Chemometric analysis of minerals and trace elements in raw cow milk from the community of Navarra,Spain

The concentrations of protein, fat, five minerals (Na, K, P, Ca and Mg) and nine trace elements (Fe, Zn, Cu, Mn, Se, Al, Cd, Cr and Pb) have been determined in 347 samples of raw cow milk from the community of Navarra, north Spain, using infrared analysis, atomic absorption spectrometry (flame and electrothermal atomisation) and inductively coupled plasma atomic emission spectroscopy. A preliminary chemometric study with the use of pattern recognition methods was carried out in order to characterise, classify and distinguish the different collected samples on the basis of their contents. Principal component analysis (PCA) has permitted the reduction of 16 variables to five principal components which interpret reasonably well the correlations of these studied variables. These variable associations may be attributed to intrinsic (lactogenesis) and other extrinsic factors, such as seasonal variation, animal feeding or geographical situation. Changes in these contents during different seasons were also assessed and consistently interpreted. Linear discriminant analysis (LDA) was used to explore cow milk samples, classifying according to season or geographical location, providing complementary information to PCA. This work shows that PCA and LDA are useful chemometric tools for the multivariate characterisation of raw cows’ milk.     

Chemometric studies of some trace elements in cows' milk

The matrix of the correlation between the concentrations of 11 trace elements determined in 45 samples of cows' milk was used as a starting matrix for principal component analysis. The space dimension was reduced from 11 variables to 5 principal components, accounting for about 80% of the total variance. After an orthogonal rotation, the first factor (F1) was found to be positively correlated with Cr, Mn, and Fe, F2 positively correlated with Ni and negatively with Cu, F3 positively with Cd and Pb, F4 positively with Zn, Sr, and Mo and F5 positively correlated with A1 and Sr. Element clusters appear to be determined by their origin. Some clusters are confirmed by principal factor analysis. A plot of the principal component scores was also applied to the differentiation of Italian Milk from different geographical origins.     

Chemometric studies of some trace elements in cows' milk

Summary The matrix of the correlation between the concentrations of 11 trace elements determined in 45 samples of cows' milk was used as a starting matrix for principal component analysis. The space dimension was reduced from 11 variables to 5 principal components, accounting for about 80% of the total variance. After an orthogonal rotation, the first factor (F1) was found to be positively correlated with Cr, Mn, and Fe, F2 positively correlated with Ni and negatively with Cu, F3 positively with Cd and Pb, F4 positively with Zn, Sr, and Mo and F5 positively correlated with Al and Sr. Element clusters appear to be determined by their origin. Some clusters are confirmed by principal factor analysis. A plot of the principal component scores was also applied to the differentiation of Italian Milk from different geographical origins.

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Chemometrische Untersuchungen über einige Spurenelemente in pasteurisierter Kuhmilch

Zusammenfassung Die Analyse der Hauptkomponenten wurde auf die Korrelationsmatrix zwischen Konzentrationen von 11 Spurenelementen in 45 Kuhmilchproben angewandt. Die Raumdimension von 11 Variablen wurde auf 5 Hauptkomponenten die 80% der totalen Varianz ausmachen, reduziert. Die orthogonal-rotierte Faktorenmatrix zeigt, daß Cr, Mn und Fe an die erste Hauptkomponente gebunden sind, Ni und Cu an die zweite, Cd und Pb an die dritte, Zn, Sr und Mo an die vierte and Al and Sr an die fünfte. Die Herkunft der Gruppen von Spurenelementen werden diskutiert. Einige Gruppen wurden bei der Analyse der Hauptfaktoren bestatigt. Das Diagramm der Hauptkomponentenwerte wurde auf die Unterscheidung von Milch aus zwei geographischen Herkünften angewandt.

