Sodium, potassium and calcium content in regional dishes consumed in Sonora, Mexico

The content of sodium, potassium and calcium was determined in 15 regional dishes, by atomic absorption spectrophotometry. The Na:K ratio was high in most of the dishes due to the high sodium content and low content of potassium found. The higher sources of the studied minerals were "tortilla de harina" with 1,372.8 mg/100 g of sodium; "chorizo con papas" with 466 mg/100 g of potassium, and "calabacitas con queso" with 244.1 mg/100 g of calcium. Two of the dishes considered as desserts, "capirotada" and "arroz con leche" showed the lowest Na:K ratio (0.66 and 0.81, respectively).     

Comparative study of the chemical composition, amino acid content and nutritive value of fresh, frozen, salted, dried and rehydrated hake

The main purpose of this study was to evaluate the influence of the freezing, on the one hand, and salting/drying processes on the other, on the nutritional value of the hake. Data on the chemical composition of fresh, quick-freezing, and salted/dried/rehydrated hake fillets is given, as well as data on the mineral composition, identification of fatty acids in the lipidic extract, and amino acid composition of their proteins. The EUD values (enzymatic ultrafiltrate digest) in all three types of samples were then calculated, thereby determining the nutritional value of the hake after each process.     

新型果蔬类消毒洗涤剂的研究和应用

通过系统的药剂学和药理学的研究和筛选,开发出更安全环保的蔬菜水果和食品类消毒洗涤剂。采用以聚六亚甲基双胍盐酸盐为主要杀菌因子的新一代果蔬类消毒洗涤剂与现有产品相比具有明显的优势,试验结果证明,爱特福家家果蔬消毒剂在100倍稀释液情况下作用5min,对金黄色葡萄球菌ATCC6538、大肠杆菌8099杀灭率对数值均大于5;20℃±1℃环境条件下,爱特福家家果蔬消毒剂100倍稀释液浸泡消毒5min,对黄瓜表面人工污染的大肠杆菌杀灭对数值均大于3。样品经37℃下存放90天,有效成分聚六亚甲基双胍盐酸盐下降率均小于2%。稳定性符合卫生部《消毒技术规范》2002年版的要求。经检验,样品对雌雄小鼠急性经口LD50值均大于5000mg/kg,该样品认定属实际无毒级。聚六亚甲基双胍盐酸盐为主成分的果蔬类消毒洗涤剂具有杀菌效果可靠、环保、稳定性好和使用方便等优点,可以高倍数稀释使用,经济合算,利于大量推广使用。产品被推荐用在水果蔬菜和食品加工过程的消毒洗涤。     

Determination of the antioxidant capacity of flavonoids in fruits and fresh and thermicaly treated vegetables

The main objective of the work was to determine the antioxidant capacity of the flavonoids in red apples with and without skin, strawberries, tomatoes and fresh onions and thermally treated: humid heat (boiled and vapor), dry heat (oven) and high frequency (microwaves). The measurement was carried out in a fluorescence spectroscopy and the statistical analysis through the Variance and Test of Duncan. The results indicate that the antioxidant capacity of the flavonoids of red apples with and without skin, strawberries, tomatoes and onions were of 0.259, 0.267, 0.278, 0.165 and 0.223 Equivalent uM Trolox. These values diminished after the thermal treatment at a higher degree by dry heat at 0.128, 0.072, 0.077 and 0.048 Equivalent uM Trolox respectively and 0.146 Equivalent uM Trolox in the boiled onion. The flavonoids showed a higher antioxidant activity in fresh state, and their activity diminished under heat (cooking).     

Changes in the nitrate and nitrite contents of fresh vegetables during cultivation and post-harvest storage

Nitrate and nitrite levels in both germinating seeds and growing vegetables were determined for the following vegetables: short-petioled cabbage (Brassica chinensis), long-footed cabbage (Brassica chinensis var. communis), field mustard (Brassica campestris), broad-leaf mustard (Brassica juncea var. rugosa) and water convolvulus (I pomoea aquatica Forsk). The seeds contained 16–32 ppm nitrogen in the form of nitrate and 0·3–0·8 ppm nitrogen in the form of nitrite. The nitrate nitrogen concentrations of the growing vegetables varied between 300 and 1200 ppm depending on species and their nitrite nitrogen contents were about 0·3–3 ppm. The nitrogen fertilizer urea seemed to induce remarkable nitrate accumulation in the growing vegetables. The influence of storage at different temperatures on the nitrate and nitrite contents of fresh and homogenized vegetables was studied. During the first few days storage temperatures of −10 or 2°C little change in the nitrate and nitrite concentrations was found. However during the first few days of storage at 26 or 32°C the nitrite concentration increased considerably while the nitrate concentration decreased. Nitrate reductase and nitrite reductase activities in the vegetables were estimated at various stages of growth but no significant changes in activity were observed.In view of the effect of dietary nitrate on salivary nitrite formation and on the endogenous formation of carcinogenic N-nitroso compounds. we suggest that more effort should be put into developing methods of cultivating low-nitrate vegetables.     

