Physicochemical characterization of mineral (iron/zinc) bound caseinate and their mineral uptake in Caco-2 cells

Lactoferrin thermal stabilization and iron(II) fortification through ternary complex fabrication with succinylated sodium caseinate

A thermally stable co-delivery system for lactoferrin (LF) and iron(II) was developed to address iron deficiency anemia. Complexes were formed between LF, succinylated sodium caseinate (S.NaCas) and FeSO4 with high yield (∼85%). LF-S.NaCas-Fe complexes achieved loading capacities for iron(II) between 2.5 and 12 mg g-1and LF loading capacities between 250 and 690 mg g-1, depending upon initial Fe2+ concentrations and LF ratios. The LF-S.NaCas complex mixtures appeared as smooth cubic particles in SEM, and gradually aggregated to amorphous particles as th iron(II) concentration increased due to iron-facilitated cross-linking. The complexation significantly improved LF thermal stability and addressed the poor solubility of iron(II) under neutral pH. After thermal treatment (95 °C, 5 min), the rehydrated complexes retained 68%-90% LF, with <10% iron(II) release. Circular dichroism spectra showed the secondary structure of the complexed LF was well retained during thermal treatment. This thermally stable system showed great potential in LF thermal protection and iron(II) fortification.

Effect of different iron ratios on interaction and thermodynamic stability of bound whey protein isolate

Whey protein isolates (WPI) are known to have mineral-binding capacity to promote iron absorption. The aim of this study was to investigate the effect of iron ratio on the conformational structure of iron-bound whey protein isolate (WPI-Fe) and its thermodynamic stability. It was shown that the iron to protein ratio affects both the iron binding capacity of WPI and the iron valence state on the surface of WPI-Fe complexes. As the iron content increases, aggregation between protein molecules occurs. In addition, WPI-Fe nanoparticles have thermodynamic stability and Fe2+ has a high affinity with WPI for spontaneous exothermic reactions. This study demonstrates that WPI-Fe complexes can be used to efficiently deliver high-quality iron source (Fe2+) for future iron supplements.

Food-to-Food Fortification of a Traditional Pearl Millet Gruel with a Natural Source of β-Carotene (Sweet Potato) Improves the Bioaccessibility of Iron and Zinc

Iron and zinc deficiencies are still a major public health concern in the Far North Region of Cameroon where staple foods are mainly mineral rich cereals which equally contain inhibitors of their bioaccessibility. The effect of food-to-food fortification of a traditional pearl millet gruel with a natural source of β-carotene on the bioaccessibility of iron and zinc was assessed. A sensory evaluation of gruels fortified at 20, 30, and 40% with mashed sweet potato was carried out. The samples were analysed for carotenoids, phytates, polyphenols, iron, and zinc contents. Bioaccessible iron and zinc were evaluated using in vitro digestion method. The gruel fortified at 20% with mashed sweet potato had better scores ( $P$  < 0.05) of taste (3.93), colour (3.36), and overall acceptability (3.80) compared to the control. Carotenoid, polyphenol, and phytate contents were higher in fortified gruels ( $P$  < 0.05) compared to the control, while iron and zinc contents were lower. A significant increase ( $P$  < 0.05) in bioaccessibility of 8.08% and 26.96% for iron and 53.79% and 62.92% for zinc was observed at 20 and 30% incorporation level, respectively. However, at 40% incorporation level, the increase in bioaccessible iron was less important and bioaccessible zinc decreased. Mashed sweet potato can be used as a fortificant to improve the bioaccessibility of iron and zinc contents of local pearl millet gruel, if added moderately.

Iron Absorption: Factors, Limitations, and Improvement Methods

Iron is an essential element for human life since it participates in many functions in the human body, including oxygen transport, immunity, cell division and differentiation, and energy metabolism. Iron homeostasis is mainly controlled by intestinal absorption because iron does not have active excretory mechanisms for humans. Thus, efficient intestinal iron bioavailability is essential to reduce the risk of iron deficiency anemia. There are two forms of iron, heme and nonheme, found in foods. The average daily dietary iron intake is 10 to 15 mg in humans since only 1 to 2 mg is absorbed through the intestinal system. Nutrient-nutrient interactions may play a role in dietary intestinal iron absorption. Dietary inhibitors such as calcium, phytates, polyphenols and enhancers such as ascorbic acid and proteins mainly influence iron bioavailability. Numerous studies have been carried out for years to enhance iron bioavailability and combat iron deficiency. In addition to traditional methods, innovative techniques are being developed day by day to enhance iron bioavailability. This review will provide information about iron bioavailability, factors affecting absorption, iron deficiency, and recent studies on improving iron bioavailability.

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.

