加热对乳中钙的状态及吸收之影响

牛乳每100g中大约含Ca100mg,为钙的重要膳食来源。生乳中总钙的2/3为胶体钙,1/3为可溶性钙,其中离子型钙约为1/4,亦即牛乳中总钙的1/12为离子型钙。     

机体钙营养与合理补钙

钙是人体中含量最多的矿物质元素,其缺乏会引起机体发生一系列病变,综述钙的生理功能、钙在体内的调节、钙的代谢、影响钙吸收的因素、我国钙缺乏现状及改善钙缺乏的方法.     

普通骨粉和超细骨粉改善骨密度功能比较

比较营养高钙冲剂与营养高钙冲剂(超细骨粉)对大鼠骨密度和钙吸收率的影响。SPF级4周龄雌性SD大鼠96只,随机分为10组,即两种受试物低、中、高剂量组,相应剂量碳酸钙对照组(低、中、高剂量组饲料钙含量分别为216.7、283.3 mg/100 g和550.0 mg/100 g),以及低钙对照组(饲料钙含量为150 mg/100 g)。喂养13周,测钙表观吸收率、骨钙含量和骨密度。营养高钙冲剂中剂量组钙表观吸收率低于相应的碳酸钙组(P0.05)。各受试物组股骨钙含量均高于低钙对照组,且与碳酸钙组相比差异无显著性(P0.05)。营养高钙冲剂低、中剂量组和"超细骨粉"低剂量组股骨中点骨密度、营养高钙冲剂低剂量组近心端骨密度均低于相应的碳酸钙组(P0.05)。"超细骨粉"低剂量组钙表观吸收率高于营养高钙冲剂组(P0.05);"超细骨粉"中剂量组近心端骨密度亦高于营养高钙冲剂组(P0.05)。营养高钙冲剂(超细骨粉)具有增加骨密度的作用,不能判定营养高钙冲剂具有增加骨密度的作用。营养高钙冲剂(超细骨粉)在增加骨密度功能方面优于营养高钙冲剂。     

采前钙处理对冬枣贮藏品质、钙形态及亚细胞分布的影响

研究了离子钙、熬合钙和纳米钙处理对冬枣贮藏后的品质及钙形态的影响,采用焦锑酸钾沉淀- 透射电子显微镜观察方法,研究了冬枣果实细胞中钙的亚细胞分布特点。结果表明,同对照(CK)相比,三种钙处理均有效的抑制了冬枣贮藏期间的褐变及硬度的变化,各喷钙处理对冬枣果实采摘时VC 的含量影响不显著,但有效的抑制了贮藏后VC 的消耗,Che-Ca(熬合钙)处理效果最佳。各处理间冬枣可溶性糖、可溶性固形物的含量差异很小,采摘时可滴定酸差异也不大,但当贮藏至第60d 时,CK 酸度的下降要高于其他喷钙处理。与CK 相比,喷钙处理冬枣的全钙、水提取钙、NaCl 溶液提取钙及醋酸提取钙的含量均有增加。冬枣果实中的钙主要以80%乙提取钙(ALc-Ca)的形式存在,贮藏至60d 时,NaCl 溶液提取钙和醋酸提取钙含量下降,ALc-Ca 的含量有所上升。各处理中细胞壁、细胞膜、液泡、液泡膜上锑酸钙颗粒分布较多;细胞之间、细胞膜和细胞壁的间隙中也有一定量的钙累积;CK 处理的细胞质中有大量钙累积,Che-Ca 处理有效地抑制了钙向细胞质的流动,细胞质中累积较少。     

超微细鲜骨粉生物学功能的研究

本文就超微细鲜骨粉中钙的吸收利用状况、骨粒大小对钙吸收的影响,以及提高钙吸收率的方法进行了一系列的探讨。结果表明,超微细鲜骨粉是一种良好的钙源,骨粉骨粒粒度大小影响钙的吸收利用, CPP能够促进超微细鲜骨粉中钙的吸收。     

