Characteristics of set type yoghurt made from caprine or ovine milk and mixtures of the two

Rheological, physico‐chemical and organoleptic studies were made on five types of yoghurt originally from pure caprine milks of an Alpine breed and local breeds, pure ovine milk of the Lacaune breed, and two mixtures containing 50% caprine milk from an Alpine breed + 50% ovine milk of the Lacaune breed and 70% caprine milk of local breeds + 30% ovine milk of the Lacaune breed. Comparison of the yoghurts showed that it was possible to produce yoghurt of good quality from the last four types of milk. In contrast, pure caprine milk from an Alpine breed was not suitable for the production of yoghurt as this milk is low in dry matter and the yoghurt that was produced had the lowest firmness and significantly inferior organoleptic characteristics. Yoghurts prepared from mixtures of 50% caprine milk of an Alpine breed + 50% ovine milk of the Lacaune breed, and 70% caprine milk of local breeds + 30% ovine milk of the Lacaune breed, were of good quality, with similar consistency, rheological and organoleptic characteristics.     

The influence of milk powder characteristics on the properties of halloumi cheese made from recombined milk*

The properties of halloumi made from recombined milks that had been prepared using milk powders processed by different methods were investigated. With skim milk powder, decreases in heat treatment of the liquid skim before drying were found to improve the stretch and melt properties of the cheese. In contrast, the level of solids in the skim concentrate before drying had no effect on the cheese characteristics. Ultrafiltration was also used to concentrate milk for spray drying. The resultant powder was recombined to give protein levels equivalent to that of normal milk and to that of milk concentrated fivefold. In both cases the recombined milks could be converted into high quality halloumi.     

Some properties of set yoghurt made from caprine milk and bovine–caprine milk mixtures fortified by ultrafiltration or the addition of skim milk powder

Set yoghurt was produced from caprine milk (A), 70% caprine-30% bovine (B) and 50% caprine–50% bovine milk (C) mixtures, and stored for 14 days at ±4°C. Two methods of fortification, namely ultrafiltration (UF) and the addition of bovine skim milk powder (SMP), were applied to the milk mixtures. Some chemical, physical, microbiological and sensory properties of the six samples were analysed on the 1st, 7th and 14th days of storage. The effects of milk type, concentration method and storage period on the physicochemical and microbiological properties of the samples were investigated statistically.     

Ripening of Camembert-type cheese made from caprine milk using calf rennet or kid rennet as coagulant

Camembert-type cheese was made from caprine milk using either calf rennet or kid 'Grandine' rennet as coagulant. The pH of all cheeses increased throughout ripening and levels of pH 4.6-soluble nitrogen increased from 8.1 to 18.2% of total nitrogen (TN) and from 6.9 to 20% TN for the cheeses made using calf rennet and kid rennet, respectively. Degradation of β-casein, measured by urea–polyacrylamide gel electrophoresis, and total and free amino acids were greater in the cheese made using kid rennet. Production of peptides, analysed by high performance liquid chromatography (HPLC), was slightly more extensive in the Camembert-type cheese made using calf rennet as coagulant. In general, a higher degree of proteolysis was found in Camembert-type cheese made from caprine milk using kid rennet than in cheese made using calf rennet as coagulant.     

Feta cheese texture: the effect of caprine and ovine milk concentration

Feta cheese was produced commercially with different caprine to ovine milk ratios. Milk fat concentrations, moisture and salt contents were similar for all the batches. However, the hardness and adhesive characteristics of the cheeses differed in relation to the milk ratio. The hardness of the cheese appeared to be correlated to increased goat milk content. Cryo-scanning electron microscopy (cryo-SEM) of the cheese samples showed that feta cheese with a higher proportion of caprine milk had a more compact and less porous appearance than feta produced from purely ovine milk. This difference in cheese structure helps to explain the difference in hardness between the samples.     

