Effects of pH on Calcium, Zinc, and Phytate Solubilities and Complexes Following In Vitro Digestions of Soy Protein Isolate

High intraluminal gastric pH values in young infants could affect the bioavailability of zinc in soy protein isolate formula. This investigation examined the effects of pH on the solubilities and complexes of calcium, zinc and phytate following in vitro pepsin and pepsin-pan-creatin digestions of soy protein isolate. The results of these in vitro studies suggested that (1) high intraluminal gastric pH values could lead to the formation of insoluble calcium-zinc-phytate complexes in the stomach following ingestion of soy protein isolate and (2) high intraluminal gastric pH values would only affect resultant soy zinc solubility in the small intestine in the absence of exogenous calcium or zinc but not in the presence of same.     

Interactions Between Phytate, Protein, and Minerals in Whey Fractions of Black Gram

Whey fractions cor taining proteins (albumins), phytate, and minerals were prepared from black gram (Phaseolus mungo L.) cotyledons and were employee to study the interactions between protein, phytate, and minerals at pH 2.80, 6.40, and 8.40. Black gram cotyledons contained 1.7% phytate, of which 88.7% existed in watersoluble form. Phytate phosphorus represented for about 89% of total phosphorus in black gram cotyledons. Recovery of phytate in fraction I (pH 2.80), fraction II (pH 8.40), and fraction III (pH 6.40) was 45%, 69%, and 4%, respectively, after 48 hr dialysis. At pH 2.80, complexation occurred between phytate and proteins. Complexation between phytate and proteins at pH 8.40 was mediated by divalent cations such as calcium, magnesium, and zinc. Fraction II had higher concentrations of divalent cations (calcium, magnesium, and zir c) than the other two fractions I and III.     

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.     

Phytate and Zinc Contents of Coffees, Cocoas, and Teas

Several samples of coffee, both instant and percolated, hot cocoa mixes, and teas, both instant and brewed, were analyzed for phytate and zinc. Phytate:zinc molar ratios were calculated. An estimation of the phytate contribution from the beverages to the total diet presented. Depending upon the source selected and the strength and quantity of the beverage consumed, there is concern that a high take of these beverages may exacerbate an already marginal zinc status.     

Interactions in Protein/Polysaccharide/Calcium Gels

Protein-polysaccharide-calcium gels were prepared using combinations of crude myofibrillar protein, whey protein concentrate, sodium alginate, methylcellulose, low methoxyl pectin, carrageenan and CaCl. The nature of the interactions taking place in the gels and the effect of freezing or heating on viscosities and water losses were investigated. In most cases the stability of the gels was increased by freezing and lowered by heating. Myofibrillar protein with added whey protein concentrate formed stronger gels with the polysaccharide gums than did the myofibrillar protein extract alone. With the exception of methylcellulose gels, electrostatic interactions seemed to be the main forces involved in the formation and stability of the gels.     

Effect of Phytate and Partially Hydrolyzed Phytate on in vitro Protein Digestibility

The effects of sodium phytate and partially hydrolyzed sodium phytate (0 - 82% hydrolyzed) on pepsin digestion of casein and bovine serum albumin were evaluated by an in vitro procedure using dialy-sates of pepsin digestion over a period of 0 – 23 hr. The inhibitory effect of phytate differed with substrate and increased with dose level. At the highest phytate level, the digestion of casein and bovine serum albumin was reduced by 14% and 7%, respectively. The inhibitory effect of the phytate was inversely correlated with the degree of phytate hydrolysis. Hydrolysis for 16 hr almost eleminated the inhibitory effect of phytate.     

