基于稳定同位素比值鉴别鱼翅干制品的品质

建立了基于元素分析-同位素比值质谱联用技术(EA-IRMS)分析鉴别鱼翅干制品品质的方法。在测定真鱼翅干制品的稳定碳、氮同位素组成的基础上,获得了真鱼翅干制品的δ13C值、δ15N值区间,通过对比待测样品与真鱼翅样品之间的差异,进而对待测样品进行真假鉴别。利用本方法共测定了24份鱼翅样品的碳氮同位素比值,结果发现:真鱼翅和假鱼翅的碳氮同位素比值有着显著差别,真鱼翅样品的δ13C和δ15N值分别分布在-16.553‰~-11.065‰和8.803‰~19.122‰之间;而假鱼翅样品的δ13C和δ15N值范围分别为-18.122‰~-16.507‰和6.253‰~7.313‰。通过碳氮同位素比值这两个指标的综合判定,得到24个鱼翅样品中有11个假鱼翅样品。该方法可简便、快速地鉴别鱼翅干制品的品质,同时可弥补PCR检测技术无法判断用鲨鱼下角料压模而成的鱼翅干制品的局限性。     

西藏青稞碳、氢、氧、氮同位素在不同生态域中差异性研究

目的研究青稞中稳定同位素在不同生态域的差异性。方法 2016年在西藏不同生态域种植不同基因型的青稞品种,利用同位素质谱仪测定不同生态域的青稞样品的稳定碳、氢、氧、氮同位素,结合Kolmogorov-Smirnov和Levene统计量分别检验所有数据的正态性和方差同质性,满足方差齐性时采用LSD多重比较,不满足方差齐性时采用Games-Howell多重比较法进行分析,解析不同生态域青稞样品中稳定碳、氢、氧、氮同位素。结果不同区域种植的青稞δ~(13)C值、δ~(15)N值、δ~(18)O值和δD值差异均极其显著(P0.01)。结论稳定碳、氢、氧、氮同位素指纹可用于青稞的产地溯源,可以进一步研究青稞中多元素组成特征及其用于青稞产地溯源的可行性。     

元素分析-同位素质谱法鉴定麦卢卡蜂蜜中碳-4植物糖掺假

目的建立元素分析-同位素质谱法(elementanalyzerstableisotopeproportionalmassspectrometry,EA-IRMS)鉴定麦卢卡蜂蜜中碳-4植物糖掺假的新方法。方法样品经前处理后,利用元素分析-同位素质谱仪测定蜂蜜的碳同位素比值δ~(13)C_H、蜂蜜中总蛋白质的碳同位素比值δ~(13)C_P、蜂蜜中花粉的碳同位素比值δ~(13)C_F。用麦卢卡蜂蜜中δ~(13)C值更为稳定的δ~(13)C_F值为标准,δ~(13)C_H值与其进行比较,参照GB/T 18932.1-2002《蜂蜜中碳-4植物糖含量测定方法稳定碳同位素比率法》计算方式,来建立新的计算麦卢卡蜂蜜中碳-4植物糖含量X(%)的计算方式。结果对纯正麦卢卡蜂蜜提出:0X(%)7,δ~(13)C_Fδ~(13)C_Pδ~(13)C_H。新方法利用测定麦卢卡蜂蜜中δ~(13)C值更为稳定的δ~(13)C_F值,代替了原有的比较不稳定的δ~(13)C_P为标准,解决了原方法对于麦卢卡蜂蜜中碳-4植物糖检测的假阳性问题。结论本方法显示出较好的准确度,大大提高了掺假检测的能力。     

酿酒专用粮基地酿酒玉米生长过程稳定同位素研究

该文为了研究酿酒玉米稳定同位素,利用稳定同位素质谱仪测定了来自酿酒专用粮基地不同地块不同生长阶段酿酒玉米各部位的C、N稳定同位素比值,结果表明,各生长阶段,~(15)N/~(14)N均最易在酿酒玉米茎部富集,在根部贫化,而~(13)C最易在酿酒玉米生长旺盛的部位富集;多施有机肥,有利于酿酒玉米富集~(15)N/~(14)N,使底茎、底叶、果实δ~(15)N偏高;多施非有机肥,会使底茎、底叶、果实δ~(15)N偏低;由于植物δ~(13)C受多种因素共同影响,海拔因素在该研究中未对酿酒玉米δ~(13)C产生显著影响。该文研究结果为监控酿酒玉米生长过程提供了初步理论数据。     