     

Chemometric approach to fatty acid profiles in Runner-type peanut cultivars by principal component analysis (PCA)

The fatty acid profiles of commercially-grown Runner-type peanut cultivars (i.e., 10 cultivars, n = 151) collected over two production years (2005 and 2006) were determined by gas–liquid chromatography. Eight major fatty acids were identified in the sample set including palmitic (C16:0), stearic (C18:0), oleic (C18:1, ω9), linoleic (C18:2, ω6), arachidic (C20:0), gondoic (C20:1, ω9), behenic (C22:0), and lignoceric (C24:0) acids. Based on the oleic to linoleic acid (O/L) ratio, these cultivars were denoted as normal, mid-, and high-oleic peanut types. Correlation coefficients (r) between the eight major fatty acids identified were generated and revealed an inverse association between oleic and linoleic acids (r = –0.997, P < 0.001), while oleic acid and linoleic acid were positively correlated to gondoic acid (r = 0.818, P < 0.001) and palmitic acid (r = 0.967, P < 0.001), respectively. Principal component analysis (PCA) of the fatty acid data yielded three significant PCs (i.e., eigenvalues ? 1), which together account for 87.18% of the total variance in the data set; with PC1 contributing 60.45% of the total. Eigen analysis of the correlation matrix loadings of the three significant PCs revealed that PC1 was mainly contributed to by palmitic, oleic, linoleic, and gondoic acids; PC2, by behenic acid; and PC3, by lignoceric acid. The score plot generated between PC1 and PC2 successfully segregated normal, mid- and high-oleic peanut cultivars, while the PC1–PC3 plot segregated normal and the combination of mid- and high-oleic acid cultivars.     

Evaluation of trace metal concentrations in some herbs and herbal teas by principal component analysis

Sixteen trace metallic analytes (Ba, Ca, Ce, Co, Cr, Cu, Fe, K, La, Mg, Mn, Na, Ni, P, Sr and Zn) in acid digests of herbal teas were determined and the data subjected to chemometric evaluation in an attempt to classify the herbal tea samples. Nettle, Senna, Camomile, Peppermint, Lemon Balm, Sage, Hollyhock, Linden, Lavender, Blackberry, Ginger, Galangal, Cinnamon, Green tea, Black tea, Rosehip, Thyme and Rose were used as plant materials in this study. Trace metals in these plants were determined by using inductively coupled plasma-atomic emission spectrometry and inductively coupled plasma-mass spectrometry. Principal component analysis (PCA), linear discriminant analysis (LDA) and cluster analysis (CA) were used as classification techniques. About 18 plants were classified into 5 groups by PCA and all group members determined by PCA are in the predicted group that 100.0% of original grouped cases correctly classified by LDA. Very similar grouping was obtained using CA.     

基于主成分分析和聚类分析的市售熏鸡食用品质分析

为探明市售熏鸡的主要食用品质特征,对国内市场主流品牌的熏鸡产品进行综合评价。调研采集6种地方特色熏鸡,测定其胸肉和腿肉的化学组成、质地特性和色泽指标,应用主成分分析(principal component analysis,PCA)筛选熏鸡品质评价指标,并通过聚类分析对熏鸡样品进行分类。结果表明,6种熏鸡各品质指标均存在不同程度的差异;主成分分析将熏鸡胸肉筛选出2个主成分因子,PC1(69. 66%)为质地因子,PC2(15. 91%)为外观色泽因子;将熏鸡腿肉筛选出2个主成分,PC1(58. 66%)为外观色泽因子,PC2(28. 87%)为质地因子,确定质地和色泽是评价熏鸡品质的主要指标。聚类分析将6种熏鸡分为两类,两类熏鸡样品品质差异显著,此分类结果与主成分分析结果一致。     

电感耦合等离子体发射光谱仪(ICP-AES)法测定牛奶及奶制品中的微量元素

目前,电感耦合等离子发射光谱仪(ICP-OES)已应用于石油化工等各领域,但在食品领域的应用甚少,尤其在测定乳及乳粉中微量元素(钙、钾、镁、钠、磷、铁、锌、锰、铜)方面的应用更少.采用电感耦合等离子体发射光谱仪(ICP-AES)测定牛奶及奶制品中的微量元素,方法中各种元素标准曲线的R2值均在0.999以上,回收率为95.26%～106.28%,栓出限为0.027～0.87 mg/L,KSD值为0.021%～2.01%.结果表明该方法精密度高、准确性好、干扰少、快速简单,可用于牛奶及奶制品中微量元素的含量测定.     

