食品添加剂对罗非鱼蛋白自溶作用的影响

以水解液中氨基态氮、可溶性蛋白及可溶性固形物含量为指标,研究13 种常用食品添加剂对罗非鱼蛋白自溶作用的影响。结果表明：在葡萄糖≤ 2.00%、苯甲酸钠≤ 0.02%、亚硫酸钠≤ 0.03%、氯化钠≤ 10%、柠檬酸≤ 0.10% 的添加量范围内,对罗非鱼蛋白自溶有一定的促进作用,超过该范围则显示抑制作用;氯化钙、抗坏血酸则对蛋白自溶具有较好的促进作用;乳酸≥ 1.00%、酒石酸≥ 0.10% 、乙二胺四乙酸二钠(EDTA-2Na)≥ 0.02%的添加量对罗非鱼蛋白自溶有一定的抑制作用;氯化钾、硫酸镁、氯化镁对罗非鱼蛋白自溶无明显作用。添加苯甲酸钠、柠檬酸、乳酸及酒石酸可使罗非鱼蛋白水解液腥味减少,并减缓其腐败变质。     

Control of grapevine powdery mildew with mineral oil: an assessment of oil concentration and spray volume

DC Tron, a highly refined mineral oil containing patented additives to prevent UV light induced breakdown, was evaluated in vineyards for control of powdery mildew. DC Tron suppressed development of powdery mildew but was not as effective as the conventional fungicide Topas. Of the oil treatments the 1% rate applied in spray volumes of 1000 L/ha was the most efficient. Poor control was achieved with oil rates less than 1% as well as spray volumes less than 1000 L/ha whereas phytotoxicity developed in many cases at concentrations greater than 1% or spray volumes higher than 1000 L/ha. In all oil treatments, powdery mildew developed less in leaves than on bunches. This difference was attributed to poor spray coverage on bunches compared to leaves.     

Milk fever in dairy cows. VIII. Effect of injected vitamin D3 and calcium and phosphorus intake on incidence.

In a field trial, effects of prepartal intermuscular injection of 10 million units of vitamin D3 on incidence of milk fever were examined both in relation to intake of calcium and phosphorous during the dry period and previous history of milk fever. Based upon intake of calcium and phosphorus cooperating herds were grouped as feeding: 1) greater than .53% of the total ration dry matter as calcium and greater than .28% as phosphorus: 2) less than .47% as calcium and greater than .28% as phosphorus; 3) greater than .47% to less than .53% as calcium and greater than .22% to less than .28% as phosphorus. Injections of vitamin D3 given approximately 1 wk prepartum reduced incidence of milk fever in cows with previous history of milk fever in all three groups but had no effect in cows with no previous milk fever. Incidence of milk fever was lower in group 3 than for cows of groups 1 and 2 with previous milk fever and than for cows of group 1 with no previous history. The results indicate that careful control of calcium and phosphorus intake during the dry period at .5% calcium and .25% phosphorus of the dry matter of the total ration will limit milk fever incidence to about 10%. Injections of vitamin D3 as described will reduce inicidence of milk fever further in cows with previous milk fever but not in cows with no previous milk fever.     

弹条扣件用弹簧钢盘条表面处理工艺

弹条扣件是高速铁路轨道结构的重要组成部件.介绍弹条用原材料60Si2CrA的化学成分及成品技术要求,抗拉强度不低于1 764 MPa,屈服强度不低于1 568 MPa,断后伸长率不低于6%,断面收缩率不低于20%.弹条专用弹簧钢盘条的表面处理包括酸洗、高压水冲洗、水洗、中和等工艺,盘条酸洗采用盐酸,温度为室温,第1个槽...     

玉米低聚肽硒螯合物的理化性质及稳定性

以玉米低聚肽和亚硒酸钠为原料制备玉米低聚肽硒螯合物,对其水分、酸溶蛋白、总氮(粗蛋白)、分子量分布进行了考察,然后以螯合态的硒含量和分子量分布为指标,研究了螯合物对温度、pH、消化方式的稳定性,结果表明:玉米低聚肽硒螯合物的螯合率为54.25%±0.24%,得率为53.02%±0.17%,水分含量为7.46%±0.07%,酸溶蛋白含量为16.38%±0.03%,总氮含量为21.17%±0.35%,分子量低于1000 u的比例为85.1512%。在25~100℃环境下,分子量低于1000 u的比例变化不超过7%,硒含量最低不小于70%;在pH=2~12的环境下,分子量低于1000 u的比例变化最高不超过16%,硒含量最低仍在75%以上;在经过胃蛋白酶、胰蛋白酶和两种酶的消化后,分子量低于1000 u的比例分别增加5%、7%和8%,硒含量最低仍在70%以上。这说明玉米低聚肽硒螯合物具有一定的热稳定性、酸碱稳定性和消化稳定性。     

