Unripened Cheeses Research Articles

Formation of Key Aroma Compounds During 30 Weeks of Ripening in Gouda-Type Cheese Produced from Pasteurized and Raw Milk.

Gouda-type cheeses were produced on a pilot-scale from raw milk (RM-G) and pasteurized milk (PM-G). Sixteen key aroma compounds previously characterized by the sensomics approach were quantitated in the unripened cheeses and at five different ripening stages (4, 7, 11, 19, and 30 weeks) by means of stable isotope dilution assays. Different trends were observed in the formation of the key aroma compounds. Short-chain free fatty acids and ethyl butanoate as well as ethyl hexanoate continuously increased during ripening but to a greater extent in RM-G. Branched-chain fatty acids such as 3-methylbutanoic acid were also continuously formed and reached a 60-fold concentration after 30 weeks, in particular in PM-G. 3-Methylbutanal and butane-2,3-dione reached a maximum concentration after 7 weeks and decreased with longer ripening. Lactones were high in the unripened cheeses and increased only slightly during ripening. Recent results have shown that free amino acids were released during ripening. The aroma compounds 3-methylbutanal, 3-methyl-1-butanol, and 3-methylbutanoic acid are suggested to be formed by microbial enzymes degrading the amino acid l-leucine following the Ehrlich pathway. To gain insight into the quantitative formation of each of the three aroma compounds, the conversion of the labeled precursors (13C6)-l-leucine and (2H3)-2-keto-4-methylpentanoic acid into the isotopically labeled aroma compounds was studied. By applying the CAMOLA approach (defined mixture of labeled and unlabeled precursor), l-leucine was confirmed as the only precursor of the three aroma compounds in the cheese with the preferential formation of 3-methylbutanoic acid.

Selection of adjunct cultures for the ripening of plant cheese analogues

Fermentation contributes to the taste and odor of plant cheeses. The selection of functional cultures for the fermentation of plant cheeses, however, is in its infancy. This study aimed to select lactic acid bacteria for ripening of soy and lupin cheese analogues. Bacillus velezensis and B. amyloliquefaciens were used for germination of seeds to produce proteolytic enzymes; Lactococcus lactis and Lactiplantibacillus plantarum served as primary acidifying cultures. Levilactobacillus hammesii, Furfurilactobacillus milii, or Lentilactobacillus buchneri were assessed as adjunct cultures for the ripening of plant cheese. Growth of bacilli was inhibited at low pH. Both Lc. lactis and Lp. plantarum were inactived during plant cheese ripening. Cell counts of Lv. hammesii remained stable over 45 d of ripening while Ff. milii and Lt. buchneri grew slowly. Sequencing of full length 16S rRNA genes confirmed that the inocula the plant cheeses accounted for more than 98% of the bacterial communities. HPLC analysis revealed that Lt. buchneri metabolized lactate to acetate and 1,2-propanediol during ripening. Bacilli enhanced proteolysis as measured by quantification of free amino nitrogen, and the release of glutamate. LC-MS/MS analysis quantified kokumi-active dipeptides. The concentrations of γ-Glu-Leu, γ-Glu-Ile, and γ-Glu-Ala, γ-Glu-Cys in unripened cheeses were increased by seed germination but γ-Glu-Phe was degraded. Lt. buchneri but not Lv. hammesii or Ff. milii accumulated γ-Glu-Val, γ-Glu-Ile or γ-Glu-Leu during ripening, indicating strain-specific differences. In conclusion, a consortium of bacilli, acidification cultures and adjunct cultures accumulates taste- and kokumi-active compounds during ripening of plant cheeses.

Production of soft unripened cheeses using acidic and salty coagulants: Investigation of technological and sensory characteristics.

Soft cheeses are coagulated milk products obtained through acidification or applying a combination of acids and heat. In this research, in order to improve technological characteristics, the effects of different coagulants (salt and acids) and process parameters (temperature and homogenization pressure) on the organoleptic, textural, and functional characteristics of soft (unripened) cheese were investigated. The results revealed significant differences between cheeses coagulated with acid and mineral salt regarding protein recovery, fat content, and moisture content (p < .05). Acidic coagulants (74%-94%) resulted in higher cheese yield compared to mineral salt (66%-88%). Texture analysis indicated that the cheese produced with acetic acid had a firmer texture, while samples treated with citric acid exhibited better cohesiveness. Cheeses produced with minerals displayed more acceptable organoleptic characteristics regarding flavor, odor, and texture. This study offers valuable technological insights into cheese production with the highest yield and maximum acceptability.