Enzymic differentiation between curds of heated and raw milk. I. milk alkaline phosphatase

Alkaline phosphatase, which is present in curds made from raw milk as well as from boiled milk, does not serve to differentiate them. It was found that incubation time or acidity (lactic acid equivalent of curd acidity incubated aseptically with heated milk) does not revive heat-denatured phosphatase. The reappearance was found to be due to phosphatase of microbial origin; it was not a case of reactivation of the denatured enzyme. Low intensity, but increasing slowly, of the activity of regenerated phosphatase in curd (permeability of the microbial cells to the testing reagents is probably limiting in the rate of reaction), presence of the enzyme in the sonicated cells of curd-forming microflora and absence of activity in the supernatant of the growth medium suggest that the formed enzyme is an intracellular one.     

商品奶与原料奶中农药与亚硝酸钠残留分析

采用高效气相色谱(GC)分析法对商品奶和原料奶中农药和亚硝酸钠残留进行分析,并分析不同饲养模式对原料奶中农药残留的影响。结果表明:在所测定的5种农药中,甲胺磷、敌敌畏和马拉硫磷等3种农药残留检出率较高,商品奶为45.0%～67.5%,原料奶为46.8%～71.2%。商品奶和原料奶中甲胺磷、敌敌畏、敌百虫、马拉硫磷和倍硫磷检出率和残留量差异不显著(P﹥0.05);而商品奶和原料奶中亚硝酸钠检出率和残留量差异极显著(P﹤0.01)。原料奶中5种农药加权平均检出率、农药加权平均残留量和加权残留总量均为规模化饲养显著低于农户散养和合作社饲养(P﹤0.05),后两者之间无显著差异(P﹥0.05)。     

Quantification of trace elements in raw cow’s milk by inductively coupled plasma mass spectrometry (ICP-MS)

The levels of trace elements are an important component of safety and quality of milk. While certain elements such as chromium are essential at low levels, an excess can result in deleterious effects on human health. International quality control standards for milk are published by the Codex Alimentarious Commission and levels of heavy metals in milk intended for human consumption are routinely monitored. This paper describes a new method for demonstrating the levels of V, Cr, Mn, Sr, Cd and Pb in raw cow’s milk, using an ICP-MS. Samples (n = 24) of raw cow’s milk were collected from dairy farms close to mines in Gauteng and North West Provinces of South Africa. In order to destroy organic matrix, each freeze dried milk sample was mineralised by using a microwave assisted digestion procedure. Concentrations of trace elements in digested milk samples were measured by ICP-MS. A whole milk powder reference material (NIST SRM 8435) was used to evaluate the accuracy of the proposed method. It was found that the levels of V, Cr, Mn, Sr, Cd and Pb obtained using the new method showed concordance with certified values.     

Heavy metals and trace elements levels in milk and milk products

Milk and dairy products are an important food in the human diet. The present investigation was carried out to determine concentrations of lead, cadmium, zinc, copper and iron in milk and dairy products and evaluate the potential health risks of metals to humans via consumption of milk and dairy products. A total of 77 samples of milk and dairy products (22 raw milk, 20 kareish cheese, 21 butter and 14 rice pudding) were collected from farms, individual farmers and dairy shops in Beni-Suef governorate, Egypt. Pb, Cd, Zn, Cu and Fe concentrations in milk and dairy products ranged from 0.044–0.751, 0.008–0.179, 0.888–18.316, 0.002–1.692 and 1.3208–45.6198 ppm respectively. Pb concentration in all samples exceeded the maximum permissible limit (0.02 mg/kg) established by codex standard. Pd and Cd intake through milk and dairy products consumption were 1.27 and 0.33 μg/kg bw/day, which represent 35.3 and 39.8 % of the tolerable daily intake. Dairy products are poor sources of iron, copper and zinc, and milk contributes little to the total iron and zinc intake. Target hazard quotient values of less than 1 indicate a relative absence of health risks associated with the consumption of milk and dairy products.     

