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Peptides responsible for bitter taste may form, as a result of the hydrolysis of protein-rich foods. The perception of bitterness is formed by the stimulation of bitter taste receptors and the interpretation of the signal sent to the brain through the nervous system. Dairy products are often characterized by bitter peptides. In studies conducted, it has been stated that the bitter peptides identified in cheese are generally originated from αs1- and β-casein. The bitter taste intensity of protein hydrolysates varies depending on the hydrophobicity of the peptide, the number of hydrophobic amino acids and its the chain length. While accelerating ripening in cheeses, methods including aminopeptidase, carboxypeptidase and adjunct cultures with starter culture have been used recently to prevent the formation of bitter taste defects. In this review; the formation and perception mechanism of bitter peptides has been explained and current studies on bitter removal methods have been presented.

Beyaz peynir, a white brined cheese, was manufactured using different blends of camel chymosin (100, 75, 50, 25, and 0%) with calf chymosin and ripened for 90 d. The purpose of this study was to determine the best mixture of coagulant for Beyaz peynir, in terms of proteolysis, texture, and melting characteristics. The cheeses were evaluated in terms of chemical composition, levels of proteolysis, total free amino acids, texture, meltability, residual coagulant activity, microstructure, and sensory properties during 90 d of ripening. Differences in the gross chemical composition were statistically significant for all types of cheeses. Levels of proteolysis were highly dependent on the blends of the coagulants. Higher proteolysis was observed in cheeses that used a higher ratio of calf chymosin. Differences in urea-PAGE and peptide profiles of each cheese were observed as well. Meltability values proportionally increased with the higher increasing levels of calf chymosin in the blend formula. These coagulants had a slight effect on the microstructure of cheeses. The cheese made with camel chymosin had a harder texture than calf chymosin cheese, and hardness values of all cheese samples decreased during ripening. The cheeses with a high ratio of calf chymosin had higher residual enzyme activity than those made with camel chymosin. No significant difference in sensory properties was observed among the cheeses. In conclusion, cheeses made with a high level of calf chymosin had a higher level of proteolysis, residual coagulant activity, and meltability. The cheeses also had a softer texture than cheeses made with a high content of camel chymosin. Camel chymosin may be used as a coagulant alone if low or limited levels of proteolysis are desired in cheese.

Iranian Ultrafiltered White cheese was produced by using different blends of coagulants (100:0, 75:25, 50:50, 25:75 and 0:100; Rhizomucor miehei and camel chymosin, respectively) and ripened for 90 days. The effect of different combinations of these coagulants on chemical composition, proteolysis and residual coagulant activity of the cheeses were studied. The results showed that pH, fat-in-dry matter, salt-in-dry matter and protein contents of the cheeses were significantly influenced by type and concentration of the coagulants. The difference between proteolytic activities of the two coagulants resulted in different levels of proteolysis in the cheeses. A direct relationship was determined between using higher concentrations of R. miehei and increasing the hydrolysis of αs1-casein in the cheeses, during ripening. The residual coagulant activity was influenced by the type and concentration of the coagulant as well. In conclusion, R. miehei provided a higher level of proteolysis and residual coagulant activity compared with camel chymosin.

Adjunct cultures including lactobacilli play important role in cheese proteolysis and bioactivity including Angiotensin Converting Enzyme (ACE)-inhibition and antioxidant activity. Four species of lactobacilli was used in the manufacture of model cheese and these were salted at different levels and the resultant cheeses were ripened at different time and temperature to understand the effect of salting and ripening conditions. The effects of the use of various of lactobacilli (Lactobacillus casei, Lb. helveticus, Lb. delbrueckii ssp. bulgaricus and Lb. plantarum), salt concentrations (1, 2, 3, 4 and 5%), ripening times (1, 30, 60, 90 and 120 days) and temperatures (5, 10, 15 and 20 degrees C) were investigated. The experiments were designed to determine the optimal salt concentration, ripening times and temperatures for optimal proteolysis, the highest levels of ACE-inhibition and antioxidant activity. The highest level of proteolysis and ACE-inhibiting activity in the model cheese was observed when ripening temperatures were between 8 and 16 degrees C, salt concentration at 2.5-3.0% and with a ripening period of about 60 days. The use of each lactobacilli contributed to the proteolysis in different manner; for example, ACE-inhibiting activity and antioxidant activity in the model cheese.

