Cheesemaking with vegetable coagulants—the use of Cynara L. for the production of ovine milk cheeses

This paper reviews the use of plant extracts as vegetable coagulants for cheesemaking. It covers the plants used as sources of coagulants, with a historical overview and particular emphasis on Cynara species. The genus Cynara  L., its composition, milk clotting and proteolytic enzymes (cardosins) and their specificity towards peptide linkages are also described. Cheeses produced in the Iberian Peninsula using Cynara  L. as coagulant are documented. Cynara  L. is still the most used vegetable coagulant in cheesemaking, and also the most investigated. However, much work remains to be done to understand its action during cheese maturation and further characterization.     

酒酿凝乳剂研制干酪初探

研究了采用酒酿代替小牛凝乳酶制作干酪的方法。包括:不同的酒酿用量、凝乳温度、凝乳时间和加热排乳清温度对制作干酪的影响,其最佳工艺参数为:酒酿5%,凝乳温度25℃,凝乳时间15～17 h,加热排乳清温度45℃。     

Influence of pasteurised milk, raw milk and different ripening cultures on biogenic amine concentrations in semi-soft cheeses during ripening

In semi-soft cheeses, produced with pasteurised milk, raw milk and different starter cultures, the concentrations of cadaverine, histamine, phenylethylamine, putrescine and tyramine were investigated. The cultures (pasteurised milk cultures, raw milk cultures and starter cultures) strongly influenced the biogenic amine concentrations in the cheeses ripened for 5 months. Two cheeses made with identical pasteurised milk, but different ripening cultures, differed greatly in their total biogenic amine concentrations (51 vs 371?mg/kg). In general, the biogenic amine concentrations increased markedly between month 2 and month 3 of cheese ripening. The high content of enterococci and Enterobacteriaceae yielded the biogenic amine concentrations. In contrast, Lactobacilli did not seem to be important. However, unspecified bacteria have to be considered, since cheeses with comparable microbiological profiles differed enormously in their biogenic amine concentrations. Semi-soft cheeses produced from pasteurised milk showed remarkably lower total biogenic amine concentrations compared to semi-soft cheeses produced from raw milk (51–1096?mg/kg vs 1011–3133?mg/kg, depending also on the ripening cultures). The highest total biogenic amine concentration (4817?mg/kg) was detected in a cheese produced from raw milk that had been stored for 36?h. In this cheese, the concentrations of cadaverine, phenylethylamine, putrescine and tyramine were higher than in all other cheeses. The highest histamine concentration was found to be in another raw milk cheese (573?mg/kg).     

Suitability of Argentinian maize hybrids for polenta production

The objective of this study was to determine the suitability of different soft-endosperm commercial maize hybrids to obtain polenta of good technological quality. Ten commercial soft-endosperm hybrids and two open-pollinated varieties (quality controls) of maize were used. Grain physical characteristics were determined, and polentas from each genotype were obtained. The chemical composition of semolina was determined, and polenta was evaluated in terms of viscoelasticity, cooking characteristics and colour. The semolina yield was between 50.96 to 69.36%. The control genotypes showed the lowest values for peak viscosity, with 3670.5 and 3966.25 cP. Hybrid Next22.6 showed the highest consistency value, while C6006, Col17, Ds507 and Srm566 presented the lowest value of all samples tested. Hybrid N7822 first, followed by Ds507 and Srm553, proved to be suitable for the food industry. The good characteristics of this dish were associated with high pasting temperature and semolina yield, and low consistency and viscosity values.     

酒酿凝乳剂研制干酪初探

随着干酪生产量的增加，小牛凝乳酶出现世界性短缺，开发微生物凝乳酶代用品已势在必行，本文进行了采用酒酿代替小牛凝乳酶制作干酪的研究。主要研究了采用不同的酒酿用量、凝乳温度、凝乳时间和加热排乳清温度对制作干酪的影响，其最佳工艺参数为：酒酿用量5％，凝乳温度25℃，凝乳时间15-17h，加热排乳清温度45℃。     

Raw milk and raw milk cheeses as vehicles for infection by Verocytotoxin-producing Escherichia coli

Raw milk and raw milk cheeses can be a source of food-borne pathogens, including Verocytotoxin (Shiga toxin)-producing Escherichia coli (VTEC/STEC). Outbreaks of VTEC O157: H7 infections have been attributed to the consumption of raw milk and associated dairy products. Although the general prevalence of VTEC O157 in raw milk and raw milk cheeses is low, it can be higher for non-O157 VTEC. The clinical significance of many of these VTEC is unclear, although some are associated with disease. Studies show that E. coli O157 strains can survive the various stages of the cheesemaking process and that raw milk and raw milk cheeses remain a potential vehicle for VTEC infections.     