Characterisation of Staphylococcus aureus isolated from artisanal unripened cheeses produced in São Paulo State, Brazil

The capacity for biofilm formation and slime production, the enterotoxigenic potential and the molecular typing of 20 Staphylococcus aureus isolated from Minas frescal and Porungo cheeses was evaluated. Profiles obtained by Rep-PCR enabled the isolates to be grouped into two major subgroups. All S. aureus isolates were capable of forming biofilms, with the majority falling under the category of strong biofilm formers. Slime production was confirmed in 80% of the isolates. A significant prevalence of genes associated with cellular adhesion and biofilm formation was identified, with icaD being the most frequently encountered (90%). Among the five genes responsible for classic enterotoxin synthesis, only the sea gene was detected. The phenotypic and genotypic diversity found in the study, mainly linked to the formation of biofilm, corroborated by the high frequency of slime producers, constitutes a potential risk to public health, highlighting the need for improved hygiene practices in the cheese production chain.

Fatty acids, lipid quality parameters, and amino acid profiles of unripened and ripened cheeses produced from different milk sources

Fatty acids and amino acids are recognized to have a significant impact on the bioactivity, aroma, and flavor of ripened cheese. In this study, fatty acid profiles, lipid quality parameters, and amino acid composition of ripened and unripened cheeses produced from different milk sources were investigated. Fatty acids and amino acids were identified by using the gas chromatography-flame ionization detector and high-performance liquid chromatography, respectively. Lipid quality indicators, including atherogenicity index, thrombogenicity index, desired hypocholesterolemic fatty acids, undesired hypercholesterolemic fatty acids, hypocholesterolemic and hypercholesterolemic fatty acids ratio, and the nutritive value index of cheese samples were calculated. The results revealed that the major fatty acids detected were myristic, palmitic, stearic, and oleic. Cheese made from goat and sheep milk, such as Kashkaval, Chevrette Frico, and goat cheese with honey exhibited higher contents of capric acid representing 8.47 %, 9.56 %, and 10.07 %, respectively. In addition, fresh Roumy cheese showed higher contents of oleic (37.15 %) and linoleic (9.18 %) acids than other cheese types. The atherogenicity index of cheese fat varied between 1.13 and 3.97 for the different samples. Furthermore, cheese samples showed similar nutritive value indices. Each cheese type had its distinctive amino acid profile, which was attributed to the enzymatic activity. Milk source and ripening were the main reason for the variations in fatty acid and amino acid contents. The findings of this study could provide interesting knowledge to the dairy industry sector and could be used as a database in the field of food composition and analysis.

Assessment of Aflatoxin M1 Contamination in Egyptian Milk and Cheese تقييم تلوث اللبن والجبن في السوق المصري بالأفلاتوکسين M1

A screening survey of the presence of aflatoxin M1 (AFM1) was carried out on 170 samples of Egyptian dairy products. Selected samples included raw buffalo or cow milk, pasteurized milk, UHT milk, fermented milk, soft cheese, hard cheese, and processed cheese were analyzed by competitive ELISA technique. Out of 60 liquid milk and fermented milk samples analyzed, 12 samples (20%) were found to be contaminated with AFM1, at levels ranging from 10.12 to 86.54 ng/kg. Eight from the positive samples (66.6%) failed to reach the acceptable level of the European Commission Regulation (50 ng/kg). Buffalo’s milk is safe regarding AFM1 contamination since all the buffalo milk samples were consistently negative. AFM1 was found in 22 samples (36.67%) of out 60 cheese samples at concentrations between 25.12 to 253.04 ng/kg. The highest mean value of AFM1, 231.39 ng/kg, was found in Ras cheese (hard type) samples followed by the processed cheeses with 114.76 ng/kg. Kariesh cheeses displayed the lowest levels, 53.32 ng/kg. Cheeses made from cow’s milk showed higher AFM1 positive samples, while cheeses made from buffalo’s milk tested were consistently negative. Regarding the cheese ripening age, out of 50 cow milk cheese samples, 26 were found to be positive to AFM1. The highest positive incidence was noted in long-term ripened hard cheeses (70%), while the lowest in fresh unripened cheeses (40%). It is highly recommended from the results that milk and cheese products have to be controlled periodically for AFM1 contamination.

