Determination of the Mineral Content in Yogurt Whey

European International Journal of Science and Technology ISSN: 2304-9693 www.eijst.org.uk DETERMINATION OF THE MINERAL CONTENT IN YOGURT WHEY Seval Sevgi KIRDAR The University of Mehmet Akif Ersoy, Burdur Vocational Higher Education, Department of Food Processing, Milk and Dairy Products Programme, 15030 İstiklal Campus, Burdur/Turkey Email: skirdar@mehmetakif.edu.tr GülayTOPRAK , The University of Mehmet Akif Ersoy, Faculty of Education, Department of Science Education, 15030 İstiklal Campus, Burdur/Turkey Email: g-lay07@hotmail.com Emel GÜZEL The University of Mehmet Akif Ersoy, Faculty of Education, Department of Science Education, 15030 İstiklal Campus, Burdur/Turkey Email: Emelim_07@hotmail.com * Corresponding Author: Seval Sevgi KIRDAR The University of Mehmet Akif Ersoy, Burdur Vocational Higher Education, . Department of Food Processing, Milk and Dairy Products Programme, 15030 İstiklal Campus, Burdur/Turkey Phone: +90 2482132275 Email: skirdar@mehmetakif.edu.tr This study was supported by the TUBITAK 2209-A National Undergraduate Student Research Projects Support Programme. 26 European International Journal of Science and Technology Vol. 6 No. 3 April 2017 Abstract Strained yogurt is an indispensable flavor of traditional Turkish and Anatolian food culture, and one of its oldest and most important elements. The basic principle of strained yogurt production is to reduce the water content and increase product longevity by removing the serum. This study aims to determine the mineral content in yogurt whey, one of the main pollutants in the dairy industry. Calcium, potassium, phosphorus, sodium and magnesium quantities were determined by simultaneous inductively coupled plasma optical emission spectrometry (ICP-OES). In these samples, Ca was 934±130mg/L, Mg was 969±257mg/L, K was 1257±159, Na was 940±104 mg/L, and P was157±23mg/L. Therefore, the pollution caused by the organic load of yogurt whey when it is discharged into the environment can be prevented, and yogurt whey can be used as auxiliary matter in production of dairy products and other nutrients by recycling its nutrients using technological methods, as is done with cheese whey. Key Words: yoghurt, strained yoghurt, yoghurt whey, mineral content 1. INTRODUCTION Yogurt has a limited shelf life that depends on the production and storage conditions; after this period, it becomes sour, deteriorates, and cannot be consumed. It is also important that the quality of the yogurt is well preserved. To make the yogurt resistant to deterioration, methods such as salting, cooking, removing water, and increasing the dry matter, heating and preventing air contact during storage have been used. These methods used for preservation have produced, various traditional yogurts “Winter Yogurt”, “Labneh”, “Peskuten”, “Kurut”, “Keş” “Kishk”, “Labnehanbaris” and “Chanklich” that have emerged in Turkey and the Middle East (GönçandOktar 1973, Rasic and Kurmann, 1978, Tamimeand Robinson 1988, Al-Kanhal 1993). One of the indispensable flavors of traditional Turkish and Anatolian nutrition cultures, strained yogurt is one of the oldest and most important items in Turkish culture (Yaygın 1999). The main principle in the production of strained yogurt is to reduce the water content by removing the serum phase of the strained yogurt to increase the product resistance to deterioration. (Kırdar and Gün, 2002, Özer 2006). Some soluble vitamins (thiamin, riboflavin) and minerals (calcium, phosphorus, potassium) are lost at the 50%–70% level during the production of strained yogurt (Seçkin, 1996). Despite this disadvantage, the higher amount of fat and protein contained in the strained yogurt has a positive effect on its nutritional value; this has been supported by many studies. Some studies have shown that the strained yogurt has higher nutritional value and 100 grams provides 83 to 161 kcal of energy, depending on the fat level (Eralp, 1953; Özer, 2006). The number of studies on strained yogurt is also increasing. Some