Zinc and Phytate Distribution in Peas. Influence of Heat Treatment, Germination, pH, Substrate, and Phosphorus on Pea Phytate and Phytase

The largest proportions of zinc and phytate, 88.7 and 97.1%, respectively, were in the Garfield pea cotyledon; the greatest concentrations were in the germ. Cooking peas by two different methods resulted in 13% phytate reduction. Peas incubated 6.5 hr from 25 to 80°C yielded maximum phytate loss (25%) at 60°C due to phytase activated hydrolysis. Germination (10 d) decreased pea phytate 75% and increased phytase activity 12-fold. Semi-purified germinated pea phytase showed temperature optimum at 45°C, pH optimum of 5.2, 30% inhibition by 1 mM inorganic P, and substrate preference for pyrophosphate. Incubation of early germinated peas at optima pH and temperature is suggested for maximum phytate reduction.     

Functional Properties and Phytate Content of Pea Protein Preparations

The functional properties of pea-protein preparations produced by an acid extraction method were evaluated and compared with those of vital wheat gluten and a soy-protein isolate and concentrate. The pea-protein preparations had better solubility in water than the other products studied. Their water absorption was lower than that of the soy-protein products but much higher than for the gluten-protein preparation. However, the fat absorption of the pea-protein product was poor but comparable to that of gluten. The pea-protein preparation had good emulsifying activity, comparable to that of the soy-protein isolates. Its phytate content was fairly high, compared to other plant-protein products.     

Sunflower Protein Concentrates and Isolates' Low in Polyphenols and Phytate

Protein concentrates and isolates from sunflower (Helianthus annuus L.), essentially free of polyphenols and/or low in phytate, were prepared from dehulled seeds by a sequential extraction procedure using organic solvents, such as hexane for defatting and acidic butanol for removing polyphenols. Phytate was removed by aqueous extraction and separation at acidic and/or alkaline conditions, depending on the relative solubility of the protein and phytate. Reduced-phytate concentrates and isolates developed off-colors unless the polyphenol concentration was less than 0.05%. The protein solubility profile of the reduced-phytate products was much better than that of the defatted meal, especially below the isoelectric point.     

利用超滤-原子吸收技术分析3种保健品中钙铁锌的存在形态

建立利用超滤-原子吸收技术分析保健品中金属元素形态的方法。通过0.45μm微孔滤膜实现样品中可溶态和悬浮态的分离,选择D101大孔树脂分离可溶态中有机态和无机态,再利用超滤技术以膜的截留分子质量分离有机态。使用微波消解-高分辨-连续光源火焰原子吸收光谱法测定不同形态的Ca、Fe和Zn,结果表明3种保健品中Ca、Fe和Zn含量都很丰富,主要以可溶态形式存在,可溶态中以有机态为主。锌铁钙口服溶液中有机态Ca主要分布在分子量300 ku的分子中,有机态Fe和Zn主要分布在分子量8 ku的分子中;黄精酵素口服液中有机态Ca和Fe主要分布在分子量300 ku的分子中,有机态Zn主要分布在分子量8 ku的分子中;固体酵素中有机态Ca、Fe和Zn主要分布在分子量300 ku的分子中。该方法具有较高的实用价值,为进一步研究保健品的功能,特别是有益金属元素的生物有效性提供基础数据。     

Protein Extractability of Turkey Breast and Thigh Muscle with Varying Sodium Chloride Solutions as Affected by Calcium, Magnesium and Zinc Chloride

Ground turkey breast and thigh muscle were extracted with various NaCl solutions with or without added CaCl₂, MgCl₂, or ZnCl₂ (0.05%). Protein solubility was increased by CaCl₂ and decreased by ZnCl₂ in each muscle type. At 4% NaCl, MgCl₂ increased thigh myosin solubility by 30%, compared to the control, whereas CaCl₂ had no effect. At 2% and 4% NaCl, breast myosin was not affected by MgCl₂ or CaCl₂. Myosin was not detected for either muscle type when ZnCl₂ was used. All three salts increased breast actin solubility but only MgCl₂ increased thigh actin solubility. The CaCl₂ resulted in the highest overall protein solubility and MgCl₂ resulted in the highest thigh myosin and actin solubility at 4% NaCl.     