Quality assessment of artisanal cheeses in the northwest region of Paraná.

Artisanal unripened cheeses produced in northwestern Paraná, Brazil, were studied for microbiological quality and sensory quality. The cheeses analyzed showed high counts of aerobic mesophilic microorganisms and S. aureus. However, even with the results showing poor microbiological quality, from a sensory point of view, consumers considered cheeses acceptable (high acceptance index). The results may indicate that there is still a lack of training and knowledge of production procedures to reduce microbiological contamination of artisanal cheese produced in northwestern Paraná.

Physicochemical properties, sensory quality, and coagulation behavior of camel versus bovine milk soft unripened cheeses

This study investigated the coagulation properties of camel milk (CM) and bovine milk (BM) and the resulting soft unripened cheeses obtained by treatment with chymosin (1000 IMCU/ML milk) or citric acid or acetic acid (30% acid/L milk). The cheeses were evaluated for yield, moisture, microstructure, texture profile, rheology, and sensory quality. CM cheeses were significantly lower in hardness and rheological properties than BM cheeses (p < .05). Photo images and scanning electron microscopy revealed the characterization of CM cheeses by a smooth and continuous casein network, thinner aggregate strands, and smaller pore spaces, while BM cheeses showed large pore spaces with irregular aggregates. Panelists evaluated the CM and BM cheeses as comparable for some attributes and preferred the cheeses prepared using citric acid. In conclusion, soft cheese with weak structures can be prepared from CM. The coagulation time for CM was longer than that for BM and the specific coagulation behavior of CM was attributed to differences between the composition of the casein fraction in CM and that in BM.

Survey on the prevalence of Listeria monocytogenes in Belgian artisanal cheeses

Description of the subject. Cheese is a vector of Listeria monocytogenes. By default, European Commission imposes its absence in cheese before sales, but fixes pH and water activity thresholds below which it cannot grow. Objectives. To study pH and water activity of Belgian cheeses and the prevalence of L. monocytogenes in these products. Method. Salt content, pH and water activity of 134 cheeses were determined. Absence of L. monocytogenes in 25 g of cheese was also checked. Results. Three samples had pH or water activity under threshold values from regulation. Nevertheless, all unripened cheeses were acid in comparison with data from foreign countries. Listeria monocytogenes was isolated from 1.49% of the samples. Conclusions. Belgian artisanal cheeses could allow the growth of L. monocytogenes, and the bacterium was isolated from two samples. Further experiments should be performed to understand the fate of the pathogen in these products.

The range of protein hydrolysis and biogenic amines content in selected acid- and rennet-curd cheeses

The aim of this experiment was to assess the range of proteolysis and biogenic amine content in the selected rennet- and acid-curd cheeses available on the Polish market, randomly chosen for the analyses: three ripened hard with eyes cheeses, three ripened hard smooth cheeses, three ripened soft moulded cheeses, three fresh unripened acid-curd cheeses, three ripened acid-curd cheeses with slimming bacteria—fried, and three ripened acid-curd cheeses with smear bacteria. The results allowed calculating the subsequent indexes and depth of proteolysis. It was found that the acid-curd short ripened cheese (harzer) was characterized by the greatest range of proteolysis and the biogenic amine content in comparison to other rennet- and acid-curd cheeses. In the assessed acid- and rennet-curd cheeses, the dominant amines were as follow, cadaverine, tyramine, and putrescine, with the exception of cheddar in which the histamine was predominant.

