加碘食盐中碘损失的实验研究(Ⅱ)

采用氯化钠增敏光度法研究了在模拟烹饪条件下加碘食盐中碘的稳定性.实验结果表明,碘盐中碘的稳定性并不理想,加碘食盐中碘的稳定性受温度与受热时间的影响较大,受热温度越高,碘损失越多;受热时间越长,碘损失越多.     

海藻碘食用盐中碘的流失情况试验

对添加海藻碘提取液为碘剂的海藻碘食用盐中碘的稳定性情况进行试验,确定在不同温度及时间条件下碘的变化规律:在300℃以下条件下海藻碘食用盐中碘基本不流失。     

红曲甜米酒生产过程中红曲色素稳定性研究

通过固态发酵的方法,制备红曲米,并从中提取出天然红曲色素。以色价为指标,研究光照、温度、受热时间及金属离子对红曲色素稳定性的影响。结果表明:光照条件对红曲色素稳定性影响的大小顺序为日光紫外灯避光处,其中,日光对红曲色素稳定性的影响最为明显;另外随着温度的升高,红曲色素的稳定性越来越差,加热时间越长,色价损失越大;金属离子中,Fe~(3+)对红曲色素的影响最大,而Cu~(2+)和Zn~(2+)影响不显著。     

红枣叶中Vc的提取及稳定性研究

介绍了用酒精、有机酸和水对红枣叶片Vc浸提率的影响,并对浸提液中Vc的稳定性进行了研究。结果表明,在相同的浸提条件下,浸提率大小为酒精溶液>有机酸溶液>水溶液。适当升高温度可以大大提高浸提率,在50℃水浴条件下,浸提6h,可使浸提率达到97%。浸提液中Vc的稳定性受热及空气的影响较大,加热和与空气接触都可以加速Vc的损失,降低pH,加适量糖对Vc起保护作用。     

加碘盐中碘的稳定性

由于在环境温度下碘容易升华，盐加碘计划的效果取决于碘载体－碘酸钾的稳定性。由于杂质，金属离子，像铁离子吸湿，水分的存在加速了碘的损失。用防潮膜包装能大大增加所有盐样品中碘的保存。     

影响玉米黄素稳定性的因素研究

通过单因素及正交试验研究温度、加热时间及p H对玉米黄素稳定性的影响。结果表明,玉米黄素在446nm处有最大吸收峰;当温度60℃,时间3 h时,玉米黄素的保存率大于92%;当温度100℃,时间3 h时,保存率仅71%,说明色素在高温下不稳定且不易长时间受热;当pH 4～12时,保存率大于97%,色素几乎不发生变化而在强酸强碱条件下易被氧化;正交试验表明影响玉米黄素稳定性的因素依次是温度加热时间p H,且最好条件为温度60℃,加热时间1.5 h, pH 8,且混合因素对玉米黄素保存率的影响大于单因素对玉米黄素保存率的影响。     

加碘精制食盐中碘酸钾的稳定性及其影响因素研究

目的：研究加碘精制食盐中碘酸钾在存储期间的稳定性及其影响因素。方法：在大理市内随机收集同一批次的碘盐样品40份,按设计要求分别存放,每隔3个月观察1次,连续3次,采用直接碘量法检测样品碘含量。结果：在阴暗的条件下,不论是以罐装或袋装的方式存放,碘样中碘的含量均值之间的差异有统计学意义,提示有碘损失。在明处的条件下,以开口方式及带盖罐装的方式存放的碘样中碘的含量均值之间的差异有统计学意义,提示有碘损失;而以小塑料袋密封的方式存放的碘样中碘的含量均值之间的差异无统计学意义,提示未发生明显碘损失。结论：经8个月的观察,发现除了以明处小塑料袋密封这种存放方式外,其他的存放方式碘都有损失,但损失量少;食盐质量、存放环境以及碘盐生产或采样时混匀程度均会影响碘含量变化而发生变异。     

海带生物活性碘的提取及应用研究

采用化学分析和动物实验方法，对海带中有机碘的提取特性、补碘特性进行了研究，结果表明：海带中无机碘、有机碘的提取收率随温度与提取时间呈规律性变化。海带中的有机碘在热稳定性、应用效果、安全性等方面，比无机碘性能优越，是开发新型碘盐、补碘保健食品的首选材料。     

