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.     

Biogenic amines and their producers in Akawi white cheese

The aim of this work was to study the biogenic amine content of brine‐ripened cheeses after one year of storage and then to investigate possible contaminating micro‐organisms with decarboxylase activity. The biogenic amine production of isolates was tested in vitro. The most frequent biogenic amines were putrescine, histamine and tyramine. The biogenic amine content detected in one cheese sample was above 120 mg/kg; this can be considered toxicologically relevant. Decarboxylase activity was found for 33 contaminating micro‐organisms. Isolates belonging to Bacillus licheniformis, Debaryomyces hansenii, Staphylococcus equorum and Serratia marcescens produced significant amounts of putrescine and cadaverine.     

Some properties of Civil cheese: a type of traditional Turkish cheese

Civil cheeses were purchased from urban vendors in the city centre of Erzurum, Turkey. The biogenic amine contents of the cheeses and their microbiological and chemical properties were determined. It was found out that biogenic amine concentrations of the samples were not exceeding the toxic doses‐values. Total aerobic mesophilic bacteria, lactic acid bacteria and Enterobacteriaceae spp. were investigated as microbial analyses in the samples while several chemical analyses were executed. Statistical analyses were carried out for the determination of the relationship between the chemical properties and the biogenic amine contents of samples, and the existence of microorganisms and biogenic amines.     

Variation in organic acids content during ripening of pickled white cheese

Nine organic acids (formic, pyruvic, lactic, acetic, orotic, citric, uric, propionic, and butyric) were analyzed during ripening of pickled White cheese for 12 mo by high-performance liquid chromatography with a reverse phase C18 (120x 5-mm) column and UV detector. The level oftotal organic acids showed an increase along the ripening period, but its composition varied during the process. Initially, lactic acid accounted for 95% of the total, after 9 and 12 mo of ripening, butyric acid constituted 20 and 27% of the total, respectively. Each organic acid presented a characteristic pattern of change during ripening. Discriminant analysis classified cheeses according to their age. Stepwise regression analysis allowed estimation of the ripening time of samples according to their organic acid levels.     

The effects of starter culture on chemical composition, microbiological and sensory characteristics of Turkish Kaşar Cheese during ripening

Kaşar cheese samples were produced from raw milk and starter culture-added pasteurized milk. Chemical, microbiological and organoleptic properties of kaşar cheeses were analysed at certain times during the ripening periods (on the 1st, 7th, 15th, 30th, 60th, 90th days). Generally, chemical parameters were not affected by starter culture. The pH, ripening index, water-soluble nitrogen and non-protein nitrogen did not show significant differences between the cheese samples. The addition of starter affected the microbiological quality of the cheeses. Starter culture-added kaşar cheeses contained low levels of total aerobic mesophilic bacteria, moulds and yeasts, and coliforms, and achieved higher organoleptic scores than those of cheeses made from raw milk. The starter cultures contributed to acidity and microbial quality of the cheese.     

Influence of starters on chemical, biochemical, and sensory changes in Turkish White-brined cheese during ripening

