干燥方法对乳蛋白氧化及机体氧化还原状态的影响

目的:研究乳蛋白经过干燥后,乳蛋白氧化及对机体氧化还原状态的影响.方法:通过不同进风温度(160、170、180℃)对全脂乳和脱脂乳进行喷雾干燥及全脂乳的冷冻干燥处理,测定其羰基、巯基含量.小鼠分为6组,分别灌胃原奶、喷雾干燥不同温度乳粉、脱脂乳粉及冷冻干燥乳粉,测定0、30、60、90、120min血液中自由基水平,测定60、90min后小鼠肝脏、空肠、十二指肠、胃组织抗氧化能力指标(丙二醛MDA、总抗氧化能力T-AOC、GSH/GSSG).结果:乳蛋白经过喷雾干燥及冷冻干燥处理后,羰基含量随温度的上升及脂肪含量的增多显著上升(p＜0.05),巯基含量呈下降趋势.冷冻干燥组羰基含量比全脂喷雾干燥组低,巯基与之相比呈上升趋势.小鼠血液自由基的最高峰出现在灌胃90min时,灌胃喷雾干燥乳粉自由基含量显著高于其他组(p＜0.05),并随温度的升高而增高.小鼠喷雾干燥组中组织总抗氧化能力T-AOC和谷胱甘肽比值GSH/GSSG均低于其他各组,丙二醛(MDA)含量高于别组.结论:喷雾干燥等加工方法会导致乳蛋白发生不同程度的氧化,导致乳蛋白理化性质的变化,短期灌胃氧化蛋白会引起机体的氧化应激,降低组织抗氧化的防御能力.     

奶粉水解蛋白掺假的定性检测

研究乳粉中水解蛋白掺假定性快速检测方法,通过向复原乳中添加水解蛋白,试样中的水解蛋白与苦味酸反应生成沉淀,根据沉淀圈的浑浊程度判断有无掺假.该方法用于检测乳粉及原料乳中水解蛋白含量在0.5％以上的定性检测,此方法操作简单,快速方便,时间短,广泛用于乳粉检测及原料乳的收购.     

喷雾干燥温度对牦牛乳粉溶解特性的影响

为探讨喷雾干燥温度对牦牛乳粉溶解特性的影响,分析了在进风温度（出口温度）分别为130（56）、150 （64）、170（73）、190（81）、210（90）℃条件下喷雾干燥牦牛乳粉样品的溶解特性参数,并通过相关性分析对其进行聚类分析。结果表明：喷雾干燥温度对牦牛乳粉的溶解特具有显著影响（P＜0.05）,170（73）℃下喷雾干燥牦牛乳粉样品具有较高的水合能力、堆积密度、溶解度,较小的休止角和分散时间,具有较好的溶解特性,优于在其他温度下干燥牦牛乳粉的溶解特性;牦牛乳粉溶解特性参数间具有较好的相关性,聚类分析可实现对不同喷雾干燥温度条件下牦牛乳粉溶解特性的区分,为对喷雾干燥温度的评价提供参考。     

温度与复原度对巴氏杀菌乳中糠氨酸含量影响的研究

采用农业部标准NY/T 939-2005中的方法对巴氏杀菌乳中的糠氨酸进行检测,测定不同杀菌温度及不同复原度条件下牛乳中的糠氨酸含量。对糠氨酸含量随温度和复原度的变化规律进行研究,得到不同复原度的复原乳在不同温度下的糠氨酸含量数据,并对数据进行分析处理,制定了不同温度下的糠氨酸与复原度的线性回归方程。研究结果可对复原乳进行的定性判别和定量检测,以避免对复原乳的误判。     

温度及光照对婴幼儿配方乳粉中VA、VD稳定性的影响

为研究不同温度条件下婴幼儿配方乳粉中VA和VD的稳定性,分别考察其在25、40、60 ℃及80 ℃储藏条件下乳粉中的含量变化;通过采用透光和避光2种方式储存的乳粉进行光照试验,研究了光照对乳粉中VA和VD稳定性的影响。结果表明,25 ℃储藏条件下,乳粉中VA和VD含量均无明显变化;40、60 ℃和80 ℃条件下,VA含量有不同程度的降解,而VD无明显变化。光照条件下,乳粉中VA和VD均发生明显降解,其中VA含量在光照1 h后损失达50%,VD含量在光照12 h后损失了将近50%。     