studies (Eralp 1953, Yaygın 1970, Toral et al., 1985, Atamer et al., 1988, Atamer et al., 1993, Yaygın 1993, Çağlar et al., 1997, Seçkin , 1996, Ayar, 2011, Seçkin and Baladura, 2012, ,Seçkin and Nergiz 1995, UysalveGönç, 1998, Kırdar and Gün 2000, Kırdar and Gün 2002, Sarı 2005, Şanal 2007, Telli et al., 2009, Sömer and Kılıç, 2012, Kalender 2014) have focused on the physical and microbiological properties, whereas others evaluated the production technology (Güldaş and Atamer, 1995, Kırdar and Gün 2000) Still other relevant studies determine the properties of residual serum from strained yogurt produced under laboratory conditions and losses in nutritional elements (Pusat 1984, Atamer et al., 1990, Seçkin 1996, Kırdar and Gün.2007), and also the pollution parameters (Toprak et al., 2015). There is only one study found in the industrial context on the use of yogurt serum (Cankurt et al., 2012). The results of the 27 European International Journal of Science and Technology ISSN: 2304-9693 www.eijst.org.uk research on the serum released after strained yogurt production under laboratory conditions and at the dairy plant level are shown in Table 1. Table 1. Research results on yogurt serum composition values Kırdar and Components (%) Pusat(1984) Şanal(2007) Gün (2007)* pH Titratable Acidity - - 3.56–3.78 0.74–1.14 Kalender (2014) Toprak et al. (2015) 4.35–4.40 0.52–0.54 - 6.33 4.78–6.15 Total Dry Matter 0.16 0.05 0.01–0.08 Fat 0.43 0.25 0.17–0.44 0.12–0.15 Protein 4.7 5.25 4.17–5.38 Lactose 0.7 0.78 0.32–1.03 Ash 38,223 Chemical Oxygen Demand (mg/L) * Composition values of the serum released after strained yogurt production at the dairy plant The average losses in nutritional value in set-type yoghurt samples from strained yogurt production produced under laboratory conditions were 51.80% of thiamine, 60.49% of riboflavin, 7.28% of protein, 0.77% of fat, 71.14% of lactose, 70.22% of sodium, 68.16% of potassium, 65.64% of calcium, and 50.21% of phosphorus. The maximum loss in amino acids was 11.38% in histidine, and the loss in amino acids was 2.24% in tyrosine. At the end of strained yogurt production, 49.69% of the essential amino acids in the serum constitute threonine, valine, methionine, isoleucine, leucine, phenylalanine, histidine, lycine, and arginine. Among the amino acids, the most abundant amino acid was histidine (11.38%). When the losses in all nutritional items that were drained from the yogurt at the end of the filtration were evaluated, it was determined that the highest loss occurred in lactose, at 71.14%, and the lowest loss was in fat, at 0.77%. The average mineral losses in sodium, potassium, calcium, and the riboflavin vitamin content were above 60%, whereas the losses in thiamine and phosphorus were approximately 50% (Seçkin, 1996). In production of strained yogurt, retention in the cloth bag and losses in serum values were investigated for the dry matter and its components; the dry matter values of strained yogurt samples having dry matter values of 12.75%, 14.06% and 15.50%, were found to be 24.67%, 23.11%, and 22.58%, respectively. The increase in yogurt dry matter ratios reduced the rate of dry matter retention in the bowl. However, the amount of substance passing to the serum had increased. The retention rates of nitrogenous and mineral salts increased with the decrease in the amount of serum separated. The retention rates of nitrogenous substances in the cloth bag were 81.87% to 87.86%, and of mineral salts 43.13% to 48.51%; 99% of the total fat was retained in the bag (Atamer et al., 1990). Based on the conventional method, the serums obtained in yogurt production are rich in protein, lactose, vitamins, and minerals. At the end of the study, it was determined that serums had, on average, 4.7% lactose, 0.16% fat, 0.43% protein, and 0.7% ash (Pusat, 1984). Toprak et al. (2015) studied the yogurt serum, which is one of the main pollutants in the dairy industry. They determined the waste composition of serum resulting from its organic components, concentration, and pollution parameters. Those researches found the Chemical Oxygen Demand 28 European International Journal of Science and Technology Vol. 6 No. 3 April 2017 (COD)(mg/L) value in yogurt serum samples obtained from strained yogurt producing dairy plants in Burdur to be 38,223 mg/L. In this study, it was aimed to determine the content of minerals that pass to the serum during the strained yogurt production that uses the traditional method in the dairy plants. It may be possible to produce alternative products by changing the direction of the studies to be done in this respect. 