基于元素含量和稳定同位素比值的宁夏贺兰山东麓地区有机葡萄酒甄别

对贺兰山东麓产区生产的有机和非有机葡萄酒的元素含量和稳定C、N同位素比值分布特征进行分析,并利用此数据对宁夏贺兰山东麓地区有机与非有机葡萄酒进行甄别。结果表明,有机与非有机葡萄酒在一些金属元素如Na、Mg、K、Al和Cu的含量上具有显著差异,而且有机葡萄酒的乙醇和丙三醇的δ~(13)C值显著低于非有机葡萄酒,但δ~(15)N显著高于非有机葡萄酒。利用C、N稳定同位素和一些金属元素含量,结合主成分分析,可对贺兰山东麓地区有机和非有机葡萄酒进行有效区分,为我国有机葡萄酒掺假检测以及该地区的葡萄酒产业发展提供技术支撑,具有重要的应用前景。     

青梅酒中乙醇稳定碳同位素的测定

建立了气相色谱-稳定同位素比值质谱法测定青梅酒中乙醇的稳定碳同位素比值(δ~(13)C)。青梅酒与丙酮混合后,用GC-IRMS法测定乙醇的δ~(13)C值。结果表明,该方法能快速准确的测定青梅酒中乙醇的碳稳定同位素比值,准确率和精确度均满足测定需求。通过测定4个品牌青梅酒中乙醇的δ~(13)C值,品牌A、B、C和D青梅酒中乙醇δ~(13)C值分别为-13.87‰~-13.56‰、-14.30‰~-13.60‰、-14.29‰~-13.86‰和-14.09‰~-13.52‰。表明本方法前处理简单、测定结果准确,可用于青梅酒的产地溯源。     

基于稀土元素和稳定同位素指纹的枸杞道地性表征

【目的】本研究旨在探讨稀土元素结合碳氮稳定同位素在枸杞原产地判别中的可行性,为枸杞地理标志产品保护提供技术支撑。【方法】采集宁夏、甘肃、青海和新疆5个产区共222份枸杞样本,利用电感耦合等离子体质谱(ICP-MS)及元素分析-稳定同位素比值质谱仪（EA-IRMS）测定枸杞中14种稀土元素及碳、氮稳定同位素比值,结合化学计量学方法分析了监测指标在枸杞成熟阶段中的变化规律,并构建了枸杞产地判别模型。【结果】La、Nd、Sc、Nd、Dy、Gd、Sm、Eu、Tb、Ho、Tm、δ13C、δ15N在枸杞成熟过程中具有显著变化,随着枸杞成熟,稀土元素及碳氮稳定同位素具有明显的变化规律;11种稀土元素在4个枸杞产区间存在显著差异,δ13C、δ15N在部分产区间存在显著差异;主成分分析可提取出5个主成分,前2个主成分可有效区分新疆、青海的枸杞样品,宁夏和甘肃的样品不能有效区分;采用Fisher线性判别分析方法构建了基于La、Nd、Sc、Y、Pr、Eu、Yb、Dy、Gd、Tb、Ho、Tm、δ13C、δ15N 14个指标的枸杞产地判别模型,判别模型正确判别率在90.1%以上。【结论】基于稀土元素和碳、氮稳定同位素指纹的差异可以有效鉴别不同产地的枸杞。     

梨白兰地中乙醇碳同位素分布特征研究

利用元素分析-稳定同位素比值质谱仪测定梨白兰地原料的糖中δ13C,发酵后用气相色谱-燃烧-同位素比值质谱法分析乙醇中碳稳定同位素比值(δ13C)。结果显示梨的糖中δ13C值分布在-27‰~-25‰,而发酵后的乙醇δ13C集中在-30‰~-27‰,且糖与乙醇的δ13C具有良好的线性正相关关系(R2=0.98);白兰地精馏过程中乙醇出现反蒸汽压分馏效应,但酒体部分(50%vol~80%vol)δ13C值波动较小,重现性较好,且与发酵醪中的δ13C值较一致。模拟实验表明,乙醇δ13C值与玉米酒精含量和蔗糖含量成正相关关系,发酵前添加蔗糖和玉米酒精均会改变产品中乙醇δ13C值,因此碳稳定同位素技术可作为检测白兰地中C4来源的酒精或发酵前C4植物糖掺假的鉴别手段。     