Turkish White-brined cheese was manufactured using Lactococcus strains (Lactococcus lactis ssp. lactis NCDO763 plus L. lactis ssp. cremoris SK11 and L. lactis ssp. lactis UC317 plus L. lactis ssp. cremoris HP) or without a starter culture, and ripened for 90 d. It was found that the use of starters significantly influenced the physical, chemical, biochemical, and sensory properties of the cheeses. Chemical composition, pH, and sensory properties of cheeses made with starter were not affected by the different starter bacteria. The levels of soluble nitrogen fractions and urea-PAGE of the pH 4.6-insoluble fractions were found to be significantly different at various stages of ripening. Urea-PAGE patterns of the pH 4.6-insoluble fractions of the cheeses showed that considerable degradation of α_s1-casein occurred and that β-casein was more resistant to hydrolysis. The use of a starter culture significantly influenced the levels of 12% trichloroacetic acid-soluble nitrogen, 5% phosphotungstic acid-soluble nitrogen, free amino acids, total free fatty acids, and the peptide profiles (reverse phase-HPLC) of 70% (vol/vol) ethanol-soluble and insoluble fractions of the pH 4.6-soluble fraction of the cheeses. The levels of peptides in the cheeses increased during the ripening period. Principal component and hierarchical cluster analyses of electrophoretic and chromatographic results indicated that the cheeses were significantly different in terms of their peptide profiles and they were grouped based on the use and type of starter and stage of ripening. Levels of free amino acid in the cheeses differed; Leu, Glu, Phe, Lys, and Val were the most abundant amino acids. Nitrogen fractions, total free amino acids, total free fatty acids, and the levels of peptides resolved by reverse phase-HPLC increased during ripening. No significant differences were found between the sensory properties of cheeses made using a starter, but the cheese made without starter received lower scores than the cheeses made using a starter. It was found that the cheese made with strains NCDO763 plus SK11 had the best quality during ripening. It was concluded that the use of different starter bacteria caused significant differences in the quality of the cheese, and that each starter culture contributed to proteolysis to a different degree.     

Effect of some technological parameters on microbiological, chemical and sensory qualities of Civil cheese during ripening

The objective of this research was to determine the effects of different ripening methods [brine salting, dry salting, incorporating with Lor cheese (LR) and vacuum packaging] of Civil cheeses on its microbiological, chemical and sensory properties. Civil cheeses were analysed on the 2nd, 30th, 60th and 90th day of ripening. Chemical compositions of the cheeses were significantly different. While the highest dry matter and titratable acidity values were determined on dry salted cheeses, the highest fat and fat in dry matter contents were found in Civil cheese ripened together with LR. The water-soluble nitrogen and ripening index values were lower in cheese ripened incorporating with LR. Excessive proteolysis was not seen in any of cheese samples. The ripening in different methods affected microbiological and sensory properties of Civil cheese. Panellists preferred vacuum packaging and dry-salting cheeses compared to the other samples on the 90th day of ripening.     

冷藏乳制作的牦牛乳硬质干酪成熟过程中生物胺含量的变化

目的:揭示冷藏原料乳制作的干酪成熟过程中生物胺含量变化规律,评价其质量安全性。方法:以冷藏24,48,72 h牦牛乳制作的硬质干酪为研究对象,利用高效液相色谱法对干酪成熟过程中生物胺含量进行测定。结果:在0～6个月成熟过程中,不同冷藏牦牛乳制作的硬质干酪中生物胺含量呈升高趋势。牦牛乳冷藏时间从24 h延长到72 h时,其干酪中总生物胺、2-苯乙胺、尸胺、酪胺和腐胺含量也依次增大。成熟4个月后,冷藏72 h牦牛乳制作的硬质干酪中各生物胺含量明显高于其余两组干酪。成熟6个月时,冷藏72 h原料乳制作的牦牛乳硬质干酪中生物胺总量和酪胺含量分别为(212.94±8.03),(81.04±3.92) mg/kg。结论:随着原料乳冷藏时间和干酪成熟时间的延长,干酪中生物胺含量增多,但是原料乳冷藏时间低于72 h时,其干酪中生物胺含量低于学者建议含量。     

Monitoring the chemical and textural changes during ripening of Iranian White cheese made with different concentrations of starter

