Effect of iron compounds on the storage stability of multiple-fortified Ultra Rice®

Ultra Rice^® is an extruded, reformed rice grain used as a carrier for micronutrients. It holds great promise for alleviating micronutrient deficiencies in populations that consume rice‐based diets. We investigated the stability of multiple‐fortified Ultra Rice^® formulations in an effort to develop a stable premix containing iron, zinc, and B vitamins. The performance of four iron sources was tested under accelerated storage conditions (40 °C, 60% RH) over a period of 32 weeks. The effects of the iron source on micronutrient retention, oxidative stability, and sensory/physical properties were measured. Formulations containing ferric pyrophosphate (FePP) were the most stable, showing minimal losses of thiamin and good sensory/physical properties. Formulations containing ferrous fumarate lost more than 50% thiamin, while those containing iron‐sodium‐EDTA showed minimal loss of thiamin but developed the most rancidity. FeNaEDTA and ferrous fumarate resulted in darker coloured grains but they had a much higher in vitro bioavailability than the formulations containing FePP. The concentrations of zinc, folic acid, and niacinamide were not affected by the presence of iron during the storage tests.     

Effects of Phytases and Dehulling Treatments on In Vitro Iron and Zinc Bioavailability in Faba Bean (Vicia faba L.) Flour and Legume Fractions

ABSTRACT: In vitro digestions were performed on faba bean flours with decreased phytate contents and on 2 dephytinized or nondephytinized faba bean fractions, a dehulled faba bean fraction, and a hull fraction with low and high fiber and tannin contents, respectively. In vitro bioavailability iron and zinc was defined as the relative amount of iron and zinc that became soluble after enzymatic treatment. Faba bean samples were sequentially digested with enzymes, including amylase, pepsin, pancreatin, and bile, under certain conditions following the enzymatic degradation procedure. Iron and zinc in vitro bioavailability of whole faba bean flours were significantly improved by phytate degradation, even if the phytate were not all degraded. Total dephytinization of dehulled faba bean led to an obvious increase in iron and zinc in vitro bioavailability, but that of hulls had no effect on either iron or zinc in vitro bioavailability. Fibers and tannins other than phytate are more important in chelating a high proportion of iron and zinc in faba bean hulls.     

Bioavailability of Micronutrients from Plant Foods: An Update

Deficiencies of iron, zinc, iodine and vitamin A are widespread in the developing countries, poor bioavailability of these micronutrients from plant-based foods being the major reason for their wide prevalence. Diets predominantly vegetarian are composed of components that enhance as well as inhibit mineral bioavailability, the latter being predominant. However, prudent cooking practices and use of ideal combinations of food components can significantly improve micronutrient bioavailability. Household processing such as heat treatment, sprouting, fermentation and malting have been evidenced to enhance the bioavailability of iron and β-carotene from plant foods. Food acidulants amchur and lime are also shown to enhance the bioavailability of not only iron and zinc, but also of β-carotene. Recently indentified newer enhancers of micronutrient bioaccessibility include sulphur compound-rich Allium spices—onion and garlic, which also possess antioxidant properties, β-carotene-rich vegetables—carrot and amaranth, and pungent spices—pepper (both red and black) as well as ginger. Information on the beneficial effect of these dietary compounds on micronutrient bioaccessibility is novel. These food components evidenced to improve the bioavailability of micronutrients are common ingredients of Indian culinary, and probably of other tropical countries. Fruits such as mango and papaya, when consumed in combination with milk, provide significantly higher amounts of bioavailable β-carotene. Awareness of the beneficial influence of these common dietary ingredients on the bioavailability of micronutrients would help in devising dietary strategies to improve the bioavailability of these vital nutrients.     

Effect of food processing of pearl millet (Pennisetum glaucum) IKMP‐5 on the level of phenolics,phytate, iron and zinc

Pearl millet is consumed as a staple food in semi‐arid tropical regions. With a view to upgrading the micronutrient status of pearl millet‐based foods, the effects of single operations and of porridge preparation scenarios on levels and in vitro solubility (IVS) of iron and zinc and mineral complexing factors (phytates: inositol phosphates and phenolic compounds) were tested. Disc milling of grain may add significant iron but this is not necessarily IVS iron. Soaking of grains results in a 25% loss of iron, but also facilitates endogenous phytate degradation, particularly when combined with milling and cooking. Germination and lactic acid fermentation both result in partial phytate degradation. Cooking does not decompose phytates, but results in complex formation of phenolic compounds as measured by a significant reduction in reactive hydroxyl groups. Because of its different distribution in the grain, zinc is generally less affected than iron. Phytate reduction by endogenous phytases is inhibited at low pH as caused by fermentation. Kanwa (alkaline rock salt) could be a functional cooking ingredient as a source of minerals and to react with phenolic substances. The relative IVS of iron was doubled by germination of grain and increased 3‐fold by fermentation of wholemeal slurry. Zinc IVS tended to increase on cooking with kanwa, but decreased in cooked fermented flour. Copyright © 2006 Society of Chemical Industry     