International audience; Bouhezza is an Algerian traditional cheese made using different types of milk (goat, sheep and cow), ripened in a goat-skin or sheep-skin bag called Chekoua or Djeld of Bouhezza. The objective of the study was the characterization of Bouhezza cheese through ten cheese preparation trials using goat raw milk. The chemical and microbiological composition and proteolysis were monitored on ripened samples. The physicochemical characteristics showed that Bouhezza is acidic with a pH value of 3.95 and 2.36% for titratable acidity as lactic acid, 13.20% for protein and 12.74% for fat. At the end of ripening, Bouhezza was classified to be a ripened, soft and mid-fat cheese. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of Bouhezza samples showed low proteolysis after 30days of ripening. Microbiological results showed a high content of lactic acid bacteria (LAB), 8 to 9 log cfu/ g, an absence of pathogenic bacteria, and a low level of contamination flora. This makes the cheese a healthy product and of an acceptable hygienic quality. Four proteolytic lactic acid bacteria were identified by 16S ribosomal deoxyribonucleic acid (rDNA) sequencing: two strains of Enterococcus faecalis, one E. faecium, and one Lactobacillus paracasei ssp. paracasei. Reversed phase-high performance liquid chromatography (RP-HPLC) of the soluble fraction at pH 4.4 showed changes occurred during ripening. This work highlights, characterizes, and improves the knowledge of cheese Bouhezza made with raw goat's milk. This product is rich in nutrients, such as proteins and minerals, that are useful to the consumer.

The objective of this work was to characterize the traditional cheese, Bouhezza made with raw goat’s milk. There were three cheese making performed; two at the laboratory scale (FH1, FH2) and one i...

Bouhezza is an Algerian cheese, which is ripened in a goat-skin bag, called Chekoua. The aim of the study was to determine the protein profiles and aromatics, which contribute to sensory properties of Bouhezza cheese. The chemical composition, proteolysis, and volatile profile have been carried out in cheese made from raw goat milk. The results showed that, the dry matter ranged from 23.07 to 51.95%, the fat-in-dry matter ranged from 10.58 to 31.77%, and the protein ranged from 28.27 to 42.09%. Water-soluble and 12% trichloroacetic acid-soluble nitrogen fractions decreased at the beginning of the ripening process and then they increased until the end of ripening. The reverse phase-high-performance liquid chromatography peptide profiles of the cheese showed the modifications occurred during the ripening process. The volatile compounds showed a diversity of odorous components which contribute to give to the cheese its particular organoleptic. There were 109 compounds identified in Bouhezza cheese. C...

The effects of partial substitution of goat's milk for sheep's milk, scalding and dry salting on the proteolysis of Urfa cheese were monitored for 240 days. For this reason, the contents of total nitrogen, water‐soluble nitrogen (WSN), and trichloroacetic acid‐soluble nitrogen (TCA‐SN) were explored as well as the chemical compositions of samples during ripening. Also, RP‐HPLC of pH 4.6‐soluble, 70% ethanol‐insoluble (EtOH‐i), and urea‐PAGE of pH 4.6‐insoluble nitrogen fractions of samples was determined. The results showed that the effects of partial substitution of goat's milk for sheep's milk on WSN and TCA‐SN were significant from sixth to eighth month of the ripening, respectively. Even though the effects of the milk type, dry salting, and scalding on the peptide profile were significant at the beginning of maturation, the peptide profile of cheeses was almost similar at the end of the storage. Furthermore, the proteolysis of Urfa cheese was limited due to dry salting during the ripening. PRACTICAL APPLICATIONS: The maturation of cheese is a complex biochemical process involving the hydrolysis of fat, breakdown of protein, and metabolism of lactose. Though the biochemical reactions during cheese ripening are not precisely understood, proteolysis is one of the most significant biochemical processes during maturation. It is known that the amino acids resulting from proteolysis are the precursors of flavor components in cheese. Milk itself is a significant source of proteolytic enzymes. And also, the curd scalding temperature and salt content of cheese affect the proteolytic activity during cheese ripening. However, limited proteolysis may be occurred during the cheese maturation due to dry salting and scalding process. Therefore, studies should focus on overcoming this problem. This study can help to overcome the limited proteolysis in the production of cheese. Also, results from the study may contribute to the industrial production of Urfa cheese.

