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%).     

Ferritin synthesis by Caco-2 cells as an indicator of iron bioavailability: Application to milk-based infant formulas

The bioavailability of iron from milk-based infant formulas was estimated by an in vitro system including enzymatic digestion, iron uptake by Caco-2 cells and ferritin determination via an enzymoimmunoassay (ELISA). Positive correlations (p < 0.01) were found between the Fe(II) added to Caco-2 cells and ferritin synthesis and between the amount of dialyzed iron added to the cell culture and ferritin synthesis. The comparison of the bioavailability of iron from different milk-based formulas showed that adapted formulas having the same composition but differing in the iron salts added yielded similar ferritin levels. The same happened with follow-up formulas differing only in the presence or absence of bifidobacterium added. However, significant differences in the amount of ferritin synthesized were recorded between the two analyzed toddler formulas. Such differences could be attributed firstly to the ascorbic acid content and perhaps also to the manufacturing process involved, because one formula was in liquid form while the other was powdered.     

Iron Content of Infant Formula Produced in the United States

Seventy-seven infant formulas were analyzed for iron. Samples were from three formulation classes: milk-base (17), milk-base plus Fe (29) and soy-base (31). Mean iron levels for the milk-based, milk-based plus Fe and soy-based formulas were 0.4, 2.1 and 2.5 mg/100 Kcal, respectively. Iron levels ranged from 0.26-4.7 mg/100 Kcal. All milk-based formulas met minimum requirement of 0.15 mg/100 Kcal of the 1980 Infant Formula Act. Fe levels of formulas produced by different firms were significantly different (α= 0.05). Mean Fe levels were 193.5%, 116.1%, and 134.1% of declared for milk-based, milk-based plus Fe and soy-based formulas, respectively.     

Metal-Catalyzed Oxidation of Ascorbate, Deoxyribose and Linoleic Acid as Affected by Phytic Acid in a Model System

Antioxidant activity of phytate was investigated in metal-catalyzed model systems. In a dose-dependent manner, phytate facilitated oxidation of Fe (II) to Fe (III) and inhibited formation of thiobarbituric acid-reactive substances (TBARS) from Fe (II)- or hemeprotein-catalyzed deoxyribose degradation. In the presence of 100 μM Fe (III), phytate inhibited reduction of Fe (III) to Fe (II) by 100 μM ascorbic acid and it consequently inhibited ascorbate oxidation. Phytate inhibited hemeprotein- and H₂O₂-catalyzed TBARS formation from linoleic acid micelles. Inhibition by phytate of iron + ascorbate-dependent lipid peroxidation depended on the concentration of ascorbate. These results indicate that phytate may be a useful antioxidant in the protection against oxidative deterioration of foods.     

我国市售婴儿配方乳粉油脂配料使用情况分析

目的:了解我国市售婴儿配方乳粉的油脂配料使用情况及脂肪酸提供情况,为提升婴儿配方乳粉的营养水平及制定产品相关标准提供参考。方法:多渠道收集婴儿配方乳粉标签信息,统计分析油脂配料的种类、组合、最高添加量构成比及标识含量,比较全脂乳产品与脱脂乳产品、牛乳基产品与羊乳基产品、高必需脂肪酸产品与全部产品间的差异。均数和率的比较分别采用t检验和卡方检验。结果:共纳入269个婴儿配方乳粉。配料表分析显示,85%的产品使用了4种及以上的油脂配料,葵花籽油和椰子油在全部产品中的添加率最高,分别为88%、76%。牛、羊乳基配方粉的油脂配料使用情况存在差异,牛乳基配方粉中脂肪、亚油酸及α-亚麻酸的标识含量略高于羊乳基配方粉(P<0.05)。脱脂乳配方粉中,棕榈油添加率为32%,显著高于全脂乳产品(P<0.05)。44例使用了棕榈油的产品中仅有4例强化了1,3-二油酸2-棕榈酸甘油三酯。结论:牛、羊乳基配方粉中的必需脂肪酸标识含量基本一致。现市售婴儿配方乳粉以多种油脂组合使用的方式,以尽可能模拟母乳脂肪酸模式,但有些油脂类原料使用的科学性还有待进一步研究。     

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.     

