A Survey on the Some Chemical and Biochemical Properties of Civil Cheese, a Traditional Turkish Cheese

Abstract

In this article, 15 randomly selected samples of Civil cheese, were purchased from different retail markets in the Erzurum province, Turkey and were investigated for some chemical and biochemical analyses. All cheese samples were analyzed for dry matter, fat, salt, ash, titrable acidity, total nitrogen, soluble nitrogen, ripening index, α_s-and β-casein degradation, γ-casein, and peptides. Dry matter, fat, fat in dry matter, salt, salt in dry matter, ash, and acidity values in samples analyzed were found to be as found between 31.33 and 40.12 g/100 g cheese; 1.00 and 7.00 g/100 g cheese; 2.49 and 18.98 g/100 g cheese; 0.11 and 0.34 g/100 g cheese; 0.27 and 1.04 g/100 g cheese; 1.42 and 5.14 g/100 g cheese and, 0.63 and 2.16%, respectively. TN, WSN/TN, TCA-SN/TN, and PTA-SN/ TN values, expressed as TN%, were found between 3.01 and 5.57 g/100 g cheese, 4.25 and 8.80 g/100 g cheese, 3.23 and 6.12 g/100 g cheese, 1.03, and 5.53 g/100 g cheese in Civil cheese samples analyzed, respectively. SDS-PAGE showed that both α_s-CN and β-CN ratios were not high compared with similar cheeses, and are not completely hydrolyzed in all Civil cheese samples. A broad range of values from chemical and biochemical analysis indicated that Civil cheeses collected from retail markets lacked standardization. Consequently, it was decided that Civil cheese samples do not undergo an excessive proteolysis.

Keywords:

• Civil cheese
• Chemical quality
• Proteolysis

INTRODUCTION

Civil cheese, an acid curd cheese with rennet added, is a popular cheese variety in Turkey. It is produced from skim milk without starter culture especially in the East Anatolia Region of Turkey, especially. Civil cheese is produced from skim milk. No starter culture is used. Civil is generally consumed fresh and it has a very pleasant flavor. It is mostly preferred by people cautious about animal fat.[1] Civil cheese is some way similar to Pasta filata cheeses, having a unique plasticizing and kneading treatment of the fresh curd in hot water, which gives the product a fibrous structure and melting and stretching properties.[2] The chemical and biochemical characteristics of Turkish commercial cheeses, White, Kasar, and Tulum cheese are well known only in some varieties. Among these, White, Kasar, and Tulum cheeses, the main varieties manufactured in Turkey, have been investigated in detail. But, the other traditional cheeses, like Civil cheese, have received little attention. The various parameters of Turkish White cheese are chracterized as dry matter of 38.60 g/100 g cheese, fat 17.80 g/100 g cheese, protein 13.60 g/100 g cheese, NaCI 5.90 g/100 g cheese, titratable acidity (La) 0.35%, ash 6.80 g/100 g cheese, and ripening indices (WSN/TN × 100) 32.90 %.[3] The various parameters of Turkish Kashar cheese are chracterized as dry matter of 58.52 g/100 g cheese, fat 25.90 g/100 g cheese, protein 27.15 g/100 g cheese, NaCI 4.67 g/100 g cheese, ash 5.24 g/100 g cheese.[4] The Tulum cheeses are characterized by dry matter as 50.97 g/100 g cheese, fat x = 29.93 g/100 g cheese protein x = 19.46 g/100 g cheese, NaCI x = 3.46 g/100 g cheese, titratable acidity x = 0.89 %, pH 4.74, ripening indices (WSN/TN × 100) 14.29 %.[5]

