Determination of Iron Species in Samples of Iron-Fortified Food

The paper presents the determination of iron forms in food products. The procedure of sample extraction was developed and optimized, preserving the content of particular forms of iron. The colorimetric method using 2,2′-bipirydyl (measurements at 520 nm) was applied in Fe(II) determinations, while in Fe(III) determinations, the colorimetric method with potassium thiocyanate (measurements at 470 nm) was applied. The total content of iron was determined by the technique of atomic absorption spectrometry, which allowed for the determination of iron content in organic and inorganic complex compounds. Detection limits of 1 mg kg^?1 were obtained for all determined iron forms, with the precision ranging between 0.7 % and 1.5 % for 10 mg kg^?1 concentration. The optimized analytical procedure was applied in the determinations of iron forms in iron-fortified food products.     

Bioavailability of Calcium in Heat-Processed Milk

Bioavailability to rats of calcium in milk subjected to the DASI Free Falling Film system (UHT) of pasteurization was compared with the bioavailability of the mineral in raw, high temperature-short time pasteurized, and stored UHT milks. In two other studies, the calcium in the milks was equilibrated with ⁴⁷Ca. Intestinal absorption (both uncorrected and corrected for endogenous fecal excretion) and femoral deposition of calcium were measured. In another study, femur calcium was determined in rats deriving calcium and phosphorus exclusively from the milks. No significant effects were attributable to heat treatment.     

Bioavailability of Iron in Fermented Soybeans

Hemoglobin depletion-repletion assay was used for determining iron bioavailability. The relative biological value (RBV) of iron in boiled nonfermented soybeans was the lowest among the products evaluated. The RBV of iron increased from 60.1% in boiled nonfermented soybeans to 86.7% by lactic acid producing microorganisms and to 87.5% by Rhizopus oligosporus fermentation (FeSO₄= 100%). Results of this research suggested that fermentation by lactic acid producing organisms and Rhizopus oligosporus increased the RBV of iron.     

Performance of Commercial Cultures in Fluid Milk Applications

Six Lactobacillus acidophilus, 5 Bifidobacterium, and 6 Streptococcus thermophilus strains were studied for characteristics that are important to activity and stability in unfermented fluid milk products. Speciation, strain relatedness, frozen concentrate stability, bile sensitivity, and lactase activity were evaluated. The microbiological stability of a culture-containing fluid milk product was also determined. Two of the bifidobacteria cultures contained >1 strain. Some strains were shown to be closely related or identical by pulsed-field gel electrophoresis of fragmented chromosomal DNA. Selective media that distinguished among all 3 added genera were identified. All lactobacilli and most of the bifidobacteria were resistant to bile concentrations varying from 1 to 3%, and all streptococci were sensitive to bile. Lactase activities were highest for S. thermophilus strains, supporting use of this species in fluid milk and dairy products to aid in the digestion of lactose by consumers. The experimental product evaluated in this study contained 10⁷ cfu/ml of both L. acidophilus and Bifidobacterium spp. and 5 × 10⁷ cfu/ml of S. thermophilus. Lactic, but not psychrotrophic, populations were fairly stable during storage. The results suggest that milk formulated with high concentrations of three different genera of probiotic bacteria can be manufactured with commercial strains.     

硫氰酸盐分光光度法测定铁强化营养盐中铁的试验方法研究

在酸性溶液中Fe3+与SCN-反应生成稳定的Fe(SCN)3砖红色络合物,在一定的Fe3+浓度范围内,络合物的颜色与Fe3+浓度成正比,用分光光度法测定。根据分光光度法测定铁而进行了条件试验,如酸度试验、显色剂用量试验、放置时间试验、精密度试验、回收试验等。     

Shelf-Life of Pasteurized Fluid Milk as Affected by Age of Raw Milk

Increasing raw milk storage time prior to pasteurization may affect product shelf-life. Raw milk was stored at 4.5°C for 0, 2, 4, and 6 days prior to pasteurizing. Milk samples from each pasteurized lot were analyzed after continuous storage at 4.5°C for 0, 4, 8, 12, 16, and 20 days. Both raw and pasteurized samples were analyzed for coliforms, psychrotrophs, and total bacteria counts. Flavor scores were also determined. No correlations were significant between raw or pasteurized samples and total bacteria or coliform counts. Related were flavor score and days held raw, shelf-life of the resulting pasteurized product, and interaction of days held raw and shelf-life of the pasteurized product. Psychrotrophic counts and age of the raw milk were correlated. From correlations of flavor scores with shelf-life of the milk, a predictive equation was: Flavor score = 8.00 – .88 R – .11 P – .0015 P² – .009 R P, where R is days held raw and P is shelf-life of the pasteurized product.     