褐土区麦田土壤有效钾及施钾指标研究

用ASI法对褐土区麦田基础土壤进行分析,以不施钾素区(NP)与推荐氮磷钾施肥区(NPK)冬小麦相对产量＜50％、50％ ～ 75％、＞75％ ～ 95％和＞95％为指标,将土壤有效钾含量分成极低、低、中、高4个等级,根据指标确定钾肥推荐施用量分别为K2O 120、90、60、45 kg/hm2.     

A voltammetric approach to an estimate of metal release from tinplate promoted by ligands present in canned vegetables

A linear sweep voltammetric (LSV) approach is proposed for achieving rapid information on metal release from tinned containers into preserved vegetables. Chopped tomato and pea preserves were chosen as prototypes for acid and nearly neutral canned food, respectively. Metal release in these vegetables tinned into both bare and lacquered containers was compared with that found in synthetic samples containing some organic complexing agents (acetic, ascorbic, citric, malic, oxalic, pyroglutamic acids) present in the vegetables considered, thus showing that some of these components affected markedly the metal release in bare cans. These ligands were concomitantly found to also affect LSV profiles recorded in parallel at Sn and Fe electrodes in synthetic samples, causing the starting potential for their oxidation to be lower, the higher the ligand activity of the species considered. The data indicated that metal release and starting potentials for metal discharge are strictly related, so that LSV is able to provide rapid and useful information on the nature of the protective effect (electrochemical or physical) of tin on the steel underlayer, as well as on the extent of Sn and Fe release.     

高锰酸钾容量法测定复混肥料中钾含量

由于采用GB/T8574—2002四苯硼酸钾重量法测定复混肥中K2O耗时较长,通过对高锰酸钾容量法测定复混肥料中氧化钾含量的研究和与国标法分析方法结果对比,表明该方法精密度、准确度可满足要求,耗时仅为国标法的1/2。     

对新鲜果蔬中维生素C的测定结果影响因素研究

针对果蔬中Vc含量的测定数据报导经常出入较大的现状,采用2,6-二氯靛酚滴定法测定常见的脐橙、蜜桔、苹果、猕猴桃、青枣、萝卜、西兰花、山楂、草莓等水果、蔬菜中维生素C含量,对维生素C的测定结果影响因素:样品色素、Vc稳定性、试剂、及滴定方式进行各种条件实验,探究测定维生素C含量的最佳方法。     

Socio-economic status,racial composition and the affordability of fresh fruits and vegetables in neighborhoods of a large rural region in Texas

Background  

Little is known about how affordability of healthy food varies with community characteristics in rural settings. We examined how the cost of fresh fruit and vegetables varies with the economic and demographic characteristics in six rural counties of Texas.     

肥料中氮、磷、钾的检测方法与实践经验

介绍常用肥料产品中氮、磷、钾的测定方法与实践经验,对从事肥料的质量检验人员有参考价值。     

Prevalence of Cyclospora sp., Cryptosporidium sp, microsporidia and fecal coliform determination in fresh fruit and vegetables consumed in Costa Rica