Since the production method for Civil cheese is not standardized, considerable variations may exist among the processing conditions and procedures. Traditionally, Civil cheese is made from skim and raw cow's milk. The skim milk is allowed to rest overnight at about 15°C to increase acidity by natural microflora. Then, acidity of the skim milk is adjusted to 22 Soxhlet Henkel (°SH) with the second part skim milk after resting at 15°C for 12 hours. Skim milk is heated up to 30°C. Then for coagulation, calf rennet is added very slowly to skim milk (approximately, 100 L milk/4 ml rennet). For coagulation of milk in Civil cheese making, enzyme is mostly used. As the heating process is slowly increased with a slow agitation, the curd forms at about 52–53°C. Curd particles are facilitated to stick to ladle within the process of mixing until the temperature reaches about 65–70°C. The cheese block is transferred onto a clean surface by paddle and kneaded by handling. The cheese block is then hung from a platform to stretch by its own weight. The stretching process is repeated until the curd has a smooth, plastic, and fibrous character. Finally, Civil cheese is cut into pieces and salted in a brine solution.[6,7]

Cheese quality is greatly influenced by the levels of peptides, amino acids, and free fatty acids resulting from proteolysis and lipolysis. Proteolysis is probably the most important biochemical event, having a major impact on the flavor and texture of most cheese varieties. Proteolysis of cheeses is generally influenced by several factors, including plasmin, chymosin, proteinases, and peptidases from the starter and non-starter bacteria, pH and moisture levels of the curds, ripening time and temperature, salt content, salt-to-moisture ratio, and humidity.[8,9] Cheese quality is also influenced by the enzymatic catabolism of amino acids.

Studies including proteolysis on this cheese are limited. Only a few researchers have studied the chemical and biochemical characteristics of Civil cheese.[1,7,10–13] Therefore, the aim of the present research was to determine its chemical state and biochemical characteristics and also to introduce the manufacture of this kind of traditional product. On the other hand, any standard is not available for this type of cheese in Turkey.

MATERIALS AND METHODS

Collection of Cheese Samples

Fifteen samples of Civil cheese were randomly collected from retail markets in Erzurum province, Turkey and were transported to the laboratory in an ice chest. The samples were labelled, stored at 5°C, and examined within 48 hours.

Chemical Analysis

Civil cheese samples were analyzed for dry matter, fat, sodium chloride, titrable acidity, and ash according to Kurt et al.[14]

Nitrogen Fractionation

The total nitrogen (TN) and nitrogen fractions were determined by Kjeldahl method.[15] The procedure by Polychroniadou et al.,[16] with modifications, was followed for water-soluble cheese extract (WSE): 20 g grated cheese was homogenized for 5 minutes with 100 ml distilled H₂O using a warring blender. The homogenate was held for 40°C for 1 hour and then centrifuged at 3000 g for 30 minutes at 4°C. The fatty layer was removed and the supernatant filtered through blue ribbon (5893, Schleicher & Schuell, Germany) filter paper. The water-soluble nitrogen (WSN) content was determined by Kjeldahl method using 5 ml WSE. WSN was expressed as a percent of TN (WSN/TN). Soluble nitrogen in 12% trichloroacetic acid (TCA-SN) was determined as described by Katsiari et al.[17] except that using blue ribbon filter paper. TCA-SN was expressed as percent of TN (TCA-SN/TN). Soluble nitrogen in 5% phosphotungstic acid (PTA-SN) was determined using Kjeldahl method as described by Freitas et al.[18] except that using blue ribbon filter paper. PTA-SN was expressed as percent of TN (PTA-SN/TN).

Preparation of Cheese Proteins and Electrophoresis

The procedure used by Yazici & Dervisoglu[1] was followed to prepare cheese samples and SDS-PAGE gels, to set electrophoresis running conditions, and to evaluate densitometric electrophoretograms.

Statistical Analysis

ANOVA were used to analyze data pertaining to various chemical characteristics of Civil cheese samples in SPSS packet program. To estimate variability in the chemical and physical characterisrics of Civil cheese samples were determined some statistical parameters including mean, standard error, range, standard deviation, correlation, and coefficient of variation for each index.[19]