关于喷雾干燥影响乳粉溶解度的研究

乳粉的溶解度是判定其质量好坏的重要指标。因为喷雾干燥工序对乳粉溶解度影响较大,本文通过正变试验确定了喷雾干燥工序中浓缩奶浓度、进风温度和高压泵压强三个主要工艺参数对乳粉溶解度的影响。通过试验可知影响乳粉溶解度好坏的因素主次排序为:高压汞压强>进风温度>浓奶浓度。     

乳蛋白中可利用赖氨酸及其封闭产物含量的测定

乳蛋白在热处理条件下,其中的氨基酸与还原糖发生美拉德反应,使得蛋白中可利用氨基酸残基发生锁闭从而降低蛋白的营养价值。本研究以可利用赖氨酸、封闭产物呋喃素与羧甲基赖氨酸(CML)含量作为美拉德反应的主要指标,建立并优化了乳蛋白样品中可利用赖氨酸、呋喃素和CML的检测方法并完成方法验证。结果表明所建方法均具有良好的线性、精密度与准确度,适用于乳蛋白样品中上述3种指标的检测。并采用该方法对6种不同热处理方式的乳制品,包括:巴氏杀菌全脂牛奶、巴氏杀菌脱脂牛奶、超高温瞬时灭菌(UHT)全脂牛奶、超高温瞬时灭菌(UHT)脱脂牛奶、低热脱脂乳粉(LH-SMP)、中热脱脂乳粉(MH-SMP)中可利用赖氨酸、呋喃素以及CML的含量进行测定。结果显示不同乳制品中的美拉德反应水平所受到热处理方式的影响:(1)液态奶中可利用赖氨酸含量高于乳粉而呋喃素与CML含量低于乳粉(P0.01);(2)LH-SMP中可利用赖氨酸含量高于MH-SMP(P0.05)而呋喃素含量低于MH-SMP(P0.01)。因此,在乳品加工过程中较低温度的热处理工艺有利于保留牛乳中的可利用赖氨酸并减少美拉德反应产物的生成,有助于更好的保留乳蛋白的营养价值。     

重量法结合氨基酸分析法测定婴幼儿配方乳粉中小分子蛋白肽含量

目的:建立婴幼儿配方乳粉中小分子肽含量的定量分析方法。方法:分别采用凯氏定氮法、重量法、离子交换色谱等方法测定婴幼儿配方乳粉中总蛋白、高分子蛋白和游离氨基酸含量,通过计算求得小分子蛋白肽含量。结果:高分子蛋白检测精密度RSD (n=6)为0.74%;17种氨基酸回收率为91.0%～103.2%,检测结果的相对偏差为0.6%～2.5%;小分子蛋白肽添加回收率为95.2%～98.2%。结论:所建方法精密度和回收率良好,可用于婴幼儿配方乳粉中小分子肽含量的测定。     

关于复原乳标识标注有关问题的通知

各省、自治区、直辖市质量技术监督局:《国务院办公厅关于加强液态奶生产经营管理的通知》(以下简称《通知》)要求:在巴氏杀菌乳生产中不允许添加复原乳,大力提倡和鼓励在灭菌乳生产中全部使用生鲜乳。自2005年10月15日起,用乳粉或在生鲜乳中添加部分乳粉生产的酸牛乳、灭菌乳必须标注“复原乳”,10月15日前生产但未标注"复原乳"的奶制品允许销售至2006年1月15日。为落实《通知》精神,规范复原乳标识标注,现就有关问题通知如下:一、使用复原乳生产加工液体乳标签必须标识的内容对于用乳粉或在生鲜乳中添加部分乳粉生产的酸牛乳、灭菌乳,其产…     