Kashkaval is the most popular hard cheese in Macedonia and other countries of Balkan peninsula. The aim of this research is to assess the differences of heat treatments effect (60, 70 and 90 °C for 5 min) in several biochemical and technological characteristics of Kashkaval cheese. Proteolysis was observed to take place at a faster rate in the Kashkaval cheeses made using the lower heat treatment. The residual enzyme activity of cheeses averaged 67.7, 43.7 and 8.4% for the cheeses heated at 60, 70 and 90 °C, respectively. Acids and esters constituted the main chemical class of the cheeses during ripening (mean abundances of these were 57.1% and 26.8% w/w of total volatiles, respectively). The colour ( L ∗ ) and meltability values decreased significantly during ripening. In conclusion, powerful correlations were observed between extents of the heat treatment and levels of residual coagulant activity, breakdown of proteins and formation of volatiles.

PubMedID: 26119429 Iranian White cheese was manufactured from ultrafiltered cows' milk using different concentrations of salt consisting of 1, 2·5, 4% and salt free. Chemical composition, proteolysis, counts for lactic acid bacteria and sensory evaluation were examined during 90 d of ripening. It was found that the use of different salt concentrations significantly influenced all chemical composition, proteolysis, total number of lactic acid bacteria and sensory characteristics of the cheeses. Increasing the salt concentrations caused a proportional decrease in proteolysis determined by both urea-PAGE of caseins and RP-HPLC of peptides. With increased salt concentration, total number of lactic acid bacteria decreased. Cheeses with 1 and 2·5% salt were suitable and acceptable in odour and flavour that may be due to the proportional level of proteolysis products. In conclusion, reducing salt concentration from 4 to 2·5 and 1% had no ineligible effect on the quality and acceptability of the cheese. © 2015 Proprietors of Journal of Dairy Research.

The thermal inactivation behaviour of calf rennet and Rhizomucor miehei protease and the effects of different concentrations of these enzymes on chemical composition, proteolysis, microstructure, hardness and meltability of Malatya cheese were studied. Thermal stability and inactivation behaviour of the two enzymes were different and influenced the level of proteolysis during ripening and the meltability of the cheeses. This influence depended not only on the type of coagulant, but also on its concentration. Salt and protein contents and pH of the cheeses were influenced by the type and concentration of the coagulant enzyme. Only small effects on the microstructure of the cheeses were visualised, also related to the type and concentration of coagulant enzyme. Hardness of the cheeses was influenced by the type and concentration of the coagulant as well. In conclusion, the microbial coagulant provided a higher level of thermal stability, proteolysis and meltability values than calf rennet.

The effects of ripening temperature and adjunct cultures (Lactobacillus helveticus and Lactobacillus casei) on the volatile compounds and sensory and textural properties of white-brined cheese were investigated. Three batches of cheese were produced: cheese A was inoculated with only cheese starter culture (Lactococcus lactis subsp. lactis plus Lactococcus lactis subsp. cremoris), cheese B was inoculated with cheese starter culture plus Lactobacillus helveticus and cheese C was inoculated with cheese starter culture plus Lactobacillus casei. Cheeses were ripened at 6 or 12 °C and analyzed at 30-day intervals up to 120 days of ripening. The use of adjunct culture and ripening temperature significantly influenced the pH and proteolysis of cheeses (P < 0.05). Acids, ketones and alcohols were found at high levels in all three cheeses. Volatiles were significantly influenced by the use of the adjunct cultures, ageing and to some extent ripening temperature (P < 0.05). Textural parameters of the cheeses were significantly affected by the adjunct culture during ripening (P < 0.05). The sensory scores of the cheese samples decreased during the ripening period. An age-related bitterness was detected by the panellists in 90 or 120-day-old cheeses with added adjunct cultures. In conclusion, the use of adjunct culture and ripening at 12 °C enhanced the volatile composition and changed the texture profiles of the cheeses.