2. MATERIALS AND METHOD In Burdur province, yogurt serum samples were taken at intervals of 1 month from three dairy plants and stored in a cold chain (+ 4 °C) and brought to the laboratory. 2.1. Physical and Chemical Analysis The pH was measured by a Mettler-Toledo AG 8603 pH meter (Switzerland). Protein was determined based on the total nitrogen, using the Kjeldahl method with subsequent multiplication by a factor of 6.38. Fat was determined using the Gerber method. Lactose was determined by the Flow Cytometry Method using Bentley S150 (USA) (IDF, 2013). Total solids content was determined by gravimetric method using the ovendrying in a laboratory oven at 105 ◦C for 24 h (AOAC, 1990). 2.2. Minerals Analysis Ash content was quantitated by dryashing the samples in a muffle furnace at 550 ◦C for 24 h. Beforesampleswereplaced in themufflefurnace, theyweredried in an oven at 105 ◦C. (IDF, 1992).Calcium, potassium, phosphorus, sodium and magnesium quantities were determined by simultaneous inductively coupled plasma optical emission spectrometry (ICP-OES) (Perkin Elmer Optima 8000, ABD). Two g of cheese on ash + 8 mL of 65 % HNO3 added to 2 mL of 30 % H 2 O2 were burned in the microwave Milestone at 200 °C for 15 minutes. This process was complemented with 50 ml of ultrapure water and the sample was removed from the container. For the mineral analysis, all the reagents were of an analytical grade. All the reagents and samples were prepared in double distilled water. The determinations were carried out at 315.8, 214.9, 279.0, 214.9, 589.7, 766.4, nm for Ca, P, Mg, Na, Mn and K, respectively. All the analyses were performed in duplicate. 2.3. Statistical analysis All of the statistical calculations were performed using SPSS Statistical Software and the obtained values were presented as the mean ±SE. (Duzgunes and Akman, 1991; Draper and Smith, 1998). 3. DISCUSSION The mean values of the chemical components of yogurt serum samples are shown in Table 2; the mean values of the mineral contents are shown in Table 3. 29 European International Journal of Science and Technology Table 2 Some qualities of yogurt serum Qualities Fat (%) Protein (%) Lactose (%) Dry Matter (%) Ash (%) pH Acidity (SH) ISSN: 2304-9693 www.eijst.org.uk Mean Values 0.368 ± 0.04 0.726 ± 0.01 3.670 ± 0.18 5.568 ± 0.28 0.383 ± 0.066 4.213 ± 0.09 27.95 ± 1.42 Table 3 Mineral content of yogurt serum (mg / L) Minerals Mean Values 934 ± 130 Ca 969 ± 257 Mg 1257 ± 159 K 940 ± 104 Na 157 ± 23 P In the yogurt serum, the concentration of Ca was 934 ± 130 mg/L; Mg, 969 ± 257 mg/L; K, 1257 ± 159 mg/L; Na, 940 ± 104 mg/L; and P, 157 ± 23 mg/L. Harper et al.,(1979), found 4100 mg/L COD, 260 mg/L fat, 446 mg/L protein, 1300 mg/L carbohydrate, 52 mg/L phosphorus, 230 mg/L sodium, 168 mg/L calcium, 28 mg/L magnesium, and a pH of 6.6 in the wastewater of a dairy plant that produces 450 tons of drinking milk, cheese, ice cream, and yogurt, which can reach 180 to 360 tons per day in wastewater. During the production of strained yogurt, the protein and fat components results in a 2.5-fold increase in the dry matter content of the yogurt. Because lactose and most of the minerals passed to the serum, approximately 9% of the serum dry matter comprises protein and fat, and the remaining 91% is composed of mineral substances and lactose. In other words, almost all the fat and protein are retained in the bag used to strain the yogurt. Similarly, some researchers have found that the lowest level of yogurt components