Increased levels of cesium-137 and cesium-134 in 34 mushroom species following the reactor accident at Chernobyl

From September to December of 1986, 85 samples of 34 species of wild mushrooms were collected, mostly in northern Baden and occasionally in neighboring areas. Cs-137, Cs-134, and the natural nuclide K-40 were determined by gamma-spectrometry. Samples from the Rhine Valley and the Kraichgau were generally much less contaminated than those from the Black Forest. With one exception, their radiocesium levels were below the Common Market limit of 600 Bq/kg. The exception was a sample of Laccaria amethystina with 1710 Bq/kg Cs-137 and 766 Bq/kg Cs-134. Relatively high levels were also found in Xerocomus badius, X. chrysenteron and Cantharellus tubaeformis. The hymenophore contained higher concentrations of radiocesium than the other parts of the body of the fruit. No correlation between the concentration of K-40 and that of the Cs nuclides was found. The ratio of Cs-137:Cs-134 was usually below 3 but reached the value of 11.8 in Piptoporus betulinus growing on birch wood. In this case, the substrate must have contained more radiocesium from the time before the Chernobyl reactor accident than from the time thereafter.     

Transport of the radioisotopes iodine-131, cesium-134, and cesium-137 from the fallout following the accident at the Chernobyl nuclear reactor into cheesemaking products

The transport of radiation contamination from milk to products of the cheese making process has been studied. The concentration of radioactive iodine and cesium in samples of sheep milk and cheese (Gruyère) products was measured for 10 consecutive production d. Milk with concentration 100 Bq/L in each of the radionuclides 131I, 134Cs, and 137Cs cheese with concentration 82.2 +/- 3.9 Bq/kg in iodine and an average of 42.3 +/- 2.3 Bq/kg in the cesium isotopes is produced. The corresponding concentrations in cream extracted from the same milk are 26.7 +/- 2.8 Bq/kg (131I) and 18.6 +/- 1.9 Bq/kg (134Cs, 137Cs).     

Determination of sulfur-containing amino acids in food products

To define the most accurate method for determination of sulfur-containing amino acids in foods, the possibility was tried of using a method suggested by Moore. The method is based on preliminary oxidation of cystine and methionine by performic acid and transformation of these substances to acid hydrolysis resistant cysteic acid and methionine sulphone. Model experiments and use of foods (wheat flour, grade II, and protein part of chicken egg) demonstrated that exposure of proteins to performic acid brings about oxidation of sulfur-containing amino acids to the hydrolysis-resistant forms which may be defined by chromatography with a greater accuracy. Experiments without preliminary oxidation by performic acid showed that foods experience an appreciable destruction (by 30-60%) of cystine and methionine. Therefore, it is advisable that during studies into amino acids contained by proteins, additional hydrolysis may be performed with preliminary oxidation of the samples by performic acid, which enables the determination of the content of methionine and cystine with a greater accuracy.     

Determination of acrylamide content of food products in Korea

Acrylamide (AA) contents of commercial market‐purchased foods and of traditional home‐cooked Korean foods were investigated. The effect of cooking method on AA amount in potatoes was also studied. AA contents of roasted barley and corn ranged from 116 to 449 µg kg^?1 and of chips ranged from 12 to 3241 µg kg^?1, representing a very high variation in AA contents among tested samples. Lower levels of AA were found in wheat flour chips compared to potato chips. AA contents of ramen noodles were below 37 µg kg^?1, whether they contained potato starch or not. The AA contents of Korean home‐cooked oil fried foods increased in the following order: yakwa < whole deep‐fried sea tangle < ground and deep‐fried lotus root < ground and pan‐fried lotus root < French fries < ground and pan‐fried potato. Lotus root and garlic also had the potential to produce AA during cooking. Pre‐treatment such as grinding, boiling, freezing and thawing increased the AA formation in oil‐fried potato. Temperature was more influential than time on AA formation during deep‐oil frying. Removing water‐soluble fractions reduced AA content of cooked potatoes. Copyright © 2006 Society of Chemical Industry     

Determination of preservatives in some food products by capillary isotachophoresis

In the food and especially preserving industry several chemical preservatives are used by which the storage life of foods is prolonged. Each preservative must fulfill hygienic and health demands. For the chemical preservatives there are determined the highest allowable quantities for concrete kinds of semiproducts and ready-made products, as well. The most used preservatives in our country are: formic acid, benzoic acid, sorbic acid, sulphur dioxide, acetic acid. Several methods were developed for the determination of the individual preservatives. Some methods do not enable the simultaneous determination of several preservatives. The chromatographic methods remove these lacks and some authors used in the determination of preservatives especially high performance liquid chromatography, as well [1, 2].     