Soft Unripened Cheeses: Invent Activity in Russia

Soft Unripened Cheeses: Invent Activity in Russia

The Analysis of the Behaviour of Listeria Monocytogenes in Fresh Cheeses with Various Spices During Storage

The aim of this work was to evaluate the growth possibilities of Listeria monocytogens in the artificially contaminated fresh cheese during storage. Three variants of acid homogenized commercial fresh cheeses: mixed herbs, red pepper and garlic-pepper were studied. The lowest value of the specific growth rate of L. monocytogenes in the fresh cheeses was reported for red pepper variant. The highest value of this parameter was determined for the fresh cheese with pepper-garlic. The use of spices in the production of fresh unripened cheeses influence the viability and growth of bacteria L. monocytogenes during storage at the temperature range 3-15oC.

Distribution of Biogenic Amines and Polyamines in Cheese

ABSTRACT Biogenic amines and polyamines were measured in unripened cheese and 4 types of ripened cheese. The study included cheeses produced from both pasteurized and raw milks. All amines were lower in unripened than in ripened cheeses. The amine contents varied among different types of ripened cheese, within the same type of cheese, and also within the parts of cheeses. The main amines in ripened cheeses were tyramine, cadaverine, and putrescine. The highest concentration of tyramine was found in hard‐ripened raw‐milk cheeses, while blue cheese had the highest level of cadaverine. Unripened cheeses could be considered as well‐tolerated products for histamine‐ and tyramine‐sensitive individuals, whereas the wide variability in biogenic amines makes it difficult to generalize this consideration for all ripened cheeses.

Free Amino Acid Profiles During Ripening of Port Salut Argentino Cheese After Frozen Storage

ABSTRACT: Free amino acid profiles of Port Salut Argentino cheeses at different storage conditions (ripening with and without previous frozen storage), ripening times (1, 6, 13, 27, and 56 d), and cheese zones (central and external) were studied. Derivatization with o‐phtaldialdehyde and a C18 column were used for chromatographic separations. Principal component analysis reduced data to 2 dimensions where unripened cheeses (1 to 13 d) were grouped independently of ripening time, sampling zone, and storage condition. Ripened cheeses (27 and 56 d) showed scattering according to ripening time. The contribution of free amino acid profiles to quality in cheeses preserved by frozen storage may be considered similar to that in traditionally ripened cheeses.

Potential Use of Presumptive Enterococci and Staphylococci as Indicators of Sanitary Condition in Plants Making Hard Italian-Type Cheese

Raw milk, pasteurized milk, unripened cheese (1 day old), and partially ripened cheese (3 months) from 42 milk lots at a plant making hard Italian-type cheese were analyzed for presumptive enterococci using kanamycin esculin azide agar pour plates. Fully ripened (≥10 months) cheeses, derived from other milk lots, were also tested. Numbers of presumptive staphylococci (Baird-Parker agar [B-P]) were determined in the partially and fully ripened cheeses. Presumptive enterococci were ubiquitous in raw milk, usually at levels of 2.1 to 3.0 log CFU/ml. Enterococci were detected in 11 (26%) of 42 pasteurized milk samples. Enterococci and staphylococci were detected in 39 (93%) and 6 (14%) of unripened cheeses and in 33 (80%) and 4 (10%) of partially ripened cheeses, respectively. Only eight and five samples of enterococci-positive unripened and partially ripened cheese, respectively, were made from pasteurized milk in which presumptive enterococci were detected. Of 42 samples of fully ripened cheese, 35 (83%) and 8 (19%), respectively, contained presumptive enterococci and staphylococci. Results suggest either that low numbers of presumptive enterococci survive pasteurization and cheese ripening or that contamination of cheese by enterococci occurs after pasteurization. Biochemical testing confirmed 63% of presumptive enterococci isolates. None of the 20 presumptive staphylococci isolates produced colonies typical of Staphylococcus aureus on B-P agar; the isolates were identified as 1 Staphylococcus epidermidis, 1 Staphylococcus xylosus, 2 Staphylococcus saprophyticus, 1 Staphylococcus warneri, 5 Kocuria spp., and 10 unidentified gram-positive, catalase-positive cocci. Three staphylococci isolates decreased in numbers by more than 3.0 log CFU/ml in 9.9 ml of skim milk heated 30 min in a 62.8°C water bath. This finding suggests that most presumptive staphylococci detected may have been prepasteurization contaminants. Unless specificity of the kanamycin esculin azide and B-P media is improved, use of presumptive enterococci and staphylococci as indicators of postpasteurization sanitation in plants making hard Italian-type cheese cannot be recommended.

