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.     

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.     

Correlation between multielement stable isotope ratio and geographical origin in Peretta cows' milk cheese

The aim of this study was to characterize the isotopic composition and protect “Peretta” cows’ milk cheese, a typical product of Sardinia, against other cheeses of the same appearance sold under the same name, but made of raw materials from northern Europe. The study was concerned with 3 types of cheese: those produced in local dairies from milk from free-grazing or pasture-grazing cows in Sardinia (local dairy product), cheeses made on an industrial scale from milk produced by intensive farming in Sardinia (factory cheese), and cheeses made with raw materials imported from other countries (imported product). To distinguish the Sardinian cheeses from the imported product, the stable isotope ratios ¹³C/¹²C, ¹⁵N/¹⁴N, D/H, ³⁴S/³²S, and ¹⁸O/¹⁶O were used. Determination of the isotopic data δ¹³C, δ¹⁵N, δ²H, and δ³⁴S was performed in the casein fraction, whereas δ¹⁸O and δ¹³C were determined in the glycerol fraction. Measurements were performed by isotope ratio mass spectrometry. A comparison between mean values of the isotope ratios by statistical analysis (ANOVA and Tukey's test) showed that the greatest difference between the 3 types of cheese (local dairy, factory, and imported products) was in the ¹³C/¹²C, ³⁴S/³²S, and ¹⁸O/¹⁶O isotope ratios. In the other parameters, either no differences (δ¹⁵N) or minimal differences (δ²H) were found. Evaluation of the data by multivariate statistical analysis (principal component analysis and hierarchical cluster analysis) revealed that the isotope characteristics of the factory products were similar to those of the cheeses produced from imported raw materials, whereas a difference was found between the local dairy-produced cheeses and the products in the other 2 categories.     

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.     

Effect of the lactoperoxidase system on the activity of mesophilic cheese starter cultures in goat milk

The effect of goats’ milk lactoperoxidase (LP) system on the activity of commercially available mesophilic cheese starter cultures was investigated. The growth and acid production of the starter cultures were measured at 2 h intervals for 8 h in goats’ milk kept at 30°C. Most of the starter cultures examined were found to be sensitive to the LP system, but varied in their susceptibility to inhibition. The activity of the mixed starter cultures CHN11, CHN22, CHN19, DCC240 and Flora Danica Normal was strongly inhibited by the LP system. However, the mixed starter culture LL 50C showed resistance to the LP system. The single strain culture Lactococcus lactis subsp. lactis NCDO 605 was inhibited by the LP system. However, the cultures Lactococcus lactis subsp. diacetylactis NCDO 176 and Leuconostoc mesenteroides subsp. cremoris ATCC 33313 were insensitive to the LP system. The results of this study indicate the need for routine screening of starter cultures for resistance to the LP system before using them for cheesemaking from goats’ milk preserved by the LP system.     

Changes in texture,composition and sensory characteristics of Camembert cheese made from a mixture of goat milk and cow milk during ripening

The study was conducted to evaluate the nutritional, textural and sensory characteristics of Camembert cheese made from goat milk, cow milk and their blends. The type of milk used affected yield, physicochemical properties and fatty acid profile of the cheeses. The percentages of C6:0, C8:0 and C10:0 acids were higher in the cheeses containing ≥ 75% goat milk. The sensory evaluation results showed differences in texture, colour, aroma and flavour among the cheeses. Cheeses made with the mixture of cow and goat milk particularly 50% goat milk mixed with 50% cow milk (50G:50C) maintained particular positive nutritional characteristics especially with respect to the mineral contents, fatty acids and consumer acceptability.     

Degree of antioxidant protection: a parameter to trace the origin and quality of goat's milk and cheese

Traceability is an essential tool in reassuring consumers and traders that food is as safe, authentic, and of good quality as expected. Today, food traceability procedures often consist of attached documents and declarations, but scientific parameters that could objectively identify a product would be preferable. Scientific efforts in this area are mostly focused on selection and validation of experimental indicators that would be useful for tracing a food product in any step of its commercial life, describing its raw materials, processing procedures, and storage conditions. In this research, milk and cheese samples from zero grazing and grazing goats were studied to identify a tracing parameter correlated to the feeding system. In particular, α-tocopherol and cholesterol were analyzed by HPLC on a normal phase column and were combined to calculate the degree of antioxidant protection (DAP). This parameter, expressed as the molar ratio between antioxidant compounds and an oxidation target, is useful for tracing and distinguishing products from grazing and zero-grazing animals. Degree of antioxidant protection values greater than 7.0 × 10⁻³ were found in samples from grazing goats and values lower than 7.0 × 10⁻³ were found in samples from zero-grazing goats, for both milk and cheese, meaning that cholesterol was highly protected against oxidative reactions when herbage was the only feed or was dominant in the goat diet. The reliability of DAP to measure the antioxidant protection of cholesterol appeared more effective when the feeding system was based on grazing than when cut herbage was utilized indoors by animals. The DAP index was able to distinguish dairy products when the grazed herbage in the goats’ diet exceeded 15%.     

