Detection of milk mixtures in Halloumi cheese

A capillary electrophoresis method has been applied to the detection of illegal addition of milk from goat and/ or cow in Halloumi cheese, traditionally made with sheep milk. The electrophoretic profiles of the casein from Halloumi cheeses have revealed that caprine para-kappa-casein and bovine alphas1-casein peaks point to the presence of low percentages of goat's and/or cow's milk added to Halloumi cheese. Stepwise multiple linear regression has been used to predict these percentages with a standard error of the estimation of 2.14%. The analytical method combined with the statistical application is valid for the prediction of percentages higher than 2% of goat's and percentages of 5% of cow's milk added to the cheese either in fresh or ripened cheese. The standard error of estimation was higher for the prediction of cow's milk than for goat's milk.     

Study of some European cheeses geographical traceability by pattern recognition analysis of multielemental data

Pattern recognition techniques (cluster, principal component, factor and discriminant analysis) were performed for tracing the geographical origin of some Emmental and Edam type hard cheeses originated from ten European countries. Two hundred and seventy-eight cheese samples were analysed on the content of elemental markers Ba, Ca, Cr, Cu, Hg, K, Mg, Mn, Mo, Na, Ni and V by atomic absorption spectrometry. Cluster analyses showed some preliminary results intimated partial grouping of cheeses according to country of origin. Principal component and factor analysis showed to be effective methods for data segregation and visualization. Canonical discriminant analysis demonstrated 85.9 and 93% potential to distinguish geographical differences and correct classification of cheeses according to multielemental data collected during the 2 years of production. Cross-validation of two testing data sets led to 86.4 and 90% correctness of cheeses classification. The stepwise discriminant analysis arranged the markers according to their influence on the discrimination procedure in descending order: Na, Cr, Cu, Ba, Ca, Hg, V, and Mg.     

Multi-element analysis for determining the geographical origin of mutton from different regions of China

Elemental fingerprints were investigated for their potential to classify mutton samples according to their geographical origin. The concentration of 25 element contents in 99 mutton samples from three pastoral regions and two agricultural regions of China were analysed by ICP-MS. Multivariate statistical analysis including principal component analysis (PCA) and linear discriminate analysis (LDA) were used for this purpose. Twenty-one elements (Be, Na, Al, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Ag, Sb, Ba, Tl, Pb, Th and U) in de-fatted mutton showed significant differences (p < 0.05). LDA gave an overall correct classification rate of 93.9% and cross-validation rate of 88.9%. Furthermore, mutton samples from agricultural regions and pastoral regions were differentiated with 100% accuracy. These results demonstrate the usefulness of multi-element fingerprints as indicators for authenticating the geographical origin of mutton in China.     

Correlation and distribution of elemental markers of origin in the production of Bryndza sheep cheese

The successful classification of Bryndza, a typical Slovak national sheep cheese, from nine different Slovak producing regions, was based on canonical discriminant analysis. Elemental markers of origin (Ba, Cr, Cu, Hg, Mg, Mn, Ni and V) were determined by graphite furnace (GF) and flame atomic absorption spectrometry (AAS). High correlations of elemental markers were found between pasture soil, grass, and Bryndza cheese originated from different regions. The concentration of these markers in pasture soils, grasses, as well as in all the milk and Bryndza cheese-making process was monitored. Their content in sheep milk, lumpy cheese, whey, boiled sheep whey and final Bryndza cheese was significantly correlated with the soil elemental markers. The final product was only slightly contaminated by the individual elements during the Bryndza production, without any significant influence on the Bryndza origin classification and/or traceability.     

Detection of milk powder and caseinates in Halloumi cheese

Halloumi cheese is traditionally manufactured from fresh milk. Nevertheless, dried dairy ingredients are sometimes illegally added to increase cheese yield. Lysinoalanine and furosine are newly formed molecules generated by heating and drying milk protein components. The levels of these molecular markers in the finished Halloumi have been investigated to verify their suitability to reveal the addition of skim milk powder and calcium caseinate to cheese milk. Because of the severe heating conditions applied in curd cooking, genuine Halloumi cheeses (n = 35), representative of the Cyprus production, were characterized by levels of lysinoalanine (mean value = 8.1 mg/100 g of protein) and furosine (mean value = 123 mg/100 g of protein) unusual for natural cheeses. Despite the variability of the values, a good correlation between the 2 parameters (R = 0.975) has been found in all cheeses, considering both the fresh and mature cheeses as well as those obtained from curd submitted to a prolonged cooking following a traditional practice adopted by a very small number of manufacturers. Experimental cheeses made by adding as low as 5% of skim milk powder, or calcium caseinate, or both, to cheese milk fell outside the prediction limits at ±2 standard deviation of the above-reported correlation regardless of curd cooking conditions or ripening length. This correlation may be adopted as a reliable index of Halloumi cheese genuineness.     

Some Volatile Plant Compounds in Halloumi Cheeses made from Ovine or Bovine Milk

The volatile flavour componds in commercial samples of fresh Halloumi cheese made from either bovine milk or a mixture of ovine and caprine milks were compared. Terpenes, such as α-pinene, β-pinene, copaene, thymol, α-caryophyllene, β-caryophyllene and δ-cadinene were all present in the ovine/caprine cheeses and, in some cases, at concentrations above their reported flavour threshold values. Only low levels of α-pinene and β-caryophyllene were found in the bovine samples, along with D -carvone and eucalyptol from mint added during manufacture. Analysis of some plants that dominated the feeds of the sheep/goats or cows that produced the original milk indicated that the terpenes are likely to have originated in the plants eaten by the animals. It was suggested that the presence of the terpenes may explain the preference of some consumers for the fresh ovine/caprine cheese.     