Biogenic Amines and Polyamines in Milks and Cheeses by Ion-Pair High Performance Liquid Chromatography

The proposed chromatographic method provides a complete resolution of twelve amines in a single run in milks and unripened cheeses, avoiding the losses of resolution linked to fluctuations in working temperature. We also propose an alternative chromatographic gradient, which can be useful for samples that have undergone long ripening periods, like ripened cheeses. According to the results of the reliability study, the method described was precise, accurate, and sensitive. The method was applied to several samples of milks and cheeses and the results showed that the biogenic amine profiles varied greatly, not only between different types of samples but also among the samples from the same kind of products. In unripened cheeses, milks, and yogurts, spermidine and spermine were the prevailing amines, but in ripened cheeses the major amine was tyramine, followed by putrescine and cadaverine.

Mineral content of some Spanish cheese varieties. Differentiation by source of milk and by variety from their content of main and trace elements

AbstractThe content in nine mineral elements (P. Ca, Na, K, Mg, Zn, Fe, Cu and Mn) was determined in 153 units of cheese belonging to nine Spanish varieties: two unripe cows milk varieties (Cebreiro and Pasiego), three ripened cows milk varieties (Ahumado de Aliva, Leon and Quesucos), three ripened goats milk varieties (Armada‐Sobado, Babia‐Laciana and Valdeteja), and one blue‐veined cows milk variety (Picón). Using a Kruskal‐Wallis one‐way analysis of variance, only significant differences were observed in P. K, Mg. Zn, Fe and Mn contents associated to animal milk species used in the manufacture. When the two varieties of unripened cheeses were compared, significant differences in all the elements were observed. The same happened when the three varieties of ripened cows milk cheeses were compared. On comparing the three varieties of ripened goats milk cheeses, only significant differences were observed in P, Ca, Na, K, Mg, Zn and Mn contents. Using stepwise discriminant analysis 76–31% of cases were correctly classified when the cheeses were differentiated according to milk species used in their manufacture. When we differentiated the cheeses according to the variety, 91–66% of cases were correctly classified in the unripe cows milk cheeses, 85% of cases were correctly classified in the ripened cows milk cheeses, and 92–59% of cases were correctly classified in the ripened goats milk cheeses.

Practical aspects of electron microscopy in cheese research.

Chemical composition, rheological behavior, and sensory attributes in foods are closely related to their microstructure. This is particularly evident in cheese. Cheeses are produced in many varieties although they consist of only a few major components such as casein, whey proteins, milkfat, and microorganisms. There are soft and hard cheeses, low-fat and high-fat (cream) cheeses, unripened cheeses, mold-ripened cheeses, and process cheeses (Mair-Waldburg, 1974; Kosikowski, 1982), all made from milk by procedures which are similar in principle. Milk proteins are coagulated and the aqueous phase containing the lactose is separated. The coagulum is compacted, frequently subjected to proteolysis during ripening, and occasionally textured, e.g., during the production of Cheddar and Mozzarella cheeses.

Reliability of Selective Media for Recovery of Staphylococci from Cheese

The reliability of 12 selective media for recovery of four different strains of Staphylococcus aureus inoculated at manufacture into three cheese types was determined. Selective medium and time of ripening had a highly significant effect (p < 0.001) on reliability of the staphylococcal count. In addition, highly significant interaction effects were observed. The most reliable medium in the overall analysis was mannitol salt agar. However, this medium was not equally reliable at all times during ripening, and use of both mannitol salt agar and Staphylococcus medium no. 110 is recommended. The tellurite- and azide-based selective media were generally unsatisfactory, however tellurite glycine agar, Vogel Johnson (VJ) agar, and azide blood agar base were totally unreliable. In general, the salt-based selective media were most reliable. This applied also to the egg yolk media that use salt as the selective agent. Salt egg yolk agar and Colbeck's egg yolk medium generally gave higher recoveries of S. aureus than did Baird-Parker medium, Crisley et al. tellurite polymyxin egg yolk agar, and Hopton egg yolk azide agar, except in the unripened cheeses. The debilitating effect of cheese ripening on the staphylococcal cells was not eliminated by the egg yolk tellurite and azide media.