Molecular surveillance of Toxoplasma gondii in raw milk and Artisan cheese of sheep,goat, cow and water buffalo origin

This study is aimed at investigating the molecular prevalence of Toxoplasma gondii in raw milk and cheese of different animal species (sheep, goat, cow and water buffalo) in Kayseri Province, Türkiye, to provide a preliminary assessment for contamination risk. A total of 200 milk and cheese samples were analysed by real-time PCR. Toxoplasma gondii DNA was detected in two (8%) ewes and one (4%) goat raw milk sample, while none of the cheese samples were positive. These results indicated that the presence of T. gondii DNA in raw milk samples sold in Kayseri Province might be a risk factor for public health.     

Prediction of indicators of cow diet composition and authentication of feeding specifications of Protected Designation of Origin cheese using mid-infrared spectroscopy on milk

The ability of mid-infrared spectroscopy (MIR) to predict indicators (1) of diet composition in dairy herds and (2) for the authentication of the cow feeding restrictions included in the specification of 2 Protected Designation of Origin (PDO) cheeses (Cantal and Laguiole) was tested on 7,607 bulk milk spectra from 1,355 farms located in the Massif Central area of France. For each milk sample, the corresponding cow diet composition data were obtained through on-farm surveys. The cow diet compositions varied largely (i.e., from full grazing for extensive farming systems to corn silage-based diets, which are typical of more intensive farming systems). Partial least square regression and discriminant analysis were used to predict the proportion of different feedstuffs in the cows' diets and to authenticate the cow feeding restrictions for the PDO cheese specifications, respectively. The groups for the discriminant analysis were created by dividing the data set according to the threshold of a specific feedstuff. They were issued based on the specifications of the restriction of the PDO cheese. The pasture proportion in the cows' diets was predicted by MIR with an coefficient of determination in external validation (R²V) = 0.81 and a standard error of prediction of 11.7% dry matter. Pasture + hay, corn silage, conserved herbage, fermented forage, and total herbage proportion in the cows' diets were predicted with a R²V >0.61 and a standard error of prediction <14.8. The discrimination models for pasture presence, pasture ≥50%, and pasture ≥57% in the cows' diets achieved an accuracy and specificity ≥90%. A sensitivity and precision ≥85% were also observed for the pasture proportion discrimination models, but both of these indexes decreased at increasing thresholds from 0 to 50, and 57% pasture in the cows' diets. An accuracy ≥80% was also observed for pasture + hay ≥72%, herbage ≥50%, pasture + hay ≥25%, absence of fermented herbage, absence of corn silage, and corn silage ≤30% in the cows' diets, but for several models, either the sensitivity or precision was lower than the accuracy. Models built on the simultaneous respect of all the criteria of the feeding restrictions of PDO cheese specifications achieved an accuracy, specificity, sensitivity, and precision >90%. Both the regression and discriminant MIR models for bulk milk can provide useful indicators of cow diet composition and PDO cheese specifications to producers and consumers (farmers, dairy plants).     

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.     

Indirect ELISA for detection of goats' milk in ewes' milk and cheese

An indirect ELISA (enzyme-linked immunosorbent assay) has been developed successfully for the detection of defined amounts of goats' milk (1–25%) in ewes' milk and cheese. The assay uses polyclonal antibodies raised in rabbits against goats' caseins (GC). The anti-GC antibodies were recovered from the crude antiserum by immunoadsorption and elution from a column containing immobilized goats' caseins. The anti-GC antibodies were biotinylated and rendered goats' milk specific by mixing them with lyophilized bovine and ovine caseins. The assay was developed in a non-competitive ELISA format and it comprised coating plates with extracts from samples. ExtrAvidin-peroxidase was used to detect the biotinylated anti-GC antibodies bound to goats' caseins immobilized on 96-well plates. The colour developed by the subsequent enzymic conversion of the substrate resulted in discernible differences in optical densities when assaying mixtures of ewes' milk and cheese containing variable amounts of goats' milk.     