The effect of the concentration of starter inoculated to milk on the composition, free tyrosine-tryptophan content, microstructure, opacity, and fracture stress of Iranian White cheese (IWC) was studied during 50 d of ripening in brine. Three treatments of cheese were made using 1-fold (IWC1S), 2-fold (IWC2S), and 4-fold (IWC4S) concentrations of a direct-to-vat mesophilic mixed culture containing Lactococcus lactis ssp. cremoris and Lactococcus lactis ssp. lactis as starter. As ripening progressed, moisture and protein contents of the treatments continuously decreased, whereas their total ash, salt, and salt in moisture contents increased. Fat content and pH of cheeses remained stable during ripening. The pH of cheese milk at the time of renneting, which decreased by increasing the concentration of starter (6.57, 6.49, and 6.29 for IWC1S, IWC2S, and IWC4S, respectively), significantly affected most of the chemical characteristics and opacity of cheese. Lower pH values at renneting decreased moisture and ash contents, whereas cheese protein content increased. The concentration of free tyrosine-tryptophan in curd increased at first 29 d but decreased between d 29 and 49 of aging. The changes observed in cheese whiteness followed the changes in moisture content of the treatments. As the concentration of starter inoculated to milk increased, the value of fracture stress at a given ripening time significantly decreased, leading to a less resistant body against applied stress. A similar trend was also observed for fracture strain during cheese ripening. The micrographs taken by scanning electron microscopy provided a meaningful explanation for decrease in the value of fracture stress. As the cheese ripening progressed or the concentration of starter increased, the surface area occupied by the protein fraction in cheese microstructure decreased, leading the way to lower the force-bearing component in cheese texture.     

Monitoring the ripening attributes of Turkish white cheese using miniaturized vibrational spectrometers

Monitoring the ripening process by prevalent analytic methods is laborious, expensive, and time consuming. Our objective was to develop a rapid and simple method based on vibrational spectroscopic techniques to understand the biochemical changes occurring during the ripening process of Turkish white cheese and to generate predictive algorithms for the determination of the content of key cheese quality and ripening indicator compounds. Turkish white cheese samples were produced in a pilot plant scale and ripened for 100 d, and samples were analyzed at 20 d intervals during storage. The collected spectra (Fourier-transform infrared, Raman, and near-infrared) correlated with major composition characteristics (fat, protein, and moisture) and primary products of the ripening process and analyzed by pattern recognition to generate prediction (partial least squares regression) and classification (soft independent analysis of class analogy) models. The soft independent analysis of class analogy models classified cheese samples based on the unique biochemical changes taking place during the ripening process. partial least squares regression models showed good correlation (R_Pre = 0.87 to 0.98) between the predicted values by vibrational spectroscopy and the reference values, giving low standard errors of prediction (0.01 to 0.57). Portable and handheld vibrational spectroscopy units can be used as a rapid, simple, and in situ technique for monitoring the quality of cheese during aging and provide real-time tools for addressing deviations in manufacturing.     

Effects of starter culture combinations using isolates from traditional cheese on the quality of Turkish white cheese

Four types of Turkish white cheese with good curd and acid formation properties were produced, one by using commercial starter culture and the other three by using different combinations of isolates from traditional cheese with no starters added. The effects of using these combinations on quality were determined. Starter culture combinations did not influence the chemical properties of cheese significantly. However, one cheese type produced from combinations of isolates of rural cheese was found to be comparable to the samples produced from commercial starter cultures in terms of sensory and microbial quality. This combination could have promise for white cheese production.     

Changes in the physicochemical,microstructural and rheological properties of traditional Kope cheese during ripening

The effect of ripening time on the microstructural, physicochemical and rheological characteristics of traditional Kope cheese ripened in clay pots was investigated. The moisture content, pH and total nitrogen (TN)/dry matter (DM) of the cheese decreased, and DM, fat in DM and water‐soluble nitrogen/TN increased during this period. Storage and loss moduli increased, while loss tangent decreased; as a result, the elasticity characteristics were greater than the viscous characteristics of the samples. Microstructure images showed that the size of pores and casein network density increased significantly during ripening and, after 90 days, the structure of many pores became very similar to each other.     