Changes during ripening in chemical composition,proteolysis, volatile composition and texture in Kashar cheese made using raw bovine,ovine or caprine milk

Kashar cheeses were manufactured from pure ovine (OV), bovine (BV) and caprine (CP) milk, and the chemical composition, cheese yield, proteolysis, hardness, meltability and volatile composition were studied during 90 days. Gross chemical composition, cheese yield and level of proteolysis were higher in OV cheeses than those of BV or CP cheeses. Glu, Val, Leu, Phe and Lys were the most abundant free amino acids (FAA) in the samples, and the concentrations of individual FAA were at the highest levels in OV cheeses with following BV and CP cheeses. Urea‐PAGE patterns and RP‐HPLC peptide profiles of the BV cheeses were completely different from the small ruminants’ milk cheeses (OV or CP). Higher and lower hardness and meltability values were observed in CP cheeses, respectively. OV cheeses resulted in higher levels of the major volatile compounds. In conclusion, the Kashar cheese made using OV milk can be recommended due to high meltability, proteolysis and volatiles.     

Comparison of the characteristics of teleme cheese made from ewe's, goat's and cow's milk or a mixture of ewe's and goat's milk

Teleme cheeses were manufactured from ewe's, goat's and cow's milk and mixture of ewe's and goat's milk. Physicochemical and biochemical analyses of the cheeses at various stages of ripening and storage were performed. Cheeses made from goat's milk had lower moisture content than those made from other milks. No significant differences in the mean values of protein, salt and water activity (a _w ) of the different cheeses at all ages studied were found. Cheeses from goat's and cow's milk had higher contents of fat and fat in dry matter (FDM) compared to that of cheeses from ewe's milk and mixed milk. Significant differences were observed in the yield and yield on 56% moisture: cheeses from ewe's milk gave the highest yield and cheese from cow's milk the lowest. Significant differences were found in the ashes content of the different cheeses at all ages. No differences in cholesterol and cholesterol/fat contents of the four types of cheeses were found. Main and trace elements showed variability among the four cheeses.     

Changes in the microbiological and chemical characteristics of an artisanal, low-fat cheese made from raw ovine milk during ripening

Changes in the microbial flora of batzos cheese made from raw ovine milk were studied during ripening. Lactic acid bacteria and Enterobacteriaceae were the predominant groups of micro-organisms. Cheeses manufactured in summer had higher microbial counts than those made in spring, with the exception of staphylococci. Nevertheless, Enterobacteriaceae and coliforms decreased more rapidly in cheese made in summer and counts at the end of storage were lower than those in spring cheese.
Enterococci predominated in the ripened curd of cheese made in spring, whereas lactobacilli were the most abundant lactic acid bacteria in cheese made in summer. Enterococcus faecium was the predominant species in spring, and Lactobacillus paracasei ssp. paracasei predominated in cheese made in summer. The pH of the cheeses was > 5.0 throughout ripening, and NaCl-in-moisture content (> 8.0%) permitted the growth and survival of salt-tolerant micro-organisms. α_s1-Casein degraded at a faster rate than β-casein; both caseins were hydrolysed more rapidly in spring than in summer. The free amino acid content became higher in summer cheese (566.24–3460.25 µg/g of glycine equivalent) than in spring cheese because of the progress of ripening. Moreover, the milk fat of the cheese was degraded more in the summer than in the spring. The results suggest that there could be advantages to using starter cultures and improving the level of hygiene during milk and cheese production in order to eliminate undesirable micro-organisms and standardize cheese quality.     

Replacement of fat with long-chain inulin in a fresh cheese made from caprine milk

The aim of this study was to evaluate the effect of the replacement of fat with long-chain inulin on textural and microstructural properties of a fresh caprine milk cheese. All the samples contained the same level of total solids (about 22%, w/w) and substitution of fat with inulin at levels from 2% to 7%. Penetrometry parameters were affected by the levels of replacement of fat with inulin; samples containing inulin were characterised by lower values of compressive force, stiffness, viscosity and adhesiveness (except for the sample with 2% fat substitution). Scanning electron microscopy (SEM) images showed that the positioning of inulin within the gel interrupted the casein/fat network. In conclusion, the rheological results were dependent on the arrangement of inulin within the protein/fat network and, in particular, as shown by SEM images, on the aggregation of inulin during cheese-making.     

