An attempt to produce ras cheese by direct acidification

Ras cheese was made from cow's milk acidified with either lactic or citric acid to pH 5·8 with and without the addition of GDL to the resultant curd from each acidulant. Also, control Ras cheese was made using lactic starter culture. The cheese made from the direct acidified milk showed slightly higher moisture and salt contents compared with the control. This was associated with slightly lower fat and acid contents. Also, the cheese made by direct acidification contained lower levels of SN, NPN, AN and TVA compared with the control cheese. The direct acidified cheese was characterized by poor body, crumbly texture and weak flavour intensity. Cheese made from citric acid-acidified milk was more acceptable than that made from milk acidified with lactic acid.     

Effect of phage on survival of Salmonella enteritidis during manufacture and storage of cheddar cheese made from raw and pasteurized milk.

The ability of Salmonella Enteritidis to survive in the presence of phage, SJ2, during manufacture, ripening, and storage of Cheddar cheese produced from raw and pasteurized milk was investigated. Raw milk and pasteurized milk were inoculated to contain 10(4) CFU/ml of a luminescent strain of Salmonella Enteritidis (lux) and 10(8) PFU/ml SJ2 phage. The milks were processed into Cheddar cheese following standard procedures. Cheese samples were examined for Salmonella Enteritidis (lux), lactic acid bacteria, molds and yeasts, coliforms, and total counts, while moisture, fat, salt, and pH values were also measured. Salmonella Enteritidis (lux) was enumerated in duplicate samples by surface plating on MacConkey novobiocin agar. Bioluminescent colonies of Salmonella Enteritidis were identified in the NightOwl molecular imager. Samples were taken over a period of 99 days. Counts of Salmonella Enteritidis (lux) decreased by 1 to 2 log cycles in raw and pasteurized milk cheeses made from milk containing phage. In cheeses made from milks to which phage was not added, there was an increase in Salmonella counts of about 1 log cycle. Lower counts of Salmonella Enteritidis (lux) were observed after 24 h in pasteurized milk cheese containing phage compared to Salmonella counts in raw milk cheese with phage. Salmonella Enteritidis (lux) survived in raw milk and pasteurized milk cheese without phage, reaching a final concentration of 10(3) CFU/g after 99 days of storage at 8 degrees C. Salmonella did not survive in pasteurized milk cheese after 89 days in the presence of phage. However, Salmonella counts of approximately 50 CFU/g were observed in raw milk cheese containing phage even after 99 days of storage. In conclusion, this study demonstrates that the addition of phage may be a useful adjunct to reduce the ability of Salmonella to survive in Cheddar cheese made from both raw and pasteurized milk.     

Important vectors for Listeria monocytogenes transmission at farm dairies manufacturing fresh sheep and goat cheese from raw milk

The aim of this study was to determine the transmission routs of Listeria spp. in dairy farms manufacturing fresh cheese made from ovine and caprine raw milk and to evaluate the impact of Listeria monocytogenes mastitis on raw milk contamination. Overall, 5,799 samples, including 835 environmental samples, 230 milk and milk product samples, and 4,734 aseptic half-udder foremilk samples were collected from 53 dairy farms in the dairy intensive area of Lower Austria. Farms were selected for the study because raw milk was processed to cheese that was sold directly to consumers. A total of 153 samples were positive for Listeria spp., yielding an overall prevalence of 2.6%; L. monocytogenes was found in 0.9% of the samples. Bulk tank milk, cheese, and half-udder samples were negative for Listeria spp. Because none of the sheep and goats tested positive from udder samples, L. monocytogenes mastitis was excluded as a significant source of raw milk contamination. L. monocytogenes was detected at 30.2% of all inspected farms. Swab samples from working boots and fecal samples had a significantly higher overall prevalence (P < 0.001) of L. monocytogenes (15.7 and 13.0%, respectively) than did swab samples from the milk processing environment (7.9%). A significant correlation was found between the prevalence of L. monocytogenes in the animal and in the milk processing environment and the silage feeding practices. Isolation of L. monocytogenes was three to seven times more likely from farms where silage was fed to animals throughout the year than from farms where silage was not fed to the animals.     