Viscous and thermal behaviour of vitamin A and iron‐fortified reconstituted rice

The viscous and thermal behaviour of five types of micronutrient‐fortified reconstituted rice premixes extruded at pre‐optimised extrusion conditions (36% moisture content, 150 rpm screw speed and 89 °C barrel temperature) have been investigated using rapid visco analyser (RVA) and differential scanning calorimetry (DSC). The highest peak viscosity (1279 cP), lowest gelatinised starch percentage (16.32) and highest enthalpy of gelatinisation (8.2 J g^?1) were recorded in rice premix fortified with retinyl palmitate and micronised ferric pyrophosphate. The scanning electron microscopic analysis (SEM) also revealed that reconstituted rice premix fortified with iron (micronised ferric pyrophosphate) and retinyl palmitate was in closer resemblance to that of natural rice than any other reconstituted rice premix. The work demonstrated that vitamin A‐ and iron‐fortified reconstituted rice with meso/micro structure and pasting behaviour close to that of natural rice can be produced using retinyl palmitate and micronised ferric pyrophosphate as vitamin A and iron source, respectively.     

Changes in mineral absorption inhibitors consequent to fermentation of Ethiopian injera: implications for predicted iron bioavailability and bioaccessibility

Possible changes in mineral bioavailability during processing of different types of injera sampled in Ethiopian households were assessed using different methods: phytic acid/mineral molar ratio, absorption prediction algorithm and in vitro availability measurements. Most foods analysed were rich in iron, but most of the iron likely resulted from soil contamination. The highest iron, zinc and calcium contents were found in teff–white sorghum (TwS) injera and flour. The lowest phytic acid/Fe and phytic acid/Zn molar ratios were found in barley–wheat (BW) and wheat–red sorghum (WrS) injeras. Although ideal phytic acid/Fe molar ratios (<0.4) were found in BW and WrS injeras, no significant difference between in vitro iron bioaccessibility and algorithm predicted absorption was observed. In injera, phytic acid degradation alone is unlikely to improve iron bioavailability, suggesting interactions with other absorption inhibitors. The use of phytic acid/Fe molar ratios to predict bioavailability may thus be less appropriate for iron‐contaminated foods.     

Potential of non‐GMO biofortified pearl millet (Pennisetum glaucum) for increasing iron and zinc content and their estimated bioavailability during abrasive decortication

Two non‐GMO biofortified and one traditional pearl millet varieties were compared in abrasive decortication studies to evaluate their potential for increasing iron and zinc content. The phytate‐to‐mineral ratios were used to estimate mineral bioavailability. Iron and zinc contents in the biofortified varieties Tabi and GB8735 were two to threefold higher than in the traditional variety. Iron content reached 7.2 and 6.7 mg per 100 g DM in the biofortified varieties, which corresponds to the target values of biofortification programs. Zinc content was, respectively, 5.6 and 4.1 mg per 100 g DM in the GB8735 and Tabi varieties. Because of the presence of phytate and other chelating factors that were only partially removed during decortication, there was no improvement in iron bioavailability in the biofortified varieties. But whatever extraction rate, phytate‐to‐zinc ratios ranged between 6 and 18; zinc absorption could be improved by using these biofortified varieties for food processing.     

Production of maize–bambara groundnut complementary foods fortified pre‐fermentation with processed foods rich in calcium,iron, zinc and provitamin A