Technological characterization of the natural lactic acid bacteria of artisanal Turkish White Pickled cheese

The aim of this study was to characterize the lactic acid bacteria (LAB) isolated from White Pickled cheeses produced with traditional methods; and to improve the quality of cheesemaking with a selection of bacterial cultures from artisanal White cheeses. LAB were isolated and identified from 30 White Pickled cheese samples collected from various cities in Turkey. Also, the numbers of several microbial groups (total aerobic mesophilic bacteria, LAB, enterococci, coliforms, moulds and yeasts) of cheese samples were enumerated. Lactobacilli, lactococci and enterococci were the most abundant microbial groups. The numbers of Enterococcus and Lactobacillus isolates were higher than those of the other LAB. Enterococcus faecalis (24.43%), Enterococcus faecium (17.61%) and Lactobacillus fermentum (19.88%) isolates were the most frequently isolated species. Lactococcus strains showed the highest acidifying activity, followed by Enterococcus and Lactobacillus strains. Proteolytic activity of Enterococcus faecalis strains was higher than that of the other enterococci species, except Enterococcus avium strains. Within lactobacilli strains, the highest mean proteolytic activity was that of Lactobacillus bifermentans, Lactobacillus brevis and Lactobacillus casei strains.     

Changes in physicochemical and organoleptic properties of traditional Iranian cheese Lighvan during ripening

Lighvan cheese was studied to determine the physicochemical and biochemical changes over 90 days of ripening in brine. Acidity, pH, dry matter, fat values, lipolysis level, water‐soluble nitrogen (WSN), total nitrogen (TN), ripening index (RI), trichloroacetic acid‐soluble nitrogen (TCA‐SN) and organoleptic assessments were analysed. Dry matter and fat values decreased during ripening. Lipolysis level, RI, TCA‐SN values and salt content increased continuously until the end of the ripening period, but total nitrogen decreased throughout a 90‐day storage period. The ripening stage was the main factor affecting the cheese’s sensory properties.     

Proteolysis in ultra-filtered and conventional Iranian white cheese during ripening

Conventional and ultra-filtered (UF) Iranian white cheeses were made with almost identical gross chemical composition and the extent and characteristics of proteolysis were studied during ripening. UF cheeses exhibited a lower rate of development of pH 4.6-soluble nitrogen than conventional cheeses. The rates of degradation of α_s1-casein and particularly β-casein were lower in UF cheeses than in conventional cheeses. Plasmin activity was lower in UF cheeses than that in conventional cheese, whereas coagulant activity was higher in the former. Noticeable qualitative and quantitative differences were observed in reverse-phase high performance liquid chromatography (RP-HPLC) peptide profiles between UF and conventional white cheeses and chemometric analysis of peak height data distributed the cheeses into two separate groups. The levels of free amino acids in UF cheeses were lower than in conventional cheeses. Lower peptide degradation and production of amino acids suggested slower ripening, which may have been associated with the weak aroma development characteristic of UF cheeses.     

Relationships between proteolytic and lipolytic activity and sensory properties (taste–odour) of traditional Turkish white cheese

Protein and lipid changes and their effects on the sensory properties (taste–odour) of Turkish white cheese were studied. Mean values for the chemical properties of white cheese were: total solids (TS) 44.39 g/100 g; titratable acidity 2.15% (as lactic acid); pH value 4.50; fat-in-dry matter 47.80 g/100 g; salt-in-dry matter 8.65 g/100 g; total nitrogen (TN) 2.50 g/100 g; water-soluble nitrogen (WSN) 0.48 g/100 g; ripening index (RI) 18.98%; tyrosine 65.00 mg/100 g; acid degree value (ADV) 385.96 mg KOH/100 g fat; volatile fatty acids (VFA) 15.54 mL 0.1 N NaOH/100 g and total free fatty acids (TFFA) 1325.96 mg/100 g cheese. Sensory scores for taste and odour were 23.67 (out of 35) and 8.28 (out of 10), respectively. The chemical qualities of the cheeses, including acidity, dry matter, fat-in-dry matter and VFA had an effect on flavour ( P  < 0.05).     