Effect of incorporation of iron-whey protein concentrate (Fe-WPC) conjugate on physicochemical characteristics of dahi (curd)

Dahi samples were prepared from milk incorporated with spray-dried iron-whey protein concentrate (Fe-WPC) conjugate and ferrous sulfate (FeSO₄) with three different concentrations of iron i.e. 15, 20 and 25 mg/L and their quality characteristics were determined. Fe-WPC conjugate incorporated dahi showed better sensory, textural and physical attributes as compared with those of FeSO₄ fortified and control dahi. Non-significant (p > 0.05) changes were observed in attributes like acidity and flavor, color and appearance, body and texture scores of dahi fortified with Fe-WPC conjugate with upto 20 mg/L iron as compared to those of control. In contrast, definite metallic flavor was perceptible in case of FeSO₄ incorporated dahi even at 15 mg/L level. Water holding capacity, viscosity and firmness were significantly (p < 0.05) higher in 20 mg/L Fe-WPC conjugate incorporated dahi samples as compared with those of 20 mg/L FeSO₄ incorporated dahi samples. In vitro bio accessibility of iron from Fe-WPC conjugate incorporated dahi was found to be significantly (p < 0.05) higher than that from FeSO₄ incorporated dahi. Therefore, the results indicated that Fe-WPC conjugate can be fortified in dahi with upto 20 mg/L without significantly altering its physicochemical properties and with a higher bioaccessibillity of iron.

Assessment of the Nutritional Value of Traditional Vegetables from Southern Chile as Potential Sources of Natural Ingredients

There is an increasing interest in consuming healthy foods motivated by the need of boosting the immune system naturally. In this sense, vegetables rich in bioactive compounds are a clear example of "superfoods" that promotes overall health and strengthen the immune response. Therefore, in this study eight traditional vegetables usually produced in southern Chile (pea, corn, carrot, leek, spinach, chard, coriander and parsley) were characterized in terms of their nutritional composition to evaluate their potential as lyophilized natural ingredients. Thus, chemical composition, amino acid profile, minerals, vitamins, carotenoids, polyphenols and pesticide residues were evaluated. Green leafy vegetables resulted to be an excellent source of proteins and dietary fibers as well as vitamins (ascorbic acid, choline, alpha-tocopherol and niacin), minerals (calcium, phosphorus and iron), carotenoids and polyphenols. Among the eight vegetables assessed spinach exhibited the more balanced nutritional profile. Moreover, 332 pesticide residues were analysed and only six were detected in a low concentration. Due to their nutritional properties, the present results suggest that vegetables produced in southern Chile could be considered as promising alternatives to develop natural food ingredients.

Structure, functional properties and iron bioavailability of Pneumatophorus japonicus myoglobin and its glycosylation products

Developing safe and efficient iron supplements is significant for the alleviation of iron-deficient anemia (IDA). Myoglobin (Mb) is a heme-protein rich in bioavailable iron. Pneumatophorus japonicus (P. japonicus), one important economic fish in China, contain a high Mb level in its dark meat normally discarded during processing. The present study aimed to determine the structure, physicochemical properties, and iron bioavailability of Mb extracted from P. japonicus. Meanwhile, the effects of glycosylation, a commonly applied chemical modification of proteins, on these parameters were evaluated. Using Box-Behnken design, the optimal conditions for Mb-chitosan glycosylation were obtained: 45.07 °C, pH 6.10 and Mb/chitosan mass ratio of 6.29. The structure and functional properties of the glycosylated Mb (Mb-gly) were investigated. Compared with the original Mb, Mb-gly obtained a more ordered secondary structure. The surface hydrophobicity of Mb-gly was found to be decreased together with the observations of elevated water solubility. Moreover, glycosylation enhanced the Mb antioxidant capacity, and improved its stability in enzymatic digestion system. Regarding to the iron bioavailability, the cellular uptake of Mb‑iron was significantly higher than FeSO₄, and further elevated by glycosylation. These results provided a basis for the development of Mb-based iron supplements, promoting the utilization of fish-processing industries wastes.

Determination of the iron bioavailability, conformation, and rheology of iron-binding proteins from Tegillarca granosa

The increased interest in achieving, solely through diet, the same effect on iron levels with supplementation, leads to numerous studies on iron absorption of iron binding proteins (IBPs). The characteristics of IBPs from Tegillarca granosa (T. granosa) and its iron utilization were determined to analyze their relationship. The results showed in T. granosa, Fe(ӀӀ) was main iron form in hemoglobin (TH) and that Fe(ӀӀ) and Fe(ӀӀӀ) coexisted in ferritin (TF). After in vitro digestion, TH was easier to be digested than TF, bovine hemoglobin, and bovine ferritin. In caco-2 cells model, iron bioavailability of TH also was the best, which related to TH's superior fluid properties, higher ratios of α-helix to β-sheet and amide I to amide II. These suggest TH could be used as a good source of organic iron and provide references for application of T. granosa in human nutrition. PRACTICAL APPLICATIONS: This research investigated the iron bioavailability and structural properties of iron-binding proteins from Tegillarca granosa (T. granosa). Moreover, the effects of iron absorption in bovine hemoglobin and ferritin were compared with those from T. granosa. The results showed the hemoglobin in T. granosa had better iron bioavailability and it could be a good source of iron. These data could provide a basic instruction of the application of T. granosa in functional food production.

