Mexican Queso Chihuahua: rheology of fresh cheese†

Rheological properties of fresh Queso Chihuahua made from raw milk (RM) or pasteurized milk (PM) were characterized using texture profile, torsion and small amplitude oscillatory shear analyses. Although the rheological properties varied significantly among the different brands with overlapping ranges for the individual RM and PM cheese brands, overall the PM cheeses were harder, chewier and more cohesive but had lower viscoelastic values than the RM cheeses. Establishing the rheological properties of Mexican Queso Chihuahua increases our understanding of the quality traits of Hispanic‐style cheeses and provides a foundation for maintaining the traditional texture of the cheese.     

Queso Chihuahua: manufacturing procedures, composition, protein profiles, and microbiology

A survey of fresh commercial Queso Chihuahua made from raw or pasteurized cow's milk was undertaken to determine the impact of cheesemaking parameters on composition, protein breakdown and microbial counts. Despite variations in the manufacturing procedure, the composition and casein breakdown of the cheeses fell within a comparatively tight range. Pathogens were not detected in any of the cheeses, but total aerobic plate counts exceeded the recommended limit for this variety. Differences in Mexican Queso Chihuahua manufacturing procedures did not substantially alter the final product, the quality of which could be improved by reduction of bacteria present.     

Mexican Queso Chihuahua: functional properties of aging cheese

Queso Chihuahua, a semi-hard cheese manufactured from raw milk (RM) in northern Mexico, is being replaced by pasteurized milk (PM) versions because of food safety concerns and the desire for longer shelf life. In this study, the functional traits of authentic Mexican Queso Chihuahua made from RM or PM were characterized to identify sources of variation and to determine if pasteurization of the cheese milk resulted in changes to the functional properties. Two brands of RM cheese and 2 brands of PM cheese obtained in 3 seasons of the year from 4 manufacturers in Chihuahua, Mexico, were analyzed after 0, 4, 8, 12, and 16 wk of storage at 4°C. A color measurement spectrophotometer was used to collect color data before and after heating at 232°C for 5 min or 130°C for 75 min. Meltability was measured using the Schreiber Melt Test on samples heated to 232°C for 5 min. Sliceability (the force required to cut through a sample) was measured using a texture analyzer fitted with a wire cutter attachment. Proteolysis was tracked using sodium dodecyl sulfate-PAGE. Compared with PM cheeses, RM cheeses showed less browning upon heating, melted more at 232°C, and initially required a greater cutting force. With aging, cheeses increased in meltability, decreased in whiteness when measured before heating, and required less cutting force to slice. Seasonal variations in the cheesemilk had minimal or no effect on the functional properties. The differences in the functional properties can be attributed, in part, to the mixed microflora present in the RM cheeses compared with the more homogeneous microflora added during the manufacture of PM cheeses. The degree of proteolysis and subsequent integrity of the cheese matrix contribute to melt, slice, and color properties of the RM and PM cheeses. Understanding the functional properties of the authentic RM cheeses will help researchers and cheesemakers develop pasteurized versions that maintain the traditional traits desired in the cheeses.     

Texture,physicochemical and sensory properties of artisanal Adobera cheese from Los Altos de Jalisco,a genuine Mexican cheese

Physicochemical and sensory properties of Adobera, a genuine, understudied Mexican raw‐milk cheese, were explored by analysing commercial samples from different manufacturers and seasons. Composition‐wise, Adobera could be considered a fresh cheese with a high moisture content (42.5%), although its relatively low water activity (0.953) and pH (5.14) and high free amino acid content (0.46 mmol/g, dry basis) could indicate otherwise. Instrumental texture corresponded to that of a semifirm cheese, while its colour was whitish‐to‐ivory. Both texture and composition were significantly affected by sampling season and cheese composition, while some attributes of sensory acceptability significantly varied with brand.     

Characterisation of Macedonian white‐brined cheese: Effect of raw or heat‐treated caprine milk

This research analysed the use of raw and pasteurised milk in the production of Macedonian white caprine milk cheese. Pasteurisation resulted in a considerable decrease in the nitrogen fractions, urea‐polyacrylamide gel electrophoresis of caseins, peptide profiles and volatiles during the maturation period. Forty‐five volatile components were detected, including twelve acids, fourteen esters, six ketones, three alcohols, four terpenes and six other compounds. It was deduced that pasteurisation of milk for the manufacture of artisanal white‐brined cheese delayed the evolution of volatiles, which are related to the unique flavour of the cheese.     