紫甘薯天然红色素的提取及其稳定性研究

以紫甘薯为原料,分别研究了其天然红色素的提取方法、工艺以及该色素在不同环境条件下的稳定性。结果表明,紫甘薯天然红色素的最佳提取条件为:0.8%的柠檬酸溶液作提取剂、料液比为1:50、温度60℃、时间4h;提取后的天然紫甘薯红色素在酸性条件下较稳定,有着较好的耐热性和光稳定性,随着pH升高,稳定性下降;对抗坏血酸较敏感,使用时应尽量在低酸性环境下及避免高温和长时间的受热。     

蔬菜中还原型VC和氧化型VC含量及稳定性研究

试验对常见蔬菜中还原型VC和氧化型VC在不同温度、时间、光照和空气等条件下的稳定性变化进行了研究。结果表明,加热时间对蔬菜的还原型VC和氧化型VC有显著性影响,加热温度对不同的蔬菜还原型VC有不同的影响;随着在空气中放置时间的延长,蔬菜还原型VC显著降低,部分蔬菜放置6 h时,氧化型VC保存率超过了100%;在酸性条件下,蔬菜还原型VC和氧化型VC损失均较小,碱性环境下,蔬菜中VC主要损失的是还原型VC,对氧化型VC影响不大。     

Adding an oxidant increases the stability of iodine in iodized salt

It has been shown that moisture plays a critical role in the stability of iodine and that reducing agents in iodized salt reduce the stability of iodine. We question whether this is valid in all cases, and have found that the reducing agent may play a more important role than moisture in decreasing the stability of iodine. We reviewed current methods to enhance iodine retention in iodized salt, and propose methods to produce stable iodized salt and to analyze its stability. Our experiments showed that when reducing impurities are removed, iodine remains stable in iodized salt, even when the salt is "wet." We suggest that the stability of iodine in iodized salt can be improved by oxidizing iodized salt with sodium hypochloride, and that the iodine content of iodized salt, after heating at 120 degrees C for one hour, can be used to reflect the quality of iodized salt. We have demonstrated that reducing agents play a critical role in the stability of iodine in iodized salt. We have shown a method of purifying salt by removing reducing materials, which can be used to produce iodized salt with sufficient stability at lower cost. We also propose an analytical method to determine the stability of iodine in iodized salt. These methods could be further developed to achieve better accuracy, precision, and reliability and be applied to a greater variety of iodized salts.     

富硒低钠盐中碘含量的测定

目的探讨富硒低钠加碘盐中碘含量的测定方法。方法通过不同的实验条件,优化国标GB/T13025.7-2012《制盐工业通用试验方法碘的测定》中氧化还原滴定法中的试剂用量,检测出富硒低钠加碘盐中的碘含量。结果改变碘化钾溶液量、淀粉溶液量、磷酸-草酸溶液量均无法测定富硒低钠盐中的碘含量;只有当次氯酸钠溶液用量≥5mL时,加入碘化钾溶液,才可以使富硒低钠加碘盐溶液显色,然后通过实验确定次氯酸钠的最佳用量,再滴定测定碘含量。结论富硒低钠加碘盐中含有还原性物质,测定其碘含量需加大次氯酸钠溶液的用量。     

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.     

Stability of iodine in iodized fresh and aged salt exposed to simulated market conditions

BACKGROUND: The salt iodization law of the Philippines required that iodized salt sold at retail not be exposed to direct sunlight, high temperature and relative humidity, and contamination with moisture and dust from the environment. However, because the majority of local consumers buy salt displayed in open heaps, it was suggested that iodized salt should be sold in the same manner for greater accessibility and availability. Objective. We aimed to provide evidence on the stability of iodine in local aged and fresh salt iodized at 100 ppm iodine and exposed to various market and storage conditions. METHODS: Samples of salt in open heaps and repacked salt were exposed for 4 weeks, and salt packed in woven polypropylene bags was stored for 6 months. The iodine content of the salt was determined by the iodometric titration method, and the moisture content was determined by the oven-drying method. RESULTS: For all types of exposed salt, iodine levels were above 60 ppm after the end of the study (4 weeks). Within each salt type, losses were greater for open-heap salt than for repacked salt. The greatest drop in moisture content occurred in the first week for most types of salt and exposure combinations. Moisture content was linearly correlated with iodine content. Iodine levels in stored salt remained above 60 ppm even after 6 months. CONCLUSIONS: Iodized salt is able to retain iodine above the recommended levels despite exposure to an open environment and use of ordinary packaging materials while being sold at retail and kept in storage.     