Determination of N-nitrosamines in food products intended for long term storage

The content of carcinogenous N-nitrosoamines (N-nitrosodimethylamine, N-nitrosodiethylamine, N-nitrosopiperidine) was determined fluorimetrically (as NBD-amines) in preserved products, food concentrates, dried fruit and mushrooms. No N-nitrosoamines were found in the concentrates and dried products. The content of N-nitrosamines did not exceed 3 g/kg. In some samples its content reached 19 microgram/kg.     

时间分辨免疫荧光法测定食物中花生过敏原成分

目的:建立双抗体夹心时间分辨荧光免疫法[Time-resolved Fluoroimmunoassay(TRFIA)]测定食物中花生过敏原蛋白成分,为进出口食品中花生过敏原成分检测和由花生导致的食物过敏性疾病的预防提供技术基础。方法:提取花生蛋白,免疫小鼠制备抗花生总蛋白的多克隆抗体,用该抗体包被酶标板,并用生物素标记该多抗作为捕捉抗体,Eu3+标记的链酶亲和素和以β-二酮体为主的增强液等试剂,建立双抗夹心TRFIA方法,检测该方法的灵敏度,同时用于13种食品中花生过敏原蛋白成分检测。结果:初步地研制出双抗体夹心TRFIA法检测食品中花生过敏原蛋白成分,具有特异性,和其最低检出限为0.1ng/mL,标准曲线在0.1～160ng/mL范围内线性良好;11种食品检测结果与食物过敏原标签标注内容相符,而2种标示不详的食品检测结果均呈现阳性。     

时间分辨免疫荧光法测定食物中鸡蛋过敏原蛋白成分

目的:建立双抗体夹心时间分辨免疫荧光法(TRFIA)用于测定食物中鸡蛋过敏原蛋白成分,为进出口食品鸡蛋过敏原成分检测提供技术基础.方法:提取鸡蛋过敏原总蛋白,免疫小鼠获得多克隆抗体,并以此抗体包被酶标板,采用生物素标记抗鸡蛋过敏原总蛋白抗体、Eu3+标记的链酶亲和素和以β-二酮体为主的增强液等试剂,建立双抗夹心TRFIA方法,用于检测10种食品中是否舍有鸡蛋蛋白成分.结果:鸡蛋总蛋白SDS-PAGE显示带大致有10条,其中主要条带有4条,分子量分别为71、55、38、14kDa;成功地研制出双抗体夹心TRFIA法检测食品中鸡蛋过敏原蛋白成分,具有特异性,其最低检出限为0.625ng/mL,标准曲线在12.5～640ng/mL范围内线性良好;8种食品检测结果与食物过敏原标签标注内容相符,而2种标示不详的食品检测结果均呈现阳性.结论:初步建立了检测食品中鸡蛋过敏原蛋白成分的双抗体夹心TRFIA,具有较好的特异性和灵敏度;该方法对于未标注鸡蛋过敏原成分的食品检测具有一定的实际应用价值.     

HPLC同时测定豆制品中常见的3种食品添加剂

采用反相高效液相色谱法快速、准确测定豆制品中的苯甲酸、山梨酸和糖精钠。3种添加剂在Zorbax sb-C18色谱柱上分离,甲醇-乙酸铵溶液(5∶95,V∶V)为流动相洗脱,流速1.0mL/min,15min内实现良好分离。方法检出限为0.5mg/kg,变异系数为0.67%～1.23%,回收率在97.7%～99.7%。该方法简便准确,适合豆制品的日常检测。