不同烹调方法对骨汤中钙含量的影响

为寻找适合大众需要的膳食钙源,用原子吸收光谱仪分析了不同烹调方法烹制的骨汤中钙含量,并探讨烹调时间对骨汤中钙含量的影响。结果显示,常用的烹调方法（包括家用压力锅和瓦堡）熬出的猪骨汤中钙含量极低,平均10～1．2mg／100ml,作为人体的钙营养补充意义不大。但加入食醋后,骨汤中钙含量明显增加（P＜0．01）,钙浓度达1780±11．6mg／100ml,且随着烹调时间的延长。汤中钙含量也显著增加（P＜0．01）,可作为一种丰富的膳食钙源。     

注意人体补钙

人体内的钙主要以羟磷灰石形式存在于骨骼和牙齿中。成年人体内的钙总含量约为700－14O0g,约99．7％以上钙存在于骨骼和牙齿,剩余的钙分布在体液及软组织中。体液中钙的含量虽然只占极少部分,但却具有极为重要的生理意义。人体吸收钙的主要部位是在酸度较大的小肠上段,特别     

酶解骨钙粉细粉与普通酶解骨钙粉增加骨密度功能比较

目的:分析比较酶解骨钙粉细粉与普通酶解骨钙粉增加大鼠骨密度功能和对钙吸收率的影响。方法:SPF级4周龄雌性SD大鼠100只,随机分为10组,即酶解骨钙粉细粉和普通酶解骨钙粉低、中、高剂量组,相应剂量碳酸钙对照组(低、中、高剂量组饲料钙含量分别为216.7、283.3、550.0mg/100g),以及低钙对照组(饲料钙含量为150mg/100g)。喂养13周,检测钙表观吸收率、骨钙含量、骨密度、骨长和骨恒质量。结果:酶解骨钙粉细粉组股骨骨密度明显高于低钙对照组且不低于相应剂量碳酸钙对照组(P>0.05);普通酶解骨钙粉组股骨三点骨密度均明显高于低钙对照组,但低剂量组股骨钙含量和远心端股骨密度均低于碳酸钙对照组(P<0.05)。酶解骨钙粉细粉和普通酶解骨钙粉相应剂量组的钙表观吸收率、骨钙含量、骨密度、骨长、总食物利用率和喂养13周时的体质量均无明显差异(P>0.05);酶解骨钙粉细粉中剂量组骨恒质量高于普通酶解骨钙粉中剂量组(P<0.05)。结论:酶解骨钙粉细粉具有增加骨密度的作用,不能判定普通酶解骨钙粉具有增加骨密度的作用。酶解骨钙粉细粉在增加骨密度功能方面优于普通酶解骨钙粉。     

食源肽螯合钙的研究进展

钙是人体必需的营养物质,在生命健康中起着重要作用。钙摄入不足常会引发骨质疏松、佝偻病等诸多疾病。近年来随着越来越多的肽螯合钙从食物中制备出来,肽螯合钙稳定性好、生物利用度高等优点备受关注,它也在诸多研究中被视为一类理想的钙源补充剂。本文就食源性肽螯合钙的研究进展进行概述,介绍了肽螯合钙的制备及分离纯化方法,分析了影响其螯合能力的因素,并探讨了其促进钙生物利用度的方式,为肽螯合钙今后在功能性食品上的开发利用提供帮助。     

不同阶段的婴幼儿该如何补钙

对于婴幼儿来说,充足的钙质摄入对其生长发育是极为重要的。钙是构成人体骨骼的主要成分,据研究证实,人体中99％的钙集中于骨骼和牙齿中,其余的钙以游离状态存在于软骨组织细胞外液及血液中。骨骼钙与血液中钙维持着动态平衡,即骨中钙不断释出,进入血液中,而血液中的钙又不断地沉积于成骨细胞中,这就是骨的更新过程。这种更新过程随着年龄的增加而减慢,幼儿的骨骼更新一次需一年至二年,而成人更新一次则需十年至十二年。     

蛋壳中碳酸钙转化成柠檬酸钙的研究

蛋壳经预处理和粉碎后,通过添加柠檬酸直接反应制备柠檬酸钙。通过单因素和正交试验分别考察了反应温度、蛋壳粉粒度和柠檬酸过量程度对蛋壳制备柠檬酸钙产品纯度和转化率的影响,结果表明在反应温度为60℃、蛋壳粉过200目筛、柠檬酸过量15%条件下得到的柠檬酸酸钙产品的纯度能达到95%以上,柠檬酸钙产率可以达到98%。     