Changes in terpenoid composition of milk and cheese from commercial sheep flocks associated with seasonal feeding regimens throughout lactation

Changes in the terpenoid content of milk and cheese from commercial sheep flocks monitored throughout lactation in the Cantabrian area of northern Spain were investigated. The flocks followed the same seasonal feeding strategy during lactation: indoor feeding in winter (early lactation) based on concentrate and forage; part-time grazing in the valley in early spring (mid lactation); and from mid spring on (late lactation), flocks were managed under extensive mountain grazing. In the present study design, seasonal feeding and lactation stage were intrinsically linked and could not be considered in isolation, and a holistic approach was necessary to consider the whole production management of the commercial flocks studied. Furthermore, the study focused on the identification of sesquiterpenoid ratios to differentiate milks and cheeses produced under extensive mountain grazing from those produced under other seasonal feeding regimens. Total abundance of mono- and sesquiterpenoids and that of individual compounds such as α-pinene, β-caryophyllene, α-humulene, α-amorphene, and γ-cadinene significantly increased in milk and cheese from indoor feeding to mountain extensive grazing. Sesquiterpenoid ratios such as γ-cadinene/α-muurolene, γ-cadinene/δ-cadinene, β-caryophyllene/α-muurolene, and (β-caryophyllene + γ-cadinene)/α-muurolene were used to differentiate mountain milks and cheeses from those from indoor feeding and part-time grazing in the valley. Multivariate discriminant analysis applied to individual terpenoids and sesquiterpenoid ratios showed milk and cheese samples classified into 2 groups: samples from indoor feeding and part-time grazing in the valley were classified together, and clearly separated from mountain milks and cheeses. The results of the present study showed that the sesquiterpenoid ratios approach could help to differentiate mountain dairy products from others obtained under other specific feeding regimens in a local environment.     

Microbiological quality of raw milk used for small-scale artisan cheese production in Vermont: Effect of farm characteristics and practices

This study 1) evaluated the overall milk quality and prevalence of 4 target pathogens (Listeria monocytogenes, Staphylococcus aureus, Salmonella spp., and Escherichia coli O157:H7) in raw milk used for small-scale artisan cheesemaking and 2) examined specific farm characteristics and practices and their effect on bacterial and somatic cell counts (SCC). Raw milk samples were collected weekly from 21 artisan cheese operations (6 organic) in the state of Vermont that manufactured raw-milk cheese from cow (12), goat (5), or sheep (4) milk during the summer of 2008. Individual samples were examined for standard plate counts (SPC), coliform counts (CC), and SCC. Samples were also screened for target pathogens both quantitatively and qualitatively by direct plating and PCR. Overall, 86% of samples had SPC <10,000 cfu/mL, with 42% <1,000 cfu/mL. Additionally, 68% of samples tested were within pasteurized milk standards for coliform bacteria under the United States’ Grade A Pasteurized Milk Ordinance at <10 cfu/mL. Log₁₀ SPC and CC did not differ significantly among species. Similarly, method of sample delivery (shipped or picked up), farm type (organic or conventional), and duration of milking (year-round or seasonal) did not have significant effects on farm aggregated mean log₁₀ SPC, CC, or SCC. Strong positive correlations were observed between herd size and mean log₁₀ SPC and between log₁₀ SPC and CC as well as SCC when data from all animal species were combined. Although SCC for cow milk were significantly lower than those for goat and sheep milk, 98, 71, and 92% of cow, sheep, and goat milk samples, respectively, were within the compliance limits of the United States’ Grade A Pasteurized Milk Ordinance for SCC. Fourteen of the 21 farms (67%) were positive for Staph. aureus, detected in 38% of samples at an average level of 20 cfu/mL. Neither L. monocytogenes, E. coli O157:H7, or Salmonella spp. were detected or recovered from any of the 101 samples tested. Our results indicate that the majority of raw milk produced for small-scale artisan cheesemaking was of high microbiological quality with no detectable target pathogens despite the repeat sampling of farms. These data will help to inform risk assessments that evaluate the microbiological safety of artisan and farmstead cheeses, particularly those manufactured from raw milk.     

Effects of dietary supplementation with extruded linseed and oregano in autochthonous goat breeds on the fatty acid profile of milk and quality of Padraccio cheese

The study aimed to evaluate the effects of linseed and oregano supplementation to the diet of goats on fatty acid profile and sensory properties of Padraccio, a typical cheese produced during spring through summer in the Basilicata region (southern Italy). Extruded linseed and dried oregano inflorescences were integrated in the pelleted concentrate supplementation (500 g/head per day) in 21 grazing goats that were randomly assigned, 7 per group, to the following experimental treatments: concentrate, concentrate with addition of linseed, and concentrate with addition of linseed and oregano. Pooled milk from each group was used in cheesemaking. From a nutritional perspective, integration of extruded linseed in the goat diet improved the fatty acid profile of Padraccio cheese. Moreover, the cheese from this group evidenced the highest scoring on color, flavor, texture, and overall liking.     