氧化镁铵盐法制备高纯过氧化镁

在氯化铵溶液体系中,以氧化镁,过氧化氢为原料,制备高纯过氧化镁。研究表明采用氧化镁活性大于100,氯化铵/氧化镁不小于10%,过氧化氢∶氧化镁不小于4∶1,反应温度大于40℃情况下,反应时间不小于30 min,可制备出纯度大于90%的过氧化镁。     

Level of thiamine diphosphate in the liver of tumor-bearing animals kept on a diet including an excessive amount of vitamin B 1

In mice bearing solid Ehrlich's carcinoma, food consumption did not differ from that in intact animals throughout the whole experiment. In mice with Ehrlich's ascites carcinoma and in rats bearing Walker's carcinosarcoma 256, the daily feed consumption decreased 2-fold by the terminal period of tumor development. In rats, the amount of vitamin B1, calculated per unit of the feed consumed, exceeded the daily requirements of vitamin B1. The content of thiamine diphosphate in the liver of tumor-bearing animals was 35% as reduced whatever the method of inoculation and site of tumor development (under the skin or inside the abdominal cavity). In rats with Walker's carcinosarcoma 256, transketolase activity was 17% as lowered (P less than 0.01). In mice with Ehrlich's carcinoma, the activity of the enzyme was 21% as decreased (P less than 0.01; an ascitic variety) or 17% as decreased (P less than 0.01; subcutaneously inoculated tumor).     

葡萄籽提取物主要质量指标研究

目的 为了确定保健食品原料葡萄籽提取物主要质量指标的参数,本实验搜集30批次葡萄籽提取物并测定了其主要质量指标。方法 采用紫外分光光度法测定了葡萄籽提取物的原花青素值、多酚含量,采用液相色谱法测定了儿茶素、表儿茶素含量,参照食品安全国家标准,测定了灰分、水分、微生物指标(菌落总数、大肠杆菌、沙门氏菌、酵母菌、霉菌)、重金属和溶剂残留等主要质量指标。结果 所有葡萄籽提取物样品中原花青素值范围在81.1%至108.2%之间;儿茶素及表儿茶素含量范围为1.12%至8.58%;多酚含量在70.1%至106.1%之间;灰分含量范围在0.2%至1.8%;水分含量范围在3.76%至5.23%。变异系数由大到小的顺序为：儿茶素、表儿茶素＞灰分＞多酚＞水分＞原花青素值。所有样品菌落总数均小于10 CFU/g,大肠杆菌、沙门氏菌均未检出,酵母菌、霉菌总数均小于10 CFU/g,甲醇、乙醇残留均小于2 mg/kg,重金属(以pb计)小于0.05 mg/kg。结论 与我国目前唯一相关标准对比,所有质量指标中,仅原花青素值的限量需要进一步调整。     

The role of coagulase-negative Staphylococcus spp. and associated somatic cell counts in the ovine mammary gland

The somatic cell count (SCC) of ewes' milk was determined by the Fossomatic method and compared with the bacteriological status of the mammary gland. Of 366 samples from uninfected udder halves, 64.5% had SCC less than 50 x 10(3) cells/ml, 81.9% had SCC less than 250 x 10(3), and 92.4% had less than 500 x 10(3) cells/ml. Of 130 bacteriologically positive samples, 91.1% had SCC more than 500 x 10(3) cells/ml and 98.8% more than 250 x 10(3). Of the examined milk samples 26.2% showed positive bacteriology during the single sampling. The most frequent pathogens isolated from the milk samples were coagulase-negative staphylococci. Considering our results, 250 x 10(3) cells/ml should be the threshold value, which could be regarded as the upper limit for normal SCC of ewes' milk.     

我国主要产烟省烤烟元素组成和化学品质评价

分别于1993年1994年在云南、贵州、河南、山东、辽宁和安徽省采用随机取样的方法,对我国近两年来烟叶化学组成进行了比较全面的分析。结果表明:我国烟叶营养元素平均含量整体上均处于正常范围,但不同地方有不同的问题。南方烟区氮肥使用的不合理情况比北方严重,烟叶钙含量过高,南方少数地区可能会因土壤绝对镁含量低而缺镁,北方石灰性土壤有可能因钙镁比例失调而出现缺镁,云贵硫含量超标样品高达20%以上。个别地方烟叶氯含量大于1.5%,但少数南方烟区部分烟叶的氯含量低于0.1%,应适当补氯。贵州、云南、山东等省的烟叶匀有50%以上烟叶铜含量低于15mg/kg,应考虑施铜,河南有些烟叶的锌含量低到无法检测,应补锌,贵州烟叶硼含量约有一半低于15mg/kg,可以考虑补硼。我国烟叶钠和铝的含量均是以河南为最高,但镉的含量却是云南和贵州高于其它省份。烟碱和还原糖整体上均处于正常范围,均以河南烟叶最接近美国认定的最佳含量,云南和贵州部分中部烟叶烟碱含量大于5%和6%,严重超标,贵州烟叶还原糖含量变异最大。      