Comparison of the volatile profiles of Arzúa-Ulloa and Tetilla cheeses manufactured from raw and pasteurized milk

Levels of volatile compounds in Arzúa-Ulloa and Tetilla cheeses manufactured from raw and pasteurized milk were investigated. Analysis of volatile compounds in six raw milk (RM) starter-free cheeses (15–45 days old) and six pasteurized milk (PM) cheeses made with deliberately added starters (15–45 days old) manufactured in different dairies, was performed on an automatic dynamic headspace apparatus coupled to a GC/MS. The volatile fraction of RM cheeses displayed 46 volatile compounds (34 for PM cheeses) including fatty acids, esters, aldehydes, alcohols, ketones, hydrocarbons and sulphur compounds. Fatty acids and several esters were only detected in RM cheeses. Moreover, the highest contents of methylketones, secondary alcohols and branched-chain aldehydes and alcohols were also observed in RM cheeses. All results confirm more intense lipolysis in RM cheeses than in PM cheeses. In addition, branched-chain aldehydes and alcohols were significantly more abundant in RM than in PM cheeses, which indicates that catabolism of branched-chain amino acids was significantly higher in RM cheeses. This study has provided useful information which will allow the selection of starter and non-starter bacteria more suitable for manufacturing Arzúa-Ulloa and Tetilla pasteurized milk cheeses with organoleptic characteristics similar to those of traditional raw milk cheeses.     

Effects of curd heating with or without previous milk pasteurisation on the microbiological quality and safety of craft‐made ‘Pasta Filata’ Kashkaval cheese curds

An empirical ‘Pasta Filata’ process used for traditional Kashkaval cheese manufacture from raw ewes’ milk improved the hygiene of fresh curd. Coagulase‐positive (RPF+) staphylococci and coliforms declined by 2.4 and 4.5 log units, respectively, and Listeria contamination was minimised. Before Pasta Filata, RPF+ staphylococci exceeded the 5‐log threshold level specified in EC Regulation 1441/2007 in raw milk curds despite the prevalence of indigenous mesophilic lactic acid bacteria. Pasta Filata favoured enterococci in raw milk curds. Pasteurisation enhanced prevalence of Streptococcus thermophilus and Lactococcus lactis starters and microbial quality and safety of pasteurised milk curds before and particularly after Pasta Filata.     

The effect of refrigerated storage of raw milk on the physicochemical and microbiological quality of Tunisian semihard Gouda‐type cheese during ripening

A Tunisian semihard Gouda‐type cheese made from milk kept at 4 °C for 24, 48, 72 and 96 h was monitored during 45 days of ripening. The effect of milk refrigeration on the evolution of physicochemical parameters in relation to the quantitative variation of the microbial population during ripening of Gouda‐type cheese was investigated. Microbiological and physicochemical analyses were performed on raw milk and cheese samples after curding, 2, 9, 16, 23, 30, 37 and 45 days of ripening time. The raw milk kept under refrigeration at 4 °C for 96 h showed the highest microbial count and proteolysis level. The duration of storage significantly reduced the cheese yield as a result of important solubilisation casein in proteoses‐peptones. Results of different nitrogenous fractions by Kjeldahl method showed enzymatic hydrolysis products of casein whose intensity depended on the maturing stage as well as the refrigeration time. Besides the evident action of the plasmin, original milk protease, on the hydrolysis of casein in soluble fractions, the proteolysis of cheese caseins is also initiated by proteolytic action of the chymosin and extracellular heat‐resistant proteases notably produced by the same psychrotrophic microflora. Lactic acid bacteria starters that constitute the dominant microflora of this type of cheese are also considered as aroma precursors.     

Isolation of lactic acid bacteria from Lighvan cheese, a semihard cheese made from raw sheep milk in Iran

The lactic acid bacteria contributing to Lighvan cheese ripening during the different stages of production were investigated. Isolated strains from different culture media were identified phenotypically to species and subspecies level. In total, 413 strains were isolated from raw milk, 1-day-old cheese and fully ripened cheese. The most abundant species belonged to Enterococcus faecium (87 isolates), Lactococcus lactis ssp. lactis (68 isolates), Enterococcus faecalis (55 isolates) and Lactobacillus plantarum (48 isolates). E. faecium, Lc. lactis and Lb. plantarum were the predominantly isolated strains from ripened cheese. Therefore, they may contribute considerably to the aroma and flavour development of Lighvan cheese.     