乳钙和干酪素磷肽的钙强化功能

<正> 钙是非常重要的营养素,能够预防骨质疏松症。但是,据有关研究显示,全球各地尤其是亚洲地区的居民,普遍存在缺钙的情况,大大影响了其国民的身体素质。有鉴于此,营养权威专家正积极讨论和复审膳食钙的需求量(RDA),并制定新的推荐钙摄入量(RDI),例如,美国最近就提高了其推荐钙摄入量的新标准,其他国家也将仿效这种做法。 为人体补充钙的有效方法,是在我们日常进食的食品中进行钙强化。提取自牛奶的乳钙,具有优良的感官性质,而且极具营养性,是理想的天然食品级钙源。另一方面,营养科学界普遍认为,钙源的溶解性决定了钙能否良好地被人体吸收,干     

Intravenous calcium infusion in a calving protocol disrupts calcium homeostasis compared with an oral calcium supplement

Hypocalcemia is a common postpartum condition in dairy cows, which negatively affects health and production. Intravenous Ca infusions are commonly included in calving protocols to prevent or mitigate the effect of hypocalcemia in multiparous cows. Thus, we sought to contrast the effect of intravenous Ca infusion against voluntary oral Ca intake on Ca metabolism. Serum total Ca (tCa) and whole-blood ionized Ca (iCa) were monitored in 24 multiparous Holstein cows after parturition. Precalving diets were formulated with a positive dietary cation-anion difference of 172 mEq/kg of DM and contained 4.1 g of Ca/kg of DM. At parturition, cows were blocked by calving sequence and calcemic status as either normocalcemic (cutoff threshold of iCa ≥1.10 mmol/L) or hypocalcemic (cutoff threshold of iCa <1.10 mmol/L). Cows in each block were randomly assigned to 1 of 2 treatments: either an oral source of Ca (Ca-Oral; n = 12) or an intravenous source of Ca (Ca-IV; n = 12). Cows in the Ca-Oral group were offered a 20-L commercial Ca suspension (48 g of Ca) for voluntary consumption. The supplement contained Ca carbonate, Ca formate, Ca propionate, and other minerals and vitamins (Farm-O-San Reviva, Trouw Nutrition, Amersfoort, the Netherlands). Cows in the Ca-IV group received a 450-mL intravenous Ca solution (13 g of Ca) that contained 298 mg/mL of Ca gluconate, 33 mg/mL of magnesium chloride, and 82 mg/mL of boric acid (AmosCAL, Kommer-Biopharm BV, Heiloo, the Netherlands). Both treatments were initiated within 25 ± 10 min after calving. The oral Ca suspension was offered to cows in a 25-L bucket and was available for 10 min. All cows in the Ca-Oral group voluntarily consumed the entire 20 L of the Ca suspension within 5 min. Blood samples for Ca analyses were collected at 0 (before treatment initiation), 1, 3, 10, and 18 h relative to treatment, and at 0700 and 1900 h for the next 2 consecutive days, to represent the 24-, 36-, 48-, and 60-h sampling time points. In Ca-IV cows, both iCa and tCa concentrations peaked at 1 h (1.54 mmol/L for iCa and 2.85 mmol/L for tCa) and declined to a nadir at 24 h following treatment initiation (0.94 mmol/L for iCa and 1.74 mmol/L for tCa). Although whole-blood iCa and serum tCa were higher at 1 and 3 h in Ca-IV cows, concentrations of iCa were greater for Ca-Oral cows at 18, 24, and 36 h and for tCa at 24 and 36 h. Our data indicate that intravenous Ca infusion immediately induced a state of hypercalcemia followed by lower whole-blood iCa and serum tCa concentrations 24 h later compared with oral Ca.     

Effect of calcium carbonate,calcium citrate,tricalcium phosphate,calcium gluconate and calcium lactate on some physicochemical properties of soymilk

Soymilk fortified with 25 mm Ca (Ca carbonate, Ca citrate, triCa phosphate, Ca gluconate or Ca lactate) was compared with the properties of unfortified soymilk (control). Calcium carbonate, Ca citrate and triCa phosphate did not significantly affect [Ca²⁺], absolute viscosity and particle size of soymilk, but Ca gluconate and Ca lactate significantly increased these properties. The pH of soymilk was significantly increased by adding Ca carbonate but significantly reduced by adding Ca gluconate and Ca lactate. Dry sediment of soymilk increased significantly with the addition of all Ca salts excluding triCa phosphate. Freezing point depression increased significantly only for Ca gluconate and Ca lactate, mainly owing to their higher solubility.     