Enhancement of flavour development in ras cheese made by direct acidification

An attempt has been made to enhance flavour development in Ras cheese made from directly acidified milk. Addition of a ripened cheese slurry, yoghurt culture (Streptococcus thermophilus + Lactobacillus bulgaricus) or cheese starter (S. lactis + L. casei + Leuconostoc citrovorum) to the chemically acidified curd enhanced flavour intensity, body characteristics, the formation of both soluble nitrogen compounds and Free Fatty Acids and stimulated bacterial growth. Sensory properties (or characteristics) of cheese from chemically acidified curd incorporating the above additives approached those of control cheese.     

Manufacture of direct acidified cheese from ultrafiltration and reverse osmosis retentates

Whole milk and retentates from ultrafiltration at 4:1 volume concentration ratio and reverse osmosis at 2.5:1 were used in the manufacture of direct acidified cheese. Yield based on component recovery was higher in cheese from milk retentates than whole milk. On a dry mass basis, an increase in cheese yield of 37.9% for reverse osmosis, and 14.7% for ultrafiltration was achieved compared with cheese from whole milk. Compositional variation in the resulting cheese affected both textural and sensory parameters. Cheese from ultrafiltration scored highest in sensory evaluation, although all cheeses were graded fair to good.     

Microbiota characterization of a Belgian protected designation of origin cheese,Herve cheese,using metagenomic analysis

Herve cheese is a Belgian soft cheese with a washed rind, and is made from raw or pasteurized milk. The specific microbiota of this cheese has never previously been fully explored and the use of raw or pasteurized milk in addition to starters is assumed to affect the microbiota of the rind and the heart. The aim of the study was to analyze the bacterial microbiota of Herve cheese using classical microbiology and a metagenomic approach based on 16S ribosomal DNA pyrosequencing. Using classical microbiology, the total counts of bacteria were comparable for the 11 samples of tested raw and pasteurized milk cheeses, reaching almost 8 log cfu/g. Using the metagenomic approach, 207 different phylotypes were identified. The rind of both the raw and pasteurized milk cheeses was found to be highly diversified. However, 96.3 and 97.9% of the total microbiota of the raw milk and pasteurized cheese rind, respectively, were composed of species present in both types of cheese, such as Corynebacterium casei, Psychrobacter spp., Lactococcus lactis ssp. cremoris, Staphylococcus equorum, Vagococcus salmoninarum, and other species present at levels below 5%. Brevibacterium linens were present at low levels (0.5 and 1.6%, respectively) on the rind of both the raw and the pasteurized milk cheeses, even though this bacterium had been inoculated during the manufacturing process. Interestingly, Psychroflexus casei, also described as giving a red smear to Raclette-type cheese, was identified in small proportions in the composition of the rind of both the raw and pasteurized milk cheeses (0.17 and 0.5%, respectively). In the heart of the cheeses, the common species of bacteria reached more than 99%. The main species identified were Lactococcus lactis ssp. cremoris, Psychrobacter spp., and Staphylococcus equorum ssp. equorum. Interestingly, 93 phylotypes were present only in the raw milk cheeses and 29 only in the pasteurized milk cheeses, showing the high diversity of the microbiota. Corynebacterium casei and Enterococcus faecalis were more prevalent in the raw milk cheeses, whereas Psychrobacter celer was present in the pasteurized milk cheeses. However, this specific microbiota represented a low proportion of the cheese microbiota. This study demonstrated that Herve cheese microbiota is rich and that pasteurized milk cheeses are microbiologically very close to raw milk cheeses, probably due to the similar manufacturing process. The characterization of the microbiota of this particular protected designation of origin cheese was useful in enabling us to gain a better knowledge of the bacteria responsible for the character of this cheese.     

