煮沸时间对不同加碘形式食盐中碘稳定性的研究

本文采用氧化还原滴定法测定加碘食盐中碘的含量,对市面上不同加碘形式的碘盐分别煮沸一定时间后进行定量测定,取各组实验结果与未煮过的食盐进行比较。结果表明,以碘酸钾为碘强化剂的碘盐和以海藻碘为碘强化剂的碘盐碘含量基本维持不变,而以碘化钾和藻类浓缩汁为混合碘强化剂的碘盐碘损失明显。     

比色法测定食盐中微量碘

比色法测定食盐中微量碘陈幼林江苏苏州商业学院２１５００６近年来,非碘盐冲击我国市场,使本已基本控制的碘缺乏病又死灰复燃,严重危害着群众的健康。此为国务院有关部门决定１９９５年元月起全国禁售非碘盐,部颁标准规定：食盐中碘含量不少于百万分之八。但部颁食盐...     

高碘盐卤水制盐的碘含量初步分析

应用含碘酸钾的高碘饱和岩盐卤水，研究了自然蒸发和加温蒸发条件下所制食盐中碘含量。所得盐中碘含量与盐卤水含碘浓度呈密切的相相关关系。加温蒸发中，卤水中析出盐的碘含量随着加温过程卤水浓缩而上升。用高碘盐卤水浸渍食盐，亦可使盐中碘含量增加。但在同样碘浓度条件下，所得盐中碘含量远低于蒸发所制得盐。本项研究将为力。碘食盐生产揭示了一个新的加碘途径。     

原子吸收光谱法测定食盐中的碘

0　前言由于碘对防治地方性甲状腺具有重要意义 ,人体每天必须从食物中摄取 2 0 0 μｇ的碘。目前的食盐大多为加碘盐 ,但食盐中加入的碘一定要有量的规定 ,加少则作用不明显 ,过多又会引起毒副作用 ,而且我国盐市场受非碘盐和假冒碘盐的冲击较大 ,因此检测食盐中的碘含量显得十分必要。碘的测定方法有 :铈 -砷催化法、硫氰酸铁 -亚硝酸催化法、四甲基四胺基二苯甲烷比色法、选择性离子电极法、气相色谱法、离子色谱法、溴氧化碘滴定法等[1 ]。碘的主要测定方法 (经典方法 )是溴氧化碘滴定法 ,即在酸性条件下 ,采用硫代硫酸钠标准溶液滴定法…     

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.     

测定食盐碘含量及其影响因素研究

用碘离子选择性电极测定食盐中碘含量并对影响因素进行探讨。在Na2SO3作还原剂,双盐桥甘汞电极作参比电极的条件下,引入表面活性剂,使碘离子的浓度在2.0×10-7mol/L~1.0×10-2mol/L范围内的对数与响应电位值呈良好的线性关系。试验结果显示:碘盐中的碘含量为27.22 mg/kg,均达到国家标准,同时讨论温度、时间等对碘含量的影响。碘的回收率在94.99%～106.3%之间,相对标准偏差RSD≤3.23%。     

碘盐中碘含量测定的标准必须统一

为了实施（中国2000年消除碘缺乏病规划纲要），加强对加碘食盐（简称“碘盐”）的质量监督和质量管理均显得十分必要。然而，目前对碘盐中碘含量的测定方法十分混乱，其混乱表现在下列方面：1检测液使用目前市场上推出一种近似“眼药水”滴瓶式的“检测液”，用以检定食盐中是否含碘。它是根据淀粉能与碘生成兰色络合物而显色的原理来确定含碘与否．o这个方法用于定性食盐含碘与否，是无可非议的。但也必须考虑到既能检出碘酸钾，也可检出碘化钾。所以有的“检测液”有1；号2号之区分。然而，有的商家却将此引伸到“定量”或“半定量”。其…     