关子铁强化营养盐中添加剂的应用

有效的铁强化剂用于铁盐的生产,结合铁离子的特性,在选择铁强化剂时要充分注意稳定性、气味和色泽.     

Bioavailability of Iron Produced by the Corrosion of Steel in Apples

The bioavailability of iron formed by the corrosion of low-carbon steel (99% Fe) in contact with Red Delicious apples was measured in a rat model using a depletion-repletion experiment. The percentage of ingested iron converted to hemoglobin iron (Conversion Efficiency) was 74, 57, and 56%, respectively, for daily doses of 110, 190, and 285 μg of this iron. (Conversion Efficiency for FeSO₄ was 46-50%). When compared with FeSO₄= 100, the relative biological value of this iron was found to range from 93–153. Ingestion of one Red Delicious apple that has been exposed to eight large iron nails for 24 hr could provide 10–15 mg iron having good bioavailability.     

铁强化鲜牛奶改善缺铁性贫血的试验研究

目的：对铁强化鲜牛奶改善缺铁性贫血的效果进行研究评价。方法：采用给予低铁饲料结合定期少量放血的方法建立缺铁性贫血大鼠模型（Hb〈100g／L）后,各组在继续喂饲低铁饲料的同时,对照组和实验组分别给予蒸馏水、乳酸亚铁溶液、普通鲜牛奶和不同剂量的铁强化鲜牛奶,实验结束时再分别测定各组动物的血红蛋白（Hb）水平,红细胞内游离原卟啉（FEP）含量,红细胞计数（RBC）,血清和肝脏中的铁含量,并观察动物的生长情况以及对体重的影响,由此判定铁强化鲜牛奶改善贫血的效果。结果：铁强化鲜牛奶三个剂量组的中期体重和结束体重、Hb水平、红细胞内FEP、RBC、血清以及肝脏中的铁含量测定结果与空白对照组比较,差异均有统计学意义;而且高剂量组的各项指标与普通奶组比较,差异有显著性,与乳酸亚铁组比较,除了体重和Hb差异有显著性,其余指标差异没有显著性。结论：铁强化鲜牛奶具有有效改善动物缺铁性贫血的作用。     

Relative Bioavailability of Dietary Iron from Three Processed Soy Products

The relative bioavailability of iron from soy flour (SF), freeze-dried soy beverage (SB) and soy concentrate (SC) was determined utilizing a hemoglobin repletion bioassay. Weanling male rats were fed a low iron depletion diet (3.5 ppm Fe) for 4 wk. For the next 2 wk groups of rats were fed repletion diets containing 0, 6, 12, or 18 ppm added iron from ferrous sulfate, SF, SB, or SC. Slope ratio analysis revealed that the relative iron bioavailabilities from SC (92%) and SF (81%) were not different from the reference standard, ferrous sulfate added to a casein-based diet, whereas that from SB (66%) was significantly less (P<0.01) than the inorganic source of iron. Analysis of results at individual iron levels suggested an iron bioavailability of SC>SF>SB.     

Color of Nonfat Fluid Milk as Affected by Fermentation

Nonfat milks inoculated and fermented with exopolysaccharide and non-exopolysaccharide producing cultures were compared to nonfat, 2% milkfat and whole milk with instrumental and sensory color measurements. L-(whiteness) and a- values (red/greeness) for fermented nonfat milks were higher than nonfat milk. No differences in L-, a-, or b- values (yellow/blueness) were found between milks fermented with exopolysaccharide as compared to non-exopolysaccharide producing strains. A trained sensory panel scored edge and center whiteness of fermented milks whiterthan nonfat milk. Milks fermented with exopolysaccharide producing cultures were scored higher than non-exopolysaccharide producing cultures with respect to edge and center whiteness. Fermentation and exopolysaccharide production may increase visual perception of whiteness in milk.     

