In vitro bioavailability of calcium and iron from selected green leafy vegetables

The objective of the present investigation was to analyze the relative influence of oxalic acid, phytic acid, tannin and dietary fiber on in vitro availability of iron and calcium from green leafy vegetables (GLV). Thirteen GLV were selected and analyzed for iron, calcium, oxalic acid, phytic acid, tannin and dietary fiber contents using standard methods. The bioavailability of calcium and iron in the GLV was estimated by equilibrium dialysis. Oxalic acid content was less than 1 g kg^?1 in four greens and ranged between 1.22 to 11.98 g kg^?1 in the remaining. Dietary fiber ranged from 19.5 to 113.7 g kg^?1. Tannin content ranged between 0.6138 and 2.1159 g kg^?1 with the exception of two GLV that had 0.1332 and 14.8619 g kg^?1. Four GLV were found to have approximately 40% bioavailable iron, while the others were in the range of 6–30%. In vitro available calcium was less than or equal to 25% in eight GLV and between 34% and 52% in five GLV. Multiple regression analysis revealed that these factors together accounted for 53% (r² = 0.53) and 45% (r² = 0.45) inhibition of iron and calcium absorption, respectively. These findings infer that calcium and iron availability is influenced by the constituents present in the GLV. Copyright © 2006 Society of Chemical Industry     

Dielectric determination of bio‐ and free‐calcium in commercial alkaline‐cooked ground corn

Using dielectric measurements, it was possible to determine the concentration of bio‐ and free‐calcium in a corn dough prepared mixing commercial powder of alkaline‐cooked ground‐corn kernel (maize), Zea mays, with different concentrations of Ca(OH)₂ and the same amount of water. This allows determining the conditions to obtain dough with high bio‐calcium content and consequently high nutritional value. The samples were placed in the interior of a small parallel‐plate capacitor. The capacitance and the cell current profiles were obtained with the corresponding relaxation times as a function of the Ca concentration. With this information, it was possible to determine the threshold concentration at which the Ca ions are not longer linked chemically to the cornstarch molecules and move freely in the interior of the dough. A model based on the ionic conductivity was developed to explain the dependence of the relaxation times with the Ca concentration.     

Phytase Activity from Lactobacillus spp. in Calcium-Fortified Soymilk

Abstract: The presence of phytate in calcium-fortified soymilk may interfere with mineral absorption. Certain lactic acid bacteria (LAB) produce the enzyme phytase that degrades phytates and therefore may potentially improve mineral bioavailability and absorption. This study investigates the phytase activity and phytate degradation potential of 7 strains of LAB including: Lactobacillus acidophilus ATCC4962, ATCC33200, ATCC4356, ATCC4161, L. casei ASCC290, L. plantarum ASCC276, and L. fermentum VRI-003. Activity of these bacteria was examined both in screening media and in calcium-fortified soymilk supplemented with potassium phytate. Most strains produced phytase under both conditions with L. acidophilus ATCC4161 showing the highest activity. Phytase activity in fortified soymilk fermented with L. acidophilus ATCC4962 and L. acidophilus ATCC4161 increased by 85% and 91%, respectively, between 12 h and 24 h of fermentation. All strains expressed peak phytase activity at approximately pH 5. However, no phytate degradation could be observed.     

适合荷叶贮藏的最佳加工技术参数研究

试验对新鲜荷叶进行杀菌,经CaCl2溶液或植酸溶液浸泡后,在不同干燥条件(温度、时间)进行干燥处理,然后放在常温下贮藏。结果表明:(1)Ca2 在荷叶干燥中有抑制自由水分散失和增强荷叶的拉伸性能的双重作用;(2)植酸除具有很强的杀菌防腐效果外,还具有很强的保水性,增加荷叶的柔韧度;(3)最佳干燥技术参数为5?2 浸泡15min、0.1%植酸浸泡10min、60℃干燥50min或5?2 浸泡15min、1%植酸浸泡10min、70℃干燥30min。     

In vitro caecum fermentation and in vivo (Gallus gallus) of calcium delivery systems fabricated by desalted duck egg white peptides and chitosan oligosaccharide on gut health

As calcium supplements, two novel calcium delivery systems were prepared with desalted duck egg white peptides (DPs) and chitosan oligosaccharide (COS) by Amadori-linkage and transglutaminase (TGase)-induced reaction, with high calcium-binding ability of promoting calcium absorption in vivo and in vitro. However, there are relatively few studies on the gut health of calcium delivery systems. In this experiment, in vitro caecum fermentation experiment and Gallus gallus intra amniotic feeding model were used to assess the gut health of calcium delivery systems and phytic acid. Results showed that two calcium delivery systems improved the microbial community structure by inhibiting the proliferation of Escherichia coli, and promoting the proliferation of Bifidobacterium and Lactobacillus. The addition of calcium delivery systems significantly increased short chain fatty acids (SCFAs) and improved the boundary membrane function of brush nutrients by significantly increasing villi structure, surface area, cup cell expansion and production of associated genes (P < 0.05). Moreover, calcium delivery systems present significant reverse of the inhibitory effect of phytic acid on gut health through in vitro and in vivo experiments. This study suggested that DPs-COS-Ca systems were superior to the commercially available calcium supplement CaCO₃ and had excellent calcium absorption and gut health regulating effects.     