passing to the serum were as fat and protein (Atamer et al., 1990, Nergiz and Seckin, 1998). The values obtained in that study are in harmony with those found by other researchers. Tamime et al. (1991) found the protein levels in the serum of Labneh produced by conventional methods using cow, sheep, and goat milk as 0.3%, 0.9% and 0.6%, respectively. The protein value obtained in the present study was 0.72%. Atamer et al. (1990) studied the retention of dry matter in the bag and losses in the serum in strained yogurt production; they found that nitrogenous substances and mineral salts passing to the serum were at maximum rates compared with other samples with the highest levels of serum separation. Those researchers found the lowest level of fat and the highest amount of minerals passed to the serum; these results agree with those of Atamer et al. (1990). In a study on changes in the chemical composition of the yogurt during the production of strained yogurt, it was found that the highest loss was in lactose; this was followed by loss of Na, K, Ca, and P elements (NergizandSeçkin, 1998). In the present study, Na was determined as 56.1 and 38.9 mg/100 g; K, 143 and 96.4 mg/100 g; Ca, 163 and 107 mg/100 g; and P, 115 and 77.8 mg/100 g in yogurt produced from whole fat cow milk and its serum, respectively. 30 European International Journal of Science and Technology Vol. 6 No. 3 April 2017 In the production of strained yogurt, 65% of normal yogurt is separated as whey. It has been reported the loss of sodium, potassium, calcium, and phosphorus was 70.2%, 68.2%, 65.6%, and 50.2%, respectively, which resulted in a significant decrease in the overall nutrient content and a protein loss of about 7.3% (Nergiz and Seçkin, 1998). Researchers have stated that mineral substances pass to the serum at a rate higher than 50%, and that this was the highest rate of passing to the serum (Atamer et al., 1990). In other words, the most abundant macro element retained the was phosphorus. During the straining, the highest loss was observed in K, followed by Na and Ca. These results are similar to the observations of Nergiz and Seçkin (1998) and De La Fuente et al. (1997). More than 90% of the potassium and sodium elements are in free form in milk and dairy products. And they are therefore easily removed in the serum. The high amounts of sodium, potassium and calcium detected in serum during the study also confirm that point. It has been reported that, with the increase in acidity, the calcium originally bound to casein in milk dissociated, and that 96.7% to 99.1% of the calcium passed to the serum, whereas only 63.2% to 77.5% of phosphorus passed to the serum. The loss in magnesium during straining, like that of phosphorus, is low compared with calcium. The elemental magnesium also binds to the nonphosphorous parts of caseins, such as to calcium. However, because magnesium is often combined with various inorganic phosphates, the rate of passing to the serum may be lower as compared with calcium (Van Hooydonk et al., 1986). 4. CONCLUSION The ratio of the nutrient components in strained yogurt that is obtained by straining the set-type yogurt through the cloth bags is increased by 2 to 3 times. However, there are significant changes in yogurt composition during straining, and serum-soluble proteins such as lactose, lactose, and most mineral substances pass into the serum. When yogurt serum is not evaluated and/or treated in any way and sent to a receiving environment, it causes a high degree of pollution and economic loss in that environment. Yogurt serum can be used as a supplement in dairy product production and other foodstuffs as a positive way to take advantage of its nutritional content. Thus, a positive use for the product obtained during production can be realized, and the economic losses can be reduced. Strained yogurt production is carried out by conventional methods in medium-sized enterprises. The obtained serum is valuable in terms of mineral matter; therefore, it should be evaluated in terms of nutritional