辽宁省大米中甲基汞的安全性评价

目的：为了给辽宁地区大米安全食用、质量管理提供可靠依据,对辽宁地区的4个城市120批次样品中甲基汞进行液相色谱-原子荧光联用检测,根据检测数据运用风险评估软件RISK@7.5、急性膳食摄入风险评估%ARfD和慢性膳食摄入风险评估%ADI等指标对辽宁地区大米进行甲基汞膳食摄入风险评估,用大份餐LP、每日允许摄入量计算最大残留限量估计值(eMRL)。结果表明,辽宁地区甲基汞的检出数量为26,检出率为21.7%,超标样品量为2,超标率为1.67%,建立辽宁地区大米中甲基汞的风险评估模型,通过模型可以模拟出辽宁地区大米中甲基汞的平均流行率=21.4%,推断出辽宁地区一般大型商场超级市场的大米中检出甲基汞种类数量小于6种的概率小于5%,大于12种的概率小于5%,一般中、小型超级市场及早市中大米检出甲基汞种类小于1种的概率小于5%,大于7种的概率小于5%。其中至少有一种样品甲基汞检出的概率为95.6%。辽宁地区一般大型商场超市大米中甲基汞超标种类小于0种的概率小于5%大于3种的概率小于5%,一般为1-3种,辽宁地区一般中、小市场及早市中大米产品中甲基汞超标种类大于0种的概率小于5%而大于1种的概率小于5%,一般为1种。甲基汞的急性膳食摄入风险(%ARfD)为0.9382%、慢性膳食摄入风险评估%ADI甲基汞为0.11%,风险均为可接受,最大残留估计限量值为0.829mg/kg。     

Marbling effects on quality characteristics of pork loin chops: consumer purchase intent, visual and sensory characteristics

These studies evaluated whether consumers detect differences among pork loin chops with low (1.05% fat), medium (2.33%) and high (3.46%) amounts of marbling when visually evaluated, when prepared under controlled conditions, and when prepared at home. Highly marbled chops appeared lighter colored, less lean, had less acceptable appearance, and were less likely to be purchased than leaner chops; they were juicier, more tender, oily and flavorful than leaner chops. These results indicate a disparity between purchase intent based on visual evaluation, and quality attributes of the cooked product. When evaluated at home, consumers rated the chops they chose (40% low, 40% medium marbled) as more tender, juicy and flavorful than chops they evaluated "blind" on-site suggesting that additional factors have a significant impact on stated purchase intent.     

泰山白首乌药材质量标准初步研究

目的研究山东著名中药材泰山白首乌各项质量标准,旨在为建立泰山白首乌GAP种植和药材的质量评价提供科学资料与依据。方法按《中国药典》2005年版附录IXH水分测定第一法、附录IXK灰分测定法、附录XA浸出物测定法对中药材泰山白首乌的水分、总灰分、水溶性浸出物和醇溶性浸出物进行含量测定,采用傅立叶变换红外光谱法[1],对其进行红外指纹图谱的研究,并用高效液相色谱法测定泰山白首乌二苯酮[2]。结论中药材白首乌的质量标准是含水量以不超过10%,总灰分不得高于4%,冷浸法水溶性浸出物量不得低于20%,95%乙醇浸出物量不得低于11%,白首乌二苯酮总量不得少于4×10-3%。     

蒽酮法测定木质素磺酸盐减水剂中总糖含量的研究

首次利用蒽酮法测定木质素磺酸盐减水剂中的总糖含量,并通过方法的线性、精密度、回收率试验以及方法的对照试验,结果表明该方法的相对标准偏差RSD小于5%,方法的回收率均在95.7%～104.7%之间,与国标法的检测结果比较,结果相对偏差D小于4.96%,因此用蒽酮法测定木质素磺酸盐中总糖含量是可行的,而且方法操作简单、方便.     