牛奶中矿物元素和稳定同位素比的测定及在产地分析中的应用

本文应用电感耦合等离子质谱仪（ICP-MS）,同位素比质谱仪（IRMS）对牛奶中Li、Na等40种元素含量和碳、氮、氢、氧稳定同位素比值进行测定,并应用于牛奶产地分析中。牛奶样品经冷冻干燥成粉末后,通过ICP-MS对元素含量进行测定,EA-IRMS测定氮稳定同位素比值（δ15N）,通过EA-IRMS直接测定牛奶中碳稳定同位素比值（δ13C）,GasBench-IRMS测定牛奶水中的氢和氧稳定同位素比值（δ2H和δ18O）。应用上述方法对德国、西班牙、意大利、澳大利亚、新西兰、中国和奥地利的牛奶样品进行检测,并对测定结果进行多元统计分析（方差分析、主成分分析、聚类分析和判别分析）,对牛奶产地的归属进行研究。研究结果表明,有10种元素（As、Se、Rb、Sr、Mo、Cd、Cs、Ba、Tl、Bi）和4种稳定同位素比（?13C、?15N、?2H、?18O）在不同国家和地区的牛奶中存在显著性差异（p?0.05）,德国和意大利,中国,奥地利,澳大利亚和新西兰的牛奶可进行一定的聚类区分,应用As、Se、Rb、Sr、Mo、Cs、Ba、Tl、δ13C、δ15N和δ2H指标的组合分析,对7个国家牛奶产地的整体判别准确率为92.4%。     

稳定同位素质谱法鉴别芝麻油中掺杂大豆油、玉米油的研究

利用稳定同位素质谱法进行芝麻油掺杂鉴别的研究。选定C3植物油大豆油、C4植物油玉米油作为掺杂油,测定了芝麻油掺入质量分数分别为5%、10%、15%、20%、30%、50%、80%掺杂油的δ~(13)C、δ~2H、δ~(18)O值。结果表明:用δ~(13)C、δ~2H二维稳定同位素比值对大豆油掺杂油样品进行判别,比仅依靠单一δ~(13)C值或δ~2H值进行判别的灵敏度有所提升,同时发现δ~(18)O值与掺杂油的比例没有明显的线性关系。二元回归模型可以对芝麻油中掺杂10%大豆油或5%玉米油定量判别。     

全脂乳粉和脱脂乳粉在1kHz～10MHz下的介电特征研究

分别研究了各4种不同品种的全脂乳粉和脱脂乳粉在1kHz～10MHz波段的介电特性。结果发现:随着频率的增加,全脂乳粉和脱脂乳粉的ξ’和ξ″值呈单调递减趋势;全脂乳粉的ξ’和ξ″值都高于脱脂乳粉,相同类型乳粉各品种间的ξ’和ξ″差异不大;全脂乳粉的ξ″值在103～105Hz频率段减小趋势明显,且ξ″值的对数与频率的对数成线性反比关系,而脱脂乳粉无此规律;全脂乳粉和脱脂乳粉的穿透深度Dp随频率的提高而减小,两类乳粉的介电特性差异可能与它们各自的脂肪和乳糖含量有关。     

Flavor Variability and Flavor Stability of U.S.-Produced Whole Milk Powder

ABSTRACT:  Flavor variability and stability of U.S.-produced whole milk powder (WMP) are important parameters for maximizing quality and global competitiveness of this commodity. This study characterized flavor and flavor stability of domestic WMP. Freshly produced (<1 mo) WMP was collected from 4 U.S. production facilities 5 times over a 1 y period. Each sample was analyzed initially and every 2 mo for sensory profile, volatiles, color, water activity, and moisture through 12 mo storage. Selected volatiles were quantified using solid phase microextraction (SPME) with gas chromatography/mass-spectrometry: dimethyl sulfide, 2-methylbutanal, 3-methylbutanal, hexanal, 2-heptanone, heptanal, 1-octen-3-ol, octanal, 3-octen-2-one, and nonanal. Multiple linear regression with backwards elimination was applied to generate equations to predict grassy and painty flavors based on selected volatiles. All WMP were between 2% and 3% moisture and 0.11 and 0.25 water activity initially. WMP varied in initial flavor profiles with varying levels of cooked, milk fat, and sweet aromatic flavors. During storage, grassy and painty flavors developed while sweet aromatic flavor intensities decreased ( P  < 0.05). Painty and grassy flavors were confirmed by increased levels ( P  < 0.05) of lipid oxidation products such as hexanal, heptanal, and octanal. Hexanal, 2-heptanone, 1-octen-3-ol, and nonanal concentrations were best predictors of grassy flavor ( R ²= 0.38,  P  < 0.0001) while hexanal, 2-methylbutanal, 3-methylbutanal, octanal, and 3-octen-2-one concentrations were best predictors of painty flavor ( R ²= 0.61,  P  < 0.0001). These results provide baseline information to determine specific factors that can be controlled to optimize U.S. WMP flavor and flavor stability.     