婴儿豆基粉中低植酸低异黄酮蛋白基料的制备工艺研究

为提升婴儿豆基配方粉的中蛋白基料的食用安全性,本研究从创新大豆蛋白制备工艺的角度出发,对大豆进行制浆浸提、酸沉、水洗等工艺获得蛋白产品,比较湿法、热烫法和半干法制浆工艺和关键环节对蛋白提取率、植酸和异黄酮去除率的影响。结果表明,当采用半干法制备蛋白浸提液后,再在pH5.15时酸沉并水洗离心获得大豆蛋白质,且体系中乳清保留量低于20%时,可以较好地控制植酸和异黄酮含量,其植酸和异黄酮含量分别为(12.08±0.46) mg/g和(1468±74) μg/g。利用此方法可较好的提高蛋白质基料的安全性,为进一步开发应用于婴儿豆基配方粉中的高安全性专用大豆蛋白粉基料奠定了基础。     

植酸钙的提取及固定化细胞植酸酶酶解

本文重点研究了以麦麸为原料提取植酸钙的工艺条件,最佳工艺条件为60℃水浴浸泡6h,通过浸泡方式的改进,以二次浸泡和动态摇床浸泡两种方式进行实验,结果发现这两种方式均使植酸钙得率提高。另外,利用在细胞壁表面产植酸酶的克鲁维假丝酵母,采用细胞固定化技术,进行植酸酶酶解。细胞固定化和酶解反应的方法都比较简单,而且多次反应后酶解率损失较低。此法为肌醇、磷酸肌醇的酶法制取提供了可行性方案。     

Calcium Additives and Sprouted Wheat Effects on Phytate Hydrolysis in Whole Wheat Bread

Whole wheat bread loaves were subjected to treatments of different fermentation periods, different sources and levels of calcium, and the addition of sprouted wheat. Phytate losses increased with increased fermentation time. Increasing the calcium level inhibited phytate hydrolysis when the calcium was provided by nonfat dry milk, CaCl₂, or nonfat yogurt, whereas phytate hydrolysis in loaves supplemented with CaCO₃ remained nearly constant. Milk-derived calcium exerted the greatest inhibition of phytate hydrolysis. The addition of sprouted wheat decreased absolute phytate losses. A comparison of phytate losses in yeasted vs nonyeasted loaves suggested that endogenous wheat phytase was quantitatively more important than yeast phytase during breadmaking.     

Myofibrillar Protein Solubility of Model Beef Batters as Affected by Low Levels of Calcium, Magnesium and Zinc Chloride

Preblended composites of semimembranosus and adductor muscles were stored 12h at 4°C with 2.0% NaCl, 0 or 0.05% CaCl₂, MgCl₂, or ZnCl₂ and 0 or 0.4% sodium tripolyphosphate (STPP). Model systems were formulated to contain 30% fat (high fat; HF) or 10% fat (low fat; LF). Divalent salts lowered extract pH and ZnCl₂ elicited the greatest reduction. At both fat levels, CaCl₂ increased and ZnCl₂ decreased protein solubility, compared to the control (p<0.05). Myosin was not detected in ZnCl₂-treated HF and LF batters without STPP and in the presence of STPP, MgCl₂ and ZnCl₂ increased myosin concentration at both fat levels (p<0.05). Zinc chloride increased actin concentration in HF batters; whereas, MgCl₂ decreased soluble actin in LF batters (p<0.05). Magnesium chloride (0.05%) increased soluble proteins in LF batters containing 0.4% STPP by increasing myosin extractability.     

Chemical Composition and Functional Properties of Acylated Low Phytate Rapeseed Protein Isolate

Protein isolates were prepared by isoelectric precipitation or dialysis of the first and second aqueous extracts of rapeseed flour which was unmodified or acylated by succinic or acetic anhydride. Acylation of the flour lowered the protein and phytic acid contents without significantly altering the amino acid composition of the isoelectrically precipitated protein isolates from the two extracts. The acylated protein isolates from the isoelectrically precipitated extracts had high nitrogen solubility, emulsifying and fat absorption properties. Isoelectrically precipitated and dialyzed acylated proteins did not differ in nitrogen solubility, but dialyzed unmodified protein isolates had nitrogen solubility which was considerably greater than that of isoelectrically precipitated proteins.     

