In-vitro iron dialysability from legumes: Influence of phytate and extrusion cooking

In-vitro iron dialysability from five Italian legumes (mottled bean, white bean, faba bean, chickpea, lentil) and the influence of phytate and extrusion cooking on it were evaluated. Iron dialysability was 2·3 and 2·4% in mottled and white bean respectively, 1·2% infaba bean, 2·7% in chickpea and 1·1% in lentil. After extrusion cooking the flours showed a marked iron contamination and a decrease in iron dialysability, but these changes were significant only for mottled bean. Enzymic phytate removal induced an increase in iron dialysability > 100% in all the raw legumes except mottled bean which showed an increase of only 57%. This finding indicates that, although phytate consistently modifies iron dialysability, it is difficult to identify a quantitative relationship between phytate content and iron dialysability.     

Effect of phytate reduction of sorghum,through genetic modification,on iron and zinc availability as assessed by an in vitro dialysability bioaccessibility assay,Caco-2 cell uptake assay,and suckling rat pup absorption model

Improved iron and zinc availability from sorghum, a commonly consumed staple, will benefit many malnourished communities in rural Africa burdened with high prevalence of iron and zinc deficiency. This research compared the effect of genetic phytate reduction in sorghum on iron and zinc bioaccessibility and uptake measured by in vitro dialysability and Caco-2 cell uptake assays to that of iron and zinc absorption measured by a suckling rat pup model. The phytate reduction (80–86%) in these sorghums significantly increased zinc availability. The Caco-2 cell method, but not the dialysability assay, proved useful in estimating zinc absorption. The measured increase in iron availability differed between the methods, possibly due to the effect of varying mineral (Ca, Fe, Zn, P) contents of the sorghums. This effect was most prominent in the iron uptake results. More research is needed to determine the effect of naturally occurring variations in mineral contents of sorghum on the iron uptake by Caco-2 cells.     

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.     

Iron (Fe) bioavailability and the distribution of anti‐Fe nutrition biochemicals in the unpolished,polished grain and bran fraction of five rice genotypes

Iron (Fe) bioavailability in unpolished, polished grain and bran fraction of five rice genotypes with a range of Fe contents was measured by in vitro digestion and cultured Caco‐2 cells of cooked grain. There was a significant difference in Fe bioavailability among the five rice genotypes tested, in both the unpolished and polished grain. The range of Fe bioavailability variation in polished rice was much wider than that of unpolished, suggesting the importance of using Fe levels and bioavailability in polished rice grain as the basis for selecting high‐Fe rice cultivars for both agronomic and breeding purposes. Milling and polishing the grain to produce polished (or white) rice increased Fe bioavailability in all genotypes. Iron bioavailability in polished rice was high in the UBON2 and Nishiki, intermediate in both IR68144 and KDML105, and low in CMU122. All genotypes had low bioavailability of Fe in bran fraction compared to unpolished and polished grain, except in CMU122. CMU122 contained the lowest level of bioavailable Fe in unpolished and polished grain and bran, because of the dark purple pericarp colored grain and associated tannin content. The level of bioavailable Fe was not significantly correlated with grain Fe concentration or grain phytate levels among these five genotypes tested. The negative relationship between Fe bioavailability and the levels of total extractable phenol was only observed in unpolished (r = ?0.83**) and bran fraction (r = ?0.50*). The present results suggested that total extractable phenol and tannin contents could also contribute to lowering bioavailability of Fe in rice grain, in addition to phytate. Copyright © 2006 Society of Chemical Industry     

Effect of oilseed protein concentrates and exogenous amino acids on the dialysability of iron and zinc

