Physicochemical and Rheological Properties of Commercial Kefir Drinks

Yıl 2020, Cilt: 18 Sayı: 4, 375 - 381, 31.12.2020

Oğuz Gürsoy Kübra Kocatürk Hande Özge Güler Dal Hasne Nazlı Yakalı Yusuf Yılmaz

https://doi.org/10.24323/akademik-gida.850881

Cited By: 5

Öz

Kefir is one of the most preferred fermented beverages, and its production constitutes a significant portion of the dairy industry. In this study, the physicochemical and rheological properties of commercial plain kefir drinks were compared. Kefir drinks of dominant brands in the Turkish kefir market (n=6) were obtained from national markets, and samples with different production dates for each brand were used as replications. The ranges for the dry matter, protein and fat contents (%) of kefir drinks were 9.49-11.97, 2.30-3.44 and 2.50-3.00%, respectively. Moreover, the pH values of samples were in a range between 3.86 and 4.06 while their total titratable acidity (%, lactic acid) values ranged from 0.71 to 0.93%. Significant differences were found among the physicochemical properties of commercial kefir drinks (p<0.05). Rheological analyses were conducted at three different temperatures (4.0, 10.0 and 25.0±0.3°C), and the power law model was used to interpret the rheological characteristics of kefir drinks, which resulted in high coefficient of determination (R2) values. Besides, the apparent viscosity values of samples (at a shear rate of 111.6 s-1) were inversely related to temperature and varied between 0.48 and 1.76 mPa.s (p<0.05). Activation energy values of samples were between 21.51 and 36.18 kJ/mol. Significant differences in physicochemical and rheological properties were found among the commercial kefir samples of different brands, indicating the compositional variations of raw materials and kefir cultures used in their production.

Anahtar Kelimeler

Kefir, Fermented milk, Consistency, Rheological behavior, Viscosity

Teşekkür

The authors thank to Cahit Burak KÜCÜKİGCİ for his technical support on the total nitrogen analyses of the present study.

Ticari Kefirlerin Fizikokimyasal ve Reolojik Özellikleri

Öz

Kefir, fermente içecekler içerisinde en çok tercih edilenlerden biri olup üretimi süt endüstrisinde önemli bir yer tutmaktadır. Bu çalışmada, ticari sade kefirlerin fizikokimyasal ve reolojik özellikleri karşılaştırılmıştır. Türkiye ticari kefir pazarında etkili olan markalara ait kefirler (n=6) Türkiye'deki ulusal marketlerden temin edilmiş ve her bir marka için farklı son kullanma tarihlerine sahip örnekler tekerrür olarak kullanılmıştır. Ticari kefir örneklerinin kuru madde, protein ve yağ içeriklerine ait aralıklar, sırasıyla %9.49-11.97, %2.30-3.44 ve %2.50-3.00 olarak bulunmuştur. Örneklerin pH değerleri 3.86-4.06 aralığında, toplam titre edilebilir asitlik (%, laktik asit) değerleri %0.71-0.93 arasında saptanmıştır. Farklı markalara ait ticari kefir örneklerinin fizikokimyasal özelliklerinde önemli değişiklikler saptanmıştır (p<0.05). Farklı sıcaklıklarda (4.0, 10.0 ve 25.0±0.3°C) yapılan reolojik analizlerde, kefir içeceklerinin reolojik özelliklerinin yorumlanmasında yüksek R2 değerlerinin elde edildiği Üssel Kural (Power Law) modeli kullanılmıştır. Örneklerin (111.6 s-1 kayma oranındaki) görünür viskozite değerlerinin sıcaklıkla ters orantılı olduğu ve 0.48 ile 1.76 mPa.s arasında değiştiği saptanmıştır (p<0.05). Örneklerin aktivasyon enerjisi değerleri 21.51 ve 36.18 kJ/mol arasında değişmiştir. Farklı markalara ait ticari kefir örneklerinin fizikokimyasal ve reolojik özellikleri arasında önemli farklılıklar belirlenmiş olup, bu farklılığın da üretimde kullanılan farklı hammadde ile kefir kültürlerinden kaynaklanabileceğini göstermiştir.

