论钙的营养与强化

钙是人体中含量最为丰富的矿物元素,但也是人类营养学上最普遍缺乏的元素。在选择钙营养强化剂时,必须充分考虑钙的含量、溶解度、吸收率、口感等钙剂自身因素,以及钙吸收促进剂、产品类型、消费对象等其它客观因素,才能实现安全、高效、经济补钙的目的。     

钙制剂研究进展

钙是人体内重要的生命元素,直接影响人的身体健康。本文综述了钙的主要生理功能、吸收机制以及影响钙吸收的因素,主要介绍了目前钙制剂的研究情况及其评价。     

提高中国居民钙摄入水平的措施探讨

钙是人体内含量最多的一种无机元素,对维持生命活动有重要的意义。中国居民钙摄入量偏低已受到社会的广泛关注。本文就我国居民钙缺乏症状况进行了概述,分析造成我国居民钙摄入量偏低的原因,探讨了提高我国居民钙摄入水平的措施。     

Calcium nutrition in adolescence

Adolescence is an important period of nutritional vulnerability due to increased dietary requirements for growth and development and special dietary habits. Calcium needs are elevated as a result of the intensive bone and muscular development and thus adequate calcium intake during growth is extremely important to reach the optimum peak bone mass and to protect against osteoporosis in the adult age, a major public health threat whose incidence is increasing in Western countries. However, most children and adolescents worldwide fail to achieve the recommended calcium intake. The hormonal changes associated with the pubertal period promote greater mineral utilization, which needs to be satisfied with suitable calcium consumption. Diet, therefore, must contribute nutrients in sufficient quality and quantity to allow maximum bone mass development. Consequently, adolescents should be educated and encouraged to consume adjusted and balanced diets that, together with healthy lifestyles, enable optimal calcium utilization.     

基于信号通路的食品中矿物元素对骨代谢影响

矿物质作为维持人体正常生理机能的第六大营养素,参与体内生理代谢、生长发育,同时矿物质元素代谢失衡也会引发一系列的疾病。近年来,越来越多的研究发现,矿物质元素的吸收对骨代谢有重要作用,尤其是钙、磷的吸收。本文从信号通路的角度,综述了食品中钙、磷元素对骨代谢的研究进展,并简述了其他矿物质元素可能影响骨代谢的作用机制,以期为食品中矿物元素对食品营养品质的影响机制提供理论基础。     

Calcium in dairy products

Increasing attention has been given to the nutritional role of calcium because many Americans do not consume their Recommended Dietary Allowance of this nutrient and because calcium deficiency may lead to the development of osteoporosis or other disorders. Calcium is absorbed in the intestines with the aid of a vitamin D metabolite and is used in the body for many essential functions. There are several ways to obtain calcium in the diet, but the best sources are milk and other dairy products because of their low cost and high bioavailability of this mineral. Some manufacturers have responded to the concern over lack of calcium in the diet by increasing its levels in milk. The amount of calcium in cheese and yogurt also can be elevated.     

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。     

Effects of Added Calcium on Texture and Quality of Canned Jalapeno Peppers

Jalapeno peppers were canned and treated with calcium chloride, calcium hydroxide, and calcium lactate. Concentrations of 0.2, 0.3, and 0.4% of calcium were used. After 3 months of storage time, the peppers were evaluated for texture, quality, and nutritional composition. Calcium hydroxide was an inadequate firming compound in this experiment because of its neutralizing effect on the acid content and the precipitation found in the can after storage. Calcium chloride at a concentration of 0.2% was found to be the most desirable firming compound because under the test conditions it did not impart a bitter taste and because its solubility properties are better than those of calcium lactate. Higher concentrations failed to significantly increase the firmness of peppers. The treatments produced no adverse effects on the flavor or the vitamin and mineral content, with the exception of calcium, in canned jalapeno peppers.     

Impact of source and level of calcium fortification on the heat stability of reconstituted skim milk powder

Calcium enrichment of food and dairy products has gained interest with the increased awareness about the importance of higher calcium intake. Calcium plays many important roles in the human body. Dairy products are an excellent source of dietary calcium, which can be further fortified with calcium salts to achieve higher calcium intake per serving. However, the addition of calcium salts can destabilize food systems unless conditions are carefully controlled. The effect of calcium fortification on the heat stability of reconstituted skim milk was evaluated, using reconstituted skim milks with 2 protein levels: 1.75 and 3.5% (wt/wt) prepared using low and high heat powders. Calcium carbonate, phosphate, lactate, and citrate were used for fortification at 0.15, 0.18, and 0.24% (wt/wt). Each sample was analyzed for solubility, heat stability, and pH. The addition of phosphate and lactate salts lowered the pH of milk, citrate did not have any major effect, and carbonate for the 1.75% protein samples increased the pH. In general, changes in solubility and heat stability were associated with changes in pH. Calcium addition decreased the solubility and heat stability. However, interestingly, the presence of carbonate salt greatly increased the heat stability for 1.75% protein samples. This is due to the neutralizing effect of calcium carbonate when it goes into solution. The results suggested that the heat stability of milk can be affected by the type of calcium salt used. This may be applied to the development of milk-based calcium enriched beverages.     