碘盐在食品工业中应用的研究

我国缺碘区域广泛 ,并大面积流行碘缺乏症。在食盐中加碘是防治碘缺乏症的有效措施 ,为此 ,世界各国先后都将在食盐中加碘列为法规。在我国 ,虽然在民用盐中成功地应用了加碘盐 ,然而对于加工食品 ,特别是腌制食品仍然未应用加碘盐。我国腌制食品种类多 ,生产量大 ,其用盐量占有很大比例。为了在我国全面推广加碘盐 ,彻底防治碘缺乏症 ,有助于碘盐法规在我国的实施 ,为此我们进行了碘盐在食品工业中应用的研究。本研究结果表明 ,加碘盐适合于食品工业使用 ,对腌制食品不会产生任何不良影响。     

Iodine content in bread,milk and the retention of inherent iodine in commonly used Indian recipes

Iodine deficiency disorders (IDD) is still a major public health problem and iodized salt remains the most effective means to control IDD in India. Few reports indicate that vegans have inadequate iodine intake while at the same time concerns are being raised on the implementation of universal salt iodization in the country. Therefore, we investigated the iodine content in bread, milk and commonly used Indian recipes prepared without iodized salt and the retention of inherent iodine therein. Results showed considerable iodine content in bread (25 μg/100 g) and milk (303 μg/L) as a positive fallout of universal salt iodization. Iodine content in 38 vegetarian recipes prepared without iodized salt was very low (2.9 ± 2.4 μg/100 g). Retention of inherent iodine (65.6 ± 15.4%) and iodine from iodized salt (76.7 ± 10.3%) in the same recipes was comparable. Thus, universal salt iodization programme remains the single most important source of dietary iodine for the Indian population.     

Effect of collagen preparations used as carriers of potassium iodide on retention of iodine and thiamine during cooking and storage of pork meatballs

The application of collagen preparations as carriers of iodine salts in the production of meat dishes was investigated in this study. Meatballs with addition of collagen fibre or collagen hydrolysate, both impregnated with potassium iodide, were cooked and cold‐ or freezer‐stored. After thermal processing and during storage of meatballs the iodine and thiamine contents were determined and compared to their contents in meatballs to which potassium iodide was introduced using iodized table salt. It has been shown that the application of both collagen preparations as carriers of potassium iodide increases the stability of this compound during cooking and storage of meatballs in comparison to its stability in products with iodized table salt. Collagen preparations, improving potassium iodide stability, also limit thiamine losses in the product. A more advantageous effect, both on iodine and thiamine retention, is achieved for the collagen preparation with a higher water binding capacity. Copyright © 2007 Society of Chemical Industry     

Iodine stability in iodized salt dual fortified with microencapsulated ferrous fumarate made by an extrusion-based encapsulation process

The development of a novel, extrusion-based process for making microencapsulated ferrous fumarate for salt double fortification has been reported earlier. This paper focuses on the results of a one-year storage test, specifically the stability of both iodine and ferrous iron in the double fortified salt (DFS) samples prepared using optimal formulations of the iron premix. The study was devised to test the effectiveness of the encapsulation system in the prevention of interaction between ferrous fumarate and iodine, and preservation of the iodine in iodized salt. The results confirmed that direct iodine–iron interaction occurred in the DFS samples when the iron compound was added without proper coating. However, when an appropriately encapsulated iron premix was used, the interaction could be completely prevented. The extrusion-based process has proven to be an effective approach to producing a stable, bioavailable iron premix, suitable for incorporation into iodized salt for combating iodine and iron deficiencies.     

降低碘耗的途径

碘盐生产过程中碘酸钾的添加系统、碘酸钾添加控制办法与碘酸钾的添加稳定性,对于保证碘盐合格率、降低生产成本有重要影响。本文从这三个方面进行分析,以期对从事加碘工作的同行有所帮助。