Iron deficiency anaemia and zinc deficiency have been persistent public health problems worldwide. Both deficiencies are attributed to poor bioavailability of minerals. The investigation was undertaken to study the effect of oilseed protein concentrates and exogenous amino acids on the dialysability of iron and zinc. Corn flour matrices with 10–20 g protein/100 g were formulated using groundnut and sesame protein concentrates. Dialysability of iron and zinc in natural and mineral fortified matrices was analysed. The effect of exogenous cysteine, histidine, glycine and lysine on mineral dialysability was analysed in groundnut and sesame protein concentrates. Dialysability of iron was enhanced with increasing protein concentration in matrices with groundnut protein but decreased in matrices with sesame protein. Dialysability of zinc increased with increasing protein concentration with both the protein concentrates. Among the amino acids, histidine enhanced dialysability of iron in natural groundnut and sesame protein concentrates, glycine in fortified groundnut and lysine in fortified sesame protein concentrates to a considerable extent. Dialysability of zinc was enhanced in natural groundnut, natural and fortified sesame protein concentrates by all amino acids. Amino acids definitely promotes the dialysability of iron and zinc, but its enhancing ability is highly specific to the food matrix.     

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.     

The bioavailability of iron fortified in whole grain parboiled rice

The present study was to evaluate the bioavailability of iron (Fe) fortified in parboiled rice grain, expressed as Fe uptake by Caco-2 cells after in vitro digestion. The bioavailability of Fe-fortified in the rice grain was closely and positively correlated with increasing concentrations of Fe in the grains of the three cultivars (r = 0.96∗∗). The uptakes of the Fe-fortified in parboiled rice milled for 120 s (34.2, 47.7 and 107 ng ferritin mg protein⁻¹ in three cultivars, respectively) were well above those of the unfortified raw (6.1, 4.9 and 5.7 ng ferritin mg protein⁻¹) or parboiled rice (4.7, 3.6 and 4.4 ng ferritin mg protein⁻¹), the high Fe rice line IR68144-2B-3-2-2 (4.0 ng ferritin mg protein⁻¹) and popular Jasmine rice cultivar KDML 105 (3.9 ng ferritin mg protein⁻¹). Increasing milling time and rinsing the Fe-fortified parboiled rice decreased Fe bioavailability, due to their negative effects on total Fe concentrations in the parboiled rice grains, but uptakes were still well above that of their unfortified raw or parboiled rice grains. Rinsing or washing the Fe-fortified and milled rice grains decreased the bioavailability to 85 ng ferritin mg protein⁻¹ in the YRF cultivar, compared to about 100 ng ferritin mg protein⁻¹ in its non-rinsed grains. Dilute acid-extractable (DAE) Fe was linearly, positively correlated with the uptake of Fe assessed by the in vitro digestion/Caco-2 cell technique (r = 0.90∗∗), which can be used as a rapid method for optimizing levels of bioavailable Fe to be fortified in the parboiled rice by parboiled-rice mills if this Fe-fortification technique should be adopted in south and southeast Asia.     

Availability of iron from milk-based formulas and fruit juices containing milk and cereals estimated by in vitro methods (solubility,dialysability) and uptake and transport by Caco-2 cells

Iron solubility, dialysability and transport and uptake (retention + transport) by Caco-2 cells as indicators of iron availability have been estimated in the in vitro gastrointestinal digests of infant foods (adapted, follow-up and toddler milk-based formulas and fruit juices containing milk and cereals (FMC)). Low correlation coefficients (in all cases R-squared ? 37.1%) were obtained between iron solubility or dialysability versus transport or uptake efficiency – a fact emphasizing the importance of incorporating Caco-2 cell cultures to in vitro systems in order to adapt the conditions to those found in in vivo assays. The highest uptake efficiency corresponded to FMC (25.6–26.1%) and toddler formulas (32.1–41.9%), the samples with the highest ascorbic acid contents and ascorbic acid/iron molar ratios. In addition, the toddler formulas contained caseinphosphopeptides with the cluster sequence SpSpSpEE, representing the binding site for minerals. In adapted formulas, greater iron uptake efficiency was obtained for the formulation containing ferrous lactate (22.7%) versus ferrous sulfate (4.7%).     

