亚甲基蓝褪色光度法测定食盐中微量碘

在硫酸介质中和溴化钾存在下,碘酸根能使亚甲基蓝氧化而褪色,且褪色的程度与碘酸根存在量成正比,从而建立了光度法测定碘的新方法.方法的最大吸收波长为545 nm.碘酸根含量在1～20μg /10 mL范围内符合比尔定律.表观摩尔吸光系数为1.0×104L·mol-1·cm-1.将该方法用于测定加碘食盐中的碘,结果满意.     

靛蓝胭脂红氧化褪色光度法测定食品中微量碘

基于稀硫酸介质中,在溴化钾的催化下,碘酸根对靛蓝胭脂红有明显的褪色作用,且褪色的程度与碘酸根的含量有关,建立氧化褪色光度法测定微量碘的方法.碘定量测定的线性范围为20 μg/25 mL～50 μg/25mL,方法的检出限为1.25×10-1 μg/mL,反应的表观摩尔吸光系数为1.354 L/(cm·mol).本法的灵敏度和选择性较高,重现性好,操作简便,用于测定海带或食盐等含微量碘较高的食品,结果满意.     

亚甲基蓝氧化褪色光度法测定食盐中的碘

在盐酸介质中,碘酸根在加热的条件下能氧化亚甲基蓝褪色,建立了亚甲基蓝氧化褪色法测定微量碘的新方法.讨论了实验条件,最大吸收峰为667 nm,碘酸钾浓度在01.2 μg/mL范围内呈线性关系,摩尔吸光系数为1.1×105 L·mol-1·cm-1.用于测定食盐中微量碘的含量,结果满意.     

溴百里酚蓝褪色光度法测定食盐中碘的研究

在酸性介质中,溴化钾存在下,碘酸根对溴百里酚蓝有褪色作用,且褪色程度与碘酸根的量有关,从而建立了碘的光度测定新方法。方法的最大吸收波长在430nm处．碘定量测定的线性范围为0．18μg／10mL。方法操作简单,快速、重现性好,用于加碘食盐中碘的测定,结果满意,     

靛蓝胭脂红褪色光度法测定食盐中碘的研究

在酸性介质中,溴化钾存在下,碘酸根对靛蓝胭脂红有褪色作用,且褪色程度与碘酸根的量有关,从而建立了碘的光度测定新方法。方法的最大吸收波长在610nm 处,碘定量测定的线性范围为0～18μg/10ml。方法操作简单,快速、重现性好,用于加碘食盐中碘的测定,结果满意。     

1-(2-吡啶偶氮)-2-萘酚(PAN)褪色光度法测定食盐中碘的研究

在酸性介质中,溴化钾存在下,碘酸根对1-(2-吡啶偶氮)-2-萘酚(PAN)有褪色作用,且褪色程度与碘酸根的量有关,从而建立了碘的光度测定新方法。方法的最大吸收波长在430nm处,碘定量测定的线性范围为0～18μg/25mL。方法操作简单,快速、重现性好,用于加碘食盐中碘的测定,结果满意。     

1-（2-呲啶偶氮）-2-萘酚（PAN）褪色光度法测定食盐中碘的研究

在酸性介质中，溴化钾存在下，碘酸根对1-（2-吡啶偶氮）-2-萘酚（PAN）有褪色作用，且褪色程度与碘酸根的量有关，从而建立了碘的光度测定新方法。方法的最大吸收波长在430nm处，碘定量测定的线性范围为0—18μg／25mL。方法操作简单，快速、重现性好，用于加碘食盐中碘的测定，结果满意。     

食盐加碘剂碘酸钾的测定研究

在硫酸介质中,碘酸钾与桑葚红反应褪色程度与碘酸根量在一定范围内呈线性关系,从而建立了碘的光度测定新方法.结果表明,方法的最大吸收波长在520 nm处,碘定量测定的线性范围为0～50 mg/25 mL,摩尔吸光系数ε=4.3×104 L/mol· cm.研究可直接测定食盐中的碘,结果满意.     