Conjugated linoleic acid content in fermented goat milk as affected by the starter culture and the presence of free linoleic acid

The effect of yoghurt starter cultures and probiotic Lactobacillus casei on the formation of conjugated linoleic acid (CLA) and microbial populations of fermented goat milk was investigated during 35 days of cold storage. The addition of hydrolysed sunflower oil as a source of free linoleic acid was investigated. The fermentation process enhanced the content of the cis9, trans11‐CLA isomer in milk, whereas the trans10, cis12‐CLA isomer was not detected in goat milk or control fermented milks. The use of both starters generated trans10, cis12‐CLA only when hydrolysed sunflower oil was supplemented. Populations of streptococci and lactobacilli were affected by the presence of hydrolysed sunflower oil.     

Volatile organic compounds of mountainous plant species and the produced milk as affected by altitude in Greece: A preliminary study

The objective of this study was to characterise the volatile organic compounds (VOCs) profile of plant species, bulk forage grazed by sheep and produced milk at different mountainous areas of Greece. The most abundant plant species of vegetation at 800 m (hill‐land) and 1300 m (highland) altitude, bulk forage and milk samples, were collected. The VOCs profiles of the plant species and milk varied. Common VOCs in milk from both areas were identified, whereas others were discriminatory for each area. Overall, the VOCs composition of mountainous milk could provide a basis for Feta cheese identification with its region.     

An indirect competitive ELISA for the detection of cows’ milk and caseinate in goats’ and ewes’ milk and cheese using polyclonal antibodies against bovine γ-caseins

 An indirect competitive enzyme-linked immunosorbent assay (ELISA) method was developed for the detection of bovine milk and caseinate in goats’ and ewes’ milk and cheese. Polyclonal antibodies were raised in rabbits and chickens against bovine γ₃-casein. In a first affinity chromatography step, antibodies recognizing caseins were absorbed on bovine casein-Sepharose. From the dialysed eluate, antibodies crossreacting with ewes’ and goats’ milk protein were completely removed by immunoadsorption onto stationary phases containing ovine casein and protein extracted from genuine ewes’ and goats’ milk cheese. The detection limit of the ELISA test was 0.1% and the method was applied successfully during an EU collaborative study of the evaluation of methods for the detection of cows’ milk. Received: 15 February 1996     

Consumer’s purchasing intention for lamb meat affected by country of origin, feeding system and meat price: A conjoint study in Spain, France and United Kingdom

Food selection and consumption can be affected by different intrinsic and extrinsic cues. In this study, the effect of three extrinsic cues (country of origin, price and feeding system) on consumer’s purchasing decisions making process for lamb meat in three European countries: Spain, France and United Kingdom was investigated, as well as the relative importance of each cue. Four countries were considered for evaluating the effect of the country of origin (local, Argentina, Switzerland and Uruguay), three feeding systems (grain-fed, grass-fed and grain + grass-fed) and different price levels (low, medium and high), which were simultaneously compared. Fifteen profiles combining the different levels for each of the factors considered where those obtained by means of an orthogonal design. These profiles were evaluated by 100, 99 and 92 consumers in Spain, France and United Kingdom, respectively. Moreover, consumers sensory evaluated lamb from four different feeding systems, grain-fed, grass-fed and two mixtures of grain and grass-fed. Conjoint analysis was carried out both for evaluating clusters of consumers in each country and for considering an overall evaluation of all the countries at the same time. In general, the origin of the meat was the most important factor in determining consumer’s purchasing decisions making process, the local one being the most preferred. Uruguayan origin was the least preferred, which indicates that Uruguayan public and private sectors would need to enhance their country and meat image as well as support market promotion and penetration strategies in the European market. For some consumers the feeding system was the most important factor for choosing any particular meat amongst others, being grass-fed animal the most preferred. These results are not in agreement with the consumer’s acceptability studies of lamb meat when taste the meat from different feeding systems in a blind condition (without information), showing a disconfirmation. Lamb meat price has a minor role in determining consumer’s purchasing decisions. However, one segment of consumers, composed mainly by men, considered that the price is the most important factor. These findings showed the importance of studying consumer preferences and their segmentation for developing market promotions, which should have a holistic approach including extrinsic factors in the evaluation of consumer’s purchasing decisions making process.     

The combination of stable isotope abundance ratios of H,C, N and S with Sr/Sr for geographical origin assignment of orange juices

Within the EU-project “Pure Juice” established stable isotope methods (δ²H, δ¹³C, δ¹⁵N) have been applied and improved in order to determine and verify the geographical origin of orange juices. In addition, new approaches employing analyses of δ³⁴S and ⁸⁷Sr/⁸⁶Sr have been developed and tested. Approximately 150 authentic orange juice samples from several regions in North- and South-America, Africa and Europe have been analysed. A discrimination of orange producing regions, based on the results which ultimately depend on geographical, climatic and lithological differences was successfully performed. Furthermore, we demonstrate that blending of single strength juice by adding concentrate can be revealed by comparing ⁸⁷Sr/⁸⁶Sr of soluble and insoluble components of the juices. We conclude that regional assignment of orange juice samples is most successful when single parameters are combined in a “multi-element approach”.