Some factors influencing the syneresis of bovine, ovine, and caprine milks

The influence of the species, fat, curd incubation temperature (25, 30, and 35 degrees C), heat treatment of milk (70 degrees C for 5 or 30 min), and milk pH on the initial volume drained, syneresis rate, and the loss of proteins in drainage was studied. The volume drained as a function of the curd incubation time (up to 60 min) was adjusted to a first-order kinetic reaction. The k values (drained rate) and the initial volume obtained applying the equation were compared to establish the possible influence of the studied factors. In general, for all the factors studied, the syneresis rate of curd from caprine and ovine milk did not differ from those described previously in the literature for the curds from bovine milk. However, for each studied factor the pattern of syneresis rate was significantly different among the species in most of the experiments.     

Qualitative and quantitative analysis of bovine milk adulteration in caprine and ovine milks using native-PAGE

Native-PAGE (polyacrylamide gel electrophoresis) was used for the simultaneous qualitative and quantitative analysis of bovine milk adulteration in caprine and ovine milk using whole milk samples as well as their whey protein fraction. Quantification was based on measuring band intensity of bovine β-lactoglobulins in all milk mixtures and bovine α-lactalbumin in caprine/bovine milk blends. Linear relationships were established between the band intensity of bovine β-lactoglobulins and α-lactalbumin vs. volume percentage of added bovine milk in all milk analysed, with the correlation coefficient from 0.9950 to 0.9998. These correlations enabling the quantification of bovine milk percentage within the wide range from 3% or 5% to 90% in caprine/bovine and ovine/bovine milk blends, respectively. The differences between the actual percentages of bovine milk present in the adulterated milk samples and those calculated using the regression lines were less than or equal to 5% for all samples. This method offers a rapid determination combined with unequivocal identification of the bovine whey proteins in almost every caprine/bovine or ovine/bovine milk mixtures.     

Proteolysis in goat cheese made from raw,pasteurized or pressure-treated milk

Primary and secondary proteolysis of goat cheese made from raw (RA), pasteurized (PA; 72 °C, 15 s) and pressure-treated milk (PR; 500 MPa, 15 min, 20 °C) were examined by capillary electrophoresis, nitrogen fractionation and HPLC peptide profiles. PA milk cheese showed a more important hydrolysis (P<0.05) of α_s1-casein than RA milk cheese at the first stages of ripening (15 days), while PR milk cheese had a level between those seen in PA and RA milk cheeses. Degradation of β-casein was more important (P<0.05) in PA and PR than in RA milk cheeses at 15 days of ripening. However, from thereon β-casein in PR and RA milk cheeses was hydrolyzed at essentially similar rates, but at lower rates (P<0.05) than in PA milk cheeses. Pressure treatment could induce proteolysis of β-casein in a way, which is different from that produced by heat treatment. There was an increase in 4.6-soluble nitrogen (WSN) and in trichloroacetic acid (TCASN) throughout ripening in cheeses, but higher contents (P<0.05) in PA and PR milk cheeses at the end of ripening were observed. PR milk cheeses contained considerably higher content (P<0.05) of free amino acids than RA or PA milk cheeses. In general, heat and pressure treatments had no significant effect on the levels of hydrophobic and hydrophilic peptides.     

Comparative performance of a mixed strain starter in cow's milk, ewe's milk and mixtures of these milks

Lactococcus lactis ssp. lactis IPLA 947, L. lactis ssp. lactis biovar. diacetylactis IPLA 838 and Leuconostoc citreum IPLA 616 and designed for Afuega'l Pitu cheese manufacture from pasteurized milk was assayed in cow's and ewe's milk, and in mixtures containing 10% and 20% ewe's milk in cow's milk. The evolution of microbial counts, pH, titratable acidity, organic acids and volatile compounds production throughout the incubation period was determined. The use of ewe's milk as a culture medium increased the metabolic activity of the starter culture reflected in a higher lactose consumption, significantly higher acidity and some carbon source-derived organic acids and volatile compounds production, as well as in slightly higher starter strains growth, although the latter was not statistically significant. Thus, it is suggested that ewe's milk or mixtures of ewe's with cow's milk can be satisfactorily used in the manufacture of this traditional cheese. Received: 27 August 1999     