BACKGROUND: Maize–bambara groundnut complementary foods are deficient in calcium, iron, zinc and vitamin A. Food‐to‐food fortification could be cheaper, safer and more easily adopted by local communities compared to the use of chemically pure compounds and vitamins to enrich such foods. RESULTS: Maize–bambara groundnut complementary foods fortified for iron, zinc, calcium and vitamin A by blending with a multi‐mix (1.41:1:2.25, w/w) of processed roselle calyces, cattle bones, and red palm oil in a 1:2.1 (w/w) ratio showed significant increases in calcium, iron, zinc and vitamin A contents of 3.26–4.225, 0.083–0.134 and 0.015–0.017 g kg^?1 and 4855.3–7493.7 µgRE kg^?1, respectively. CONCLUSION: The maize–bambara groundnut foods had calcium, iron, zinc and vitamin A contents that satisfy the proposed nutrient requirements for infants. Only the maize–bambara groundnut and maize–bambara groundnut malt fermented by backslopping [(MB)_b and (MB_m)_b] containing red palm oil emulsified with Brachystegia eurycoma had calcium contents significantly (P < 0.05) higher than Nutrend, a complementary food produced by Nestle (Nigeria) PLC. These products are from raw materials produced in commercial quantities by rural farmers using household level technologies which the rural and urban poor can more easily access in order to reduce micronutrient malnutrition. Copyright © 2010 Society of Chemical Industry     

Modulation of chelating factors,trace minerals and their estimated bioavailability in Italian and African sorghum (Sorghum bicolor (L.) Moench) porridges

Factors able to modulate chelating factors, trace minerals and their bioavailability were investigated in porridges of five sorghum (Sorghum bicolor (L.) Moench) varieties: from Nigeria, Senegal, Burkina Faso and two from Italy. Effects of variety and traditional fermentation and cooking were assessed on iron‐binding phenolic groups, phytates and iron and zinc content and bioavailability. Chelating factors, trace elements as well as the effect of processing (mainly fermentation) were modulated by variety. Fermentation decreased iron‐binding phenolic groups until 49% and phytate content until 72% as well as increased phytase activity 3.4–16.4 fold, leading to enhancement of iron and zinc estimated bioavailability. Cooking alone had almost no effect. The lowest chelating factors content and the highest trace minerals bioavailability were shown by fermented Senegal landrace, whereas the Italian varieties overall showed the worst results. The results indicate that selection of traditional varieties and appropriate processing methods can improve sorghum nutritional value.     

Predicting relative concentrations of bioavailable iron in foods using in vitro digestion: New developments

In vitro methods have been developed for the prediction of iron bioavailability from foods and supplements. The dialyzability method measures dialyzable iron, released during a simulated gastrointestinal digestion, as an index of iron bioavailability. A new setup, that involves six-well plates and a ring insert that holds the dialysis membrane, is proposed for the application of the dialyzability method with the objective to increase efficiency and to allow testing small-volume samples. A series of solutions (water, ascorbic acid, and phytate), liquid foods (fresh milk and condensed milk), and solid foods (bread + meat meal, corn flakes), were tested in the presence or absence of added iron and digested with the new setup and the setup previously described for the dialyzability method. In both cases, percent dialyzable iron in each treatment remained similar (P > 0.05). These results suggest that the new setup can be employed in future applications with similar food matrices of the dialyzability method.     

Advantages and limitations of in vitro and in vivo methods of iron and zinc bioavailability evaluation in the assessment of biofortification program effectiveness

ABSTRACT

Biofortification aims to improve the micronutrient concentration of staple food crops through the best practices of breeding and modern biotechnology. However, increased zinc and iron concentrations in food crops may not always translate into proportional increases in absorbed zinc (Zn) and iron (Fe). Therefore, assessing iron and zinc bioavailability in biofortified crops is imperative to evaluate the efficacy of breeding programs. This review aimed to investigate the advantages and limitations of in vitro and in vivo methods of iron and zinc bioavailability evaluation in the assessment of biofortification program effectiveness. In vitro, animal and isotopic human studies have shown high iron and zinc bioavailability in biofortified staple food crops. Human studies provide direct knowledge regarding the effectiveness of biofortification, however, human studies are time consuming and are more expensive than in vitro and animal studies. Moreover, in vitro studies may be a useful preliminary screening method to identify promising plant cultivars, however, these studies cannot provide data that are directly applicable to humans. None of these methods provides complete information regarding mineral bioavailability, thus, a combination of these methods should be the most appropriate strategy to investigate the effectiveness of zinc and iron biofortification programs.     

Nutritional potential, bioaccessibility of minerals and functionality of watermelon (Citrullus vulgaris) seeds

Watermelon (Citrullus vulgaris) seeds are high in protein and fat, on enriching protein, it can find application as a protein source in various food formulations. Most of the processed foods are generally fortified with micronutrients. The effect of the matrix on the mineral bioavailability is highly important and hence investigated. Defatted flour and protein isolate were prepared from watermelon seed meal and chemical composition and functionality was analyzed by standard techniques. Multiple regression analysis was done to study the compositional influence on the mineral bioaccessibility. Invitro digestibility of the protein was good. The seeds were a moderate source of iron and zinc. The percent bioaccessibility of all the minerals were found to correlate (R = 0.97-0.99) with the concentration of phytate, tannin and oxalate contents. The seed components exhibited good functionality with good macro and micronutrient density and can find application in many food products.     