Proteolysis during ripening of Manchego cheese made from raw or pasteurized ewes' milk. Seasonal variation

Changes in nitrogen compounds during ripening of 40 batches of Manchego cheese made from raw milk (24 batches) or pasteurized milk (16 batches) at five different dairies throughout the year were investigated. After ripening for six months, degradation of p-kappa- and beta-caseins was more intense in raw milk cheese and degradation of alpha(s2)-casein in pasteurized milk cheese. Milk pasteurization had no significant effect on breakdown of alpha(s1)-casein. Hydrophobic peptide content did not differ between raw and pasteurized milk cheese, whereas hydrophilic peptide content was higher in raw milk cheese. There were no significant differences between seasons for residual caseins, but hydrophobic peptides were at a higher level in cheese made in autumn and winter and hydrophilic peptides in cheese made in winter and spring. Raw milk cheese had a higher content of total free amino acids and of most individual free amino acids than pasteurized milk cheese. The relative percentages of the individual free amino acids were significantly different for raw milk and pasteurized milk cheeses. The relative percentages of Lys and lie increased, while those of Val, Leu and Phe decreased during ripening. There were also seasonal variations within the relative percentages of free amino acids. In raw milk cheeses, Asp and Cys were relatively more abundant in those made in autumn, Glu and Arg in cheeses made in winter, and Lys and Ile in cheeses made in spring and summer. Biogenic amines were detected only in raw milk cheese, with the highest levels of histamine, tryptamine and tyramine in cheeses made in spring, winter and spring, respectively.     

Determination of cow milk-casein in sheep and goat cheese by immunoelectrophoresis

By means of crossed immunoelectrophoresis according to the method of Clarke and Freeman combined with a modification of the silver staining technique of Willoughby and Lambert, using a commercial anti-bovine casein rabbit serum, in sheep's and goat's cheese it is possible to evaluate the added cow's milk in a clear and reproducible way down to a level of 0.1-0.2%. The lower detection limit is within the lower scale after the addition of starter cultures usual in the production of cheese from raw milk and more than tenfold below the amounts of starter cultures used in the production of cheese from heated milk. Because of the possibility of using casein for detection, this method is suitable for analysis, not only in cheese made from raw milk, but also in that made from heated milk.     

Improving the quality of Ras cheese made without starter

Trials were carried out to produce Ras cheese of good quality without the use of starter. Cheese was made from cows' milk, pasteurized and acidified with lactic acid or citric acid to pH 5·8; cheese was also made after adding 4·5 g glucono-δ-lactone per kg to the acidified curd. Control cheese was made by the traditional method.The cheese had poor body and texture, weak flavour intensity, and low levels of soluble nitrogen compounds and free volatile fatty acids.Incorporation into the cheese curd of mixtures containing Fromase 100 (fungal protease) and Piccantase B (fungal lipase) or Fromase 100 and Capalase K (animal lipase) enhanced flavour intensity and body characteristics and accelerated the formation of both soluble nitrogen compounds and free volatile fatty acids. The organoleptic properties of the experimental cheese with added enzymes were comparable to the control cheese.     

猪血浆粉蛋白对软质鲜干酷的影响

研究了添加猪血浆粉对鲜干酪品质特性及生产性状的影响,得到一种新型软质鲜干酪的生产工艺.通过向牛乳中加入少量猪血浆蛋白粉,在修饰干酪的风味特征、理化特性的基础上,既提高了干酪的氨基酸营养平衡和利用价值,也同时为我国的猪血资源利用探索新的途径.研究对比了凝乳酶和转谷氨酰胺(TG)酶新型干酪的质构特性.经TG酶处理的干酪硬度是经凝乳酶处理的干酪硬度的1.6倍,凝乳酶处理组的弹性可达0.89,TG酶处理组的弹性略小,约为0.77,通过计算,各组的咀嚼性均在1.0左右,无显著性差异.通过研究确定了猪血蛋白粉的添加量为2%,此时产品颜色微泛黄,无明显腥味,产品持水性增加,出品率提高.     