Effect of proteins, phytates, ascorbic acid and citric acid on dialysability of calcium, iron, zinc and copper in soy-based infant formulas

The possible effect of ascorbic acid, citric acid, proteins and phytate on dialysability of Ca, Fe, Zn and Cu in soy-based infant formulas is studied, taking dialysability as a measure of the amount of element available for absorption. Different dialysis percentages for similar element contents in different formulas are found. A regression analysis was applied between Ca, Zn, Cu and Fe dialysis percentages and soy-based formula components to estimate the possible influence of the latter on the dialysability of the elements. Significant correlations were found between citric acid contents and dialysability of Zn and Fe. No correlations were found between protein, ascorbic acid and phytic acid contents and the dialysis percentages of the four minerals. However, we must to point out that the range of protein contents was narrow and the ascorbic acid: iron ratio was high in our formulas.     

Effect of proteins,phytates, ascorbic acid and citric acid on dialysability of calcium,iron, zinc and copper in soy‐based infant formulas

The possible effect of ascorbic acid, citric acid, proteins and phytate on dialysability of Ca, Fe, Zn and Cu in soy‐based infant formulas is studied, taking dialysability as a measure of the amount of element available for absorption. Different dialysis percentages for similar element contents in different formulas are found. A regression analysis was applied between Ca, Zn, Cu and Fe dialysis percentages and soy‐based formula components to estimate the possible influence of the latter on the dialysability of the elements. Significant correlations were found between citric acid contents and dialysability of Zn and Fe. No correlations were found between protein, ascorbic acid and phytic acid contents and the dialysis percentages of the four minerals. However, we must to point out that the range of protein contents was narrow and the ascorbic acid: iron ratio was high in our formulas.     

Study of the hard-to-cook property of stored yam tubers (Dioscorea dumetorum) and some determining biochemical factors

In an attempt to investigate the hard-to-cook phenomenon in Dioscorea dumetorum tubers during storage, selected physical and chemical characteristics were monitored. A 3 × 5 factorial experiment with storage conditions (15 °C, 59% RH; 30 °C, 75% RH; 45 °C, 86% RH) and storage period (0, 2, 4, 7 and 14 days) as variables was carried out. Changes in cooked hardness, water absorption, water-holding capacity and solid loss of steeped tubers as well as phytate, total phenols and lignin contents were monitored. Water uptake and solid loss of steeped tubers decreased significantly (P ⩽ 0.05) with storage period, suggesting that storage affects cell wall membrane permeability of the tubers. Cooked hardness analyses indicated significant difference (P ⩽ 0.05) between fresh and stored tubers and its rate varied with storage time and storage conditions. Cooked hardness values correlated negatively (r = −0.922–0.857, P ⩽ 0.05, d.f. = 146) with phytate and total phenols. A multiple mechanism for D. dumetorum tubers hardening is presented which includes phytate loss as a minimal contributor to cooked hardness during the first days of storage and total phenol loss via a lignification-like mechanism as a major contributor.     

Solvent retention capacity values in relation to the Czech commercial wheat quality

Technological quality in the sets of eighty commercial wheat samples was evaluated by grain milling traits (test weight, thousand kernel weight, grain hardness as Particle Size Index, one‐stream flour yield) and common analytical parameters (wet gluten and protein contents, Zeleny test value, falling number) together with the solvent retention capacity (SRC) method (AACC 56‐11). For the commercial wheat, the latter analytical procedure (originally designed for flour quality analysis) was verified also for grain wholemeal. Within the mentioned sample group, anova revealed the strongest effect of the harvest year, both for milling and for technological parameters. For the SRC profiles, the effect of the sample form used dominated the crop year influence. The grain SRCs were correlated with the milling traits foursome, while an agreement between the flour SRC profiles and technological quality data was not so tight. However, the flour lactic acid SRC was associated with the wet gluten and protein contents (r = 0.24, P < 0.05), and the protein quality as Zeleny value with the flour water SRC (r = 0.24, P < 0.05). Relationship between Zeleny's value and flour lactic acid SCR was confirmed by nonlinear Spearman correlation (R = ?0.26, P < 0.05).     

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.     

