不同钙剂对高钙奶稳定性的影响

研究了不同的钙剂及用量和不同的稳定剂对中性高钙奶稳定性的影响。结果表明，以碳酸钙为代表的电离度较小的分子钙，其电离产生的钙离子对体系的稳定性影响相对较小。因此，主要通过提高中性高钙奶的悬浮效果，可解决由于加入碳酸钙而引起的体系出现沉淀的问题；以乳钙为代表的有机分子钙，由于乳钙自身在水溶液中具有很好的分散性．且可能因其电离度较碳酸钙大，故而乳钙对中性高钙奶体系的影响主要是游离的钙离子与乳状液中界面上的乳蛋白通过桥连作用，引起体系絮凝，可通过加入螯合剂螯合体系的钙离子来解决。     

“合诚”高钙奶稳定剂对高钙奶体系的稳定作用

全国第三次营养调查结果表明，我国居民缺钙现象比较普遍，利用高钙奶进行补钙是一种既科学又经济方便的方法。目前高钙奶中添加的钙剂主要为碳酸钙和乳钙等分子钙剂，容易出现沉淀、絮凝和乳析等问题，添加合适的乳化稳定剂有助于解决这些困扰乳制品生产商和消费者的问题。为此，我们分析了几种高钙奶稳定剂在高钙奶体系中的作用。高钙奶的制作参照谢继志等的方法进行，     

高钙甜牛奶饮料的研制

对高钙甜牛奶饮料生产中不同钙剂和稳定剂对产品品质 的影响进行了研究。结果表明,以乳钙为钙强化剂,添加 量为3.65g/L,稳定剂为0.15％(高钙奶稳定剂与甜牛奶稳 定剂之比为2:1),高钙奶乳化剂为0.15％,柠檬酸钠为 0.08％,精制白糖为8％时产品较好,钙离子含量可迭 1.5mg/mL。本文针对配料的特点,确定了合理、可行的配 方及生产工艺,产品具有钙含量高、稳定性好、口感佳等 特点。     

高钙奶苦味原因分析

通过有苦味的高钙奶样品中的细菌总数、蛋白质水解度、寡肽含量、游离氨基酸含量、蛋白酶活性等指标的测定,对高钙奶在保质期末出现苦味的原因进行分析。结果表明苦味高钙奶和无苦味牛奶样品中的细菌总数无显著差异(p≥0.05),苦味高钙奶中的寡肽、游离氨基酸含量,特别是苦味氨基酸含量显著高于无苦味牛奶样品(p<0.05),苦味牛奶样品中的蛋白酶活性显著高于无苦味牛奶样品(p<0.05),同时高钙奶中添加的碳酸钙和稳定剂中的蛋白酶也有较高活性。高钙奶苦味主要是由于牛奶中的内源或外源性蛋白酶水解酪蛋白,生成苦味的游离氨基酸、寡肽等造成的,针对这一原因,可通过提高原料乳和添加剂的卫生质量、控制生产加工过程中的卫生、调整和改进杀菌工艺等方法,以避免高钙奶的苦味问题。     

天门冬氨酸钙溶液的电离度的研究

通过使用钙离子选择电极用电极电位法测量了在不同深度和不同ＰＨ溶液下的天门冬氨醋钙的电离度情况，研究了天门冬氨酸钙的结构。结果表明，当天门冬氨酸钙的深度大于焊，它呈分子钙结构，反之，呈离子钙结构。     

低分子质量大豆种皮果胶对大豆蛋白乳状液贮藏稳定性的影响

利用大豆种皮作为试验原料制备大豆种皮果胶(SHPP),研究添加低分子质量大豆种皮果胶类多糖(SHPP-LMW)对大豆蛋白乳状液稳定性的影响。通过分析添加不同质量分数的多糖乳状液界面张力、粒径分布、流变特性及显微结构的变化,考察SHPP-LMW对大豆蛋白乳状液稳定性的影响。结果表明,添加SHPP-LMW对大豆蛋白乳状液稳定性的影响较大。添加0.5%SHPP-LMW的乳状液其界面张力较低,黏度较大,粒度分布较均匀,且乳状液颗粒较小,D50、D4,3和D3,2均较小。随着贮藏时间的延长,该乳状液变化较小,具有较高的贮藏稳定性。     

生物解离大豆过程中形成的乳状液结构

以不同酶解时间（1、2、3?h）、不同酶添加量（1%、2%）生物解离大豆过程中形成的乳状液为研究对象,探究乳状液中乳滴聚集机制、结构特征及分子间相互作用。通过乳状液中蛋白水解度、显微镜观察、Zeta电位、十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（sodium dodecyl sulfate-polyacrylamide gel electrophoresis,SDS-PAGE）、荧光色谱等指标的测定发现：经过蛋白酶酶解,乳状液中蛋白水解度在7%左右;生物解离使乳状液蛋白被酶解成分子质量较小的肽段,乳状液油脂与蛋白之间的亲和力降低,乳滴出现聚集,Zeta电位绝对值减小;SDS-PAGE条带上出现了由二硫键引起的大分子质量的蛋白聚集体;另外,乳状液荧光光谱中,乳状液相对于相同酶解条件下大豆分离蛋白荧光强度明显减弱,可能是由磷脂的存在、蛋白质-油脂之间的相互作用及蛋白质聚集体导致。     

O/W型乳状液氧化稳定性的研究进展

水包油乳状液应用广泛,选用不同种类植物油其乳状液体系稳定性各有差异。乳化剂种类较多,乳清蛋白等动物蛋白类型乳化剂稳定效果由于大豆分离蛋白等植物蛋白。加入抗氧化剂可提高乳状液氧化稳定性。通过对比得到非极性抗氧化剂稳定效果在乳状液中优于极性抗氧化剂,氧化剂复合使用稳定效果更佳。研究抗氧化剂自由基清除机理发现反应竞争表现促氧化趋势。天然抗氧化剂如维生素E、生育酚等安全性高,市场前景广阔。乳状液中油脂氧化影响因素较多,不同体系相互作用不同。     

纳米碳酸钙/十聚甘油单硬脂酸酯乳化协同效应研究

该文报道一种碳酸钙纳米颗粒与十聚甘油单硬脂酸酯(SWA-10D)非离子表面活性剂乳化协同效应。SWA-10D具有较强水溶性,当浓度接近或超过临界胶束浓度时稳定O/W型乳状液,对液体石蜡―水体系,单一纳米碳酸钙稳定O/W型乳状液,加入微量SWA-10D有利于提高乳状液稳定性;对大豆油―水体系,单一纳米碳酸钙稳定W/O型乳状液,加入微量SWA-10D导致乳状液稳定性下降;这一现象系为SWA-10D在碳酸钙表面吸附,使碳酸钙表面亲水性增加所致。该研究在超稳定食品乳状液制备领域具有潜在应用价值。     

水酶法提油过程中破乳方法研究进展

该文对水酶法提油过程中形成的乳状液稳定性及其影响因素进行分析,包括液滴粒径、ζ-电位、水解度和表面疏水性,以及这些因素在不同破乳过程中的变化。目前常用的破乳方法,主要分为物理法破乳、化学法破乳、酶法破乳以及复合破乳,该文阐述各种破乳方法的基本原理,以及乳状液的稳定性变化并举例说明。着重介绍酶法破乳的研究进展,并对该技术进行的前景进行展望。     

含乳(钙奶)饮料中钙含量的测定

目前对含乳饮料中钙含量的测定一般采用GB12398-90<食物中钙的测定方法>,有原子吸收分光光度法和EDTA滴定法.     

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.     

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.     

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     

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.     

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。     

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。     

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.