AN IMPROVED DIFFERENTIAL SCANNING CALORIMETRY STUDY FOR THERMAL PROPERTIES OF PEKMEZ SAMPLES ADULTERATED WITH SUGAR SYRUP

Abstract

This research was carried out to determine the pH, titratable acidity, ash, specific gravity, color (L*, a*, b*), water activity, electrical conductivity, glass transition temperature (Tg) and melting characteristics of grape and mulberry pekmez samples adulterated with different levels (10%, 30%, 50%) of high fructose corn syrup (HFCS). Ash, titratable acidity and electrical conductivity values have decreased significantly (P<0.05) with the level of adulteration and determined that these properties can be used as a criterion in the determination of adulteration. Two glass transition temperatures occurring between -25.64℃ to -32.58℃ (Tg1) and 23.29℃ to 31.22℃ (Tg2) were detected in all pekmez samples. The single glass transition temperature was determined in the pekmez samples diluted with water, and both the glass transition temperatures and the onset, peak, end temperatures and enthalpy values of the melting peaks increased significantly with the increase in the amount of adulteration (P<0.05).

Keywords

• Pekmez
• differential scanning calorimetry
• glass transition temperature
• adulteration
• sugar syrup

ŞEKER ŞURUBUYLA TAĞŞİŞ EDİLEN PEKMEZ ÖRNEKLERİNİN TERMAL ÖZELLİKLERİ İÇİN GELİŞTİRİLMİŞ BİR DIFFERENTIAL SCANNING CALORIMETRY ÇALIŞMA

Abstract

Bu araştırma, farklı seviyelerde (%10, %30, %50) yüksek fruktozlu mısır şurubu (HFCS) ile tağşiş edilmiş üzüm ve dut pekmezlerinin pH, titre edilebilir asitlik, kül, özgül ağırlık, renk (L*, a*, b*), su aktivitesi, elektriksel iletkenlik, camsı değişim sıcaklığı (Tg) ve erime özelliklerinin belirlenmesi amacıyla yürütülmüştür. Tağşiş seviyesi arttıkça kül, titre edilebilir asitlik ve elektriksel iletkenlik değerlerinin önemli derecede (P<0.05) azaldığı ve bu özelliklerin tağşişin belirlenmesinde kriter olarak kullanılabileceği belirlenmiştir. Pekmez örneklerinin tamamında -25.64°C ile -32,58°C (Tg1) ve 23.29°C ile 31.22°C (Tg2) arasında oluşan iki camsı geçiş sıcaklığı tespit edilmiştir. Su ile seyreltilen pekmez örneklerinde tek camsı geçiş sıcaklığı belirlenmiş olup, tağşiş miktarının artmasıyla hem camsı değişim sıcaklıkları hem de erime piklerinin başlangıç, pik, bitiş sıcaklıkları ve entalpi değerleri önemli derecede artış göstermiştir (P<0.05).

Keywords

• Pekmez
• differential scanning calorimetry
• camsı değişim sıcaklığı
• tağşiş
• şeker şurubu

References

1. Ahmed, J., Ramaswamy, H.S., Khan, A.R. (2005). Effect of water activity on glass transitions of date pastes. Journal of Food Engineering, 66: 253–258. https://doi.org/10.1016/j.jfoodeng.2004.03.015
2. Al-Farsi, K.A., Al-Habsi, N.A., Rahman, M.S. (2018). State diagram of crystallized date-syrup: Freezing curve, glass transition, crystals-melting and maximal-freeze-concentration condition. Thermochimica Acta, 666: 166–173. https://doi.org/10.1016/j.tca.2018.06.003
3. Anonymous (2011). TS 12001 Dut Pekmezi Standardı, TSE, Ankara.
4. Anonymous (2017). Türk Gıda Kodeksi Üzüm Pekmezi Tebliği (No:2017/8). Tarım ve Orman Bakanlığı. 30 Haziran 2017 tarih ve 30110 sayılı Resmi Gazete, Ankara.
5. AOAC (2000). Official Methods of Analysis AOAC INTERNATIONAL, 17th Edition, Washington DC, USA.
6. El Darra, N., Rajha, H.N., Saleh, F., Al-Oweni, R., Maroun, R.G., Louka, N. (2017). Food fraud detection in commercial pomegranate molasses syrups by UV-VIS spectroscopy, ATR-FTIR spectroscopy and HPLC methods. Food Control, 78: 132-137. https://doi.org/10.1016/ j.foodcont.2017.02.043
7. Erbil, D. (2020). Endüstriyel ve geleneksel yöntemlerle üretilmiş farklı pekmez çeşitlerinin bazı fizikokimyasal ve kalite özelliklerinin belirlenmesi. İstanbul Teknik Üniversitesi Fen Bilimleri Enstitüsü Gıda Mühendisliği Anabilim Dalı Yüksek Lisans Tezi, İstanbul, Türkiye, 115 s.
8. Fellows, P.J. (2000). Food processing technology principles and practice. 2nd Edition, Woodhead Publishing Ltd, Cambridge, England, 575 p.