甲酚红氧化褪色光度法测定海带中的微量碘

在硫酸介质中、在溴化钾催化条件下,碘酸根对甲酚红有褪色作用,且褪色的程度与碘酸根的量有关,碘定量测定的线性范围为20μg/25mL～50μg/25mL,检出限为6.57×10-1μg/25mL,回收率为98.1%～104.2%。该法重现性好、准确度高、操作简便,是测定海带中微量碘的一种较理想的方法。     

氧化褪色光度法测定食品中的碘

研究了在硫酸介质中,碘酸根在KBr催化作用下氧化罗丹明B,使其褪色的最佳条件,建立了测定微量碘的新方法。通过实验,测得最大吸收波长为490nm,表观摩尔吸光系数为1.5×104L·mol-1·cm-1,碘测定的线性范围为0～75μg/25mL,检测限为1.2×10-7mol/L。本方法的相对标准偏差为0.28%～1.9%;回收率为97.9%～101.2%。用于食品中碘的测定,结果令人满意。     

Stability of iodine in salt fortified with iodine and iron

BACKGROUND: Determining the stability of iodine in fortified salt can be difficult under certain conditions. Current methods are sometimes unreliable in the presence of iron. OBJECTIVE: To test the new method to more accurately estimate iodine content in double-fortified salt (DFS) fortified with iodine and iron by using orthophosphoric acid instead of sulfuric acid in the titration procedure. METHODS: A double-blind, placebo-controlled study was carried out on DFS and iodized salt produced by the dry-mixing method. DFS and iodized salt were packed and sealed in color-coded, 0.5-kg, low-density polyethylene pouches, and 25 of these pouches were further packed and sealed in color-coded, double-lined, high-density polyethylene bags and transported by road in closed, light-protected containers to the International Council for the Control of Iodine Deficiency Disorders (ICCIDD), Delhi; the National Institute of Nutrition (NIN), Hyderabad; and the Orissa Unit of the National Nutrition Monitoring Bureau (NNMB), Bhubaneswar. The iodine content of DFS and iodized salt stored under normal room conditions in these places was measured by the modified method every month on the same prescribed dates during the first 6 months and also after 15 months. The iodine content of DFS and iodized salt stored under simulated household conditions was also measured in the first 3 months. RESULTS: After the color code was broken at the end of the study, it was found that the DFS and iodized salt stored at Bhubaneswar, Delhi, and Hyderabad retained more or less the same initial iodine content (30-40 ppm) during the first 6 months, and the stability was not affected after 15 months. The proportion of salt samples having more than 30 ppm iodine was 100% in DFS and iodized salt throughout the study period. Daily opening and closing of salt pouches under simulated household conditions did not result in any iodine loss. CONCLUSIONS: The DFS and iodized salt prepared by the dry-mixing method and stored at normal room conditions had excellent iodine stability for more than 1 year.     

强化碘盐消除碘缺乏病

中国盐业是一个古老而传统的行业,几千年来,这个行业都是由中央政府管辖。目前,中国盐业共有 １３００个产销企业,职工４０万人。近几年,盐的产量很稳定,在２８００万～２９００万吨之间。海盐产量占６８％,井矿盐占２４％,湖盐占８％。其中食用盐约７００万吨,国家对食盐的生产和销售实行专营,对工业盐实行市场经济运行。 中国盐业总公司是中国盐业的排头兵企业,成立于 １９５０年,负责组织盐业的产销、科研和贸易。另外,中国盐业总公司是食盐加碘消除碘缺乏病的主要实施机构。 一、中国政府对消除碘缺乏病的重视 中国政府历…     

A high dietary iodine increases thyroid iodine stores and iodine concentration in blood serum but has little effect on muscle iodine content in pigs