Manufacture of processed cheese from Iraqi white soft cheese

Processed cheese was made from different samples of Iraqi white soft cheese by adding 3.5% emulsifying salts and 15–25% water depending on the chosen type of processed cheese. Arabic gum was used to firm the cheese at a rate of 0.08%. Total solids ranged from 46.8–43.4% in the firm and spread types, respectively. Laboratory processed cheese gave excellent quality compared with local processed cheese.     

The fate of Listeria monocytogenes during the manufacture of Camembert-type cheese: A comparison between raw milk and milk treated with high hydrostatic pressure

Camembert-type cheese was produced from: raw bovine milk; raw milk inoculated with 2 or 4 log CFU/ml Listeria monocytogenes; raw milk inoculated with L. monocytogenes and subsequently pressure-treated at 500 MPa for 10 min at 20 °C; or uninoculated raw milk pressure-treated under these conditions. Cheeses produced from both pressure-treated milk and untreated milk had the typical composition, appearance and aroma of Camembert. Curd and cheese made from inoculated, untreated milk contained large numbers of L. monocytogenes throughout production. An initial inoculum of 1.95 log CFU/ml in milk increased to 4.52 log CFU/g in the curd and remained at a high level during ripening, with 3.85 log CFU/g in the final cheese. Pressure treatment inactivated L. monocytogenes in the raw milk at both inoculum levels and the pathogen was not detected in any of the final cheeses produced from pressure-treated milk. Therefore high pressure may be useful to inactivate L. monocytogenes in raw milk that is to be used for the production of soft, mould-ripened cheese.

Industrial relevance

This paper demonstrates the potential of high pressure (HP) for treatment of raw milk to be used in the manufacture of soft cheeses. HP treatment significantly reduced the level of Listeria monocytogenes in the raw milk and so allowed the production of safer non-thermally processed camembert-like soft cheese.     

Traditional Colonial-type cheese from the south of Brazil: A case to support the new Brazilian laws for artisanal cheese production from raw milk

Artisanal Colonial-type cheese is made from raw milk and is the main cheese produced by rural families of the southern region of Brazil. The aim of this study was to investigate, identify problems, and propose solutions for the current situation of small family farms producing and informally selling artisanal Colonial-type cheese located in the western part of Santa Catarina State in Southern Brazil. A semistructured questionnaire was employed in 12 rural properties to analyze the mode of production. Physical-chemical and microbiological analyses of water, raw milk, and cheese were performed, and it was found that 92, 50, and 100% of the samples, respectively, were outside of the current Brazilian regulatory parameters. None of the cheesemakers involved in this study met the requirements, as established by law, for artisanal cheese production from raw milk. This study concluded that technical support and changes in public policy are needed to ensure the preservation of this artisanal cheese, considering the historical importance and cultural traditions of these local communities and the socioeconomic importance of cheesemaking to family farming. Furthermore, more research on the safety of the cheese produced from raw milk is needed as well as the development of specific microbiological standards for artisanal Brazilian cheeses. Public policies aimed at guaranteeing food safety that formalize the commercialization of these cheeses will increase food security in those communities that currently produce artisanal cheese informally.     

Determination of bovine lactoferrin concentrations in cheese with specific monoclonal antibodies

In order to determine bovine lactoferrin concentration in cheese, bovine lactoferrin-specific monoclonal antibodies have been raised and an ELISA has been developed to determine lactoferrin concentrations in milk, whey and experimental soft, semi-hard and Swiss-type cheeses made with raw or pasteurised milk. The lactoferrin concentration in cheese was shown to depend on the cheese-making process, with higher values in Swiss-type and semi-hard cheeses than in soft cheeses. Furthermore, Western-blotting analysis of lactoferrin in cheese showed that this protein stayed intact throughout ripening in raw milk cheese, whereas it was partially hydrolysed in cheeses made with pasteurised milk. Based on these observations, we propose that cheese may constitute a natural dairy source of lactoferrin beneficial to health.     