Selection, application and monitoring of Lactobacillus paracasei strains as adjunct cultures in the production of Gouda-type cheeses

Raw milk cheeses have more intense flavours than cheeses made from pasteurized milk and harbour strains with potential adjunct properties. Two Lactobacillus paracasei strains, R-40926 and R-40937, were selected as potential adjunct cultures from a total of 734 isolates from good quality artisan raw milk Gouda-type cheeses on the basis of their prevalence in different cheese types and/or over several production batches, safety and technological parameters. Conventional culturing, isolation and identification and a combined PCR-DGGE approach using total cheese DNA extracts and DNA extracts obtained from culturable fractions were employed to monitor viability of the introduced adjuncts and their effect on the cheese microbiota. The control cheese made without adjuncts was dominated by members of the starter, i.e. Lactococcus lactis and Leuconostoc pseudomesenteroides. In the cheeses containing either R-40926 or R-40937, the respective adjuncts increased in number as ripening progressed indicating that both strains are well adapted to the cheese environment and can survive in a competitive environment in the presence of a commercial starter culture. Principal component analysis of cheese volatiles determined by steam distillation-extraction and gas chromatography-mass spectrometry could differentiate cheeses made with different concentrations of adjunct R-40926 from the control cheese, and these differences could be correlated to the proteolytic and lipolytic properties of this strain. Collectively, results from microbiological and metabolic analyses indicate that the screening procedure followed throughout this study was successful in delivering potential adjunct candidates to enrich or extend the flavour palette of artisan Gouda-type cheeses under more controlled conditions.     

Survey of raw milk cheeses for microbiological quality and prevalence of foodborne pathogens

Cheese may be manufactured in the United States using raw milk, provided the cheese is aged for at least 60 days at temperatures not less than 35 °F (1.7 °C). There is now increased concern among regulators regarding the safety of raw milk cheese due to the potential ability of foodborne pathogens to survive the manufacturing and aging processes. In this study, 41 raw milk cheeses were obtained from retail specialty shops, farmers’ markets, and on-line sources. The cheeses were then analyzed for the presence of Listeria monocytogenes, Salmonella, Escherichia coli O157:H7, Staphylococcus aureus, and Campylobacter. Aerobic plate counts (APC), coliform and yeast/mold counts were also performed. The results revealed that none of the enteric pathogens were detected in any of the samples tested. Five samples contained coliforms; two of those contained E. coli at less than 10² cfu/g. Three other cheese samples contained S. aureus. The APC and yeast-mold counts were within expected ranges. Based on the results obtained from these 41 raw milk cheeses, the 60-day aging rule for unpasteurized milk cheeses appears adequate for producing microbiologically safe products.     

Use of powdered vegetable coagulant in the manufacture of ewe's milk cheeses

A powdered vegetable coagulant obtained from the cardoon Cynara cardunculus and characterised as free of viable micro‐organisms, soluble and stable without the need for preservatives was evaluated, and compared with crude aqueous extract, in batches of Los Pedroches cheese, by determining various chemical, biochemical, microbiological and sensory parameters. Parameters were monitored over 3 months of ripening. High casein hydrolysis was observed after 2 days of ripening. The soluble nitrogen values reached at the end of ripening were over 34% of the total nitrogen in cheeses produced with both types of coagulant. For most parameters studied, no differences were observed between the two types of coagulant, although higher counts were observed for some microbiological groups in cheeses produced with crude aqueous extracts. The sensory quality of cheeses was practically identical with both types of coagulant. © 2002 Society of Chemical Industry     

Nutrient profiles of commercial goat milk cheeses manufactured in the United States

Thirty varieties of commercial goat milk cheeses collected from 13 manufacturers in 11 states of the US were evaluated. Concentration profiles of basic nutrients, major and trace minerals, their correlations, and mineral ratios in the caprine cheeses were determined to compare nutritional parameters among the varieties. Mean percentage of moisture, fat, protein, and ash for plain soft, semi-soft, hard, pepper, garlic, and herb cheeses were 59.8, 22.5, 18.9, 1.74; 43.2, 28.5, 26.2, 2.83; 27.4, 32.3, 25.4, 3.58; 57.3, 22.9, 21.6, 1.32; 64.3, 18.3, 16.7, 1.34; 59.1, 21.8, 17.3, 1.60, respectively. Ranges of mean concentrations (mg/100 g wet basis) of S, P, K, Mg, Ca, Na, Cl, Fe, Al, Mn, Cu, and Zn were: 2.00 to 8.05; 192 to 785; 7.03 to 103; 10.3 to 78.0; 57.1 to 1035; 225 to 924; 96.0 to 1260; .52 to 8.73; .47 to 22.1; .08 to .40; .44 to 1.32; .49 to 4.13, respectively. Twenty of the 30 varieties were very high or high moisture cheeses, which would suggest slow coagulation as the major mode of fabrication. Wide variations in the concentrations of P, K, Ca, Na, Cl, Fe, Al, and Zn were found among and within varieties of the cheeses. High concentrations and variations in Fe and Al in the cheeses indicate a significant possibility of uptake of these elements into the products during farmstead manufacturing processes. Percentage of moisture was negatively and significantly (P less than .05 or P less than .01) correlated with the concentrations of ash, fat, protein, and most of the minerals. Percentage of ash was positively and significantly correlated with the concentrations of macrominerals but negatively and less correlated with concentrations of Fe, Al, Mn, and Cu. The Na:K ratio was the highest of the five mineral ratios. Differences were significant for Ca:P, Ca:Mg, and Na:K ratios among the six types of goat cheese tested.     