Authenticity assessment of dairy products

The authenticity of dairy products has become a focal point, attracting the attention of scientists, producers, consumers, and policymakers. Among many others, some of the practices not allowed in milk and milk products are the substitution of part of the fat or proteins, admixtures of milk of different species, additions of low-cost dairy products (mainly whey derivatives), or mislabeling of products protected by denomination of origin. A range of analytical methods to detect frauds have been developed, modified, and continually reassessed to be one step ahead of manufacturers who pursue these illegal activities. Traditional procedures to assess the authenticity of dairy products include chromatographic, electrophoretic, and immunoenzymatic methods. New approaches such as capillary electrophoresis, polymerase chain reaction, and isotope ratio mass spectrometry have also emerged alongside the latest developments in the former procedures. This work intends to provide an updated and extensive overview since 1991 on the principal applications of all these techniques together with their advantages and disadvantages for detecting the authenticity of dairy products. The scope and limits of different tools are also discussed.     

牛羊乳的比例对Halloumi干酪得率及品质的影响

探究部分牛乳替代羊乳时Halloumi干酪的产率和品质。结果表明:提高原料乳中羊乳的体积比时,Halloumi干酪的产率、蛋白含量也显著提高,当牛羊乳的体积比为0∶1和1∶1时,产率分别高达12.03%和11.99%,两者差异性不显著(P>0.05);且羊乳的比率越高,Halloumi的硬度和咀嚼性显著越强(P<0.05),但弹性和凝聚性差异性不显著(P>0.05);但牛羊乳体积比1∶1的Halloumi干酪在气味和质地方面的得分显著高于牛羊乳的体积比为0∶1综合各项品质指标,最终确定牛羊比最佳配体积比为1∶1。     

Characterization of Swiss vineyards using isotopic data in combination with trace elements and classical parameters

The objective of this work was to study methods to check the geographical origin of Swiss wines. Authentic grape samples from the vintages 2000 and 2001 were collected in representative locations, and the wines produced from these samples were subjected to isotopic (²H/¹H_ethanol; ¹⁸O/¹⁶O_{wine water}), elemental (Mn, Al, B, Ba, Ca, Fe, Mg, Na, Rb, Sr, Zn) and FT-IR (ethanol, pH, total acidity, volatile acidity, malic acid, fructose, tartaric acid, lactic acid, succinate, citric acid, glycerol, 2,3-butandiol, dry matter and relative density (d₂₀)) analyses. The results showed that the variables ¹⁸O/¹⁶O_{wine water}, strontium, rubidium, and ethanol%, when considered in a monovariate approach, allowed the best discrimination of the geographical origins of Swiss wines. By using a combination of all variables (multivariate approach), Switzerland was divided in four main production zones with a separation power that has never before been achieved. These zones were defined as Tessin, Valais, Romandie and Alemanique. A fifth zone (Graubünden) could be evidenced in vintage 2001.     

The effect of sodium chloride substitution with potassium chloride on texture profile and microstructure of Halloumi cheese

The effect of partial substitution of NaCl with KCl on texture profile and microstructure of Halloumi cheese was investigated. Four batches of Halloumi cheese were made and kept in 4 different brine solutions (18%, wt/wt), including A) NaCl only, B) 3NaCl:1KCl, C) 1NaCl:1KCl, and D) 1NaCl:3KCl and then stored at 4°C for 56 d. The texture profile was analyzed using an Instron universal machine, whereas an environmental scanning electron microscope was used to investigate the effect of NaCl substitution on the microstructure of cheeses. No significant difference was found in hardness, cohesiveness, adhesiveness, and gumminess among experimental cheeses at the same storage day. Hardness, cohesiveness, and gumminess decreased significantly during storage period with the same salt treatment, whereas adhesiveness significantly increased. Environmental scanning electron microscope micrographs showed a compact and closed texture for cheeses at the same storage period. The microstructure of all cheeses became more closed and compact with storage period. Calcium content negatively correlated with hardness and Na and K contents during storage with the same salt treatment.     

In-situ Iberian pig carcass classification using a micro-electro-mechanical system (MEMS)-based near infrared (NIR) spectrometer

Iberian pig (IP) products are gourmet foods highly appreciated at international markets, reaching high prices, because of its exquisite flavors. At present, there aren't practical and affordable analytical methods which can authenticate every single piece put on the market. This paper reports on the performance of a handheld micro-electro-mechanical system (MEMS)-based spectrometer (1600-2400 nm) for authentication-classification of individual IP carcasses into different commercial categories. Performance (accuracy and instrumental design) of the instrument was compared with that of high-resolution NIRS monochromators (400-2500 nm). A total of 300 carcasses of IPs raised under different feeding regimes (“Acorn”, “Recebo” and “Feed”) were analyzed in three modes (intact fat in the carcass, skin-free subcutaneous fat samples and melted fat samples). The best classification results for the MEMS instrument were: 93.9% “Acorn” carcasses correctly classified, 96.4% “Feed” and 60.6% “Recebo”, respectively. Evaluation of model performance confirmed the suitability of the handheld device for individual, fast, non-destructive, low-cost analysis of IP carcasses on the slaughterhouse line.     

Identification of Slovakian, Polish, and Romanian bryndza cheeses origin by factor analysis of some elemental data

Study of traceability of typical sheep cheese bryndza made in Slovakia, Poland, and Romania was realized by means of some special elemental markers determined by atomic absorption spectrometry. Principal component factoring was used for elements variability determination, differentiation, and visualization of used data. Elemental markers Ba, Cu, Cr, Mg, and Ni enable effective identification of majority of Slovak bryndza cheese producing areas. As the best elemental markers of origin, enabling successful multiregional differentiation of Slovakian, Polish, and Romanian bryndza cheeses, Cr, Hg, Mn, and V were used.