Beaten ewe's milk cheese is a traditional autochthonous type of cheese manufactured in Macedonia with a relatively high nutritional value and sensory characteristics. The objective of this study was to characterise the gross composition, proteolysis and volatile profiles of the cheese that is supplied from different retails. The ranges for gross composition were from 31.53% to 42.83% (w/w) for moisture, 41.99% to 50.98% (w/w) for fat-in-dry matter, 2.03% to 8.25% (w/w) for salt content and 20.74% to 33.35% (w/w) for protein. Proteolysis results showed various levels of soluble nitrogen ranged from 3.15 to 33.50 for water-soluble nitrogen (WSN) and from 1.11% to 6.79% for nitrogen soluble in 12% trichloroacetic acid (TCA-SN). The ranges for total free amino acids were from 1.65 to 8.06 mg Leu/g. Lower proteolysis was observed in the cheese samples due to high salt contents. In total, 65 volatile compounds were identified in Beaten cheese. As a conclusion, the variation of the peptide profile, electrophoresis and volatile contents of Beaten cheeses are due to the lack of standardised manufacture protocols.

Four different types of mould-ripened Civil cheese were manufactured. A defined (nontoxigenic) strain of a Penicillium roqueforti (SC 509) was used as the secondary starter with and without addition of the whey cheese (Lor); in parallel, secondary starter-free counterparts were manufactured. Chemical composition, microbiology and proteolysis were studied during the ripening. The incorporation of whey cheese in the manufacture of mould-ripened Civil cheese altered the gross composition and adversely affected proteolysis in the cheeses. The inoculated P. roqueforti moulds appeared to grow slowly on those cheeses, and little proteolysis was evident in all cheese treatments during the first 90 days of ripening. However, sharp increases in the soluble nitrogen fractions were observed in all cheeses after 90 days. Microbiological analysis showed that the microbial counts in the cheeses were at high levels at the beginning of ripening, while their counts decreased approximately 1–2 log cfu/g towards the end of ripening.

Summary Kashar cheeses were manufactured from pure ovine (OV), bovine (BV) and caprine (CP) milk, and the chemical composition, cheese yield, proteolysis, hardness, meltability and volatile composition were studied during 90 days. Gross chemical composition, cheese yield and level of proteolysis were higher in OV cheeses than those of BV or CP cheeses. Glu, Val, Leu, Phe and Lys were the most abundant free amino acids (FAA) in the samples, and the concentrations of individual FAA were at the highest levels in OV cheeses with following BV and CP cheeses. Urea-PAGE patterns and RP-HPLC peptide profiles of the BV cheeses were completely different from the small ruminants’ milk cheeses (OV or CP). Higher and lower hardness and meltability values were observed in CP cheeses, respectively. OV cheeses resulted in higher levels of the major volatile compounds. In conclusion, the Kashar cheese made using OV milk can be recommended due to high meltability, proteolysis and volatiles.

The objective of this study was to determine the gross composition, proteolysis, and volatile and texture profiles during ripening of industrial (IND) and traditional (TRD) Beaten (Bieno sirenje) cheeses made by using ewe milk. In the course of the analyses, statistical differences were determined in some physicochemical parameters, nitrogen fractions, and total free amino acid levels between TRD and IND types of cheese. Higher levels of proteolysis were observed in IND cheeses than in TRD cheeses during ripening. Levels of residual β- and αs-caseins were 72.2 and 48.7%, respectively, in 180-d-old TRD cheeses. However, the residual levels were 52.8% for β-casein and 18% for αs-casein in IND cheeses. Similar differences were noted for the reversed-phase HPLC peptide profiles of 2 types of cheeses. Also, higher concentrations of peptides were eluted in IND cheeses than in TRD cheeses during ripening. A total of 73 volatile compounds, including alcohols (16), esters (17), acids (14), terpenes (7), ketones (5), aldehydes (4), and miscellaneous (10) were identified. The IND cheeses contained higher levels of carboxylic acids, esters, alcohols, and terpenes than the TRD cheeses; however, the same levels of methyl ketones were determined in the 2 types of cheeses at the end of ripening. These may be due to some differences (e.g., pasteurization and scalding temperature, among other factors) in the manufacture of the 2 types of Beaten cheeses. The textural profile of Beaten cheeses showed that TRD production method resulted in firmer, less fracturable, and stiffer cheeses than the IND production method. In conclusion, the results suggest that the use of industrial production method (pasteurization of cheese milk and curd scalding at 70°C) in the manufacture of Beaten ewe milk cheese enriched the volatile profile of the cheese.