科学储存是增强加碘盐实效的重要环节

对储存过程中影响碘盐碘损失的诸因素进行调查研究,根据实测数据说明:在碘盐储存过程中,应全面考虑存放地点、存放条件、温度等因素,以保证加碘盐对碘缺乏病的防治实效。     

改善碘盐仓储状况 确保供应合格碘盐

为预防和医治碘缺乏病，国内外经验证明，推广食用加碘盐是安全、经济、可靠、服用方便、易于坚持、行之有效的方法。该省从７０年代末开始生产加碘食盐，当时是以碘化钾作碘剂，为防止碘酸钾中碘的逸失，加入稳定剂。从１９９０年起全国范围内，改换稳定性高的砗酸钾作碘剂生产加碘食盐，这在一定程度上增强了加碘食盐中碘含量的稳定性。因此为了保证居民能吃上合格的碘盐，除在生产碘盐的过程中，严格控制能造成碘剂逸失的杂质含量     

北京朝阳区世纪华联2012年2月盐品牌销售数量分析

根据卫生部规定,3月15日起,各地根据实际情况执行新的《食用盐碘含量》国家标准,新标准列出了3个含碘浓度供选择：20毫克／千克、25毫克／千克、30毫克／千克。目前北京市场上的食盐以无碘盐和低碘盐为主。     

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.     

Basic chemical characteristics of fresh, non-packed and vacuum-packed sheep-tail and tail-fat stored frozen for different periods

Fatty tails were obtained after the slaughter of Morkaraman sheep, which are a common breed of fatty-tailed sheep in Turkey. Fat obtained from sheep tails, (called tail-fat) is used either in fresh condition or after frozen storage. This fat is commonly used as a food source in many countries in which fat-tail sheep breeds are raised; but there has been no detailed research on fatty tails or the tail-fat. In this work some quality criteria such as water, fat and nitrogen content, 2-thiobarbituric acid and peroxide numbers, free fatty acids, melting point, iodine and saponification numbers were studied in sheep tails and sheep tail-fat, both in the fresh condition and after storage at -18 ± 1°C for up to 60 days. The effect of vacuum packaging versus storage in netting bags (no-protection, non-packed), was also determined. The fat content of the tails was around 94%. Thus, the tail is a concentrated fat source. Some quality criteria of the tail and the tail-fat were determined and are given in the text. Overall results indicated that both the tail and the tail-fat can be effectively used in various types of food and food processing, especially after performing some technological and refining processing. If the fatty tail has to be stored, it should be vacuum packed and stored frozen. At -18°C, vacuum-packed tail samples could be stored around 45 days, but in the netting bags, this storage period should not exceed 30 days.     

Efficacy of Insecticide Incorporated Bags against Major Insect Pests of Stored Paddy in Sri Lanka

A study was conducted to evaluate the efficacy of an insecticide (deltamethrin) incorporated bags (Zerofly®) against the insect attacks during paddy storage under Sri Lankan conditions. The study was conducted at Institute of Post Harvest Technology (IPHT), Anuradhapura andat the warehouse of Paddy Marketing Board (PMB), Anuradhapura. Paddy sample in Zerofly® sacks were stacked at both locations and for controls, untreated polysack bags were used. Paddy samples that were collected before storage and at monthly intervals during the storage period were analysed for moisture content, weight loss due to insect damages, Thousand Grain Mass (TGM), germination percentage, Total Milling Yield (TMY) and Head Rice Yield (HRY). Data was analyzed using Analysis of Variance (ANOVA) by Statistical Analysis System (SAS). The moisture content of paddy grains fluctuated between 13.3 – 14.3% during storage period but any significant difference was not observed among bag types. The level of insect damages in control was increased with storage time while the initial level of insect damage of treated bags remained unchanged. The mass loss due to insect damagesof grains was significantly higher (p=0.05) in untreated bags than treated bags. The insect damage was reduced by 3.5-4.a% using Zerofly® bags during paddy storage. In addition, dead insect bodies were found onouter surface of the insecticide incorporated bags but no live or dead insects were found on untreated bag surface during storage. Mainly rice weevil (Sitophils oryza) and lesser grain borer (Rhysoperthadominica) were found in paddy samples of untreated bags and number of insects increased with time. The germination percentage of grains in untreated bags was significantly higher than to thecontrol. It was reduced from 93% to 60-64% and 93% to 82-83% in control and treated bags respectively. During the six months of storage, TGM did not show any significant difference (p=0.05) among different treatments. TMY and HRY resulted significantly (p=0.05) lower values of paddy stored in untreated bags than Zerofly® bags. Use of insecticide incorporated bags can reduce the loss of TMY and HRY of paddy during storage. The study revealed that insecticide treated bags are an appropriate packaging material to protect stored paddy from insect infestations under Sri Lankan conditions.     