钙强化剂和钙强化食品的研究进展

综述了钙吸收机理,钙营养强化剂与钙强化食品的研究现状.     

微囊乳钙补钙剂的测定研究

微囊乳钙是以乳清为原料,经去除部分蛋白质、乳糖成分后得到乳矿物盐,再采用微胶囊技术包埋制成的高效补钙剂.文中采用扫描电镜、红外光谱仪、X-射线衍射光谱仪、X-射线荧光光谱仪等仪器和方法,测定一种进口的微囊乳钙产品的结构与性质.结果表明,微囊乳钙颗粒表面凹凸,大小不均,粒径在2～100μm-间;主要成分为磷酸钙盐,灰分含量约78.5％～78.9％,蛋白质1.93％,样品可溶于中酸性至强酸性溶液中.     

Effect of calcium and fat intake on calcium metabolism in calves

Ten male Holstein calves were fed diets with or without 5% added animal fat in combination with low and high dietary calcium (.15 or .98%) for 4 wk. After 3 wk, the animals were orally dosed with calcium-45. One week later they were killed and tissue samples taken. Except for lower calcium-45 in bile, added dietary fat had no marked influence on calcium metabolism. Net absorption of calcium-45 (not excreted in feces) ranged from 82% for calves fed low calcium to 53% for those given high calcium. Calcium-45 in bone was substantially higher in calves fed .15% calcium. Tailbone biopsies revealed rapid uptake of calcium-45 with approximately as much incorporated during the 1st d as in the following 6 d. Calcium-45 in blood peaked 24 h following dosing. Calves fed .15% calcium had higher calcium-45 in blood and bile than those receiving .98% calcium. Calcium-45 values in soft tissue were low and did not differ materially among treatments. The decreases in radioactive calcium absorption and bone deposition with higher dietary calcium indicated that variable absorption was a major factor in calcium homeostasis. Added fat did not materially effect calcium metabolism with either low or high dietary calcium.     

硫酸钙在膳食钙中的应用现状及优势

中国式补钙的背后,国内外营养学界普遍建议,通过高钙食物来补充钙,减少补充剂摄入量。通过探讨在膳食中较为常用的硫酸钙、碳酸钙、氯化钙和磷酸钙4种无机钙盐在食品中的应用及其优缺点,最终认为天然、无毒、高性价比的硫酸钙在膳食钙的应用中更胜一筹。     

离子选择性电极法测定味精生产中的钙含量

拟定了以钙离子选择电极为指示电极，饱和甘汞电极为参比电极，EGTA标准溶液为滴定荆的电位滴定法测定味精生产过程中钙含量的分析方法。该方法的测定结果与原子吸收法基本一致，标准偏差在0．018～0．025之间，相对标准偏差在1．00％～2．12％之间，回收率在95．0％～102．3％范围内。     

生物活性肽促钙吸收机制与钙离子通道

近年来,第4代补钙产品——促钙吸收肽(如酪蛋白磷酸肽)的研究已成为热点,其主要是通过钙离子通道发挥促钙吸收作用。钙离子通道是一组跨细胞膜的蛋白质,它控制着Ca~(2+)进入细胞的过程,TRPV6和Cav1.3是钙在肠道跨膜吸收的2种重要钙离子通道。TRPV6是TRPV离子通道家族成员中高选择性的Ca~(2+)转运通道,由钙结合蛋白D9k(Calbindin-D_(9k))和维生素D共同参与调节。Cav1.3在去极化条件下被激活,从而发挥重要的促钙吸收作用,但其不依赖于Calbindin-D_(9k)和维生素D的调控。小肽转运蛋白是一种低亲和力、高容量的协同转运载体,其不仅可以消除氨基酸之间的相互竞争,加速蛋白合成,也可促进动物对矿物质的吸收与利用。本文概述了生物活性肽通过其与2种最常见的钙离子通道(TRPV6、Cav1.3)的作用及小肽转运系统(Pep T1转运)转运,以促进钙的高效吸收,旨在阐明活性肽的高效促钙吸收机制。