Genotypic and environmental variation in phytic acid content and its relation to protein content and malt quality in barley

Phytic acid or phytate is a chelating agent, which is involved in binding minerals (such as K⁺, Ca²⁺, Zn²⁺, Fe²⁺, etc.) and making them unavailable for dietary absorption. It is also involved in forming complexes with protein, making protein less soluble, and affecting enzymatic degradation, gastric absorption, and malting processes. The phytic acid and protein contents of barley grains are influenced by genetic and environmental factors. This study investigated differences in phytic acid and protein contents in grains of 100 barley (Hordeum vulgare L.) genotypes or cultivars. Eight barley cultivars were selected and grown at seven locations for two years to study the effects of genotypic and environmental factors on phytic acid content (PAC) and its relation to malt quality. The phytic acid contents of 100 barley genotypes ranged from 3.85 mg g⁻¹ to 9.85 mg g⁻¹, with a mean of 7.01 mg g⁻¹. The effects of cultivars, locations, time and their interactions were highly significant, but the variation was mainly attributed to the environment (location and time). The correlation between grains phytic acid and protein content was significant and positive. Whereas, the correlation between grain phytic acid content and malt extract was significant and negative. The relationship between phytic acid and protein contents of barley is important as it affects the malting process, malt yield and quality, and final beer quality. Barley grain for malting and feed uses should have low phytic acid content.     

Physical properties and carotenoid content of maize kernels and its nixtamalized snacks

Vitamin A and protein deficiencies afflict hundreds of millions of people, and because maize is a staple food providing a large portion of energy and nutrients for many, its genetic fortification or biofortification could significantly contribute to alleviating malnutrition. Therefore, we measured carotenoid and tryptophan contents for grain, nixtamalized (lime-cooked) maize, and processed snacks of 13 maize genotypes including landraces, quality protein maize (QPM) and non-QPM hybrids. An average 36% loss of provitamin A and an 8% increase in tryptophan were observed following nixtamalization and subsequent snack preparation by deep-frying. The correlations for physical properties of grain and maize flour with provitamin A were calculated to investigate whether secondary traits may be useful as indicators of provitamin A content. The correlation of chroma values with provitamin A contents was significant (P < 0.05) for 15% and 25% hydrated maize flour (r = 0.57 and r = 0.51, respectively), but was not significant for whole maize kernels.Industrial relevanceYellow maize is used as food and feed. Possible methodologies for rapid carotenoid estimation for industrial purposes like corn flakes or for the poultry industry will be of importance. One of the objectives of this work was to establish correlation between physical parameters and carotenoid concentration in maize. The correlation of chroma values with provitamin A contents was significant (P < 0.05) for 15% and 25% hydrated maize flour (r = 0.57 and r = 0.51, respectively), which could be explored as a methodology for rapid and inexpensive estimation of provitamin A and total carotenoids in maize. Lime-cooking is the traditional method for maize preparation in Mexico and Central America. The estimation of carotenoid losses during this process and the bioavailability studies are important to measure the impact of biofortified maize in the populations with provitamin A deficiencies. During this work we have determined that an average 36% loss of provitamin A and an 8% increase in tryptophan were observed following nixtamalization and subsequent snack preparation by deep-frying.     

The inhibitory effect of albumin extracts from white beans (Phaseolus vulgaris L.) on in vitro iron and zinc dialysability: role of phytic acid