The objective of the study was to determine the effects of exopolysaccharide (EPS)-producing or non-EPS-producing starters on proteolysis, physical and microstructural characteristics of full-fat or low-fat Tulum cheeses during ripening. For this purpose, Tulum cheese was manufactured using full- or low-fat milk with EPS-producing and non-EPS-producing starter cultures. Chemical composition, proteolysis, texture profiles and microstructure of the cheeses were studied during 90 days of ripening. Urea-PAGE of water-insoluble and RP-HPLC peptide profiles of water-soluble fractions of the cheeses showed that the use of starters resulted in different degradation patterns in all cheeses during ripening. Although ß-casein exhibited similar degradation patterns in all cheeses, small differences are present in ?s1-casein degradation during ripening. Reducing fat in Tulum cheese changed the RP-HPLC peptide profile of the cheeses. The use of EPS-producing cultures improved the textural characteristics and changed the microstructure and proteolysis of low-fat Tulum cheese. © 2013 Institute of Food Science and Technology.

a b s t r a c t The objective of the study was to determine the gross composition, proteolysis and volatile compounds in Gokceada goat cheese and to provide initial information on its manufac- turing and ripening processes. Gokceada goat cheese is traditionally manufactured from raw goat milk in Gokceada (Imbros) island, Canakkale, Turkey. In the present study, 23 commercial samples were characterized. Urea-polyacrylamide gel electrophoresis of the water-insoluble fractions showed that both s- and -caseins were extensively decom- posed, but -casein was less degraded compared to s-casein. RP-HPLC of peptide profiles in the water-soluble fractions demonstrated qualitative and quantitative differences among the samples. Sixty volatile compounds were identified by SPME/GC-MS technique with alcohols and esters as the principal class of volatile components in the cheeses. In general, relatively large variability in gross composition and concentration of volatile aroma was found, which probably reflects lack of standardization in the production of the cheese.

Levels of proteolysis of 75 samples belonging to 11 Turkish cheese varieties, including Civil, Canak, Dil, Divle Tulum, Ezine, Hellim, Malatya, Mihalic, Orgu, Urfa, and Van Otlu, were comparatively studied. The cheeses were mainly produced using traditional methods; however, some varieties were industrially produced. Chemical composition and the levels of soluble nitrogen fractions of the cheeses varied depending on the cheese variety. Gel electrophoresis of the cheeses showed that the samples presented different gel patterns with αs1-casein being extensively degraded in many cheeses; whereas the hydrolysis of αs1-casein in Malatya and Hellim was observed to be limited. Peptide profiles by RP-HPLC of the water-soluble fractions were largely different for many of the samples, but some similarities were visualized. Multivariate analysis of the RP-HPLC data grouped the cheeses according to their peptide profiles. The results suggested that each variety of cheese had different levels of proteolysis. The manuf...

The development of proteolysis in white-brined Turkish cheese made by using wild strains of Lactococcus lactis subsp. lactis (namely MBLL9, MBLL23 and MBL27) was monitored for 90 days. Proteolysis in cheeses was investigated using urea-PAGE gel electrophoresis of pH 4.6-insoluble and RP-HPLC of both 70% ethanol-insoluble and 70% ethanol-soluble nitrogen fractions. Results indicated that developments of proteolysis in the experimental cheeses were strain dependent. The degradation of casein fractions was more evident in the cheeses made using strain MBLL23. The lowest levels of proteolysis and development of acidity were obtained in the cheese made using strain MBLL9.

The effect of pasteurization of cheese milk and cooking temperature of the curd on proteolysis of Malatya cheese was examined during ripening. The cheeses that were characterized by the scalding of curd in hot whey were manufactured from raw or pasteurized milk and the curds were scalded in hot whey at 60, 70, 80 or 90 °C. Differences in the levels of pH 4.6-soluble nitrogen between cheeses were significant (P < 0.05) after 30 days of ripening. Urea-polyacryl-amide gel electrophoresis of the pH 4.6-insoluble fractions showed that both αs1- and β-caseins were not extensively degraded, especially after 30 days of ripening, but β-casein was less degraded than αs1-casein. Analysis of peptide profiles of the pH 4.6-soluble fractions by RP-HPLC showed significant differences in the concentrations of some peptides between the cheeses. Principal component analysis distinguished the cheeses made from raw or pasteurized milk based on their peptide profiles. The results suggest that the pasteurization of cheese milk had a greater effect on peptide profiles of cheese than scalding temperature of the curd.