Factors controlling histamine production in Swiss cheese inoculated with Lactobacillus buchneri

Swiss cheese was made from raw milk inoculated with various concentrations of a histamine-producing strain of Lactobacillus buchneri. Histamine production in these cheeses was proportional to the initial number of L. buchneri present in the raw milk. The highest inoculum level tested was 10(5) L. buchneri/ml. This cheese contained 80 mg of histamine/100 g of cheese after 90 d of storage. Only 15 mg of histamine/100 g of cheese were detected after 90 d at the lowest inoculum level, 10(2) L. buchneri/ml. No histamine was detected in any of the Swiss cheese samples until after the brining stage. Perceptible growth of L. buchneri also did not occur until after the warm room treatment. Therefore, control of histamine formation in Swiss cheese requires control of the number of histamine-producing bacteria in the raw milk. A 5.5% NaCl concentration in DeMan, Rogosa, Sharpe (MRS) broth inhibited the production of histamine by L. buchneri, but the concentrations of NaCl typically found in Swiss cheese were not inhibitory. The histamine-producing isolate of L. buchneri survived heating at 49 to 80 degrees C for 10 min, suggesting that this organism would easily survive the normal heating process applied to raw milk used prior to making Swiss cheese.     

Indigenous raw milk microbiota influences the bacterial development in traditional cheese from an alpine natural park

Nostrano di Primiero is a 6-month ripened cheese produced from raw milk collected in the Paneveggio-Pale di San Martino Natural Park area in the Italian Dolomites. In summer, this cheese is made using milk collected from two different areas, Passo Rolle and Vanoi, in the Paneveggio Natural Park. During the experiment, the milk from the two areas was separately processed, and cheeses were made in the same cheese factory using the same technological process. The microbiota of raw milk and cheeses of the two areas was isolated and the dominant population was monitored by RAPD analysis and identified by 16S rRNA sequence. The milk of the Passo Rolle area was mainly composed of mesophilic strains, thermophilic Streptococcus thermophilus, and low amounts of enterococci were also found; the milk of the Vanoi area was dominated by mesophilic microbiota mostly Lactococcus lactis ssp. cremoris and ssp. lactis and Lactobacillus paracasei ssp. paracasei. The plating of the natural starter culture revealed the presence of a relevant community of thermophilic cocci and lower amounts of enterococci. The dynamic population analysis showed the importance of the natural starter culture in the first 2 days of cheese ripening in both cheeses. Moreover, the large biodiversity observed in the raw milks was also detected in the cheeses during ripening. The Vanoi cheese was dominated by Enterococcus faecium and Streptococcus macedonicus in the first two days and mesophilic 21 Lb. paracasei ssp. paracasei became the most represented population after 15 days of ripening. In the first few days, the Rolle cheese was characterized by being mainly composed of thermophilic S. macedonicus and S. thermophilus and secondarily by mesophilic cocci. During ripening, the microbiota composition changed, and at 15 days, mesophilic lactobacilli were the dominant population, but later, this was mainly composed of mesophilic cocci and lactobacilli. The taxonomical identification by 16S rRNA sequence confirmed a large biodiversity related to raw milk microbiota and only five strains of S. macedonicus, Lactobacillus plantarum, 21 Lb. paracasei ssp. paracasei, Lactobacillus fermentum and E. faecium were detected in both cheeses.     