A survey of the microbiological quality of Sharri,a hard mountain cheese from Kosovo

The microbiological quality of a hard mountain unpasteurised sheep cheese from three randomly selected manufacturing locations in Kosovo was investigated. Forty‐eight samples of row milk, coagulum, 8–10 days ripening cheese and of ready to eat cheese (45‐days in brine) were tested. Seventy‐five per cent of raw milk samples failed to comply with EU regulation 853/2004. All of coagulum and ripened cheese failed to comply with EU regulation 2073/2005 on process hygiene criteria. Despite the high incidence of coagulase‐positive staphylococci even in the final product [>10⁵ colony‐forming units (cfu)/g], Staphylococcal enterotoxin was detected in none of the samples and no samples were positive for Listeria monocytogenes and Salmonella enteritidis.     

Short communication: characterization of microflora in Mexican Chihuahua cheese

This work was performed to identify the bacterial species present in 10 Chihuahua cheeses obtained from commercial producers in Mexico using 16S rRNA gene analysis. As expected, some of the agar media initially used for isolation were not very selective, supporting the growth of several unrelated bacterial species. Sequence analysis identified potential pathogens, including Escherichia coli and Staphylococcus aureus, in all raw milk samples and 2 pasteurized milk samples. Streptococcus thermophilus and Lactococcus lactis ssp. lactis were identified in 9 and 6 samples, respectively, and would serve as acidifying agents during cheese production. Lactobacilli were identified in all cheeses, with the most prevalent being Lactobacillus plantarum identified in 7 raw milk and 1 pasteurized milk cheeses. Leuconostoc mesenteroides and Streptococcus macedonicus were identified in 4 raw milk cheeses and both were present in all pasteurized milk samples, suggesting that they may play a role in the development of traditional Chihuahua cheese attributes.     

Biochemical changes during the ripening of homemade 'San Simón da Costa' raw milk cheese

'San Simón da Costa' cheese is a traditional smoked variety produced in the northwest of Spain from cow's milk. Biochemical changes were determined during its ripening. Its high calcium and phosphorus content and its low NaCl and sodium content stand out. This cheese undergoes moderate proteolysis. The most abundant free amino acid at the end of the ripening was glutamic acid, followed by tryptophan, leucine, arginine and phenylalanine. The lipolysis throughout ripening is slight; the most abundant free fatty acid being oleic, followed by palmitic and butyric acid.     

Volatile composition and sensory properties of industrially produced Idiazabal cheese

The volatile composition and sensory properties of industrially produced Idiazabal cheeses made from ewes’ raw milk (RM) or pasteurised milk (PM) and with addition of different starter cultures were compared. Cheeses were analysed at 90 and 180 d of ripening. Acids were the major volatile compounds in RM cheeses. Methyl ketones were the major volatile compounds in PM cheeses at 90 ripening days. However, the content of acids strongly increased with ripening whereas the content of ketones decreased in PM cheeses. The concentration of esters was higher in RM cheeses than in PM cheeses. No differences were found in the content of alcohols. Most aldehydes, hydrocarbons, terpenes and furans identified were minor volatile compounds in both RM and PM cheeses. In RM cheeses, characteristic sensory attributes for the aroma of Idiazabal cheese were present at 3 months, whereas in PM cheeses those desirable sensory attributes did not appear until 6 months of ripening.     

Chemical composition and microbial evaluation of Argentinean Corrientes cheese

The chemical and microbial composition of an artisanal cheese made from raw cow's milk produced and consumed in the province of Corrientes (north-eastern Argentina) was evaluated using standard methods. Corrientes cheese has high moisture content (50–60%), normal protein and fat contents (21–27 and 22–26% respectively), and is low in salt (0.5–2.0% w/w). Microbial counts also varied significantly between samples (colony-forming units per gram ranges covering logs of 5–11), probably due to environmental contamination in the raw material. These results will help produce higher quality Corrientes cheeses with well-defined characteristics.     