Summary The performance and relative contribution of four single strains of lactococci (UC317, NCDO763, HP or SK11) as starters for cheese-making and ripening properties of Beyaz cheeses were compared. Gross composition, secondary proteolysis (water-soluble, 12% trichloroacetic acid-soluble, 5% phosphotungstic acid-soluble nitrogen fractions and total free amino acid contents), lipolysis (acid degree values, ADV) and cheese grading were monitored during 90 days of ripening. Chemical composition of whey samples obtained during cheese-making were found to be quite similar; however, whey samples obtained from NCDO763 or HP cheeses had the highest and the lowest pH values, respectively (P 0.05). The highest concentrations of soluble nitrogen and total free amino acid contents were observed in the cheeses made with NCDO763. The cheeses made with different strains of lactococci showed marked differences in cheese proteolysis during ripening.

The effects of use of adjunct cultures (Lactobacillus helveticusandLb. casei) and ripening temperatures (6 or 12 °C) on proteolysis and angiotensin-I converting enzyme (ACE)-inhibitory activity in white-brined cheeses were investigated during 120 d ripening. Proteolysis was monitored by urea-polyacrylamide gel electrophoresis (urea-PAGE) and reversed phase-HPLC (RP-HPLC) of water-insoluble and -soluble fractions of the cheeses, respectively. Urea-PAGE patterns of the samples revealed that the intensities of the bands representing casein fractions decreased in the experimental cheeses, being more pronounced in the cheeses made with adjunct cultures. Similarly, peptide profiles and the concentrations of individual and total free amino acids were influenced by both the adjunct cultures and ripening temperatures. The ACE-inhibitory activity of the water-soluble extracts of the cheeses were higher in the cheeses made using adjunct cultures (especiallyLb. helveticus) and ripened at 12 °C. The ACE-inhibitory activity did not decrease during ripening. The contribution ofLb. helveticusto the development of proteolysis and ACE-inhibitory peptide activities were higher than that ofLb. casei. To conclude, the use ofLb. helveticusas adjunct culture in white-brined cheese and ripening at 12 °C would be recommended to obtain white-brined cheese with high ACE-I-inhibitory peptides activity and higher levels of preoteolysis.

Changes in chemical composition, proteolysis, lipolysis, texture, melting and sensory properties of low-fat Kashar cheese made with three different fat replacers (Simplesse® D-100, Avicel Plus® CM 2159 or β-glucan) were investigated throughout ripening. The low-fat cheeses made with fat replacers were compared with full- and low-fat counterparts as controls. Reduction of fat caused increases in moisture and protein contents and decreases in moisture-in-non fat substance and yield values in low-fat cheeses. The use of fat replacers in the manufacture of low-fat Kashar cheese increased water binding capacity and improved overall quality of the cheeses. Use of fat replacer in low-fat cheese making has enhanced cheese proteolysis. All samples underwent lipolysis during ripening and low-fat cheeses with fat replacers had higher level of total free fatty acid than full- or low-fat control cheeses. Texture attributes and meltability significantly increased with addition of fat replacers. Sensory scores showed that the full-fat cheese was awarded best in all stages of ripening and low-fat variant of Kashar cheeses have inferior quality. However, fat replacers except β-glucan improved the appearance, texture and flavour attributes of low-fat cheeses. When the fat replacers are compared, the low-fat cheese with Avicel Plus® CM 2159 was highly acceptable and had sensory attributes closest to full-fat Kashar cheese.

Du Beyaz peynir (fromage turc saumure) a ete conserve durant neuf semaines dans des saumures de quatre concentrations en sel differentes (12, 14, 16 ou 18 g NaCl.100 g -1 ) a 7 ± 1 °C, dans le but d'etudier l'effet de la concentration en sel durant la maturation sur la composition, la proteolyse, la texture et les caracteristiques sensorielles du fromage. Des differences significatives ont ete constatees pour les valeurs de pH, de la matiere seche, de la teneur en proteine totale, la durete, la fraction d'azote soluble dans l'acide trichloroacetique a 12 % (w/v), et l'hydrolyse de la caseine β, tandis qu'aucune difference n'a ete observee pour la quantite d'azote soluble dans l'eau et l'hydrolyse de la caseine α s1 . Les fromages matures-dans la saumure a 12 % de sel ont obtenu les meilleurs scores pour la flaveur et l'acceptabilite globale. Les resultats obtenus dans cette etude montrent que la proteolyse et l'acceptabilite globale des fromages Beyaz peynir sont moins elevees pour les fromages matures dans des saumures de concentrations en sel superieures a 14 %.