There is still iodine deficiency in many populations, which justifies efforts to increase this trace element in food such as milk, eggs and meat by fortifying compound animal feeds with extra iodine. The iodine requirement of growing pigs is in the order of 100-200μg/kg feed (as a supplement) and the effects of this dosage range or higher on pork iodine concentration should be determined including the action of relevant iodine antagonists in feed, e.g., rapeseed. In three experiments on a total of 208 pigs [Pietrain×(Landrace×Large White)] the iodine concentration of meat (m. longissimus) - 71 samples -, blood serum - 100 samples - and of the thyroid - 100 samples - was analysed by intracoupled plasma-MS. In Experiment 1, 4×10 pigs received diets without or with rapeseed cake (0 and 3.2mmol glucosinolates/kg diet) either with 125 or with 250μg iodine/kg. In Experiment 2, the three groups with 46 pigs each were fed high iodine diets (1200μg supplementary iodine/kg) without or with 100 or 150g solvent extracted rapeseed meal/kg diet (0; 0.8 and 1.2mmol glucosinolates/kg). In Experiment 3, 3×10 pigs received either 600μg iodine/kg feed (1) or the 5-fold dosage (600+2400μg iodine/kg diet) administered 7 days (2) or 18 days (3) before slaughtering. The group means of pork iodine content were in the relatively small range from 3 to 16μg/kg, which contrasted to the enormously varying dosage range from 125 to 3000μg iodine/kg diet. There was a certain iodine dosage effect in Experiment 3 when - in comparison to the control - a 3-fold higher meat iodine concentration resulted from a 5-fold higher diet iodine concentration. In Experiment 1 with the low iodine offer, rapeseed cake with glucosinolates decreased the serum iodine level whereas in Experiment 2 this did not happen due to higher iodine fed and lower glucosinolates exposure. The thyroid iodine reflected the dietary iodine better than blood serum iodine and the serum better than muscle. However, in Experiment 2, 1200μg iodine/kg diet produced only half the serum iodine concentration than half as much dietary iodine in Experiment 3 (600μg iodine/kg diet), which may result from rapid elimination of blood iodine and a higher urinary excretion by longer duration of feed withdrawal before blood sampling. The muscle of pigs has to be classified as a low iodine food. Thus, there are no possibilities to concentrate this trace element reproducibly in amounts relevant for human nutrition in pork.     

Determination of iodine concentration in salt dual fortified with iron and iodine

The applicability of the iodide catalyzed reaction (Sandell-Kolthoff) between Ce⁴⁺ and As³⁺ for the determination of iodine in salt samples fortified with iron and iodine has been studied. A method verification program is presented; the catalytic method was compared with isotope dilution inductively coupled plasma-mass spectrometry (ICP-MS), for which the long-lived iodine nuclide ¹²⁹I was used. Two-way analysis of variance (ANOVA) revealed that both methods yielded consistent iodine results across salt samples from Morocco and the Ivory Coast that were either free of iron or fortified with different iron species. Although some bias was present, no influence of iron on the catalytic reaction was detected.     

中国高水碘地区人群膳食碘摄入量评估

目的评估中国高水碘地区人群膳食碘摄入量及其潜在风险。方法利用2002年中国营养与健康状况调查数据库中的食物、食盐消费量数据和饮用水推荐摄入量,以及中国食物成分表及盐碘和水碘监测数据,估计我国高碘地区13个性别～年龄组人群在食用加碘食盐和不加碘食盐情形下的膳食碘摄入量,并与我国推荐的膳食碘摄入量标准进行比较。结果水碘介于150～300μg/L地区,无论食用加碘食盐或不加碘食盐,各组人群的膳食碘平均摄入量均介于推荐摄入量(RNI)和可耐受最高摄入量(UL)之间;水碘高于300μg/L地区,7岁以上男性和11岁以上女性(含孕妇和乳母)食用加碘食盐时的碘平均摄入量均超过UL,而所有人群食用不加碘食盐时的碘摄入量均介于RNI～UL之间。两类地区所有个体碘摄入量均超过RNI;但食用加碘食盐时,摄入量超过UL的个体比例为10.5%和24.9%,远高于食用不加碘食盐的1.5%和1.7%。在两类地区饮用水对膳食碘的贡献率均高于食盐。结论在食用不加碘食盐的情况下,我国高水碘地区居民的膳食碘摄入量是适宜和安全的,食用加碘食盐会增加碘过量的风险;饮用水是高碘地区膳食碘的最主要来源。     

The iodine content of pastures

Marked species and seasonal differences in iodine content of grasses have been found and preliminary results indicate varietal variation in perennial ryegrass and white clover. Nitrogen fertilisers lowered the iodine content of grasses. The general level of iodine was low in the herbages studied and seldom attained the level recommended as the nutrient requirement for pregnant or lactating stock.     