食品中含硫氨基酸含量测定前处理条件的研究

为了建立食品中含硫氨基酸含量测定的前处理条件,该文选取了玉米粉、黄豆、鱼肉、婴幼儿配方乳粉、全蛋粉5种食品作为样品,对比了氧化剂不同配制比例、氧化时间和氧化温度对不同食品中含硫氨基酸测定结果的影响。结果发现,由于食品基质的不同,氧化剂配制比例、氧化时间和氧化温度对这5种食品中含硫氨基酸含量的测定结果产生了不同的影响。根据结果数据分析,在氧化剂配制比例为1∶9(体积比),氧化温度为0℃,氧化时间为16 h条件下,该文中提到5种食品都可以得到较好的实验结果。对于玉米粉、鱼肉和婴幼儿配方食品也可以选取氧化剂配制比例为1∶9(体积比),50℃下氧化5 min作为氧化条件。     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.     

Review of techniques to manufacture micro-hydrogel particles for the food industry and their applications

Microgels are ‘soft’ microscopic cross-linked polymeric particles that are being increasingly exploited in a variety of industries for rheology control, encapsulation and targeted delivery. They are valued because of the ability to tune their functionality to address specific applications in oil recovery, coatings, drug delivery, cosmetics, personal care and foods. Food microgels are typically biopolymer hydrogels in the form of microspheres, nanospheres (also called nanogels), spheroids and fibres. The utilisation of engineered microgels in foods has so far been limited, despite their great potential to address several needs in the food industry, including: satiety control, encapsulation of phytonutrients and prebiotics, texture control for healthier food formulations (e.g. reduced fat products), and targeting delivery to specific areas in the digestive tract. We review the scientific and patent literature on the utilisation and manufacturing methods for producing microgels with an emphasis on micro-hydrogels for food applications.     

12—A CRITIQUE OF SOME HYPOTHESES RELATING TO THE HETEROGENEITY OF THE HIGH-SULPHUR PROTEINS OF WOOL

Joubert and Burns prepared a large number of fractions from the high-sulphur proteins of wool and estimated their molecular weights and amino-acid compositions. Their data have been re-examined in order to look for statistically significant interrelations between amino acids and between the proportion of various amino acids and molecular weight. Statistical analysis of the data is also used to examine the credibility of some hypotheses concerning the mechanism of keratin biosynthesis and to provide further evidence for the existence of families of proteins within the high-sulphur fractions of wool.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of     

The Latest Data about Development of Chinese Printing Industry in 2013

In the 2014 China（Shanghai）International Printing Week,Director Wang Yanbin released the latest data about development of Chinese printing industry in 2013.According to statistics,in 2013,the total output value of Chinese printing industry exceeded 1trillion Yuan for the first time,reaching 1.03985 trillion Yuan.There were 105,000 printing enterprises in China,employees were 3.415 million.The total asset was 1.06247 trillion Yuan;     

The State Council Issued "Directory of Government Approved Investment Projects(2013 Edition)"

正On December 2nd,2013,the State Council issued the notification of"Directory of Government Approved Investment Projects(2013 Edition)"(hereafter referred to as"notification").It is pointed out in the"notification"that in order to further deepen reforms in investment systems and administrative examination and approval systems,simplify administrative procedures and delegate powers to lower levels,earnestly     

China textile machinery: taking off in progress

正Among the 1600 exhibitors who take apart in the ITMA ASIA+CITME2014 2/3 are Chinese manufactures.If the numerous figures failed to attract your attention,the increase of quality should draw your focus.To adopt the demand of developing textile machine market,domestic textile machinery enterprises now follow the slogan of"technology drives development"to enhance product competitiveness.Our domestic sellers will showcase product ranging from spinning,weaving,dyeing and printing,     

Top Ten News of China's Paper Industry 2013

On December 24th, 2013, the meeting on the selection of top 10 news of China＇s paper industry 2013 sponsored by 〈China Paper Newsletters〉 was held in Beijing. The yearly selection of the top l0 news, which began in 2000, has become a brand activity widely recognized in the industry thanks to the support from the authorities at all levels and public participation.