Potential of Alginate Encapsulated Ferric Saccharate Microemulsions to Ameliorate Iron Deficiency in Mice

Iron delivery systems for controlled release of iron and enhancement of iron absorption and bioavailability

Iron deficiency is a global nutritional problem, and adding iron salts directly to food will have certain side effects on the human body. Therefore, there is growing interest in food-grade iron delivery systems. This review provides an overview of iron delivery systems, with emphasis on the controlled release of iron during gastrointestinal digestion, as well as the enhancement of iron absorption and bioavailability. Iron-bearing proteins are easily degraded by digestive enzymes and absorbed through receptor-mediated endocytosis. Instead, protein aggregates are slowly degraded in the stomach, which delays iron release and serves as a potential iron supplement. Amino acids, peptides and polysaccharides can bind iron through iron binding sites, but the formed compounds are prone to dissociation in the stomach. Moreover, peptides and polysaccharides can deliver iron by mediating the formation of ferric oxyhydroxide which is absorbed through endocytosis or bivalent transporter 1. In addition, liposomes are unstable during gastric digestion and iron is released in large quantities. Complexes formed by polysaccharides and proteins, and microcapsules formed by polysaccharides can delay the release of iron in the gastric environment and prolong iron release in the intestinal environment. This review is conducive to the development of iron functional ingredients and dietary supplements.

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.

Bioavailability of nanotechnology-based bioactives and nutraceuticals

Bioaccessibility and bioavailability of some hydrophobic bioactives (e.g., carotenoids, polyphenols, fat-soluble vitamins, phytosterols and fatty acids) are limited due to their low water solubility, and in some instances low chemical stability. Nanotechnology involving nanometric (r<500nm) delivery systems, can be used to improve the solubility and thus enhance the bioaccessibility and bioavailability of hydrophobic compounds. Nanometric delivery systems, derived from food grade phospholipids and biopolymers adopt many forms, including liposomes, micelles, micro/nanoemulsions, particles, polyelectrolyte complexes, and hydrogels. The small particle sizes and customized materials used to create delivery systems confer their unique properties such as higher stability and/or resistance to enzymatic activity in the gastrointestinal tract. This chapter provides an overview of bioaccessibility and bioavailability of different classes of hydrophobic bioactive compounds, focusing on nanometric delivery systems and methods of evaluation.

Use of Lipid Nanocarriers to Improve Oral Delivery of Vitamins

The chemical environment and enzymes in the gastrointestinal (GI) membrane limit the oral absorption of some vitamins. The GI epithelium also contributes to the poor permeability of numerous antioxidant agents. Thus, lipophilic vitamins do not readily dissolve in the GI tract, and therefore they have low bioavailability. Nanomedicine has the potential to improve the delivery efficiency of oral vitamins. In particular, the use of lipid nanocarriers for certain vitamins that are administered orally can provide improved solubility, chemical stability, epithelium permeability and bioavailability, half-life, nidus targeting, and fewer adverse effects. These lipid nanocarriers include self-emulsifying drug delivery systems (SEDDSs), nanoemulsions, microemulsions, solid lipid nanoparticles (SLNs), and nanostructured lipid carriers (NLCs). The use of nontoxic excipients and sophisticated material engineering of lipid nanosystems allows for control of the physicochemical properties of the nanoparticles and improved GI permeation via mucosal or lymphatic transport. In this review, we highlight recent progress in the development of lipid nanocarriers for vitamin delivery. In addition, the same lipid nanocarriers used for vitamins may also be effective as carriers of vitamin derivatives, and therefore enhance their oral bioavailability. One example is the incorporation of d-α-tocopheryl polyethylene glycol succinate (TPGS) as the emulsifier in lipid nanocarriers to increase the solubility and inhibit P-glycoprotein (P-gp) efflux. We also survey the concepts and discuss the mechanisms of nanomedical techniques that are used to develop vitamin-loaded nanocarriers.

Iron Encapsulation in Water-in-Oil Emulsions: Effect of Ferrous Sulfate Concentration and Fat Crystal Formation on Oxidative Stability

Iron deficiency is a major global human health concern. Encapsulation of iron in functional food products may help to solve this problem. However, iron is highly reactive and may promote rapid lipid oxidation in fatty foods. In this study, the effect of ferrous sulfate (0.1 to 0.5 wt%) and rice bran stearin (0 or 30 wt%) on the physical properties, oxidative stability, and encapsulation efficiency of 20 wt% water-in-oil (W/O) emulsions stabilized with polyglycerol polyricinoleate was investigated. In the presence of rice bran stearin crystals in the continuous oil phase, W/O emulsions had smaller mean droplet diameters (d ∼ 250 nm) and better physical stability than its absence (d ∼ 330 nm). An increase in the ferrous sulfate concentration in the water droplets led to a decrease in the oxidative stability of the W/O emulsions. However, the presence of rice bran stearin significantly (P ≤ 0.05) improved their oxidative stability. Moreover, addition of rice bran stearin also significantly (P ≤ 0.05) improved the encapsulation efficiency and delayed ferrous sulfate release from the W/O emulsions. The impact of pH and ionic strength on the encapsulation efficiency of the W/O emulsion was also investigated. Ionic strength affected the encapsulation efficiency much more than pH. The W/O emulsions created in the present study may be useful for the encapsulation and delivery of iron and other water-soluble nutrients into food products.

PRACTICAL APPLICATION

Water-in-oil (W/O) emulsions may be used to encapsulate, protect, and deliver water-soluble bioactive compounds or nutrients into food products. In this study, W/O emulsions stabilized using an oil-soluble surfactant (polyglycerol polyricinoleate, PGPR) and fat crystal network (rice bran stearin) were shown to be useful for encapsulation and delivery of iron into foods. This strategy may be a promising approach to reduce iron deficiency, a major nutritional deficiency for people with inadequate food supplies.