Bu çalışmada, farklı oranlarda buzağı renneti ve deve kimozini karıştırılarak (%0, %25,%50, %75 ve %100) Beyaz peynir üretilmiş ve 90 gün süreyle olgunlaşmaya tabi tutulmuştur.Peynirlerin 90 günlük olgunlaşma boyunca kimyasal bileşimleri, protein hidrolizi, kalıntı enzimaktivitesi, toplam serbest amino asit miktarları, eriyebilirliği, tekstürel, mikro yapısal ve duyusalözellikleri belirlenmiştir. Peynirlerin kimyasal bileşimleri arasındaki farklılığın istatistikselolarak önemli olduğu saptanmıştır. Enzim karışımının olgunlaşma süresince peynirlerin proteolizseviyeleri üzerinde etkili olduğu belirlenmiştir. Olgunlaşmanın sonunda yüksek oranda buzağırennetinin kullanıldığı peynirde proteolizin daha yüksek olduğu görülmüştür. Farklı oranlardaenzim kullanımının protein elektroforezine ve peptit profillerine önemli ölçüde yansımadığıgörülmüştür. Peynirlerin eriyebilirlik durumunun enzim karışımı ile önemli ölçüde etkilendiği,ancak peynirlerin mikroyapısında çok az değişikliğe neden olduğu belirlenmiştir. Enzimkarışımının peynirlerin kalıntı enzim aktivitesi ve sertlik değerleri üzerinde etkili olduğu tespitedilmiştir. Tüm peynirlerin duyusal özellikleri arasında istatistiksel açıdan önemli bir farkbulunmamıştır. Sonuç olarak, buzağı rennetinin yüksek oranda kullanılarak üretildiği peynirlerdedeve kimozini kullanılarak üretilen peynirlere oranla daha yüksek proteoliz ve eriyebilirlikdeğerleri gösterdiği belirlenmiştir.Anahtar Kelimeler: Beyaz peynir; süt pıhtılaştırıcı enzimler; proteoliz, buzağırenneti, deve kimozini In this study, Beyaz peynir was manufactured by using different blends of calf rennet orcamel chymosin (0%, 25%, 50%, 75% ve 100%) and the experimental cheeses were ripened for90 days. The cheeses were evaluated in terms of chemical composition, protein hydrolysis,residual coagulant activity, total levels of free amino acids, meltability, textural, microstructureand sensory properties during 90 days of ripening. Differences in the gross chemicalcomposition of these cheeses were statistically significant for all types of cheeses. The levels ofproteolysis were highly dependent on the usage of coagulant in different rates during ripening.Higher proteolysis was observed in the cheeses made using high content in calf rennet.Electrophoresis of proteins and peptide profiles of the cheeses were not influenced by the usageof enzyme in different amounts. Meltability of the cheeses was significantly affected by thedifferent blends of enzyme. However, different amounts of coagulant had a slight effect on themicrostructure of cheeses Residual coagulant activity and hardness of the cheeses were alsoinfluenced by different amounts of the coagulant. There was no significant difference amongsensory properties of the cheeses. In conclusion, cheeses made using high level of calf rennetprovided higher level of proteolysis and meltability than cheeses made using high content ofcamel chymosin.Keywords: Beyaz peynir; milk-clotting enzymes; proteolysis, calf rennet, camelchymosin. 90