Lipolysis in cheddar cheese made from raw, thermized, and pasteurized milks

The evolution of free fatty acids (FFA) was monitored over 168 d of ripening in Cheddar cheeses manufactured from good quality raw milk (RM), thermized milk (TM; 65°C × 15 s), and pasteurized milk (PM; 72°C × 15 s). Heat treatment of the milk reduced the level and diversity of raw milk microflora and extensively or wholly inactivated lipoprotein lipase (LPL) activity. Indigenous milk enzymes or proteases from RM microflora influenced secondary proteolysis in TM and RM cheeses. Differences in FFA in the RM, TM, and PM influenced the levels of FFA in the subsequent cheeses at 1 d, despite significant losses of FFA to the whey during manufacture. Starter esterases appear to be the main contributors of lipolysis in all cheeses, with LPL contributing during production and ripening in RM and, to a lesser extent, in TM cheeses. Indigenous milk microflora and nonstarter lactic acid bacteria appear to have a minor contribution to lipolysis particularly in PM cheeses. Lipolytic activity of starter esterases, LPL, and indigenous raw milk microflora appeared to be limited by substrate accessibility or environmental conditions over ripening.     

Microbiological study of Manura, a hard cheese made from raw ovine milk in the Greek island Sifnos

Changes in the microbial flora of Manura, a raw ovine milk cheese, were studied during ripening. In general, the various microbial groups developed better on the cheese surface than in the interior, but red wine treatment had an inhibitory effect on their growth and microbial counts decreased ( P  < 0.05) more rapidly on the cheese surface than in the interior. NaCl and moisture of the cheese affected microbial levels significantly. Thus, Enterobacteriaceae and coliforms were reduced sharply ( P  < 0.05) during ripening on a straw bed (∼3 months) and they were not detected in mature cheese. Lactic acid bacteria predominated over the other microbial groups throughout ripening. Leuconostoc mesenteroides ssp. cremoris , Pediococcus pentosaceus and Lactobacillus paracasei ssp. paracasei , frequently found in maturing cheese, could be used as starters to make this cheese. Moreover, the lactic acid bacteria predominating in mature cheese, such as Weissella paramesenteroides , Lactobacillus bifermentans and Lactobacillus brevis , may contribute to cheese ripening through their biochemical activities.     

Effect of technological parameters on the characteristics of kasseri cheese made from raw or pasteurized ewes' milk

Two groups of kasseri cheese (pasta filata type) were manufactured from raw or pasteurized ewes' milk, without starter cultures. Cheeses of each group were divided into two subgroups: the first was ripened and stored at 4°C and packaged in plastic film; the second ripened and stored at 15°C and coated with paraffin wax. Milk pasteurization and technological parameters had a significant effect on the pH ( P  < 0.05), while only technological parameters had an effect on the total solids content. At day 120, the range of mean cfu/g counts for the mesophilic aerobic flora was 9.5 × 10⁷−1.4 × 10⁸; for the thermophilic streptococci, the range was 2.6 × 10⁷−7.6 × 10⁷; and for the thermophilic bacilli, 9.8 × 10⁶−1.7 × 10⁷. Changes in the N fractions became significant after 30 days of ripening. For mature 120-day-old cheeses, the percentage of total N soluble at pH 4.6 was 22.7%–22.9% in raw milk cheeses and 19.0%–21.7% in pasteurized milk cheeses. The percentage of total N soluble at 12% TCA was 10.1%–12.2% in raw milk cheeses and 7.3%–11.5% in pasteurized milk cheeses; the percentages of total N soluble at 5% PTA were 3.1%–4.0% and 2.6%–3.6%, respectively. The residual α_s-casein percentages at day 120 ranged between 63% and 78% of the respective area at day 1; the residual β-casein ranged between 67% and 75%. There were some characteristic differences in the reverse phase-HPLC peptide profiles of the four cheeses. In general, the effect of the different ripening conditions was more pronounced in cheeses made from pasteurized milk.     