The presence of Cyclospora sp., Cryptosporidium sp. and microsporidia and the levels of fecal coliforms were determined in lettuce, parsley, cilantro, strawberries and blackberries acquired in local agricultural markets of the Central Valley of Costa Rica, in order to establish the possible transmission risk of these microorganisms and other pathogens from the consumption of these raw products. During the second semester of 2001 and the first of 2002, 50 different samples of each product, 25 taken in the dry season and 25 in the rainy season and coming from five different local agricultural markets were evaluated. The fecal coliforms count was done according to the technique recommended by Vanderzant & Splittstoesser. The parasite determination was done using Zielh Nielsen and Weber staining techniques from a sediment obtained through the rinse of the mentioned products, using sterile peptonated water 0.1% and centrifuging at 900 G for 15 min. One hundred per cent of vegetable samples had fecal coliforms and the greatest prevalence was obtained during the rainy season. Although all vegetables presented fecal coliforms in high concentrations, lettuce and cilantro presented statistical difference between rainy and dry season, being greater during the rainy season. Fecal coliforms were not detected in strawberries and blackberries probablydue to its low pH. All products evaluated presented, at least once, Cryptosporidium sp., Cyclospora sp. and microsporidia, showing the risk they represent to Public Health. Cryptosporidium was present in all products but strawberries. Microsporidia was present in all products except blackberries and Cyclospora was only isolated from lettuce during the dry season. These results show the importance of introducing in the country Good Agricultural Practices, especially due to the resistance of Cryptosporidium and Cyclospora to disinfecting agents.     

腐植酸钾对栽培五味子钾素含量及果实品质影响的研究

试验结果表明：腐植酸钾处理和硫酸钾 磷酸二氢钾处理下相比，五味子植株钾素含量差异不显著，相比对照处理钾素含量差异极显著。五味子果实在腐植酸钾处理和硫酸钾 磷酸二氢钾处理下相比对照果实中各种有效成分含量明显增加，并且腐植酸钾处理效果好于硫酸钾 磷酸二氢钾处理，对栽培五味子果实品质有明显改善作用。     

复混肥料中钾含量的快速测定

现行标准GB/T8574-2002中复混肥料钾含量采用四苯硼钾重量法,其准确度高,精密度好,但整个分析过程时间长达4 h。笔者通过查找文献资料得知四苯硼钾沉淀在温度小于265℃热稳定性很好,在160℃烘15 min以上其质量能恒定,分析结果准确。本实验对四苯硼钾采用30 min的烘干时间,使分析时间由4 h缩短为3 h。采用本法使原来每班只分析1次钾含量,改为分析2次,从而加强了钾含量的控制分析。1实验部分称取含氧化钾约400 mg的试样2～5 g(准至0.0002 g),置于250mL锥形瓶中,加约150mL水,加热煮沸30 min,冷却,转移到250 mL容量瓶中,用水稀释至刻度,混匀,…     

高钾有机悬浮肥的制备及其应用

为克服现有液体肥养分含量低、稳定性不高的缺点,以硝酸钾、磷酸二氢钾、尿素硝铵溶液、腐植酸等原料制备一种稳定性好的高钾有机悬浮型液体肥。通过单因素实验考察各工艺条件对悬浮肥稳定性的影响,并测定悬浮肥各项指标。结果表明,最佳工艺条件为助剂A用量4.0 g/L、消泡剂用量2.0 m L/L、研磨温度30~35℃、研磨时间45 min;在此条件下所得悬浮肥ρ(腐植酸)≥40 g/L、ρ(K_2O)≥285 g/L、ρ(总养分)≥500 g/L,悬浮率97%,热贮及冷贮性状稳定。黄瓜盆栽试验结果显示:与商品悬浮肥相比,自制悬浮肥可提高黄瓜可溶性糖、有机酸质量分数及产量,分别提高2.24%、0.85%、6.29%,效果略优于商品悬浮肥,具有推广使用价值。     

烧结法制备含低水溶钾的六钛酸钾晶须

研究了烧结法制备的六钛酸钾晶须（PTW）中的水溶钾.实验发现：水溶钾并不是来自PTW晶体的溶解;水溶钾溶出很缓慢;悬浮液pH值随水溶钾含量增加而升高.根据实验现象,从PTW生长机理分析认为PTW表面纳米缝隙中存在的微量K₂O导致水溶钾的产生.将烧结法制备的PTW在pH=4.5的溶液中浸泡8 h以上或者超声波清洗,可以获得水溶钾含量少于0.1‰（质量）,且满足复合材料使用要求的PTW.硅烷偶联剂(A186) 改性PTW不影响水溶钾析出,而无机包裹(SiO₂) PTW水溶钾析出减少.     

A new method for cement content determination of fresh concrete

A new method for the rapid determination of the cement content of fresh concrete based on flotation principles is presented. Results may be obtained within a time of 20 minutes and are independent of type of cement, grain-size of aggregate, age of the mix and the testing temperature. The method is specially suited for site application.     

氯化钾盐水中铁含量的分析

介绍了采用邻菲啰啉分光光度法与ICP等离子发射光谱仪法分析氯化钾盐水中铁含量的方法。