End-use quality characteristics of hermetically stored paddy

Four paddy varieties (Bg 352, Bg 300, Bg 358 and Bg 360) were stored in hermetic IRRI bags and common woven polyethylene bags (polybags) at room temperature either uninfested or infested with rice weevils (Sitophilus oryzae (L.)). After 9 months of storage, samples were tested for insect mortality, gas contents, moisture content (m.c.), thousand grain mass (TGM), porosity, hardness, whiteness, total milled rice yield (TMR), head rice yield (HRY), gelatinization temperature, amylose (AC), crude protein (CP), crude fat, free fatty acid (FFA), thiamine and niacin contents and sensory characteristics. These properties after storage were compared with their initial condition. The oxygen content dropped from 21% to 7% and 13.8% for infested and uninfested IRRI bag samples, respectively. The results showed that m.c., of the IRRI bag samples increased significantly (P < 0.05) by 5% when compared to the initial sample but it increased by 15% in polybag stored samples. After 9 months, dry matter loss (DM) was 65% higher in polybag than IRRI bag samples. Highest DM loss was observed in Bg 300 and the lowest DM loss was observed in Bg 358 and Bg 360. Paddy samples stored in IRRI bags showed reduced whiteness compared to polybag stored samples. Storage in IRRI bags significantly increased (P < 0.05) TMR, HRY, AC and sensory values compared to polybag samples. However, paddy samples stored in polybags significantly increased (P < 0.05) their CP and FFA contents while decreasing sensory values, thiamine and niacin contents. The FFA value of polybag samples was 2.5 times higher than IRRI bag samples. Hermetic storage of dry paddy improved overall paddy quality but different end-use quality parameters were observed in the two paddy grain types of short round (Bg 352 and Bg 300) or intermediate bold (Bg 358 and Bg 360).     

The effects of post-harvest handling on physical,chemical and functional properties of cowpea (Vigna unguiculata) seed

Damage by insects and mould, proximate composition, cooking rate and functional properties of sun-dried and stored cowpea (Vigna unguiculata) seeds were evaluated. Cowpea samples spread between black polythene films were placed on cement (CS), Wooden (WS) and corrugated iron sheet (CIS) surfaces, respectively, and sun-dried for 5 h. Storage lasted 6 months in jute and polythene bags. Results show that sun-drying and storage in polythene bags significantly (p < 0.05) lowered the extent of insect and mould damage, moisture-loss at drying, emulsion activity and stability, foaming capacity and foam stability. Treated cowpea seeds could be stored safely for about 5 months. In contrast, storage in jute bags significantly (p < 0.05) lowered only foam stability. Moisture loss during sun-drying principally lengthened cooking time as storage duration progressed. Therefore, assessment of moisture content before and during storage is a preferred quality index of cowpea seeds stored in polythene bags. © 1999 Society of Chemical Industry     

Effect of low‐cost storage and packaging on quality and nutritive value of fresh and dehydrated carrots

Fresh carrots (Daucus carota L cv ‘Nantes’) were packed in Netlon and ventilated low‐density polyethylene bags and stored in ambient, cool chamber and cool store conditions. Blanching and drying conditions were standardised and the sliced carrots were dehydrated to 7–9% moisture content using the best blanching and drying combination. Dehydrated carrots were packed in single and double layers of high‐density polyethylene bags and stored in ambient and cool store conditions for 9 months. The shelf‐life of fresh carrots varied from 3 to 20 days depending on the packaging and storage condition. A reduction in β‐carotene and ascorbic acid content and an increase in electrolyte leakage were observed during storage of fresh carrots. Blanching and drying caused a significant reduction in β‐carotene and ascorbic acid content, which further decreased during storage of dried product. The storage study of dried product showed that retention of β‐carotene and ascorbic acid was better in double‐packed and cool‐stored samples, and it also showed minimum browning during storage. © 2000 Society of Chemical Industry     

Impact of opening hermetic storage bags on grain quality,fungal growth and aflatoxin accumulation