基于质量评价的孔雀石绿快检试剂盒筛选策略

目的建立快速筛选出技术指标合格的市售水产品孔雀石绿残留快速检测试剂盒的方法。方法选用5种市售孔雀石绿快检试剂盒比较其操作步骤、检测时间、提取效率,同时参考SN/T 2775-2011和GB/T19857-2005进行灵敏度、特异性、假阴性率与假阳性率等技术指标测试,提出基于质量评价的试剂盒快速筛选策略。结果 5个品牌的孔雀石绿检测试剂盒质量参差不齐,品牌A、B与C的灵敏度99%,特异性≥85%、假阴性率 1%,假阳性率≤15%,不符合试剂盒评价标准;品牌D与品牌E的灵敏度≥99%、特异性≥85%、假阴性率≤1%,假阳性率≤15%,符合试剂盒评价标准。结论对市场销售的水产品中孔雀石绿残留检测试剂盒要进行采购前、采购中的质量评价,在评价时综合考虑操作步骤的简便性、时效性、评价批次、样品来源等,同时兼顾灵敏度、特异性、假阴性率与假阳性率技术指标,快速筛选出符合标准的试剂盒。     

COMPARISON OF PUDDING, SOUP AND CUSTARD PREPARED FROM SOYMILK OR LOWFAT MILK

Soymilk (4% and 6% solids) was substituted for lowfat milk in chocolate pudding, tomato soup and baked egg custard. The substitution of soymilk produced a less viscous pudding that was darker in color and less sweet than that made with lowfat milk. Pudding prepared with 6% solids soymilk was also less smooth than the control. In tomato soup, soymilk increased viscosity and produced a lighter color product with a less intense tomato flavor than soup made with lowfat milk. Baked custard prepared with soymilk was less smooth, darker in color and less sweet. All products were judged to have less characteristic flavors than controls.     

Evaluation of high protein oat forage for dairy cattle

Spear, a high protein oat variety, was evaluated during 2 consecutive yr for yields of forage dry matter and for feeding value as a silage to heifers, steers, and lactating cows. In yr 1 and 2, Spear yielded 7% and 13% less forage dry matter per hectare than Burnett, a comparative oat variety. Crude protein contents in silages were similar for varieties both years. In yr 1, Holstein heifers fed high protein and medium protein oat silages gained the same amount of weight but less weight than heifers fed alfalfa-brome hay. In a total collection digestion trial with six lactating cows, digestibilities of Spear were less than Burnett oat silage or alfalfa-brome hay. In yr 2, Spear and Burnett silages were fed ad libitum without a concentrate mixture to seven Holstein heifers each. Average daily gains were higher with Spear than Burnett. Apparent digestibilities as determined with steers tended to be less for Spear than Burnett. Dry matter intakes, milk yield, and composition were similar in a switchback lactation trial with ten cows fed spear or Burnett in oat silage supplemented with a concentrate at 1 kg per 3 kg milk produced.     

连续式杏果去核机设计

研究了杏子的物理特征,并依据特征采用十字式刀头冲压的原理设计了一种冲压式半自动连续去杏核装置。该装置采用凸轮分割器及滑块装置组合的设计方式,可实现装杏子的链板一走一停,并且在链板每次间歇停顿时,冲刀完成1次冲压去核的动作。经试验验证:利用该装置对杏果进行去核处理,去核率达到96%以上,杏肉带出率2.4%,杏核残留率3%。     

高效毛细管电泳法测定羊肚菌(Morchella sextelata)菌丝中单核苷类化合物含量的研究

建立了羊肚菌Morchella sextelata菌丝中单核苷类化合物的含量高效毛细管电泳测定方法。确定采用菌粉按照1∶30加水先超声后水浴的方法提取样品,最佳电泳条件为pH为9.4的50 mmol/L硼砂缓冲液以及1.0 mg/mL的β-环糊精为运行缓冲液,分离电压为25 kV,进样时间为8 s。在最佳电泳条件下,5种标准品在20 min内得到了分离,精密度试验中同一批次三次进样的标准品混合物迁移时间RSD均小于0.89%,峰面积RSD均小于2.9%;在稳定性试验中,5种标准品在8 h内迁移时间RSD均小于0.61%,峰面积RSD均小于4.73%。表明标准品在8 h内具有良好的稳定性。结果表明:该方法能够测定出羊肚菌中含有3-脱氧腺苷、腺苷和尿苷。通过建立标准曲线测得羊肚菌菌丝中3-脱氧腺苷含量为4.38 mg/g,腺苷含量为6.6 mg/g,尿苷含量为7.8 mg/g。3种单核苷类化合物的回收率在95.5~100.8%之间,且RSD小于4.9%(n=3)。表明该方法适用于羊肚菌Morchella sextelata菌丝中的单核苷类化合物的测定。     

烟草薄片丝平均长度快速测定方法

根据烟草薄片较天然烟叶均质化程度高的特点,建立了一种新的烟草薄片丝平均长度快速测定方法,并对其检测结果准确性、精确性、平行性进行验证。结果表明:该方法用于检测烟草薄片丝平均长度准确性高,与被测量值真值之间误差小于3%、精确性误差小于1%、平行性误差小于1%。