The effects of carbon dioxide addition to cheese milk on the microbiological properties of Turkish White brined cheese

This study invest0igated the effect of CO₂ added to achieve three pH levels: pH 6.1, pH 6.2 and pH 6.3 for treatments X, Y, Z, respectively, on some microbiological properties of Turkish White (TW) brined cheese. For each pH, four batches of cheese were produced from: raw milk with no added carbon dioxide (UR), raw milk with carbon dioxide (TR), pasteurised milk with no carbon dioxide addition (UP) and pasteurised milk with carbon dioxide addition (TP). The microbiological analysis of TW brined cheeses was carried out for 90 days of maturation period. Total aerobic mesophilic bacteria, mesophilic lactic acid bacteria, yeasts and moulds and coliform group were determined in control and CO₂ treatment groups. Mesophilic bacteria count was determined as 5.14, 5.29, 5.67 log cfu/g for pH 6.1, 6.2 and 6.3, respectively, in CO₂‐treated raw milk cheeses. Yeasts and moulds reduction increased significantly by applying CO₂ (P < 0.01). For TW cheese samples, the most significant microbial inactivation was detected at sample groups of pH 6.1.     

Influence of starter and nonstarter on the formation of biogenic amine in goat cheese during ripening

Two commercial starters were investigated for their potential ability to decarboxylate amino acids during goat cheese ripening. Two batches of goat cheese were produced with identical pasteurized milk but different starter cultures. One of them contained Lactococcus lactis subsp. lactis and Lactococcus lactis subsp. cremoris and the other Lactococcus lactis subsp. lactis. The amine contents, microbial counts, proteolysis-related parameters, pH, total solids and salt content were studied in raw materials and cheeses. In raw materials, polyamines were the prevailing amines, whereas the main amines in cheeses were putrescine, tryptamine and, in particular, tyramine (94.59 mg/kg). Aerobic mesophilic microorganisms and Lactococcus counts increased throughout ripening, while Enterobacteriaceae were no longer detectable in cheese after 30 days of ripening. Amine concentration rose during cheese ripening in both batches. Moreover, the decarboxylase activity of microorganisms isolated from samples during cheese ripening was assayed and discussed.     

Physicochemical, microbiological and sensory changes during ripening and storage of Xinotyri, a traditional Greek cheese from raw goat's milk

Physicochemical, microbiological and sensory characteristics, evolution of lipolysis monitored by measuring acid degree value (ADV) and the main mineral elements were studied during ripening and storage of artisanal Xinotyri cheese from raw goat's milk. Cheeses were characterized by a high content in total solids (TS; 83%) and fat (59% of TS), and very low pH (4.0), water activity (0.87) and moisture (17%). Protein and salt contents at the end of storage were 31% and 2.8%, respectively. Lipolysis increased, while variations in mineral (Ca, P, Mg and Zn) content were found during ripening and storage. Cheeses were free of Salmonella and Listeria in 25 g, while enterobacteria, pseudomonads, and coagulase-positive staphylococci were < 100 cfu/g. Mesophilic lactic acid bacteria increased above 8 log cfu/g by day 6, but declined by 2–3 logs in the ripened cheese (45 days) and by 3–4 logs during cheese storage at 4°C for up to 180 days.     

Changes in the rheological properties of Iranian UF-Feta cheese during ripening

The frequency sweep test was used to evaluate storage modulus (G′), loss modulus (G′′) and loss tangent [tan (δ)] of Iranian UF-Feta cheese during ripening period (3, 20, 40 and 60 days). With development of ripening, storage and loss moduli increased at varying rates. The rate of increase in G′ was greater than that in G′′ resulting in a reduction in tan (δ). That is, storage modulus was dominant to loss modulus and as a result the elasticity nature was greater than the viscous nature of cheese samples. Due to the disruption of fat globules and proteolysis, protein matrix rearranged and formed a more compact texture containing aggregates of casein. Ripening did not influence the pH level and also the concentrations of dry matter, fat, salt, and total nitrogen in dry matter. However, water soluble nitrogen increased significantly (P < 0.05).