Purdue Improved Crop Storage (PICS) bags are used by farmers in Sub-Saharan Africa for pest management of stored grains and products, including maize. These bags hermetically seal the products, preventing exchange with external moisture and gases. Biological respiration within the bags create an environment that is unsuitable for insect development and fungal growth. This study was conducted to determine the impact of routine opening of the storage bags for maize consumption on fungal growth and aflatoxin contamination. Maize with moisture contents (MC) high enough to support fungal growth (15%, 16%, 18% and 20%) was stored in PICS bags, which were opened weekly and exposed to humid conditions (85% RH) for 30 min over a period of 8 weeks and 24 weeks. Monitors indicated that oxygen defused into the open bags but did not reach equilibrium with the bottom layers of grain during the 30-min exposure period. Fungal colony forming units obtained from the grain surface increased 3-fold (at 15% MC) to 10,000-fold (at 20% MC) after 8 weeks. At both 8 weeks and 24 weeks, aflatoxin was detected in at least one bag at each grain moisture, suggesting that aflatoxin contamination spread from a planted source of A. flavus-colonized grain to non-inoculated grain. The results indicate that repeatedly breaking the hermetic seal of the PICS bags will increase fungal growth and the risk of aflatoxin contamination, especially in maize stored at high moisture content. This work also further demonstrates that maize should be properly dried prior to storage in PICS bags.     

Storage of chickpea grains (Cicer arietinum L.) in triple layer bags prevent losses caused by Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae) under laboratory conditions

Present study envisages the potential of triple layer bags for reducing pulse beetle infestation under laboratory conditions over six months of storage. It was observed that when chickpea grain was stored in jute bags with bruchid infestation, the germination percentage decreased significantly from 84.67 to 18.67% in six months of storage. But, the grain stored in jute bags without infestation the germination percentage decreased from 92.00 to 73.33% only. On the other hand, grains stored in triple layer bags with bruchid infestation, the germination percentage merely decreased from 86.00 to 78.33% in six months of storage and triple layer bags without infestation the germination percentage only decreased from 91.67 to 90.67%. The per cent grain damage over a period of six months storage also increased significantly from 14.54 to 70.67% and 0.00–26.45% in jute bag with bruchid infestation and jute bag without infestation, respectively. However, per cent grain damage in triple layer bags with bruchid infestation increased only from 15.15 to 25.70% and triple layer bags without bruchid infestation showed negligible increase from 0.00 to 2.64% grain damage in six months of storage. The corresponding per cent weight loss of infested grain was increased significantly from 8.51 to 55.67% in six months of storage in jute bag with bruchid infestation and from 0.00 to 15.08% in jute bag without infestation. Whereas, per cent weight loss of infested grain in triple layer bags with bruchid infestation increased only from 7.83 to 15.70 in six months of storage and triple layer bags without bruchid infestation recorded a mere per cent increase in weight loss from 0.00 to 1.48%. Benefit cost ratio showed that grains stored in triple layer bags for 6 months has highest benefit cost ratio (1.23) compared to jute bag storage (0.39).     

PICS bags safely store unshelled and shelled groundnuts in Niger

We conducted an experiment in Niger to evaluate the performance of hermetic triple layer (Purdue Improved Crop Storage- PICS) bags for the preservation of shelled and unshelled groundnut Arachis hypogaea L. Naturally-infested groundnut was stored in PICS bags and woven bags for 6.7 months. After storage, the average oxygen level in the PICS bags fell from 21% to 18% (v/v) and 21%–15% (v/v) for unshelled and shelled groundnut, respectively. Identified pests present in the stored groundnuts were Tribolium castaneum (Herbst), Corcyra cephalonica (Stainton) and Cryptolestes ferrugineus (Stephens). After 6.7 months of storage, in the woven bag, there was a large increase in the pest population accompanied by a weight loss of 8.2% for unshelled groundnuts and 28.7% for shelled groundnut. In PICS bags for both shelled and unshelled groundnuts, by contrast, the density of insect pests did not increase, there was no weight loss, and the germination rate was the same compared to that recorded at the beginning of the experiment. Storing shelled groundnuts in PICS bags is the most cost-effective way as it increases the quantity of grain stored.