三种不同来源大豆分离蛋白流变性质的比较

为了了解加工工艺、pH值等因素对大豆分离蛋白的功能性质的影响,本试验研究了温度和pH值等外界条件分别对氧化大豆分离蛋白(ESR)、低脂质含量大豆分离蛋白(LRSP)和市售大豆分离蛋白(CSPI)三种蛋白的流变性质的影响。温度或pH值升高时,三种蛋白的粘度随剪切速率的增大而降低的速度加快,ESR变化显著,LRSP、CSPI发生变化,但CSPI整体粘度低于前两者。初步的试验结果表明,实验室生产的ESR和LRSP质量明显优于市场上购买的CSPI。     

Interactions of Calcium,pH, Temperature,and Chymosin During Milk Coagulation,

Holstein milk samples with good and poor chymosin-coagulation characteristics were coagulated in the Formagraph using different combinations of five levels of chymosin, three pH, and three temperatures in the presence and absence of .02% added calcium chloride.All the main factors significantly altered both coagulation time and curd firmness. Multiple comparisons of mean coagulation times showed that lower concentrations of chymosin (.01, .02, and .03 rennin units/ml milk) were significantly different in altering coagulation time and were different from higher concentrations (.04 and .05 rennin units/ml milk). The three pH produced significantly different mean coagulation times. Addition of more than .02 rennin units/ml milk was not necessary for adequate curd firmness in 30 min after chymosin addition where the pH of the milk was 6.4 or lower. Addition of .02% calcium chloride to milk was not necessary for adequate curd firmness 30 min after chymosin addition if other milk coagulation factors were adequately adjusted (pH ≤ 6.4; chymosin concentration = .02 rennin unit/ml milk; temperature = 37°C).     

Zinc, Iron and Copper Availability as Affected by Orthophosphates, Polyphosphates and Calcium

Male weanling tats were fed an adequate diet supplemented with 0.42% P from either hexametaphosphate or orthophosphate, each at two levels of Ca intake (0.53% or 1.06%). Polyphosphates represented 13% of the total fecal phosphorus at the 0.53% Ca intake; this fraction was increased to 27% at the 1.06% Ca intake. Hexametaphosphate caused a 15% increase in fecal iron, a 12% decrease in liver iron and a 15% decrease in fecal zinc losses. These effects were markedly enhanced by supplemental Ca. Orthophosphate was without effect at the 0.53% Ca intake, but caused an 11% increase in fecal zinc losses at the 1.06% Ca intake.     

Nano Zinc Oxide-Loaded Calcium Alginate Films with Potential Antibacterial Properties

In this work, zinc oxide nanoparticles-loaded calcium alginate films were investigated for their moisture uptake behavior at different temperatures. The equilibrium uptake data was interpreted quantitatively by GAB isotherm models. The monolayer moisture contents were 0.301 ± 0.003, 0.0214 ± 0.092, and 0.171 ± 0.102 at 20, 30, and 37°C, respectively. The water vapor transmission rate was found to be 0.816 ± 0.143, 1.42 ± 0.045, and 1.632 ± 0.064 g s⁻¹ m⁻² respectively. For the moisture content range of 0.2 to 0.6, the net ∆H and ∆S values were found to be 22.73 to 11.14 KJ/mol and 0.064 to 0.034 KJ/mol/K, respectively. The moisture uptake of films increased with water activity but showed negative temperature dependence. The enthalpy of sorption (∆H) and differential entropy (∆S) were determined at different moisture content values, ranging from 0.2 to 0.6 g/g db. The two parameters showed a higher degree of correlation. The equilibrium moisture content data was used to evaluate harmonic mean temperature T _hm. Finally, the biocidal action of films was tested against model bacteria Escherichia coli.