主成分分析法用于食品样品分类研究

利用化学模式识别技术的主成分分析(PCA)法对取自江西不同地区的谷物、蔬菜、水果的24个样品进行分类研究,所涉及的变量包括金属离子K、Na、Ca、Mg、Mn、Fe、Zn、Cu、Cr、Pb和有机物蛋白质、碳水化合物、脂肪、VB1、VB2。结果表明,运用PCA法可获得大量样品的统计特征,对变量进行适当的选择能够有效地分辨不同的样品。     

Comparison of trace elements in milk of four species.

The objective of this study was to compare trace elements in milks of four species. Milk samples of 4 ml or more were obtained from guinea pigs, dairy cattle, horses, and humans. The milks were analyzed for the trace elements Al, B, Ba, Cu, Fe, Li, Mn, Mo, Si, Sr, Ti, and Zn by inductively coupled argon plasma spectroscopy. Zinc ranged from more than 4 ppm in guinea pig milk to less than 2 ppm in mare milk. Strontium was over 1 ppm in the milk of guinea pigs and less than .1 ppm for the human. Iron ranged from over .7 ppm for the guinea pig to less than .2 ppm for the cow. Copper was over .5 ppm in guinea pig milk and only .05 ppm for cow milk. Boron ranged from .59 to .10 ppm, Si from .58 to .16 ppm, Al from .45 to .10 ppm; and Ba from .22 to .08 ppm in milks of the four species studied. Titanium ranged from a trace to .11 ppm. Lithium, Mn, and Mo all were less than .04 ppm. Milk Mn was surprisingly low relative to bodily needs.     

Carcass and meat quality of light lambs using principal component analysis

Eighty-six male light lambs of Manchego breed were used in this study. Principal component (PC) analysis was performed to study the relationship between carcass quality variables (n=22) and between meat quality measures (n=21). The carcass quality was assessed using objective and subjective measurements of conformation and fatness besides the joints proportion and tissues proportion of the leg. The measurements used to evaluate meat quality were pH in longissimus dorsi and semitendinosus muscles, the colour, moisture, water holding capacity, cooking losses, texture and sensorial analysis on longissimus dorsi. The five first PCs explained about 77% of the total variability for carcass measures whereas for meat quality the 74% of the total variability was explained for the eight first PCs. All the carcass measurements showed similar weight to define the first PC, whereas the muscle and bone proportion as well as muscle:bone ratio of the leg were useful to define the second PC. The meat quality measures that were more effective to define the first PC were the meat colour measurements, whereas the sensorial variables defined the second PC. The projection of the carcass quality data in the first two PCs allowed to distinguish clearly between heavier carcasses (higher than 6.5 kg) and lighter carcasses (lower than 5.5 kg). The carcasses with a weight higher than 6.5 kg were on the left side of the figure, where the variables of conformation and fatness lie. The group of medium carcass weight were placed between the two previous groups. The projection of the meat quality data in the first two PCs did not differ between hot carcass weights, although there was a trend, the lighter carcasses lay on the left side of the graph, which implies small differences between meat quality in this range of carcass weight.     

Relationship between gilt behavior and meat quality using principal component analysis

Pig on-farm behavior has important repercussions on pig welfare and performance, but generally its relationship with meat quality is not well understood. We used principal component analysis to determine the relationship between meat quality traits, feeding patterns, scale activity, and number of conflict–avoidance interactions. The first principal component indicated that gilts with greater daily feed intake stayed longer in the feeder and their meat had increased intramuscular fat (IMF), was lighter in color, and, in the second principal component, had better juiciness, tenderness, chewiness, and flavor. Meat from gilts with lower scale activity scores appeared to have more IMF but greater drip losses (DL). The third principal component suggested that dominant gilts could gain priority access to the feeder, eating more and growing fatter. In conclusion, except for the slight associations with IMF and DL, gilt scale activity and conflict-avoidance behaviors were not good indicators of final meat quality attributes.     