The role of phytic acid in determining iron and zinc dialysability in albumin extracts from raw, cooked and cooked/dephytinized white beans, has been investigated. Albumin extract from raw beans was characterized by high iron (19mg/100g), zinc (6.9mg/100g) and phytic acid (11.5μmol g⁻¹) contents and a low mineral dialysablity (Fe 0.48%, Zn 2.5%). Cooking did not influence the mineral dialysability from beans but significantly increased the dialysability of iron (1%, p < 0.001) and zinc (5.3%, p < 0.001) from the albumin extract. Slight modifications in the composition of inositol phosphates after cooking, both in beans and in albumin extract, were observed. The improvement in iron and zinc dialysability from cooked/dephytinized samples was strictly dependent on the residual IP(6 + 5) (inositol hexa + pentaphosphates) content. Compared to cooked beans, in cooked/dephytinized bean a reduction of IP(6 + 5) of 49% led to an increase of the iron and zinc dialysability (29% p < 0.05 and 42%, p < 0.001, respectively). Albumin extract from this sample showed a reduction of 58% in iron and of 45% in zinc content, an almost complete reduction in IP(6 + 5) content (0.6 μmol g⁻¹) and a strong increase in the iron and zinc dialysability. The albumin digests showed peptides of similar MW profiles but of different amino acid compositions. In particular, in peptides which derived from digestion of albumin extracted from cooked/dephytinized beans, a strong increase in cysteine content was found, indicating that, after the disruption of phytate-mineral-protein complexes cysteine-rich fragments were released. The study indicates that phytic acid is responsible for the low iron and zinc dialysability from the albumin bean fraction and indicates the significance of the amino acid composition of the protein digestion products for the enhancement of mineral dialysability.     

Antioxidant and free radical scavenging activities of whole wheat and milling fractions

The effects of milling on the phenolic content and antioxidant capacity of two wheat cultivars, namely CWAD (Canadian Western Amber Durum; Triticum turgidum L. var. durum) and CWRS (Canadian Western hard red spring; Triticum aestivum L.) were studied. The milling of wheat afforded several fractions, namely bran, flour, shorts and feed flour. In addition, semolina was the end-product of durum wheat milling. Among different milling fractions the bran had the highest phenolic content while the endosperm possessed the lowest amount and this was also reflected in free radical and reactive oxygen species (ROS) scavenging capacity, reducing power and iron (II) chelation capacity of different milling fractions in the two cultivars. This study demonstrated the importance of bran in the antioxidant activity of wheat, hence consumption of whole wheat grain may render beneficial health effects.     

Effect of whole amaranth flour on bread properties and nutritive value

This study investigated the effect of replacing wheat flour by whole Amaranthus cruentus flour (up to 40 g/100 g) to evaluate its potential utility as a nutritious breadmaking ingredient. The incorporation of amaranth flour significantly increased protein, lipid, ash, dietary fibre and mineral contents. Breads with amaranth have significantly higher amounts of phytates and lower myo-inositol phosphates, which could predict low mineral bioavailability at high levels of substitution (30–40 g/100 g). An increase in crumb hardness and elasticity was observed, and tristimulus colour values were significantly affected when the amaranth concentration was raised. Mineral contents, both micro- and macroelements, were increased significantly by the wheat flour substitution. Whole amaranth flour could be used as a partial replacement for wheat flour in bread formulations, increasing the product’s nutritional value and raising dietary fibre, mineral and protein levels, with a significant slight depreciation in bread quality when used in proportions between 10 and 20 g/100 g. Thus, the inclusion of amaranth flour could be limited to a maximum proportion of 20 g/100 g, thereby maintaining both product quality as well as the nutritional benefit of this ingredient.     

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.     

Effect of phytase treatment on iron bioavailability in faba bean (Vicia faba L.) flour

The effect of dephytinisation, using an exogenous phytase under optimal conditions (pH 5.5, 37 °C), and subsequent removal of the soaking solution after processing, on the bioavailability of iron from faba bean (Vicia faba L.) flour was studied. Soaking of the faba bean flour led to a considerable reduction in the content of iron (39%), whereas a lower reduction in iron content (10%), was obtained after additional treatment with phytase, than in the soaked faba bean flour. The digestive utilisation of iron from the raw and soaked faba bean flours by growing rats was negligible, but increased significantly as a result of phytase treatment. The low iron absorption obtained for the former two treatments, during an experimental period of 10 days, was not reflected in any of the haematological indices (red blood count, haemoglobin, haematocrit) or tissues (femur, heart, kidney) studied, with the exception of the sternum. The latter appears to be a useful indicator of iron bioavailability.