Anahtar Kelimeler

Kefir, Fermente süt, Kıvam, Reolojik özellik, Viskozite

Kaynakça

• [1] Farnworth, E.R. (1999). Kefir: From folklore to regulatory approval. Journal of Nutraceuticals, Functional and Medical Foods, 1(4), 57-68.
• [2] Gürsoy, O., Kınık, Ö. (2006). Türkiye'de fonksiyonel süt ürünleri pazarı: Gerçekler, beklentiler, öneriler. Türkiye 9. Gıda Kongresi, 24-26 Mayıs, 2006, 123-124p.
• [3] Karagözlü, N., Karagözlü, C., Ergönül, B. (2007). Survival characteristics of E. coli O157: H7, S. typhimurium and S. aureus during kefir fermentation. Czech Journal of Food Sciences, 25(4), 202.
• [4] Güzel-Seydim, Z.B., Kök-Tas, T., Greene, A.K., Seydim, A.C. (2011). Functional properties of kefir. Critical Reviews in Food Science and Nutrition, 51, 261-268.
• [5] Eryılmaz, H. (2018). Farklı Kefir Kültürleri ve Sütlerle Elde Edilen Kefirlerin Mineral Içeriklerinin ve Antioksidan Özelliklerinin Incelenmesi. Yüksek Lisans Tezi. Munzur Üniversitesi, Fen Bilimleri Enstitüsü, Gıda Mühendisliği Anabilim Dalı, Tunceli.
• [6] Kosikowski, F. (1982). Cheese and Fermented Milk Food. F.V. Kosikowski and Associates Brooktondale, New York.
• [7] Marshall, V.M. (1993). Starter cultures for milk fermentation and their characteristics. International Journal of Dairy Technology, 46(2), 49-56.
• [8] Kaur, I.P., Chopra, K., Saini, A. (2002). Probiotics: potential pharmaceutical applications. European Journal of Pharmaceutical Sciences, 15(1), 1-9.
• [9] Vélez-Ruiz, J.F., Barbosa-Cánovas, G.V. (1998). Rheological properties of concentrated milk as a function of concentration, temperature and storage time. Journal of Food Engineering, 35(2), 177-190.
• [10] Farnworth, E.R. (2008). Handbook of fermented functional foods. CRC press, 602.
• [11] Kök-Taş, T., Seydim, A.C., Özer, B., Güzel-Seydim, Z.B. (2013). Effects of different fermentation parameters on quality characteristics of kefir. Journal of Dairy Science, 96(2), 780-789.
• [12] Ünal, F.N., Kalyas, A., Gürbüz-Kaçan, Z., Şengül, M., Ürkek, B. (2020). Ticari kefirlerin bazı kalite parametrelerinin belirlenmesi. Gıda, 45(3), 555-563.
• [13] İçier, F., Bozkurt, H., Gürbüz, S. (2008). Characterisation of rheological behaviour of kefir and smooth yoghurt. Akademik Gıda, 6(5), 6-11.
• [14] Oysun, G. (2001). Analyses Methods in Milk and Dairy Products, Ege University Agricultural Faculty Press, Izmir.
• [15] Steffe, J.F. (1996). Rheological Methods in Food Process Engineering, Freeman press. East Lansing, USA.
• [16] Marcotte, M., Hoshahili, A.R.T., Ramaswamy, H.S. (2001). Rheological properties of selected hydrocolloids as a function of concentration and temperature. Food Research International, 34(8), 695-703.
• [17] Barukčić, I., Gracin, L., Režek Jambrak, A., Božanić, R. (2017). Comparison of chemical, rheological and sensory properties of kefir produced by kefir grains and commercial kefir starter. Mljekarstvo, 67(3), 169-176.
• [18] Irigoyen, A., Arana, I., Castiella, M., Torre, P., Ibanez, F.C. (2005). Microbiological, physicochemical, and sensory characteristics of kefir during storage. Food Chemistry, 90(4), 613-620.
• [19] Doğan, M. (2011). Rheological behaviour and physicochemical properties of kefir with honey. Journal für Verbraucherschutz und Lebensmittelsicherheit, 6(3), 327-332.
• [20] Atalar, I., Dervisoglu, M. (2015). Optimization of spray drying process parameters for kefir powder using response surface methodology. LWT-Food Science and Technology, 60(2), 751-757.
• [21] Goncu, B., Celikel, A., Guler-Akin, M.B., Serdar Akin, M. (2017). Some properties of kefir enriched with apple and lemon fiber. Mljekarstvo, 67(3), 208-216.
• [22] Shaker, R.R., Jumah, R.Y., Abu-Jdayil, B. (2000). Rheological properties of plain yogurt during coagulation process: impact of fat content and preheat treatment of milk. Journal of Food Engineering, 44(3), 175-180.
• [23] Janhøj, T., Frøst, M.B., Ipsen, R. (2008). Sensory and rheological characterization of acidified milk drinks. Food Hydrocolloids, 22(5), 798-806.
• [24] Gursoy, O., Yilmaz, Y., Gokce, O., Ertan, K., (2016). Effect of ultrasound power on physicochemical and rheological properties of yoghurt drink produced with thermosonicated milk. Emirates Journal of Food and Agriculture, 28(4), 235-241.
• [25] Ertekin, B., Guzel-Seydim, Z.B. (2010). Effect of fat replacers on kefir quality. Journal of the Science of Food and Agriculture, 90, 543–548.
• [26] Cais-Sokolińska, D., Wójtowski, J., Pikul, J. (2016). Rheological, texture and sensory properties of kefir from mare’s milk and its mixtures with goat and sheep milk. Mljekarstvo, 66(4), 272-281.
• [27] Garrote, G.L., Abraham, A.G., De Antoni, G.L. (2001). Chemical and microbiological characterization of kefir grains. Journal of Dairy Research, 68, 639-652.
• [28] Tunick, M. H. (2010). Activation energy measurements in rheological analysis of cheese. International Dairy Journal, 20(10), 680-685.
• [29] Deswal, A., Deora, N.S., Mishra, H.N. (2014). Effect of concentration and temperature on the rheological properties of oat milk. Food and Bioprocess Technology, 7(8), 2451-2459.
• [30] Abu‐Jdayil, B., Shaker, R.R., Jumah, R.Y. (2000). Rheological behavior of concentrated yogurt (Labneh). International Journal of Food Properties, 3(2), 207-216.