Distribution and identification of culturable airborne microorganisms in a Swiss milk processing facility

Airborne communities (mainly bacteria) were sampled and characterized (concentration levels and diversity) at 1 outdoor and 6 indoor sites within a Swiss dairy production facility. Air samples were collected on 2 sampling dates in different seasons, one in February and one in July 2012 using impaction bioaerosol samplers. After cultivation, isolates were identified by mass spectrometry (matrix-assisted laser desorption/ionization-time-of-flight) and molecular (sequencing of 16S rRNA and rpoB genes) methods. In general, total airborne particle loads and total bacterial counts were higher in winter than in summer, but remained constant within each indoor sampling site at both sampling times (February and July). Bacterial numbers were generally very low (<100 cfu/m³ of air) during the different steps of milk powder production. Elevated bacterial concentrations (with mean values of 391 ± 142 and 179 ± 33 cfu/m³ of air during winter and summer sampling, respectively; n = 15) occurred mainly in the “logistics area,” where products in closed tins are packed in secondary packaging material and prepared for shipping. However, total bacterial counts at the outdoor site varied, with a 5- to 6-fold higher concentration observed in winter compared with summer. Twenty-five gram-positive and gram-negative genera were identified as part of the airborne microflora, with Bacillus and Staphylococcus being the most frequent genera identified. Overall, the culturable microflora community showed a composition typical and representative for the specific location. Bacterial counts were highly correlated with total airborne particles in the size range 1 to 5 µm, indicating that a simple surveillance system based upon counting of airborne particles could be implemented. The data generated in this study could be used to evaluate the effectiveness of the dairy plant’s sanitation program and to identify potential sources of airborne contamination, resulting in increased food safety.     

钝顶螺旋藻奶粉的研制

螺旋藻粉经特殊处理所得分散性好,风味清新的螺旋藻液,与鲜牛乳及其他原料混合,可制成具有保健功能的适合各种人群的螺旋藻奶粉。     

基于Real-time PCR法检测乳粉中牛源性成分定量研究

基于Real-timePCR建立了乳粉中牛源性成分相对定量检测方法,并对牛的特异性引物与探针进行了特异性、灵敏度和稳定性测试。通过模拟不同浓度牛乳粉与马乳粉混合样本,根据其△Ct值的函数关系进行线性拟合进而绘制标准曲线,建立乳粉中牛源性成分的相对定量检测。结果显示,该方法的最低检测限为0.000 01 mg/mL,回收率为91.11%～119.2%,组间变异系数≤0.58%、组内变异系数≤1.44%。说明该方法在特异性与稳定性上适用于乳粉中牛源性成分及含量的掺假检测。     

低乳糖奶粉的研制

研究了低乳糖奶粉的制作,通过乳糖酶的添加量、乳糖酶的水解温度、水解时间及水解时的pH对乳糖水解率、牛乳中微生物的影响,确定了低乳糖奶粉的水解条件;并对工艺条件进行了讨论。     

关于制定新疆驴乳和驴乳粉地方标准的研究

驴乳具有蛋白质中乳清蛋白比率高，低脂肪、低胆固醇，富舍不饱和脂肪酸等营养特点，有较大的开发利用价值，新疆已在全国率先推出了驴乳粉产品。论述了制定驴乳及驴乳粉地方标准的必要性；根据对驴乳和驴乳粉化学成分的测定结果，参照牛乳和乳粉的相关国家标准和行业标准，提出了制定《生鲜驴乳收购标准》及《驴乳粉和调味驴乳粉》两个地方标准的建议；并对标准中涉及的名称定义、技术要求、项目设定、技术指标等内容提出了具体意见。     

近红外快速检测奶粉乳清粉成分研究

采用Perten8620近红外奶粉分析仪检测奶粉的近红外光谱特性，建立了奶粉近红外检测的校准模型。结果表明，近红外检测技术无需称重和化学试剂，可在1min以内快速检测奶粉和乳清粉的蛋白、脂肪、水分等指标，其准确性和精度可以达到在国际允许的误差范围内。根据近红外技术可能在短时间内收集大量样品的光谱图，开发了新检测项目的校准曲线。     

模拟母乳及婴儿配方奶粉的研究

介绍了人乳中的主要功能因子及其对婴儿的生长发育所具有的生理意义。比较、分析了现阶段婴儿配方奶粉与人乳成分中存在的差别及不足，并针对婴儿的生长特点及现阶段生产技术，对婴儿配方奶粉的生产及发展进行了叙述。     

The functionality of milk powder and its relationship to chocolate mass processing, in particular the effect of milk powder manufacturing and composition on the physical properties of chocolate masses

Summary The functionality of twelve different milk powders that are used for chocolate mass processing was investigated. In two types of spray‐dried and one type of roller‐dried powder, the milk fat and milk fat fractions were integrated. Depending on the production process, the amount of free fat available in the milk powders varied greatly. A good correlation was found between the free fat content of the milk powder and the viscosity of the chocolate mass when comparable particle sizes were used. This study reports on the development of spray‐dried milk powders, which when used in chocolate processing produced low viscosities, comparable with those obtained by using roller‐dried milk powder. Calorimetric analysis showed that the shape of the milk powder particles has no influence on the calorimetric qualities of chocolate masses. Only when milk fat was added in a free form, was a higher ‘mixing effect’ in the crystallization peak of cocoa butter and milk fat observed.