RESULTS AND DISCUSSION

Chemical and Biochemical Properties

The results of some chemical and biochemical properties of the cheese samples are presented in Table 1. There were wide ranges variations in the compositional factors. This seems to indicate that there is no a standardized production method for Civil cheese manufacture. Different methods used for the cheese manufactures use different manufacturing practices, which were reported by Sengul and Ertugay.[20] As seen in Table 1, dry matter, fat, fat in dry matter, salt, salt in dry matter, ash, and acidity values in samples analyzed was were found between 31.33 and 40.12 g/100 g cheese, 1.00 and 7.00 g/100 g cheese, 2.50 and 18.98 g/100 g cheese, 0.11 and 0.34 g/100 g cheese, 0.27 and 1.04 g/100 g cheese, 1.42 and 5.14 g/100 g cheese, 0.63 and 2.16%, respectively. The highest coefficient of variation was observed in cheese samples. It was found similar results in the fat and fat in dry matter contents values among samples examined except for two samples. This difference in the fat content may be due to the fat content of the raw milk, either full fat or non fat. Actually, this product does not have a standard production technique and also the use of different raw materials.[20] Bakirci and Andic[11] determined the fat ratio in Cecil cheese (Civil cheese in Muş province) as between 0.10–0.90 g/100 g cheese. The average fat values obtained from our Civil cheese samples was much higher than the values found by Bakirci and Andic,[11] Kurt and Oztek,[6] and Caglar et al.[7] These differences may be derived from the different type of milk used in the manufactures. Since Civil cheese is a traditional cheese type, there is not any standard for this product in our country. However, when the samples compared within the TS-3001 Tulum Cheese Standard,[21] fat in dry matter contents of all samples were found below at least limit of TSE 3001 (at least 20 g/100 g cheese). Salt contents of all the samples were found in low levels because salt is not used in Civil cheese production. These results obtained from our study were accordance with similar to the results of Caglar et al,[7] Bakirci and Andic,[11] and Sengul and Ertugay.[20] As it can be seen in Table 1, Ash contents of the samples changed ranged from 1.42 to 5.14 g/100 g cheese and had an average of 2.11 g/100 g cheese. The ash content of cheese samples was similar to the salt in dry matter content because of the direct contribution of salt into the ash content. The average ash content determined by Kurt and Oztek[6] was calculated to be 6.25 g /100 g cheese in Civil cheese. Bakirci and Andic[11] also determined this content as 9.40 kg/100 kg Cecil cheese. The ash content in Civil cheese samples is much lower than it is in Cecil cheese. That difference is due to the salt-free samples analyzed. The acidity value of the samples ranged from 0.63 to 2.16%. Kurt and Oztek[6] determined the acidity values between 0.83 and 3.80% in Civil cheese samples, with an average of 1.83%. As for Caglar et al.,[7] they found the average acidity value in Civil cheese as 5.72%. Our values results were much lower than those we found in the literature. This indicates that the lack of standardization of the ripening conditions is due to the fact that we analyzed fresh Civil cheese samples. The differences in dry matter, fat, salt, and ash contents in Civil cheese samples results from different origin of raw materials and non-standard production of Civil cheese.

Table 1 Some chemical and physical characteristics of Civil Cheese.

Parameters	Dry matter (g/100 g cheese)	Fat (g/100 g cheese)	Fat in DM (g/100 g cheese)	NaCI (g/100 g cheese)	Salt in DM g/100 g cheese)	Ash (g/100 g cheese)	Acidity	TN (%)	WSN/TN (%)	TCA-SN/TN (%)	PTA-SN/TN (%)
x ^a	36.06	2.07	5.81	0.19	0.55	2.11	1.25	4.36	5.90	4.30	2.02
Min-Max	31.30–40.12	1.0–7.0	2.49–18.98	0.11–0.36	0.27–1.07	1.42–5.14	0.63–2.16	3.01–5.57	4.25–8.80	3.23–6.12	1.03–5.53
Sd ^b	2.23	1.71	4.72	0.097	0.28	1.00	0.48	0.64	1.22	0.75	1.05
CV ^c	6.18	82.61	81.09	51,05	50.91	47.39	38.40	14.68	20.68	17.44	51.98
n ^d	15	15	15	15	15	15	15	15	15	15	15
^aMean; ^bStandard deviation; ^cCoefficient of variation; d Number of samples analyzed; sd/mean × 100 = CV; DM: dry matter.