Bu çalışmada, bazı Lactococcus spp. cinsi starter bakteriler ile Lactobacillus spp. cinsi yardımcı kültür bakteri kombinasyonları (A peyniri: Lactococcus lactis ssp. lactis ve Lactococcus lactis ssp. cremoris karışımı klasik kültür, B peyniri: klasik kültür + Lactobacillus helveticus ve C peyniri: klasik kültür + Lactobacillus casei) kullanılarak Beyaz peynir üretilmiş ve iki farklı sıcaklıkta (6 °C ve 12 °C) 120 gün süre ile olgunlaştırılmıştır. Yardımcı kültür kullanımı peynirin fiziksel, kimyasal, mikrobiyolojik, tekstürel, duyusal özellikleri ile aroma oluşumu üzerine ve Angiotensin dönüştürücü enzim-inhibisyon aktivitesi üzerine önemli düzeyde etkili olduğu saptanmıştır. Yardımcı kültür ilave edilen peynirlerin pH ve titrasyon asitliği değerlerinin birbirinden farklı değerler aldığı belirlenmiştir. Yardımcı kültür kullanımı, duyusal ve tekstürel özellikler üzerinde farklılık yaratırken, farklı sıcaklıkta olgunlaştırılan peynirler arasında bu parametreler açısından bir farklılık bulunamamıştır. Yardımcı kültür kullanımının suda çözünen ve % 12 TCA’da çözünen azot değerlerinde farklılık gösterirken, farklı depolama sıcaklıklarının etkisi sınırlı olmuştur. Peynirlerin serbest amino asit düzeyleri arasında farklılık bulunmuş ve en yüksek konsantrasyonda Leu, Glu, Arg ve Lys amino asitlerinin olduğu belirlenmiştir. Peynirlerin suda çözünmeyen fraksiyonlarının üre-jel elektroforezinde, ?s1-kazeinin önemli düzeyde parçalandığı, ?-kazeinin hidrolize karşı daha dirençli olduğu belirlenmiştir. 120 günlük olgunlaşma süresince RP-HPLC peptit profilleri üzerine yardımcı kültür kullanımının ve farklı olgunlaşma sıcaklıklarının önemli düzeyde etkilerinin olduğu bulunmuştur. Peynirler arasında aroma profili açısından da farklılıklar belirlenmiş olup, farklı sıcaklıkta olgunlaştırmanın aroma üzerine etkisinin de önemli olduğu saptanmıştır. Olgunlaşma süresi ilerledikçe her iki depolama sıcaklığında peynirlerinin ACE-inhibisyon aktivitesinde artış olduğu saptanmıştır. Olgunlaşma süresince peynirlerin azot fraksiyonları, toplam FAA, RP-HPLC ile belirlenen peptit konsantrasyonu, aroma profilinde artışlar olmuş, tekstürel özellikleri olgunlaşma süresi, sıcaklık ve yardımcı kültür farklılığı parametrelerinin sertlik değerleri üzerine etkili olduğu, diğer parametreler üzerine ise olgunlaşma sıcaklığının etkisinin önemli olmadığı bulunmuştur. Yardımcı kültür kullanımının ve farklı depolama sıcaklıklarının, Beyaz peynir kalitesinde önemli ölçüde etkili olduğu sonucuna varılmıştır. In this study, Turkish white-brined cheese was manufactured using Lactococcus spp. as starter culture and Lactobacillus spp. strains as adjunt culture (A cheese: Lactococcus lactis ssp. lactis and Lactococcus lactis ssp. cremoris traditional cultures, B cheese: traditional cultures + Lactobacillus helveticus and C cheese: traditional cultures + Lactobacillus casei) and experimental cheese were different temperature (6 °C ve 12 °C) ripened for 120 days. It was found that the use of adjunt culture have significantly influenced the physical, chemical, microbiological, textural and sensory properties, ACE-inhibition activity and flavor formation. pH and titratable acidity values were significantly different in adjunt culture added cheeses. Use of adjunt culture resulted in differences in sensory and textural properties of the cheeses; however, no significant differences were found between cheeses in terms of ripening temperature. In addiation, water and 12 % TCA- soluble fractions were found to be significantly different but, the effect of ripening temperature was limited on the parameters. There were significant differences among the concentrations of free amino acids levels in cheeses and Leu, Phe, Glu, Arg and Lys were the most abundant amino acids. Urea-gel electrophoresis of waterinsoluble fractions of the cheeses showed that ?s1-casein significantly degraded during ripening; however, ?-casein was more resistant to to hydrolysis. RP-HPLC peptide profiles were significantly influenced by adjunct culture and ripening temperature. Differences between cheeses have been determined in terms of aroma profile, and the effect of ripening temperatures on aroma profile of the cheese samples were statistically significant. As ripening period progressed, ACE-inhibitory activities of the cheeses increased in both storage temperature. Nitrogen fractions, total FAA, RP-HPLC peptide concentrations increased during ripening, and ripening period, temperature and adjunct culture has significantly influenced the textural properties (especially hardness values); however, other paramters were not influenced by ripening temperature. İt was concluded that use of different adjunt culture and ripening temperature significantly affected the quality of white-brined cheese.