Phytate × Calcium/Zinc Molar Ratios: Are They Predictive of Zinc Bioavailability?

The utility of the phytate/zinc and phytate × calcium/zinc molar ratios for predicting zinc bioavailability from processed soybean foods was investigated. Weight gain and bone zinc accumulation in rats fed various soy protein products were plotted against the calculated molar ratios. The phytate × calcium/zinc ratio was a better predictor of zinc bioavailability in similarly processed products than was the phytate/ zinc ratio. However, in some cases the phytate × calcium/zinc ratio was not effective since some processing procedures apparently altered binding of phytic acid to minerals and other food components.     

Protein and mineral content of a novel collection of wild and weedy common bean (Phaseolus vulgaris L)

Protein and total calcium, iron, and zinc were determined in 70 accessions of wild and weedy common bean (Phaseolus vulgaris L) from different sites in two Mexican states (Jalisco and Durango). Protein digestibility, essential amino acid profiles, tannins, phytic acid and extractable iron were determined in selected accessions. The phytate/zinc and the phytate × (calcium/zinc) molar ratios were also determined as predictors of zinc bioavailability. For comparative purposes, two cultivated common beans were included. The wild and weedy beans contained more protein and similar protein digestibility compared with cultivated samples. The contents of sulfur amino acids were low in all samples; additionally, beans from Jalisco had higher contents of sulfur amino acids than cultivated ones. Beans from Durango showed higher leucine, valine and aromatic amino acids contents than cultivated beans. Some wild and weedy beans from Jalisco and Durango showed high contents of calcium (7470 mg kg⁻¹), iron (280 mg kg⁻¹), and zinc (33.1 mg kg⁻¹). The phytic acid × (calcium/zinc) molar ratios of some wild and weedy beans were similar to those of cultivated beans. Amounts of extractable iron were in the order of 26–74%. © 2000 Society of Chemical Industry     

Phytate dephosphorylation by Lactobacillus pentosus CFR3

Studies on phytate‐degrading enzymes from lactobacilli are scarce, despite its potential in improving the nutritional quality of plant‐based foods. Therefore, the current investigation deals with the phytate‐degrading enzyme produced by a native Lactobacillus pentosus strain. Phytase activity was highest towards the end of the exponential phase. Activity increased in the presence of maltose (381.1%) compared with glucose. The presence of phytate in the media stimulated the enzyme production. The enzyme of interest was a 70 kDa protein with a pH and temperature optima of 5.0 and 55–60 °C, respectively. It retained 46% of activity after exposure to 70 °C for 20 min and also showed broad substrate specificity. It was completely inhibited by Hg²⁺, Fe²⁺ and PMSF while being activated by Co²⁺. This report is the first to show dephytinisation of autoclaved finger millet flour either by fermentation with L. pentosus or by treatment with the corresponding cell‐free extract.     

Iron content and availability studies in some Sri Lankan rice varieties

Thirty‐eight rice varieties, grown in Low Country Wet Zone, during Yala (2006) and Maha (2006/2007) seasons were screened for stable high iron rice varieties and were statistically analysed. Iron contents ranged 1.89–3.73 mg 100 g^?1 and varied significantly (P < 0.05) with variety and season. Selected fifteen high iron rice varieties, at degree of polishing 8–10% were analysed for iron, zinc and phytate. High iron contents in endosperm were observed in Suduru Samba (0.47 mg 100 g^?1), Basmati 370 (0.37 mg 100 g^?1), Kalu Heenati (0.42 mg 100 g^?1), Rathu Heenati (0.44 mg 100 g^?1) and Sudu Heenati (0.37 mg 100 g^?1). Phytate contents of polished rice varieties ranged from 200–300 mg 100 g^?1. Large reduction in iron content (84.5–93.6%) was observed in polished rice while the reduction in phytate content (18.9–40.8%) was low. Percentage dialyzability of iron in selected endosperm high iron rice varieties ranged from 1.73 to 8.71. Dialysability of iron in cooked polished rice did not show a relation to the phytate content in raw rice.     