9. Guizani, N., Al-Saidi, G.S., Rahman, M.S., Bornaz, S., Al-Alawi, A.A. (2010). State diagram of dates: Glass transition, freezing curve and maximal-freeze-concentration condition. Journal of Food Engineering, 99: 92–97. https://doi.org/ 10.1016/j.jfoodeng.2010.02.003
10. Karababa, E., Isikli, N.D. (2005). Pekmez: A traditional concentrated fruit product. Food Review International, 21: 357-366. https://doi.org/ 10.1080/87559120500222714
11. Karataş, N., Şengül, M. (2018). Effect of storage on some chemical and physical properties, antioxidant activity of mulberry pekmez. Turkish Journal of Agricultural and Natural Sciences, 5: 34-43. https://dergipark.org.tr/en/pub/turkjans/issue/34475/381429
12. Kaya, C., Akaydın, M.D., Esin, Y. (2012). Chemical properties of some commercial liquid and solid grape pekmez products. Academic Food Journal, 10: 32-39. https://dergipark.org.tr/ en/download/article-file/1189202
13. Le Meste, M., Champion, D., Roudaut, G., Blond, G., Simatos, D. (2002). Glass transition and food technology: A critical appraisal. Journal of Food Science, 67: 2444-2458. https://ift.onlinelibrary.wiley.com/doi/epdf/10.1111/j.1365-2621.2002.tb08758.x
14. Lee, J.H., Choi, K.H., Kim, S.H., Park, K.S., Park, S.H., Kim, J.S., Jang, K.H. (2013). Physicochemical characteristics and electric conductivity of various fruit wines. International Food Research Journal, 20: 2987-2993.
15. Luyet, B., Rasmussen, D. (1968). Study by differential thermal analysis of the temperatures of instability of rapidly cooled solutions of glycerol, ethylene glycol, sucrose and glucose. Biodynamica, 10: 167-191. https://pubmed.ncbi.nlm.nih.gov/5725455/
16. Özesmer, B. (2021). Geleneksel ve endüstriyel yöntemlerle üretilen bazı üzüm pekmezlerinin fizikokimyasal ve duyusal özelliklerinin karşılaştırılması. Kahramanmaraş Sütçü İmam Üniversitesi Fen Bilimleri Enstitüsü Gıda Mühendisliği Anabilim Dalı Yüksek Lisans Tezi, Kahramanmaraş, Türkiye, 65 s
17. Rasmussen, D., Luyet B. (1969). Complementary study of some non-equilibrium phase transitions in frozen solutions of glycerol, ethylene glycol, sucrose and glucose. Biodynamica, 10: 319-331.
18. Roos, Y.H. (2010). Glass transition temperature and its relevance in food processing. Annual Review of Food Science and Technology, 1: 469-496. https://www.annualreviews.org/doi/pdf/10.1146/annurev.food.102308.124139
19. Roos, Y.R., Karel, M. (1991a). Amorphous state and delayed ice formation in sucrose solutions. International Journal of Food Science and Technology, 26: 553-566. https://doi.org/10.1111/j.1365-2621.1991.tb02001.x
20. Roos, Y.R., Karel, M. (1991b). Water and molecular weight effects on glass transitions in amorphous carbohydrates and carbohydrate solutions. Journal of Food Science, 56: 1676-1681. https://doi.org/10.1111/j.1365-2621.1991.tb08669.x
21. Sadeghi, M., Mehryar, E., Razavi, J., Mireei, S.A. (2016). Moisture sorption isotherm and glass transition temperature of date powder in terms of various model systems. Journal of Food Process Engineering, 39: 61-68. https://onlinelibrary.wiley.com/doi/epdf/10.1111/jfpe.12199
22. Singh, K.J, Roos, Y.H. (2005). Frozen state transitions of sucrose-protein-cornstarch mixtures. Journal of Food Science, 70: 198–204. https://ift.onlinelibrary.wiley.com/doi/epdf/10.1111/j.1365-2621.2005.tb07136.x
23. Singh, K.J., Roos, Y.H. (2010). Physical state study of (sugar mixture)-polymer model systems. International Journal of Food Properties, 13: 184–197. https://doi.org/10.1080/10942910802259184
24. Şimşek, A., Artık, N. (2002). Studies of compositions of concentrates from different fruit. Gıda, 27: 459-467. https://dergipark.org.tr/ tr/pub/gida/issue/6961/92812
25. Tosun, M. (2014). Detection of adulteration in mulberry pekmez samples added various sugar syrups with 13C/12C isotope ratio analysis method. Food Chemistry, 165: 555-559. https://doi.org/10.1016/j.foodchem.2014.05.136.
26. Tosun, M., Keleş, F. (2012). Testing methods for mulberry pekmez adulterated with different sugar syrups. Academic Food Journal, 10: 17-23. https://dergipark.org.tr/en/download/article-file/1189287
27. Yaman, N. (2019). Dut, keçiboynuzu ve üzüm pekmezlerine glukoz şurubu katılarak yapılan tağşişin fourier dönüşümlü kizilötesi (FTIR) spektroskopisi ile tespiti. Tekirdağ Üniversitesi Fen Bilimleri Enstitüsü Gıda Mühendisliği Anabilim Dalı Yüksek Lisans Tezi, Tekirdağ, Türkiye, 75 s.
28. Yılmaz, M. (2012). Pekmez ve pekmeze benzer gıdalarda taklit, tağşiş ve coğrafi köken tayini araştırması. Yıldız Teknik Üniversitesi Fen Bilimleri Enstitüsü Kimya Anabilim Dalı Kısaltılmış Doktora Tezi. İstanbul Sanayi Odası, İstanbul, Türkiye. 63 s.
29. Yılmaz, M., Afsar, H. (2012). An approach to determination of geographical origin and authenticity of grape and some grape products using SNIF NMR. Journal of Engineering and Natural Sciences Sigma, 30: 102–112. https://sigma.yildiz.edu.tr/storage/upload/pdfs/1636107910-tr.pdf