Microbiological and chemical characterization of Fiore Sardo, a traditional Sardinian cheese made from ewe's milk

The purpose of this study was to assess the chemical and microbial characteristics of 12 batches of artisanal Fiore Sardo, a protected designation of origin (PDO) hard cheese made from raw ewe's milk without addition of starters, during maturation. High standard deviations were observed for moisture percentage, total solids percentage and NaCl percentage content, possibly owing to differences in manufacturing processes and/or milk composition. Total mesophilic bacteria varied between 10 log₁₀ cfu/g in 48-h-old cheese samples and 3 log₁₀ cfu/g in 9-month-old samples. Total coliforms and staphylococci showed the highest counts at 48 h of ripening then decreased significantly, dropping to levels below 2 log₁₀ cfu/g at 3 months of maturation. Lactic acid bacteria and enterococci were the dominant micro-organisms throughout maturation. They were mainly represented by the species Lactococcus lactis ssp. lactis, Enterococcus faecium, Lactobacillus plantarum and Lactobacillus casei group. Low levels of yeasts were detected throughout the maturation period of the cheese. Debaryomyces hansenii and Kluyveromyces lactis var. lactis were the prevalent yeast species isolated.     

Manufacture of dry‐ and brine‐salted soft camel cheeses for the camel dairy industry

Two experiments were conducted in a camel cheese study to (i) compare camel cheese to bovine cheese made from bovine milk standardised to simulate camel milk, and (ii) describe the technology for manufacture of dry (SCC‐D) and brine‐salted soft camel cheese (SCC‐B). Comparable cheese yield (camel: 7.4 ± 0.15, cow: 7.3 ± 0.55 kg/100 kg of milk) and levels of dry matter loss in whey were observed. Clotting time was 234 s for both cheeses which were made using thermophillic starters. Cheese yield was 9.31 ± 0.64 kg/100 kg with 425.6 ± 38.2 g/kg cheese dry matter for SCC‐D and 8.22 ± 0.90 kg/100 kg with 469 ± 73.8 g/kg dry matter for SCC‐B.     

Changes in microbial populations, kinds of lactic acid bacteria and biochemical characteristics of Greek traditional feta cheese during ripening

Three batches of feta cheese manufactured from raw (R) and thermized (TS) milk with yogurt as a starter were studied. Enterobacteriaceae and coliforms underwent a more accelerated decrease in TS cheese. Nonstarter lactic acid bacteria (NSLAB) were counted at higher levels in R than in TS cheese throughout ripening and predominated over the other microbial groups. The composition of NSLAB in the fresh cheese was similar for both cheese types. Proteolysis products (noncasein nitrogen soluble in 12% trichloroacetic acid, nitrogen soluble in 5% phosphotungstic acid /100 total nitrogen) were higher in R than TS cheese. Degradation of αs-casein was in R > TS, while a small reduction of β-casein during storage was recorded only for TS cheese.     

The biodiversity and evolution of lactic flora during ripening of the Iranian semisoft Lighvan cheese

Ninety‐five isolated strains of Lactic acid bacteria (LAB) were identified from Lighvan cheese. The LAB evolution showed the dominance of lactococci and lactobacilli in the first stage and substitution of these genera by enterococci at the end of ripening. The most predominant strains were Enterococcus faecium (22.44%), Lactococcus lactis ssp. lactis (20.4%), Lactobacillus plantarum (18.36%) and E. faecalis (14.28%), respectively. Eleven and 51 different carbohydrate fermentation profiles were observed according to API 20 STREP and API 50 CH, respectively. API 20 STREP dendogram showed identical fermentation profiles of some E. faecalis and E. faecium strains, indicating that these strains might be well adapted to the whole cheese manufacture.     

Viability of the Lactobacillus rhamnosus HN001 Probiotic Strain in Swiss‐ and Dutch‐Type Cheese and Cheese‐Like Products

The objective of this study was to determine the viability of the probiotic Lactobacillus rhamnosus HN001 in Swiss‐type and Dutch‐type cheese and cheese‐like products (milk fat is substituted by stearin fraction of palm fat) during manufacture, ripening, and storage. The use of the probiotic L. rhamnosus HN001 in Dutch‐type cheese and cheese‐like products significantly (P = 0.1) changed their chemical composition (protein and fat content) and an insignificant increase (approximately 1.6% in cheese‐like products and approximately 0.3% in cheese) in yield. L. rhamnosus HN001 did not affect the rate of changes in the pH of ripened cheese and cheese‐like products. A minor increase in probiotic counts was observed in initial stages of production and were partially removed with whey. Ripened cheese and cheese‐like products were characterized by high survival rates of probiotic bacteria which exceeded 8 log CFU/g after ripening. An insignificant reduction in the number of viable probiotic cells was noted during storage of Swiss‐type and Dutch‐type cheese, whereas a significant increase in probiotic cell counts was observed in cheese‐like products during storage.