Use of wild Lactobacillus strains in an adjunct culture for a Roncal-type cheese

The effect of an added adjunct culture consisting of facultatively heterofermentative lactobacilli (FHL) on the volatile compounds and sensory characteristics of a Spanish ewes'-milk cheese was examined. Three cheese batches were prepared using a commercial starter, one from raw milk, another from pasteurized milk, and a third from pasteurized milk with an added culture of wild Lactobacillus. paracasei+Lb. plantarum. Analysis of the volatile compounds was carried out by the purge and trap method and gas chromatography with a mass spectrometer and disclosed a total of 86 compounds belonging to the chemical families hydrocarbons, fatty acids, esters, ketones, aldehydes, and alcohols. After ageing for 120 and 240 days, the cheese samples underwent sensory analysis by a panel of expert assessors. The attributes evaluated were characteristic odour and odour intensity and characteristic aroma and aroma intensity. Pasteurization of the milk had an effect on the formation of certain volatile compounds, adversely affecting the characteristic flavour of the cheese. Use of the adjunct culture in addition to the commercial starter improved the flavour of the cheese made from the pasteurized milk, which earned sensory scores similar to those awarded to the cheese made from the raw milk. Use of adjunct cultures consisting of indigenous FHL strains could help to conserve the traditional characteristics of Roncal cheese made from pasteurized milk, although some technical adjustments to the Regulations would be needed.     

Effect of milk thermisation and farming system on cheese sensory profile and fatty acid composition

The effect of milk thermisation and farming system on the sensory profile and fatty acid (FA) composition of a traditional cheese under real production conditions was evaluated. Raschera Protected Designation of Origin (PDO) cheese, which is produced in North-West Italy, was chosen as a case study. Cheese samples were collected in summer and winter from dairy plants that processed raw milk (IR) or thermised milk (IT) collected from intensive farms, or raw milk (ER) collected from extensive farms. The sensory profile and FA composition of IR and IT cheese were similar. The ER summer cheeses had a lower cream odour, butter odour and aroma. They had a higher rennet, strong toasted, silage, barn, garlic, boiled vegetables, and smoked odours and aromas, a higher hazelnut odour, and tasted more bitter. The ER summer cheese also expressed a more favourable FA composition for human health, which allowed it to be distinguished among the other Raschera cheese.     

Manufacture of heat and acid coagulated cheese from ultrafiltered milk retentates

Ultrafiltration technology was used for the production of direct acidified cheese. Process parameters were optimized for cheese manufacture from whole milk retentates at 4:1 volume concentration ratio. Sensory evaluation indicated that cheese from ultrafiltration was preferred equally to traditional manufacture when the cheese was of similar composition, while citric acid was the preferred acidulent. An increase in cheese yield of 3.3% and an increase in yield on dry matter mass basis of 14.7% was achieved by use of ultrafiltration. Yield efficiencies based on protein, fat or total solids increased with retentate concentration.     

Impact of milk preacidification with CO2 on cheddar cheese composition and yield

Preacidification of milk for cheese making may have a beneficial impact on increasing proteolysis during cheese aging. Unlike other acids, CO(2) can easily be removed from whey. The objectives of this work were to determine the effect of milk preacidification on Cheddar cheese composition, the recovery of individual milk components, and yield. Carbon dioxide was injected inline after the cooling section of the pasteurizer. Cheeses with and without added CO(2) were made simultaneously from the same batch of milk. This procedure was replicated 3 times. Carbon dioxide in the cheese milk was about 1600 ppm, which resulted in a milk pH of about 5.9 at 31 degrees C. The starter culture and coagulant addition rates were the same for both the CO(2) treatment and the control. The whey pH at draining of the CO(2) treatment was lower than the control. Total make time was shorter for the CO(2) treatment compared with the control. Cheese manufactured from milk acidified with CO(2) retained less of the total calcium and fat than the control cheese. The higher fat loss was primarily in the whey at draining. Preacidification with CO(2) did not alter the crude protein recovery in the cheese. The CO(2) treatment resulted in a higher added salt recovery in the cheese and produced a cheese that contained too much salt. Considering the higher added salt retention, the salt application rate could be lowered to achieve a typical cheese salt content. Cheese yield efficiency of the CO(2) treated milk was 4.4% lower than the control due to fat loss. Future work will focus on modifying the make procedure to achieve a normal fat loss into the whey when CO(2) is added to milk.