The total nitrogen (TN) content, expressed as Percent (%) of the cheese was measured minimum as ranged from 3.01 g/100 g cheese, maximum as to 5.57 g/100 g cheese g/100 g cheese in the analyzed samples (Table 1). Caglar et al.[7] determined TN content in fresh Civil cheese as 30.52 g/100 g cheese in average. These values are higher than the values we found in Civil cheese. The reason for this may be skim milk using in Civil cheese production. In other research that were found similar results, Prieto et al.[22] determined that the final values of total nitrogen of in Leon cow milk cheese was around 3.50% during ripeneding period for 90 days.

Proteolysis

Proteolysis is referred to by many authors[23,24] as the most important set of biochemical events taking place during cheese ripening, owing to their major impact on texture and flavor development. During proteolysis, proteins are degraded to primary products (polypeptides), and subsequently to secondary products such as small and medium-size peptides, and eventually free amino acids.[25]

The WSN/TN, TCA-SN/TN, and PTA-SN/ TN values, expressed as % TN in cheese were found between 4.25 and 8.80 g/100 g cheese, 3.23 and 6.12 g/100 g cheese, 1.03 and 5.53 g/100 g cheese in Civil cheese samples analyzed, respectively (Table 1). These results show that Civil cheeses do not undergo an excessive proteolysis. Yazici and Dervisoglu[1] also found similar results in 180 d-old Civil cheese. Prieto et al.[22] also determined that the final values of amino nitrogen and ammonia nitrogen (PTA-SN/ TN) and water insoluble nitrogen (TCA-SN/TN) ranged from 1.90 to 4.00 g/100 g cheese and 3.40 to 5.10 g/100 g cheese in Leon cow milk cheese during ripening period for 90 days. In contrast, Ayar[26] also determined WSN/TN, TCA-SN/TN and PTA-SN/ TN values in Kashar cheese (a kind of yellow cheese made of unpasteurized milk sheep's and cow's) between 2.62 and 35.43 g/100 g cheese, 1.42 and 25.12 g/100 g cheese, 0.72 and 5.42 g/100 g cheese, respectively. By comparing our results with the relevant literature values we determined that Civil cheeses do not generally undergo an excessive proteolysis; we also noted that our values were lower in degree. Prieto et al.[22] also determined that the final values of amino nitrogen and ammonia nitrogen (PTA-SN/ TN) and water insoluble nitrogen (TCA-SN/TN) ranged between 1.90 and 4.00 g/100 g cheese and 3.40 and 5.10 g/100 g cheese in Leon cow milk cheese during ripening period for 90 days. These values were in accordance with the results obtained from our study. The values for the non-protein nitrogen fraction (TCA-SN) in our study were lower than those of WSN, which is expected considering that Kuchroo and Fox[27] showed this fraction to contain mainly small peptides (2–20 residues) and FAA. Such TCA-SN fraction is thus traditionally regarded as a ‘‘ripening depth’’ index, as most peptides that are a part of the WSN fraction will precipitate in the presence of 12 % TCA. In addition, a very broad range of values for WSN/TN, TCA-SN/TN and PTA-SN/ TN values showed the differences amongin Civil cheese samples (Table 1) may be related to the a lack of. The reasons for this situation are: the different milk quality and composition of milk used in cheese production; the different differences in proteolytic activity of microbial flora in cheese samples; compositional variation of the cheeses; and the different water, salt, protein, and acidity of the samples.[26,28–30]