我国人口的缺钙现状及改善措施

钙是人体健康和长寿不可缺少的重要元素,钙的生理功能及缺钙对人体健康的影响日益受到重视。由于国民膳食结构、饮食习惯、营养状态、生理因素等的影响,我国人口的缺钙状况令人忧虑,合理补钙正受到关注。乳和乳制品中的钙最易被肌体吸收,因此食物中增加乳和乳制品,以及含钙较多的豆制品、海产品非常重要。同时,为改变国民膳食结构中钙含量偏低的缺陷,应加强对钙强化食品的研究和开发,增加食物的含钙量。     

Increasing calcium solubility from whey mineral residues by combining gluconate and δ-gluconolactone

Insoluble milk mineral residues from whey processing, dominated by hydroxyapatite and calcium hydrogen phosphate, dissolved isothermally in aqueous gluconate/δ-gluconolactone, spontaneously forming solutions supersaturated in both calcium hydrogen phosphate and calcium gluconate. Calcium concentration of maximally supersaturated solutions was proportional to gluconate concentration, indicating gluconate assisted dissolution, while gluconolactone increased calcium available for dissolution and supersaturation. Precipitation of calcium gluconate, rather than of calcium hydrogen phosphate, was critical for supersaturation robustness. For calcium gluconate ionic product:solubility product of calcium gluconate ratios <12, the supersaturated solutions had a lag phase for precipitation of several weeks, which increased to several months by addition of solid calcium saccharate prior to dissolution of the mineral residues. Such supersaturated solutions with up to 7 g calcium L⁻¹, corresponding to a factor of supersaturation of >100 times compared with equilibrium calcium hydrogen phosphate solubility, may be exploited for increasing calcium availability of whey mineral based functional foods.     

Effect of water composition on aluminium,calcium and organic carbon extraction in tea infusions

Tea infusion is the second world wide consumed beverage. In this study, total aluminium and calcium concentrations, total organic carbon and total polyphenol content were determined and compared with respect to the origin of tea leaves, their particle size (broken or whole leaves) and also the mineral composition of four waters. It appeared that the higher the mineral content, the lower the extraction yield of aluminium, total organic carbon and total polyphenols. This could be due to calcium uptake by leaves. Calcium present in mineral waters could be complexed with pectins present in cell walls thus leading to a decrease in the element extraction.     

钙与乳蛋白的相互作用机制及对其功能特性的影响研究进展

钙作为人体骨骼生长和调节生理功能的重要物质,广泛存在于乳品中。钙与乳中蛋白质如αs-酪蛋白、β-酪蛋白、κ-酪蛋白、α-乳白蛋白和β-乳球蛋白等发生相互作用,影响乳蛋白的结构稳定性,进而使其热稳定性、乳化性、溶解性、起泡性和凝胶性发生改变。本文综述了钙与各种乳蛋白之间的相互作用机制以及对其功能特性的影响,对系统理解钙与乳蛋白的结合具有重要意义,为钙类功能性乳品的深入研究以及工业化生产提供理论依据。     

Proportions of calcium,magnesium, phosphorus and potassium extractable by water or ethanol from apple fruit tissue,in relation to length of storage,orchard factors and storage disorders

Calcium, magnesium, phosphorus and potassium were measured in residues of samples of Cox's Orange Pippin apples stored in air at 2.8-4.4°C, removed at intervals and extracted with either distilled water or 75% ethanol. Little potassium was left in the residue after extraction with water, but 15% remained after extraction with ethanol. More phosphorus (85%) was extracted by ethanol than by water. Calcium and magnesium became less soluble during storage. Higher proportions of calcium and magnesium were removed by water than by ethanol initially but, whereas these differences between solvents remained fairly constant for calcium, those for magnesium decreased. When decreases in proportions of soluble calcium and magnesium were small little bitter pit and no breakdown developed in the fruit. Little change in the proportions of mineral constituents, other than phosphorus occurred whilst the fruit was on the tree during the 6 weeks before harvest. Proportions of phosphorus remaining in the residues after extraction with either solvent diminished, especially during the 3 weeks before harvest when apples had been sprayed with calcium nitrate. Otherwise orchard treatments had little effect on the proportions of mineral constituents that could be extracted. Although symptoms developed when the proportion of calcium insoluble in water rose above 40% of the total, some increases in susceptibility to bitter pit caused by orchard treatment or storage conditions were not associated with differences in insoluble calcium.     

Core‐Shell Collagen Peptide Chelated Calcium/Calcium Alginate Nanoparticles from Fish Scales for Calcium Supplementation

We report simple methods for preparing collagen peptide chelated calcium (cpcc) and a novel cpcc‐loaded nanoparticle from marine fish scales for calcium supplementation. Cpcc nanoparticles have an average diameter of approximately 150 nm and a calcium content of up to 130.4 g/kg. Calcium alginate was selected to encapsulate cpcc for the preparation of core‐shell cpcc/calcium alginate nanoparticles. The core‐shell nanoparticles were mainly 200 to 500 nm in diameter. The ratio of calcium to sulfur was approximately 1.6:1. In vivo experiments indicated both cpcc and core‐shell cpcc were able to improve calcium absorption and prevent calcium deficiency. Especially core‐shell cpcc worked well to increase femur bone mineral density and femur calcium content in rats significantly. The study demonstrated that cpcc and core‐shell cpcc nanoparticles were ideal for calcium supplementation.     

