amount of total thermal loss (49.40%). Differences in color indicators between samples were found to be insignificant. The only exception is that all samples were slightly less bright compared to the control. It is very important that the a* redness value did not decrease during the study, which is a very important indicator for meat systems and products.
Period of project implementation: 2020-04-14 - 2020-12-31
Project coordinator: Kaunas University of Technology