The results of casein fractions of Civil cheeses are presented in Table 2. SDS-PAGE profile of Civil cheeses is also included as an example of the separation of casein fractions (Fig. 1). As can be seen from Table 2, the αs-casein (αs –CN), β- casein (β –CN,) and, γ- casein and other peptides fractions of Civil cheeses changed between 39.65 and 52.2%, 46.65%; 25.35 and 39.60, 34.00 %, and 11.20 and 35.10, 19.38%, respectively. It was reported that αs –CN ratios to be 40.10% in Provolone cheese and 55.30% in Kariesh cheese,[31] 13.10–55.30% in soft goat cheese,[32] 49.40% in Kulek cheese ripened 90 days,[33] 28.10–54.90% in Kashkaval cheese,[34] and 20.60–30.10% in Civil cheeses ripened 180 days (SDS-PAGE showed that both αs-CN and β-CN were not completely hydrolyzed in all Civil cheese samples (Fig. 1). The low formation of γ-CNs and peptide was evident, indicating freshness of all the cheeses. Yazici and Dervisoglu[1] reported that αs–CN, β-CN ratios in Civil cheese at the end of 180 days determined between 21.40 and 30.10%, 18.20, and 23.40%, respectively. β –CN ratios were reported to be 17.60–26.50% in Kashkaval cheese, 11.50% in Roquefort, 17.50% in Mish,[31] 21.70–29.90% in soft goat cheese,[32] 18.3–22.4% in Kulek cheese ripened 90 days,[33] and 18.20–25.10% in Civil cheeses ripened 180 days,[1] respectively. These values show that degradation of αs – and β – CN in our cheeses was lower than that found in the Civil cheese by Yazici and Dervisoglu.[1] However, our values do not give us the degradation ratios of αs – and β –CN fractions because we do not know the initial concentration of the fractions. However, γ-casein and other peptides fractions were higher level. This situation shows that Civil cheese samples in our study do not undergo an excessive proteolysis. On the other hand, other authors reported an almost complete hydrolysis of the β-CN in Pecorino Romano cheese during 1-year ripening.[35] The geographical zone of cheese making, season of production, ripening temperature and duration and type of dairy are all factors that influence the extent of proteolysis.[36]

Table 2 Casein fractions of Civil cheeses (% of total scanning density).

	Casein fractions
Statistical parameters	αs -CN	β -CN	γ -CN and peptides
x ^a	46.65	34.00	19.38
Range	39.65–52.20	25.35–39.60	11.20–35.10
Sd ^b	3.50	3.83	6.52
CV ^c	7.50	11.26	33.64
n ^d	15	15	15
^aMean; ^bStandard deviation; ^cCoefficient of variation ; ^dNumber of samples analyzed.

Figure 1 SDS-PAGE profile of Civil cheeses.

Table 3 shows the correlation coefficients among the casein fractions and the other chemical and biochemical properties of Civil cheese. Since γ- caseins are degradation products of β-casein,[31,37–39] a highly negative correlation between β-casein and γ- caseins and other peptides was observed in Civil cheese. There was a highly significant and positive correlation between dry matter and total nitrogen, WSN/TN and TCA-SN/TN, and TCA-SN/TN and γ- caseins and other peptides and a negative correlation between dry matter and PTA-SN/TN, salt in DM and TN, TCA-SN/TN and γ- caseins and peptides, and αs –and β-caseins (P < 0.01). The correlation between the casein fractions, except αs- CN, and WSN/TN was also significant (P < 0.05). This indicates the degradation of β-casein and accumulation of γ- caseins and peptides results in increasing WSN/TN.

Table 3 Correlation coefficients between casein fractions and some chemical and biochemical properties of Civil cheese.

	Dry matter (kg/100 kg cheese)	Fat in DM (kg/100 kg cheese))	Salt in DM (kg/100 kg cheese)	Ash (kg/100 kg cheese)	Acidity (%)	TN (%)	WSN/TN (%)	TCA-SN/TN(%)	PTA-SN/TN (%)	αs –CN (%)	β –CN (%)
Fat in DM	−0.13
Salt in DM	−0.53 ^b	0.56 ^b
Ash	0.81	0.27	0.25
Acidity	−0.59 ^b	0.43	0.53 ^b	0.22
TN	0.64 ^a	−0.56 ^b	−0.84 ^a	−0.00	−0.60 ^b
WSN/TN	−0.19	0.36	0.22	0.04	0.39	−0.23
TCA-SN/TN	0.14	0.09	0.01	−0.21	−0.06	−0.11	0.67 ^a
PTA-SN/TN	−0.65 ^a	0.13	0.33	−0.15	0.61 ^b	−0.33	0.19	−0.28
αs -CN	−0.06	0.08	0.01	0.01	0.39	−0.22	−0.34	−0.48	0.32
β -CN	−0.39	0.01	0.36	0.06	0.26	−0.25	−0.61 ^b	−0.82 ^a	0.48	0.58 ^b
γ -CN and peptides	0.26	−0.05	−0.21	−0.04	−0.37	0.26	0.54 ^b	0.74 ^a	−0.45	−0.88 ^a	−0.90 ^a
^aCorrelation coefficient, significant at the P < 0.01 level; ^bCorrelation coefficient, significant at the P < 0.05 level.