Robust PCR‐based method for quantification of bovine milk in cheeses made from caprine and ovine milk

To prevent fraud and enhance quality assurance, credible analysis of dairy products is crucial. A common problem is the addition of cheaper bovine milk to caprine and/or ovine dairy products and when not declared addition of bovine milk constitutes fraud. The aim was to develop a rapid, robust and sensitive method for the identification of adulteration of caprine and/or ovine cheeses with bovine milk. New quantitative real‐time polymerase (qPCR) assays were designed for the specific determination of bovine DNA (Cow1) and bovine, caprine and ovine DNA (BoCaOv). These were applied to 17 samples of caprine cheese and 24 of ovine cheese. Results showed that 17% (7/41) of these cheeses contained >5% bovine milk. As bovine milk was not declared as an ingredient in any of the samples, this represents adulteration. Other cheeses that contained detectable bovine milk at ≤5% (22%; 5/41) might pose a health risk to people allergic to bovine milk.     

Isolation and characterisation of caseinmacropeptide from bovine,ovine, and caprine cheese whey

Based on the thermostability of caseinmacropeptide (CMP) and on the differences in molecular weight of its polymeric and monomeric forms, we have developed a method of isolating CMP from whey protein concentrate (WPC) and from liquid sweet cheese whey, particularly suited to large-scale industrial production. This procedure includes acidification and heating and ultrafiltration of cheese whey to give a CMP powder with a protein content from 75 to 79%. CMP obtained from WPC and from pure bovine, ovine, and caprine cheese whey were characterized. The CMP recovery was close to 71-76% and the purity determined by RP-HPLC ranged from 75 to 90%.     

Microbiological and biochemical characteristics of Canestrato Pugliese cheese made from raw milk, pasteurized milk or by heating the curd in hot whey

Canestrato Pugliese cheeses were produced from raw ewes' milk (R and R(II) cheeses), pasteurized ewes' milk (P cheese) and by heating the curd in hot whey according to a traditional protocol (T cheese). R(II) differed from R cheese mainly by having been produced from raw milk with a higher number of somatic cells, 950.000 vs. 750.000 ml(-1), respectively. Compared to P and T cheeses, R and R(II) cheeses had a higher concentration (one or two orders of magnitude) of cheese-related bacteria such as adventitious mesophilic lactobacilli, enterococci and staphylococci. At the end of ripening, all cheeses contained less than 1.0 log cfu g(-1) of total and fecal coliforms, and Escherichia coli and Staphylococcus aureus were not detected. As shown by phenotypic identification and RAPD-PCR, R cheese contained the largest number of mesophilic lactobacilli species and the greatest diversity of strains within the Lactobacillus plantarum species. Primary proteolysis did not differ appreciably among the cheeses. On the contrary, both urea-PAGE and the RP-HPLC analyses of the water-soluble N fractions showed the more complex profiles in cheeses produced by raw milks. R and R(II) cheeses had the highest values of water-soluble N/total N (ca. 30%) and the highest concentration of total free amino acids (ca. 40 mg g(-1) which approached or exceeded those reported for Italian cheeses with very high level of proteolysis during ripening. The main differences between R-R(II) and P-T cheeses were the concentrations of aspartic acid, proline, alanine, isoleucine, histidine and lysine. The water-soluble extracts of R and R(II) cheeses contained levels of amino-, imino- and di-peptidase activities, which were about twice those found in P and T cheeses. Cheeses differed slightly in the concentration of total free fatty acids that ranged between 1673 and 1651 mg kg(-1) in R and R(II) cheeses, and 1397 and 1334 mg kg(-1) in P and T cheeses. Butyric, caproic, capric, palmitic, oleic and linoleic acids were found at the highest concentrations.