The Behavior and Stability of Iron-Ascorbate Complexes in Solution

The thermodynamic stability constants for ferric and ferrous ascorbate complexes, change in net redox potential with pH, and efficacy of bathophenanthroline as an iron reagent in the presence of ascorbate were determined. The stability constants for the ferric and ferrous ascorbate complexes were found to be in the range 1.90 × 10³ to 2.61 × 10⁴ and 7.69 × 10^-3 to 6.95 × 10^-2, respectively. The stability of ferric ascorbate over a wide range of pH values suggests its potential use as an iron additive in foods. Redox potential decreased with an increase in pH. Bathophenanthroline analysis of these solutions for free iron proved to have limitations in the presence of ascorbate.     

Preparation of the Cooked Cured-Meat Pigment, Dinitrosyl Ferrohemochrome, from Hemin and Nitric Oxide

The cooked cured-meat pigment dinitrosyl ferrohemochrome was synthesized from hemin, an iron (III) porphyrin, and gaseous nitric oxide in buffered solutions. Reductants used were ascorbic acid, isoascorbic acid, sodium ascorbate, and sodium dithionite. The purity of the pigment so obtained was better than 97%. Sodium ascorbate was the most effective reducing agent. Application of this pigment to meats reproduced the characteristic color of nitritecured products on thermal processing.     

Phytase and Citric Acid Supplementation in Whole-Wheat Bread Improves Phytate-phosphorus Release and Iron Dialyzability

ABSTRACT Conditions were established for maximizing phytate breakdown in whole‐wheat flour (wwf) during bread baking and for assessing the effects of dephytinization on dialyzability of intrinsic and added iron in the bread. Three different sources of phytase (Aspergillus niger, A. fumigatus, and Escherichia coli) with various levels of citric acid (0 to 6.25 g/kg wwf) were used. Supplementing citric acid at 6.25 g/kg wwf enhanced phytate degradation catalyzed by intrinsic phytase from 42% in the untreated bread to 69% (P < 0.05). Supplementation of microbial phytase (285 units/kg) plus 3.125 or 6.25 g citric acid/kg wwf further enhanced phytate reduction up to 85%. Compared with the untreated bread, citric acid alone and the combination of citric acid and phytase enhanced total iron dialyzability by 12‐ and 15‐fold, respectively, while the combination of phytase, citric acid, and ascorbic acid improved total iron dialyzability in the mixture by 24‐fold.     

BETA-AMYLASE SULPHYDRYL AND DISULPHIDE GROUP REACTIONS. ADDITIONAL ASPECTS ON ENZYME INHIBITION BY ASCORBIC ACID

Cysteine, EDTA and certain other sulphydryl and chelating agents activated barley β-amylase at pH 7 but not at pH 4·35. Apart from oxalate and citrate the same reagents prevented ascorbic acid inhibition of the enzyme. A partial purification of the enzyme was effected on SP-Sephadex C-50 in the presence of mercaptoethanol and Ellman's reagent was reduced when incubated with ascorbic acid and the more active fraction which was isolated. When Ellman's reagent was added to an enzyme system containing additional copper which was incubated with ascorbic acid, a reduction of the synthetic disulphide reagent still occurred. An observable increase in absorbance at 360 nm was also noted in a similar enzyme system. The results suggest that the ascorbate free radical is readily attracted to the exposed disulphide bonds of β-amylase     

Counteracting the inhibitory effect of tea on the in-vitro availability of iron from cereal meals

Studies were carried out on the in-vitro availability of iron to determine the effect of addition of tea, milk and ascorbic acid to a standard cereal meal in all possible combinations. The availability of iron from the cereal meal was low (3.92%). Tea, when added to the meal, had a significant depressing effect on available iron (2.56%). Addition of 100 mg ascorbic acid or 200 g milk completely counteracted the inhibitory effect of tea, and addition of both ascorbic acid and milk brought about an even greater enhancement in the in-vitro availability of iron than when either was added alone. This investigation reveals that milk is as effective a factor as ascorbic acid in counteracting the depressing effect of tea on in-vitro iron availability.     