and economical losses by evaluating it as whey and not simply discarding it. In addition, other nutritional elements that enter industrial waste during yogurt straining should be determined, and the ways of benefiting from them should be investigated. It is possible to suggest alternative products by changing the direction of the studies to be done on this subject. Studies on the use and evaluation of industrially produced yogurt serum are needed. Acknowledgements The authors also thank the TUBITAK. This study was supported by the TUBITAK 2209-A National Undergraduate Student Research Projects Support Programme. This work was accepted at the International Conference on Agriculture, Forest, Food Sciences and Technologies (ICAFOF 2017 Cappadocia / Turkey). (15-17 May 2017 Kapadokya-Nevşehir Turkey, oral presentation) 31 European International Journal of Science and Technology ISSN: 2304-9693 www.eijst.org.uk REFERENCES Al-Kanhal, H.A. (1993) Manufacturing Methods and Quality of Labneh. Egyptian Journal of Dairy Science, 21 (1): 123-131. AOAC, (1990). Official Methods of Analysis.15th ed. Assocation of Official Analytical Chemists, Washington, DC. USA. Atamer, M., Sezgin, E., Yetişmeyen, A. (1988)Investigation of Some Qualities of Torba Yogurts.Food, 13 (4): 283-288 (In Turkish). Atamer, M., Yetişmeyen, A., Ergül, E.(1990)A study on the retention of dry matter and its components in the torba yogurt and the losses in serum. Food, 15(1) 35-39 (In Turkish). Atamer, M., Yıldırım, M., Dağlıoğlu, O. (1993)Effect of Acidity Development, Lipolysis, Oxidation and Proteolysis on the Taste-Aroma Exchange of Set and Condensed Yoghurt during Storage.Turkish Journal of Veterinary and Animal Sciences , 17 (1): 49-53. Ayar A. (2011)Variations in the amount of mineral substances during yoghurt production by traditional methods.[Online] Available: http://www.akademikgida.com /kategoridetay.asp? id=376 (Erişimtarihi 22. 04. 2013). Cankurt H, Sağdıç O, Yetim H. (2012)Evaluation of yoghurt whey in the production of turnip juice. 3th. Traditional Food Sempozym, 10-12 May, Konya, 643 (In Turkish). Çağlar A, Ceylan ZG, Kökosmanlı M. (1997)A study on the chemical and microbiological properties of Strained Yogurt.Food 22 (3): 209-215.(In Turkish). De La Fuente, M. A., Belen, C. and Juarez, M. (1997). Determination of major minerals in dairy products digested in closed vessels using microwave heating. Journal Dairy Science, 80: 806-811. Draper N.R., Smith H. (1998). Applied Regression Analysis, (3rd ed), Newyork;Wiley. Düzgüneş O., Akman O. (1991).Variations Resources. Ankara University Faculty of Agriculture Press,, No: 1200, Ankara, Turkey, p146 (in Turkish). Eralp, M. (1953).StrainedYogurd, Printing press Nur. Ankara.(In Turkish). Gönç S, Oktar E (1973):Research on theTechnologicalandChemicalComposition of WinterYoghurt in the Hatay Region, Ege UniversityJournal of Agriculture, 10 (1) 97-110, İzmir.(In Turkish). Güldaş M, Atamer M. (1995). Effect of Yogurd pasteurization norm and storage temperature on quality in long-time yoghurt production.Food 20 (5): 313-319.(In Turkish). 32 European International Journal of Science and Technology Vol. 6 No. 3 April 2017 Harper W.J., Delaney R.A.M., Igbeka I.A., Parkin M.E., Schiffermille, W.E., Ross T.E., Williams R.A.(1979). Strategies for Water ana Waste Reduction in Dairy Food Plants. EPA 600/2-79. IDF (International Dairy Federetaion) (1992).Trace Elements in Milk and Milk Products. Bulletin of the International Dairy Federation, No:278. IDF, (2013) (TS ISO 9622:2015). Milk and liquid milk products – Guidelines for the application of mid-infrared spectrometry)No: 141. Kalender, M. (2014).Effect of addition inulin at different levels on the production of fat-reduced condensed yoghurtÇukurova University Institute of Natural and Applied Sciences Department of Food Engineering, MSc Thesisp 90.(In Turkish). Kırdar, S., Gün, İ. (2000).A Research on Quality Criteria of Strained Yogurts Produced in Burdur. S.D.Ü. Journal of Institute of Natural and Applied Sciences, 4(1),103-110.