Bioavailability of Zinc and Iron from Mature Winged Bean Seed Flour

The relative bioavailability of zinc and iron from mature winged bean (Psophocarpus tetragonolobus) flour was determined utilizing standard rat bioassay procedures. Weight gain of rats after 21 days and total bone (tibia) zinc resulting from zinc addition to the standard diet as zinc carbonate or from zinc endogenous to winged bean flour were compared. The relative bioavailability of winged bean zinc was calculated to be 85% (P < 0.05) and 93% (N.S.) when weight gain and log tibia zinc were the criteria of evaluation. The results of the hemoglobin repletion assay indicated that iron from winged bean was 89% (N.S.) as bioavailable iron from ferrous sulfate.     

牛奶中微量铁的动力学测定方法研究

在PH:2.5～3.5的含柠檬酸等有机配体的Fe~(3+)-Phen溶液,在一定波长光的照射下,能够定量的生长Fe3+-Phen。据此笔者提出并建立了一种光致催化动力学测定牛奶中微量铁的新方法。实验研究结果表明,该方法具有选择性好及灵敏度高等特点,其测定线性范围为0.1～0.8μg/mL,回收率高达98％以上。     

Continuous Supercritical Fluid Processing of Anhydrous Milk Fat in a Packed Column

A continuous supercritical carbon dioxide processing system was designed, built and operated to investigate its performance for fractionation of anhydrous milk fat (AMF). Packed columns showed mass transfer efficiencies five times greater than a spray column, Short- and medium-chain fatty acids were concentrated in the extract fractions and their amounts decreased as separation pressure increased. The ratio of unsaturated to saturated fatty acids in the raffinate fraction was 0.68 compared to 0.52 in the original AMF. The proportions of low-melting triglycerides in the range —42 to 15°C were greater in the extract fractions (44–72%) compared to the original AMF (29%).     

Economic Value of Milk Components for Fluid Milk,Cheese, Butter,and Nonfat Dry Milk and Responses to Selection

The consequences of genetically and mechanically altering milk composition were investigated. A base price plus a component differential method of payment was shown to be equivalent to the sum of the components of milk yield (carrier, fat, and protein) times their relative economic value. Relative economic values of carrier, fat, and protein were derived for fluid milk. Linear programming models were developed to simulate the movement of milk through cheese and through butter and NDM manufacturing processes. These models were used to estimate the cost of moving milk through the respective plants, and these values were equated to the “breakeven” cost of carrier. New economic values for fat and protein were developed on these respective values of carrier in the cheese, and in the butter and NDM processes. Seven selection and marketing alternatives were investigated to determine the expected differences in economic returns by varying the selection criteria and the end products of value.     

Effect of Heat Processing of Dried Egg White on In Vitro Iron Bioavailability

Egg white (EW) was desugared, adjusted to either pH 7 or pH 9, and freeze-dried. Portions were held at 25°, 50°, 60°, 70° or 80°C for 1 wk. In vitro iron bioavailability (IVIB) was estimated by the method of Kane and Miller (1984) and no differences in IVIB were observed due to EW pH. IVIB of EW held at 50°, 60°, or 70°C was not different (P>0.05) than that of EW held at 25°C [9.87% dialyzable iron (DI)]; only the 80°C treatment led to IVIB lower (6.76% DI, P<0.05) than the 25°C control. Differential scanning calorimetry and nondissociating electrophoresis showed that native protein structure, including that of the iron-binding protein ovotransferrin, was maintained after the 70°C treatment but not after the 80°C treatment.     

Iron-Enriched Bread: Interaction Effect of Protein Quality and Copper on Iron Bioavailability

These studies examined the bioavailability of iron in iron-enriched breads. The test breads also contained added protein in the form of gluten, soy or nonfat dry milk. Bioavailability was assessed based on net hemoglobin synthesis in rats initially made iron deficient and then fed bread-based diets containing 38.5 ppm iron (NRC requirement for rat, 35 ppm) and 3.75, 5.00, or 6.25 ppm copper (NRC requirement for rat, 5 ppm). More hemoglobin was synthesized on milk-supplemented (83 mg/mg iron) and on soy-supplemented (85 mg/mg iron) bread diets than on gluten-supplemented (59 mg/mg iron) bread diets. Copper appeared to have no influence on hemoglobin regeneration or on hepatic iron accumulation under the conditions of this experiment.