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.     

Iron Binding by Sodium Alginate

Sodium alginate was dispersed in iron chelate solutions and incubated for 10 min. The alginate was precipitated with acetone and the iron in the supernatant measured. Bound iron was calculated. The effects of pH, iron: alginate ratio, chelator, and competing cation on iron binding by alginate were determined. Binding increased as the pH decreased and as the iron:alginate ratio increased; the chelator used (EDTA, NTA, ascorbic acid, citrate) affected complexing. Binding decreased in the presence of calcium. In vitro iron availability studies indicated that alginate-iron complexes are disrupted during digestion.     

发芽时间对糙米糖蛋白抗氧化能力的影响

为了明确发芽时间对糙米糖蛋白含量及抗氧化性能的影响,本研究将糙米分别发芽12、24、36、48、60、72 h、84、96 h,考察发芽糙米中的糖蛋白对DPPH自由基、超氧阴离子自由基、羟自由基的清除能力、铁离子还原能力和抗亚油酸氧化能力的影响,以抗坏血酸为阳性对照,研究发芽时间和糙米糖蛋白浓度与抗氧化能力的相关性。结果发现,糙米发芽84 h时,4 mg/mL的糖蛋白有最佳的抗氧化能力。此时,糖蛋白对羟自由基和超氧阴离子自由基的清除能力优于抗坏血酸,清除率分别为99.49%和99.39%;对DPPH自由基清除能力、铁离子还原能力和抗亚油酸能力稍弱于抗坏血酸,清除率为88.11%,吸光度值分别为2.06和0.211。糙米糖蛋白的抗氧化能力受发芽时间和样液浓度的影响,发芽时间与DPPH自由基、羟自由基的清除率和抗亚油酸氧化能力呈极显著正相关(P<0.01),与铁离子还原能力呈显著正相关(P<0.05);糖蛋白浓度与超氧阴离子清除率,铁离子还原能力和抗亚油酸氧化呈极显著正相关(P<0.01)。     

Antioxidant Activities and Polyphenolic Properties of Raw and Osmotically Dehydrated Dried Mushroom (Agaricus bisporous) Snack Food

Total polyphenolics and free radical scavenging properties of extracts obtained from osmotically dehydrated, and spiced mushroom snack food with raw unprocessed mushrooms were studied. Sensorially acceptable mushroom snack was prepared in the laboratory by osmotically dehydrating Agaricus bisporous in 5% salt solution followed by addition of an adequate combination of spices and vacuum drying. The extracts of raw and dry snack-mushrooms were then evaluated for their scavenging activities against the 2,2-diphenyl-1-picryhydrazyl (DPPH) free radical and 2,2-azobis-3-ethylbenzthiazoline-6-sulfonic acid (ABTS). The scavenging activity of free extracts of raw and dry snack mushrooms on DPPH radical were 76% and 72%, respectively. The ABTS radical scavenging activity of the free extracts of raw sample expressed as ascorbic acid equivalent antioxidant activity (AEAC) was 2.76 mg ascorbic acid equivalents/100 g and 2.67 mg ascorbic acid equivalents/100 g snack mushroom. Both free and bound polyphenolic contents in mushroom snacks were slightly higher than raw mushrooms whereas total flavonoids levels decreased marginally. No change in antioxidants status of the dry snack product was observed when dry snack stored at ambient temperature for up to 15 days. The results of this study suggested that mushroom snacks prepared using a combination of the above methods was able to retain a significant amount of antioxidants, phenols and flavonoids and mushroom snacks may prove to be an alternative nutritious snack.     