Optimization of the Red Tilapia (Oreochromis spp.) Viscera Hydrolysis for Obtaining Iron-Binding Peptides and Evaluation of In Vitro Iron Bioavailability

Iron deficiencies continue to cause significant health problems in vulnerable populations. A good strategy to combat mineral deficiency includes fortification with iron-binding peptides. This research aims to determine the optimal conditions to hydrolyze red tilapia viscera (RTV) using Alcalase 2.4 L and recovery of iron-binding protein hydrolysate. The result showed that under the optimal hydrolysis condition including pH 10, 60 °C, E/S ratio of 0.306 U/g protein, and substrate concentration of 8 g protein/L, the obtained hydrolysate with 42.5% degree of hydrolysis (RTVH-B), displayed the maximal iron-binding capacity of 67.1 ± 1.9%. Peptide fractionation was performed using ultrafiltration and the <1 kDa fraction (FRTVH-V) expressed the highest iron-binding capacity of 95.8 ± 1.5%. Iron content of RTVH-B and its fraction was assessed, whereas iron uptake was measured indirectly as ferritin synthesis in a Caco-2 cell model and the result showed that bioavailability of bound minerals from protein complexes was significantly higher (p < 0.05) than iron salt in its free form, increased 4.7 times for the Fe2+-RTVH-B complex. This research suggests a potential application of RTVH-B as dietary supplements to improve iron absorption.

Peptide-metal complexes: obtention and role in increasing bioavailability and decreasing the pro-oxidant effect of minerals

Bioactive peptides derived from food protein sources have been widely studied in the last years, and scientific researchers have been proving their role in human health, beyond their nutritional value. Several bioactivities have been attributed to these peptides, such as immunomodulatory, antimicrobial, antioxidant, antihypertensive, and opioid. Among them, metal-binding capacity has gained prominence. Mineral chelating peptides have shown potential to be applied in food products so as to decrease mineral deficiencies since peptide-metal complexes could enhance their bioavailability. Furthermore, many studies have been investigating their potential to decrease the Fe pro-oxidant effect by forming a stable structure with the metal and avoiding its interaction with other food constituents. These complexes can be formed during gastrointestinal digestion or can be synthesized prior to intake, with the aim to protect the mineral through the gastrointestinal tract. This review addresses: (i) the amino acid residues for metal-binding peptides and their main protein sources, (ii) peptide-metal complexation prior to or during gastrointestinal digestion, (iii) the function of metal (especially Fe, Ca, and Zn)-binding peptides on the metal bioavailability and (iv) their reactivity and possible pro-oxidant and side effects.

Bioavailability assessment of zinc enriched lactobacillus biomass in a human colon carcinoma cell line (Caco-2)

The present study utilizes lactobacilli strains having the potential to accumulate a significant amount of Zinc (Zn) in their biomass and ability to deliver the same mineral in a highly bioavailable form. A human origin Lactobacillus fermentum SR4 and Lactobacillus rhamnosus GG (LGG) were studied for their ability to accumulate Zn by growing them in the medium containing Zn salt. Further, Zn enriched cell lysates were prepared by Ultrasonication, as an organic Zn source. Various functional groups involved in bacterial Zn binding were identified by FT-IR spectroscopy and elemental Zn in bio-chelated cell lysate complex was confirmed by SEM and Energy Dispersive X-ray Spectrometry (EDX). Experimental data demonstrated a significantly higher (P < 0.05) bioavailability of Zn chelated by SR4 followed by LGG i.e., 57% and 48%, as compared to the commercially available inorganic (ZnSo₄) and even organic (Zinc gluconate) forms tested which has 15.6% and 21.7% respectively.

Spray-Dried Whey Protein Concentrate-Iron Complex: Preparation and Physicochemical Characterization

Poor absorption of iron from food and oral iron formulations results in extensive use of high-dose oral iron, which is not tolerated. Disposal of whey, a byproduct of the cheese industry, causes environmental pollution. Whey proteins have the ability to bind significant amount of iron, thereby reducing its chemical reactivity and incompatibility with other components in foods. To make iron compatible with food, it was complexed with whey protein concentrate (WPC). After complexation, centrifugation and ultrafiltration techniques were utilised to eliminate the insoluble and free iron from the solution. To enable the availability of whey protein concentrate–iron (WPC–Fe) complex in the powder form, spray drying technique was used. Optimized spray drying conditions used for the preparation were: inlet temperature 180 °C, flow rate 2.66 mL/min and solution of total solids 15%. The complex was observed to be stable under different processing conditions. The in vitro bioaccessibility (iron uptake) of the bound iron from the WPC–Fe complex was significantly higher (p<0.05) than that from iron(II) sulphate under simulated gastrointestinal conditions. WPC–Fe complex with improved iron bioaccessibility could safely substitute iron fortificants in different functional food preparations.