(In Turkish). Kırdar, S., Gün, İ.(2002).Physical, chemical and microbiological properties of strained yoghurt consumed in Burdur.Food, 27(1), 59-64.(In Turkish). Kırdar,S.S., Gün, İ. (2007). Some Properties of Serum obtained in Yoghurt Production. S.D.Ü. Journal of Institute of Natural and Applied Sciences, 11(1): 26-28.(In Turkish). Nergiz C, Seçkin AK.(1998). The losses of nutrients during the production of strained (Torba) yoghurt. Food Chemistry, 61 (1/2): 13-16.(In Turkish). Özer, B. H. ( 2006). Yogurt Science and Technology.SidasMedya Ltd. Şti. İzmir, 490s.(In Turkish) Pusat, C. (1984). A Study on the Physical and Chemical Properties of Yoghurt Whey, Graduation thesis, E.Ü. Zir.Fak.TarımÜrünleriTek. Böl.SütBilveTek.Anabilim Dalı, İzmir. (In Turkish) Rasic JL, Kurman JA (1978): Yoghurt. Technical Dairy Publishing House, Copenhagen, Denmark.pp.1-466. Sarı H. (2005).A research on losses of some nutrient components and mineral matters in süzme yoghurt pruduction processSelçukUniversity Institute of Natural and Applied Sciences Department of Food Engineering, MSc Thesis, Konya, 64 s.(In Turkish). Seçkin, A.K.(1996). Research on the losses of nutrients of yoghurt during the production of straned yoghurt.Celal Bayar University Institute of Natural and Applied Sciences Department of Food Engineering, MSc Thesis,Manisa, p60.(In Turkish). Seçkin, A. K., BaladuraE. (2012). Effect of using some dietary fibers on color, texture and sensory properties of strained yogurt . Gıda, 37(2):63-69. 33 European International Journal of Science and Technology ISSN: 2304-9693 www.eijst.org.uk Sömer VF, BaşyiğitKılıç G. (2012). Determination of microbiological, physicochemical properties and biogenic amine contents in durable yoghurts. 3. Traditional Foods Sempozym 10-12 May, Konya, p480.(In Turkish). Şanal H. (2007).Determination of element content in strained yogurts produced from different types of milk. Mustafa Kemal University Institute of Natural and Applied Sciences Department of Food Engineering, MSc Thesis, p66.(In Turkish). Tamime, A. (1978). The Production of Yoghurt and Concentrated Yoghurt FromHydrolysed Milk. Cultured Dairy Products Journal, 13 (3): 16-21. Tamime A. Y., Robinson, R. K. (1988). Fermented Milks and Their Future Trends. Part II. Technological Aspects. Journal of Dairy Research, 55 (2): 281-307. Tamime, A.Y., Kalab, M., Davies, G., Mahdi, H.A. (1991). Microstructure and firmness of labneh (high solid yoghurt) made from cow's, goat's and sheep's milk by a traditional method or by ultrafiltration. Food Structure, 10, 37-44. Telli, N., Tekinşen, K.K., Nizamlıoğlu, M., Bayar,N., Köseoğlu, İ.E. (2009). Some Microbiological and Chemical Properties of Strained Yoghurt Produced in Konya. 3th.National Veterinary Food Hygiene Congressi, 14-16 May, Bursa, p4.(In Turkish). Toprak, G., Kırdar S.S., Güzel, E. (2015). Determination of Pollution Parameters in Terms of Environmental Pollution of Yoghurt Whey. 27. NationalChemistryCongress, 801s, 23-28 Agus.2015 / Çanakkale.(In Turkish). Töral, A. R., Tekbıyık, L., İldeş, Z.(1985).Chemical and Technological Investigations on Strained Yogurts in Denizli Province.Journal of PendikVeterinaryMicrobiologyInstitute, 17 (1-2): 23-34.(In Turkish). Uysal H, Gönç S (1998)Studies on the Comparison of Milk Concentrated with Vacuumand Ultrafiltration (UF) to Strained Yogurt and Produced by Classical Method, V. Milk and Milk Products Symposium, Tekirdağ. MPM Yayınları, No:621, 220-229, Tekirdağ (InTurkish). Van Hooydonk, A. C. M.,Hagedoorn, H. G., and Boerrıgter, I. J. (1986). pH-inducedphysico-chemical changes of caseinmicelles in milk and their effect on renneting. 1. Effect of acidification on physicochemicalproperties. NethelandsMilkandDairyJournal, 40: 281-296. Yaygın H (1970) Tulum Yogurt, E.U, Agr. Fac. Journal; 7(1) 25-34.(In Turkish) Yaygın, H. (1993)Incentives for Milk Industry Investments 5th.Turkish Dairy Congress p218, Ankara (In Turkish) Yaygın H (1999)Yogurt technology. Akdeniz University Faculty of Agriculture Food Engineering Department Press No: 75 Antalya.(In Turkish) 34