A comparison of carnosine and ascorbic acid on color and lipid stability in a ground beef pattie model system

Ascorbic acid (0.1%) significantly inhibited metmyoglobin formation on the surface of ground beef but not in the bulk of the product where oxygen tension was lower. Carnosine (1.0%), however, significantly inhibited metmyoglobin formation and brown color development throughout the product. The combinations of carnosine and ascorbic acid were also very effective on inhibition of metmyoglobin formation and brown color development. Carnosine increased meat pH, cook yield and salt-soluble protein, but ascorbic acid had no effect on cook yield, and decreased meat pH and salt-soluble protein. Carnosine was more effective on inhibition of lipid peroxidation than ascorbic acid. Carnosine inhibited copper(II)-catalyzed ascorbate oxidation in a dose-dependent manner in model systems. Carnosine in conjunction with ascorbic acid may be useful as a meat additive for increasing shelf-life as well as stabilizing color of meat products.     

IRON SOLUBILITY FROM SEAFOODS WITH ADDED IRON AND ORGANIC ACIDS UNDER SIMULATED GASTROINTESTINAL CONDITIONS

Iron absorption from foods is dependent on the type of food consumed and other factors such as ligands which may have enhancing or inhibiting effects on iron absorption. In this study, iron (Fe²⁺ or Fe³⁺) and two organic acids (ascorbate and citrate) were added to three seafood surimis (scallops, prawns, and cod) and then subjected to simulated gastrointestinal conditions (pH 2, 4, and 6) to evaluate iron solubility. Soluble iron decreased with increasing pH in all samples and control. In cod, a combination of ascorbic and citric acid (1:2) was most effective to increase soluble iron; however, in scallops and prawns citric acid alone was best. After sequential pH and enzyme treatments, it was found that the effectiveness of iron solubilization depended primarily upon the type of seafood present and to a lesser extent the oxidation state of the iron salt.     

Effect of Acid Pretreatment on the Stability of Ascorbic Acid Complexes with Various Iron Sources in a Wheat Flake Cereal

The effect of acid incubation of ascorbic acid with each of five iron sources (ferrous sulfate, ferric chloride, ferric orthophosphate, hydrogen and electrolytically reduced iron) on iron solubilization in a wheat flake cereal was evaluated. Incubation produced more soluble iron at pH 2 but not necessarily at the endogenous pH of the cereal nor at pH 6. At pH 2, Fe⁺² rather than Fe ⁺³ was produced, apparently by a reduction of bound Fe ⁺³ and subsequent release of Fe⁺². At pH 6, the soluble iron was mainly in a complexed form. This indicates that acid incubation with ascorbate might facilitate bioavailability of iron if it were incorporated by fortification techniques.     

Analysis of vitamins A,E and C,iron and selenium contents in infant milk-based powdered formula during full shelf-life

The stability of vitamins A, E and C, and the iron and selenium content were determined in two types of long chain-polyunsaturated fatty acid (LC-PUFA) supplemented milk-based powdered infant formulas (IF), during an 18-month storage period at 25 and 40 °C. The first type (IF-A) was supplemented with vitamin A as retinol acetate. The second type (IF-B) was supplemented with vitamin A as retinol palmitate. Both types were also supplemented with vitamin E as α-tocopherol acetate and with vitamin C as ascorbic acid. The two formulas studied had higher vitamin A (140% and 139%), vitamin E (109% and 198%) and vitamin C (167% and 118%), but lower iron (65.0% and 65.3%) and selenium (72.9% and 79.4%) than the amounts declared on the label. As expected, all the studied vitamins showed decreases during storage, and these decreases were higher in formulas stored at 40 °C. The losses of vitamin A at 40 °C after 18 months of storage were 27.5% in IF-A and 29% in IF-B, while vitamin E losses under the same conditions were 23.1% and 28.1%, and vitamin C losses under the same conditions were 28.4% and 48.6%. All these losses justify the over-fortification of the aforementioned vitamins in these LC-PUFA supplemented IFs. Iron and selenium content remained unchanged throughout storage.