Assessment of iron bioavailability from twenty elite late‐maturing tropical maize varieties using an in vitro digestion/Caco‐2 cell model

An in vitro digestion/Caco‐2 cell model was used to assess iron bioavailability of twenty elite late‐maturing tropical maize varieties grown in three diverse agroecologies in West and Central Africa (WCA). Kernel‐iron concentration of the varieties, averaged across locations, varied from 19.2 to 24.4 mg kg^?1, while mean kernel‐zinc concentration ranged between 19.4 and 24.6 mg kg^?1. Significant differences in iron bioavailability were observed among varieties, but the environment had no significant effect. Mean bioavailable iron ranged between 14% below and 43% above the reference control variety, TZB‐SR. Variety DMR‐LSR‐Y with the highest concentrations of kernel‐iron and ‐zinc of 24–25 mg kg^?1 across the three locations had a similar quantity of bioavailable iron as the reference control, TZB‐SR. In the long run this variety could be potentially effective in reducing iron deficiency because of its high kernel‐iron. The most promising varieties were Mid‐altitude STR synthetic and ACR91SUWAN‐1‐SRC1. They had kernel‐iron and ‐zinc levels of 22–24 mg kg^?1 and bioavailable iron 24–36% higher than the reference control, TZB‐SR. Additional research is necessary to determine if the increases in kernel‐iron concentration and bioavailable iron observed in this study can significantly improve the iron status of individuals in WCA at risk for iron deficiency. Copyright © 2004 Society of Chemical Industry     

Dephytinisation of Sangak and Barbari bread made from different extraction rate flours increases iron and zinc bioaccessibility in Caco‐2 cells

Bread is a staple food in many countries and an important source of iron and zinc. The bioavailability of these minerals is generally low because of the content of phytic acid. Traditional Iranian breads were prepared with flours of different extraction rates, Sangak at 93% and Barbari at 82%. Breads were dephytinised by addition of Aspergillus niger phytase during in vitro digestion. The effect upon iron and zinc bioaccessibility in the Caco‐2 cell model was investigated. The cellular uptake of iron and zinc was lower from Sangak, compared to Barbari, despite higher mineral content in Sangak. Dephytinisation of both breads increased iron uptake in the Caco‐2 cells (0.65 vs. 1.64 in Sangak and 0.77 vs. 1.97 ng mg^?1 protein in Barbari). Zinc uptake increased from 0.98 to 2.8 in Sangak and from 1.4 to 2.9 ng mg^?1 protein in Barbari. Thus, dephytinisation substantially improves iron and zinc bioaccessibility.     

Changes in iron,zinc and chelating agents during traditional African processing of maize: Effect of iron contamination on bioaccessibility

The effect of the different unit operations of processing traditionally used to produce four maize foods commonly consumed in Africa on the nutritional composition of the products was investigated, using Benin as a study context. The impact of the processes on lipid, fibre, phytate, iron and zinc contents varied with the process. The lowest IP₆/Fe and IP₆/Zn molar ratios, the indices used to assess Fe and Zn bioavailability were obtained in mawè, a fermented dough. Analysis of maize products highlighted a significant increase in iron content after milling, as a result of contamination by the equipment used. Evaluation of iron bioaccessibility by in vitro enzymatic digestion followed by dialysis revealed that the iron contamination, followed by lactic acid fermentation, led to a considerable increase in bioaccessible iron content. Extrinsic iron supplied to food products by the milling equipment could play a role in iron intake in developing countries.     

Comparison of enhancement in bioaccessible iron and zinc in native and fortified high‐phytate oilseed and cereal composites by activating endogenous phytase

In developing countries, iron and zinc deficiencies are mostly attributable to poor bioavailability of iron and zinc. The study aimed at enhancing the bioaccessibility of minerals in high‐phytate oilseed and cereal flour mixes by activating the intrinsic phytase of wheat flour. The flour mixes were fortified with iron and zinc separately for comparison. The flour mixes were incubated at optimum conditions of temperature and pH for phytase activation. Phytase activation enhanced bioaccessible iron by 43–162% in native and 40–168% in fortified wheat–soya, 83–192% in native and 97–240% in fortified wheat–groundnut flour mixes in relation to control flour mixes. Bioaccessible zinc was enhanced by 87–183% in native and 30–113% in fortified wheat–soya, 31–65% in native and 61–186% in fortified wheat–groundnut flour mixes. Endogenous phytase activation was effective in enhancing bioaccessibility of iron and zinc in native and fortified flour composites economically.