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。     

米糠深加工技术的分析与评价(Ⅰ)--米糠制油及脱脂米糠的利用

米糠富含脂质、蛋白质、矿物质、维生素等多种营养物质,是一种具有很大潜力的食品资源、化工原料和药物原料.对米糠制油技术及脱脂米糠的利用技术进行了综合性评述,为米糠的综合开发利用提供参考.     

1,2,6-三磷酸-3,4,5-三乙酸肌醇酯的制备及其抗油脂氧化活性研究

植酸水解得到1,2,6-三磷酸肌醇(PP56),PP56与三乙胺反应生成相应的铵盐.以二氯甲烷为溶剂,脂酶Novozyme 435催化,该铵盐与乙酸反应生成1,2,6-三磷酸-3,4,5-三乙酸肌醇酯.以过氧化值(POV)为指标研究不同剂量的1,2,6-三磷酸-3,4,5-三乙酸肌醇酯对菜籽油的抗氧化性能,结果表明:1,2,6-三磷酸-3,4,5-三乙酸肌醇酯对菜籽油具有明显的抗氧化作用且存在剂量效应关系,在浓度为0.06%时其抗氧化能力和0.02%BHT相当.     

乳酸钙处理对发芽大豆植酸降解和主要营养物质含量的影响

研究低浓度乳酸钙对大豆发芽过程中植酸降解以及主要营养物质含量的影响。在大豆发芽4?d期间,施用0.27?mmol/L乳酸钙喷淋对大豆植酸降解效果显著,并且提高锌、铁元素的生物利用率,利于人体对其吸收。此外,可溶性蛋白、可溶性糖含量不断下降,而游离氨基酸的含量随着可溶性蛋白含量下降而上升。总蛋白质含量与氨基酸总量基本保持稳定或略有下降,但氨基酸组成发生较大变化,在17?种氨基酸中,天冬氨酸和组氨酸含量随着发芽时间的延长而增加,其他氨基酸含量均呈下降趋势。乳酸钙处理条件下,促进了天冬氨酸和缬氨酸等氨基酸的累积和其他氨基酸含量的降低。乳酸钙作为优质钙元素补充剂,用低浓度喷淋处理可促进大豆发芽并大量降解抗营养因子植酸,提高营养品质。     

石墨炉原子吸收分光光度计法测定柠檬酸中钙的含量

本文采用石墨炉原子吸收分光光度计测定柠檬酸中钙的含量。实验结果表明，吸光度与钙的浓度呈良好的线性关系，回收率在90．6％-115．4％之间，相对标准偏差为1．9％-4．4％，检出限为0．2ng／g，实验结果令人满意。     

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.     

氨基酸螯合钙奶味咀嚼片的研制

选择膳食补钙效果较好的奶粉及氨基酸螯合钙为原料,以目前较流行的咀嚼型为剂型,设计出具有较高钙吸收率和较好口感的功能型补钙咀嚼片的实验方案和工艺流程。通过正交实验确定出咀嚼片的最佳工艺配方,最后还制定出了产品的质量指标。     

饮料中钙的溶解性研究

以纯柠檬酸溶液为体系研究了钙在其中的溶解性，研究结果表明在不超过国家规定的钙的添加量范围内，一般不同出现柠檬酸饮料钙盐沉淀问题，柠檬酸的最大许可深度为０．０８７ｍｇ／ｇ。     

Heat‐induced coagulation of whole milk by high levels of calcium chloride

This study investigated the interaction of calcium ions and milk proteins during heat‐induced coagulation of milk. Addition of 20–200 mM calcium chloride to milk caused coagulation on heating to 70 °C. Preheating milk at 90 °C for 10 min or ultra‐high temperature treatment at 140 °C for 6 s increased the sensitivity of milk proteins to coagulation. The former treatment was more effective than the latter in coagulating proteins. A maximum of 98% of the protein in milk preheated at 90 °C for 10 min was coagulated by 50 mM added calcium chloride at 70 °C with holding for 5 min.     

高钙酸性含乳饮料的研制

对高钙酸性含乳饮料的工艺及配方设计进行了研究。叙述了工艺设计，包括原料选择、主要设备、工艺流程、操作要点、工艺参数等。还根据各种原料的不同特点，确定使用何种原料及用量，最终得出最佳配方为：脱脂奶粉3.5％，白砂糖10％，稳定剂0．4％，乳酸0．3％，柠檬酸0．35％，柠檬酸钙0．1％，香料0．1％(均为质量分数)，其余为水。     

植酸及植酸胺在气相防锈纸中的应用及适用性

对植酸及植酸胺在气相防锈纸中的适用性进行了探讨，其中包括防锈原纸浸渍植酸或植酸胺后纸张强度，外观质量的变化等，并进行了植酸及植酸胺对黑色金属及各种有色金属的气相防锈能力的检测和评价。结果表明：未调节pH（pH为5．0～4．0）的植酸并不适用于气相防锈纸；植酸腰对黑色金属、铜、铝有非常好的缓蚀效果，但其对锌的缓蚀能力并不理想。     

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.