Triacylglycerol composition of protected designation of origin cheeses during ripening. Authenticity of milk fat

Triacylglycerol (TAG) composition by carbon number in 2 protected designation of origin cheeses, Mahón (cheese from cow milk) and Manchego (cheese from ewe milk) that were manufactured by 3 different producers was analyzed during cheese ripening using gas chromatography with a short capillary column. The TAG composition at different times during cheese ripening was also analyzed in cheeses from different batches produced at the same plant. Lipolysis levels in the Mahón and Manchego cheeses during ripening were low; free fatty acid values ranged from 2,500 to 4,000 ppm at the end of ripening. The TAG composition did not change significantly during ripening. The TAG values obtained from each cheese sample were substituted into the multiple regression equations that have been proposed to detect foreign fats in milk fat. The values obtained using the equations for bovine (proposed by the European Union) and ovine milk (proposed by our laboratory) were within the normal range. Accordingly, these equations can be considered useful for detecting foreign fat in these cheeses during the ripening period contemplated during this study.     

Innovative Caciocavallo cheeses made from a mixture of cow milk with ewe or goat milk

This study assessed and compared the physicochemical, microbiological, and sensorial characteristics of Caciocavallo cheeses, made from cow milk and a mixture of cow with ewe or goat milk, during ripening. Different cheese-making trials were carried out on an industrial scale following the standard procedure of pasta filata cheeses, with some modifications. The percentage of the different added milk to cow milk influenced compositional and nutritional characteristics of the innovative products, leading to a satisfactory microbiological and sensorial quality.     

The behavior of selected microorganisms during the manufacture of high moisture Jack cheeses from ultrafiltered milk.

Whole milk was pasteurized and concentrated two times by ultrafiltration. Starter cultures, Lactococcus lactis ssp. cremoris and Lactococcus lactis ssp. lactis, were propagated in either reconstituted skim milk, two times UF retentate, or UF permeate, or a direct vat system was used for the starter culture. The cheese milk was simultaneously inoculated with starter culture and Pseudomonas fragi 4973, Staphylococcus aureus 196E, and Salmonella typhimurium var. Hillfarm. Control whole milk, UF control milk, inoculated whole milk, and inoculated UF milk were made into Monterey Jack cheese using traditional procedures. The process of cheese manufacture was followed by determination of pH, titratable acidity, and microbial population levels. The cheeses were stored for 6 mo and analyzed every month for percentage solids and microbial population levels. Generally, numbers of contaminant microbes increased at a similar rate during manufacture in all cheeses. During the 6-mo ripening period, bacterial starter culture population levels remained high, psychrotrophs declined slowly, Staphylococcus levels remained stable, and Salmonella populations decreased. No Staphylococcus enterotoxin was detected by reverse passive latex agglutination assay.     

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.     

Enhancing market value of milk by adding cultures.

Fluid milk and several dairy products are an excellent medium to generate an array of products that fit into the current consumer demand for health-driven foods. Several technologies associated with culture addition, fermentation, or both are available for creating an assortment of flavors and textures in milk products. It appears that accentuating the positive attributes of inherent milk constituents, incorporating health-promoting cultures, and offering a variety of flavors and textures to the consumer could enhance milk consumption. Recent advances in probiotic research show much promise in new product development of functional foods based on milk. Several scientifically sound clinical studies have verified some of the anecdotal reports of the past. Among the reported beneficial effects of consuming certain strains of cultures, or their metabolites, or both are enhanced immune response, balancing of colonic microbiota, vaccine adjuvant effect, reduction of fecal enzymes implicated in cancer initiation, treatment of diarrhea associated with travel, antibiotic therapy, control of rotavirus and Clostridium difficile, control of ulcers related to Helicobacter pylori, reduction of serum cholesterol, antagonism against food-borne pathogens and tooth decay organisms, and amelioration of lactose malabsorption symptoms. The mode of action in most cases seems to involve modulation of ecosystem of the gastrointestinal tract of the host. Several strains belonging to genera Enterococcus, Lactobacillus, and Bifidobacterium, which have desirable clinical benefits, are now available. They are being incorporated in yogurts, dairy snacks, breakfast foods, drinks, refrigerated desserts, cheeses, spreads, frozen desserts, and unfermented sweet cultured milk.