Effects of iodine intake and teat-dipping practices on milk iodine concentrations in dairy cows

Two studies were conducted to determine the effects of dietary iodine and teat-dipping practices on iodine concentrations in milk. In the first study, 63 cows in mid lactation were assigned to a 3×3 factorial design in which the main effects were dietary iodine levels (0.3, 0.6, and 0.9 mg of dietary I/kg of dry matter) and 3 different postdip managements (chlorhexidine with dip cup, 1% iodine dip cup, and 1% iodine by manual spray). During the 13-d pre-experimental period and the 15-d experimental period, noniodized sanitizers were used in premilking management. During the pre-experimental period, the levels of milk iodine averaged 241.2±5.8 μg/kg, and no relationship was found with lactation number, days in milk, or milk production. Milk iodine concentrations increased linearly with iodine intake. Although teat dipping with 1% iodine had no effect on milk iodine concentration, the same solution applied by spraying greatly increased milk iodine levels. The second study was conducted to determine the effects of udder preparation before milking on milk iodine concentrations. Thirty-two lactating cows were assigned to 4 treatments: no predip (Con); predip with a predip solution containing 0.5% iodine+complete cleaning (Comp); predip with a postdip solution containing 1% iodine+complete cleaning (Post); and predip with a predip solution containing 0.5% iodine+incomplete cleaning (Inc). During the 14-d pre-experimental period and the 19-d experimental period, cows were fed the same diet, and noniodized sanitizers were used for postmilking dipping. During the last week of treatment, milk iodine averaged 164, 189, 218, and 252±9.8 μg/kg for Con, Comp, Post, and Inc, respectively. Preplanned orthogonal contrasts indicated that predipping with a 0.5% iodine predip solution completely wiped off (Comp) tended to increase milk iodine content above that of the control and that the iodine content of Post and Inc were higher than that of the Comp treatment. The results of the first experiment confirm that, to preserve milk safety, iodine should not be fed above requirements. Spraying iodine-based teat-dipping solutions results in large increases in milk iodine content and should be avoided. Predipping teats with an iodine-based sanitizer is an acceptable practice, but must be performed with the appropriate product and completely wiped off before milking.     

Short communication: Feed iodine concentrations on farms with contrasting levels of iodine in milk

In a previous study, milk iodine concentration from 501 farms across Canada was found to vary considerably and appeared to be influenced by feeding practices. Farms with contrasting levels of milk iodine from a subset of 200 participating farms were used to determine the relationship between milk iodine concentration and the concentration of this mineral in different feeds and complete diets given to lactating dairy cows. The 30 farms with the lowest levels of iodine in milk (low group) and the 30 farms with the highest levels (high group) were selected. Samples of bulk tank milk, all feed ingredients, and water were collected. Additionally, each farmer completed a questionnaire providing information on feeding management. The iodine offered on each of the farms was estimated from the amount of the feed in the diet recommended by the Ration’L software (Valacta, Ste-Anne-de-Bellevue, QC, Canada) and the iodine concentration in the feed sampled and analyzed using inductively coupled plasma mass spectrometry. The dietary concentration of iodine offered daily was 33% lower for the low group compared with the high group; that is, 1.20 ± 0.099 versus 1.81 ± 0.195 mg/kg of dry matter (DM), respectively. Milk iodine concentrations averaged 146 ± 13.9 μg/kg for the low group and 487 ± 44.6 μg/kg for the high group. A linear relationship was found between dietary iodine concentration and milk iodine level, as follows: milk iodine (μg/kg) = 145 (±66.9) + 113 (±39.4) dietary iodine concentration (mg/kg DM). However, the low R² value (0.15) indicates that other factors, such as milking management and the presence of goitrogens, may have affected the concentrations of iodine in milk. Forages supplied approximately 17% of iodine requirements in the average lactating cow diet. Therefore, variations in the iodine content of forages are unlikely to cause iodine overfeeding. In contrast, 27% of the mineral mix samples presented iodine concentrations >100,000 μg/kg of DM (and up to 322,000 μg/kg of DM). More than 85% of the farms tested were feeding iodine levels higher than the dietary iodine recommendations (0.5 mg of iodine/kg of DM). Iodine supplements should be used with caution in lactating cow diets.     

天然碘酱油的研制

介绍了天然碘酱油的工艺生产流程。该产品不仅营养价值高,风味独特,而且还具有一定的保健作用。