利用无机物和多糖制作复合膜的研究

本文考察了添加碳酸钙、氧化钙、石英矿粉、磷酸氢钙于壳聚糖/淀粉复合膜。对比了微波处理前后几种添加物壳聚糖/淀粉复合膜的性能,发现:微波处理前后膜机械强度为碳酸钙>石英矿粉>磷酸氢钙>氧化钙。微波中档处理时间20s,4种复合膜微波处理后性能都有一定程度增加。通过溶胀系数考察了其交联程度,实验提供了混合膜的交联依据。通过3种溶剂实验发现:石英矿粉可食性膜交联程度较理想。     

Rheological properties of reduced lactose whey dispersions

The rheological behaviour of reduced lactose whey (RLW) dispersions of several different types of whey products was investigated with dynamic small amplitude oscillatory (SAOS) rheometry and rotational rheometry. The different aggregation states of the proteins were measured by using size-exclusion chromatography (SEC) with multiangle laser light scattering (MALLS). Differences in the mineral content (especially calcium and phosphate) of the RLW samples contributed to their different rheological properties. Calcium phosphate/whey protein aggregates were probably formed when the mineral content increased, resulting in an increase in the size of the aggregates and higher viscosity. These complexes were also more sensitive to heating.     

Long‐chain fatty acid supplemented infant formula does not influence calcium and magnesium bioavailability in weanling rats

The influence of infant formula supplementation with long‐chain‐polyunsaturated fatty acids (LCPUFA) on calcium and magnesium bioavailability was assessed in rats. Two test diets containing a plain, unsupplemented (PF) or supplemented (SF) infant formula as the fat source and a control diet (C) were administered to weaning rats and food intake and body weight gain were monitored for 28 days. In order to assess calcium and magnesium bioavailability, during the last week faeces and urine were collected and apparent absorption and retention were calculated. Food intake and body weight showed no significant differences between PF and SF but were lower in both groups compared with C. Calcium and magnesium intake did not differ between PF and SF, although both parameters were lower compared with C. Calcium absorption efficiency in PF and SF was significantly higher than in C. However, both groups showed higher urinary calcium excretion and thus no differences were observed in calcium retention. Magnesium absorption efficiency was also significantly higher in PF and SF compared with C, but magnesium absorption was significantly lower in SF compared with PF and C. Nevertheless, urinary magnesium excretion and magnesium retention were similar in the three groups. The consumption of a diet containing an infant formula supplemented with LCPUFA compared with the plain formula does not affect calcium and magnesium bioavailability in rats. Copyright © 2005 Society of Chemical Industry     

Stimulation by Calcium of the Formation of Active Extracellular Proteinase by Pseudomonas fluorescens spp.

Pseudomonas fluorescens produced extracellular proteinase in mineral salts medium in response to the addition of small molecular weight compounds derived from skim milk. Further fractionation of these compounds on Sephadex G-10 gave a highly stimulatory fraction lacking in peptides or amino acids but high in calcium. Further studies showed that proteinase production in mineral salts medium containing calcium was 29 to 64% of that in skim milk. Zinc, manganese, and magnesium ions failed to substitute for calcium. At 20 and 5°C, 50 and 10 μM calcium, respectively, were required for half maximum synthesis. Several complex media supported variable growth and enzyme synthesis; however, this variability did not seem related to the calcium content of the medium. Calcium was required for the formation of active extracellular proteinase by a number of strains of Pseudomonas fluorescens when growing in mineral salts medium. These results suggest that milk proteins are not essential for proteinase synthesis by Pseudomonas fluorescens.     

Effects of legume processing on calcium,iron and zinc contents and dialysabilities

Legumes are a good source of calcium, iron and zinc, but are also a source of phytates and dietary fibre components that can negatively affect the bioavailability of these minerals. To estimate the latter, an in vitro dialysis method can be applied that gives the dialysability of a mineral as an estimate of its availability for absorption. Calcium, iron and zinc contents and dialysabilities in three legumes (beans, chickpeas and lentils) and the effects of cooking treatments and industrial processing on these parameters were studied. Beans had the highest calcium content (1.54 g kg^?1 dry matter (DM)) and chickpeas the lowest iron content (46.9 mg kg^?1 DM), whilst the zinc contents were similar in all three raw legumes (33.7–36.9 mg kg^?1 DM). Traditional and microwave cooking reduced the mineral contents by 9.7–36.4% for calcium, 14.2–31% for iron and 11.1–28.9% for zinc. The dialysabilities of calcium with respect to the values for the raw products were also reduced by these cooking techniques. Industrially processed legumes had higher dialysabilities of calcium, iron and zinc than traditionally or microwave cooked legumes. © 2001 Society of Chemical Industry