CONCLUSION

In this article, Civil cheeses collected from retail markets were found to have a broad range of variations, based on chemical and biochemical properties and casein fractions. This broad variation can be attributed at the lack of standardization of milk, manufacturing steps, and ripening conditions. WSN/TN values, expressed as % TN in cheese were found between 4.25 and 8.80 g/100 g cheese. TCA-SN/TN and PTA-SN/ TN values also showed the differences among Civil cheese samples. This can be explained by either different composition of raw milk or no available standard production methods. In addition, SDS-PAGE showed that both αs-CN and β-CN were not completely hydrolyzed in all Civil cheese samples. It was found that αs–CN, β–CN and, γ-casein and other peptides fractions of Civil cheeses changed between 39.65 and 52.20%, 25.35 and 39.60%, 11.20 and 35.10%, respectively. Based on the biochemical values, it can be concluded that the degree of proteolysis is not extreme in Civil cheese. Significant correlation has been found between the casein fractions and chemical and properties of Civil cheese. The low formation of γ-CNs and peptide was evident, indicating the freshness of all the cheeses. This study will be a basic source for future studies in this area and contribute to the introduction of Civil cheese. To categorize the biochemical changes in Civil cheese, additional work should be conducted and producers should focus more attention on the standardization of the cheese.

ACKNOWLEDGMENTS

Authors thank the Atatürk University Research Center for funding this project.

Notes

4. Akyuz, N.; Coskun, H. Van Otlu peynirlerinin üretimi ve peynire katilan otlarin peynirin çeşitli özellikleri üzerine etkisi. Her Yönüyle Peynir. 1994, Trakya Üniversitesi Tekirdağ Ziraat Fakültesi Yayin No:125/9, 200–206.

5. Sengul, M.; Cakmakci, S. Erzincan Tuulum peynirinin bazi kalite kriterleri üzerine ambalaj materyali ve olgunlaşma süresinin etkisi. Doğu Anadolu Tarim Kongresi Bildiri Kitabi. 1998, 14–18 Eylül, Erzurum Atatürk Üniversitsei Ziraat Fakültesi, Erzurum-Türkiye, 1687–1698.

7. Caglar, A.; Kurt, A.; Ceylan, Z.G.; Hursit, S. The Research on Conservation in Different Shape of Civil Cheese. V National Productive Center Publication No: 621. Milk and Milk Products Symposium, Ankara, Turkey.1998; 65–78.

13. Ozdemir, C.; Ozdemir, S.; Celik, S.; Dagdemir, E. Carzof Civil peynirinin mikrobiyolojik ve kimyasal özellikleri. Süt Endüstrisinde Yeni eğilimler Sempozyumu (Editor: Prof. Dr. Necati Akbulut). 2003, 22–23 Mayis, Bornova-İzmir, Türkiye, 453–457.

14. Kurt, A.; Cakmakci S.; Caglar, A. Süt ve Mamülleri Muayene ve Analiz Metodlari Rehberi. 1993, Erzurum, Turkiye.

19. SSPS. SSPS for Windows, 11.5. 0. SSPS Inc., 2002, Chicago, IL. USA

21. TS 3001. Türk Standartlari Enstitüsü. Tulum Peyniri Standardi (TS 3001). Türk Standartlari Enstitüsü. 1989, Necatibey Cad. No: 112, Bakanliklar, Ankara.

26. Ayar, A., Çeşitli aroma maddelerinin beyaz peynirin duyusal, mikrobiyolojik ve kimyasal özelliklerine etkileri üzerinde bir araştima (doktora tezi). Yüzüncü Yil Üniversitesi Fen Bilimleir Enstitüsü. 1996, .Van, Turkey, 149.

34. Alrubai, A. Cheese: Chemistry, Physics and Microbiology PhD thesis. Major cheese groups. Faculty of Agriculture, Beograd University, Beograd, Volume 2. Chapman and Hall: New York, 1979; 263–277.