Interpreting sensory data by combining principal component analysis and analysis of variance

This paper compares two different methods for combining PCA and ANOVA for sensory profiling data. One of the methods is based on first using PCA on raw data and then relating dominating principal components to the design variables. The other method is based on first estimating ANOVA effects and then using PCA to analyse the different effect matrices. The properties of the methods are discussed and they are compared on a data set based on sensory analysis of a candy product. Some new plots are also proposed for improved interpretation of results.     

微波消解-电感耦合等离子体串联质谱法测定新疆黑枸杞红酒中微量元素的主成分分析

建立电感耦合等离子体串联质谱(inductively coupled plasma tandem mass spectrometry,ICP-MS/MS)分析方法测定新疆黑枸杞红酒中22种微量元素含量,并进行主成分分析.黑枸杞红酒经微波消解处理,采用ICP-MS/MS测定22种微量元素含量,在MS/MS模式下以O2为反...     

Enzymic differentiation between curds of heated and raw milk II. Milk peroxidase

Unlike phosphatase, peroxidase, once destroyed by heating of milk, is not regenerated by the acidity or microbial growth of curd formation or by reasonable ageing. This reveals that curd-forming micro-organisms do not have or form peroxidase. The test was repeated in various heating conditions of milk. Peroxidase is destroyed even when the temperature of milk is gradually raised to 80 °C (in 3 min). Less-heated milk, e.g. pasteurised milk and its corresponding curd, retain this enzyme. A positive test in the curd of raw milk is not affected by reasonable ageing or increased acidity but by excessive fermentation (secondary fermentation or putrefaction) which again can be halted by addition of formalin. The peroxidase test, therefore, appears to be a test for differentiating curds of heated and unheated milk.     

Use of principal component analysis to investigate the origin of heptadecenoic and conjugated linoleic acids in milk

The aim of this paper was the application of principal component analysis (PCA) 1) to elucidate mutual metabolic relationships between milk fatty acids (FA) and 2) to illustrate the origin of milk FA, in particular C17:1 and cis-9,trans-11 conjugated linoleic acid. Data were combined from 3 experiments with lactating Holstein-Friesian cows offered diets based on grass or legume silage and concentrates. Loading plots of PCA based on milk FA concentrations showed 4 groups of milk FA, having similar precursors or metabolic pathways in the rumen and/or mammary gland: medium-chain saturated FA, de novo synthesized from acetate and beta-hydroxybutyrate; monoenoic milk FA, products of delta9-desaturase activity in the mammary gland; odd chain FA of rumen microbial origin and C18:0, n-6 C18:2, and n-3 C18:3 of dietary origin or the result of rumen biohydrogenation. Loading plots of PCA based on both milk and duodenal FA concentrations as well as on milk FA yields and duodenal FA flows further illustrated the importance of postabsorptive synthesis of the milk medium chain saturated and monoenoic FA and the direct absorption from the blood stream of odd chain FA, C18:0, n-6 C18:2, and n-3 C18:3. In all loading plots, milk oleic acid (C18:1) appeared intermediate between clusters of 18-carbon FA and monoenoic FA, illustrating its dual (dietary and endogenous production) origin. Milk C17:1 was suggested to be a desaturation product of C17:0, in common with other milk monoenoic FA. Finally, the PCA technique, based on milk FA patterns of one experiment, was applied to investigate factors determining cis-9,trans-11 conjugated linoleic acid concentrations in milk. Within the range of diets and cows studied here, we showed changes in cis-9,trans-11 conjugated linoleic acid to be mainly dependent on vaccenic acid supply and to a lesser extent on variation in desaturase activity.