Modification of Bovine Milk Protein System by Transglutaminase (in English)

Abstract

In this study the effect of transglutaminase (tgase) on individual bovine milk proteins in skim milk samples was investigated with a kinetic approach in skimmilk samples. Raw and preheated (80 oC/ 5 minutes) samples were incubated with tgase with 2 different enzymes with the protein ratios of 1:10 and 1:20 for upto 4 hours at 3 different incubation temperatures (4, 30 and 42 oC). It was found that tgase had no effect on the native whey proteins. The highest reaction rate constant value (k) was found for κ-casein, and it was followed by β-casein and α-casein, respectively in heated and unheated skimmilk samples. The crosslinking reaction was almost completed within the first 5 minutes at 42 oC for κ-casein. The Ea value (activation energy) of β-casein (29 kj/mol) was found to be lower than that of α-casein (45 kj/mol). On the other hand, when the kinetic parameters were evaluated, it is postulated that tgase can be used for cheese manufacturing (30 oC, at 1:10 E:P ratio) and yoghurt production (42 oC, at 1:20 E:P ratio). This approach will be investigated in further studies.

Keywords

• milk, proteins, transglutaminase, cross-linking

Transglutaminaz ile İnek Sütü Protein Sisteminin Modifikasyonu (İngilizce)

Abstract

Bu çalışmada, yağsız süt örneklerinde tranglutaminazın (tgaz) süt proteinleri üzerine etkisi, kinetik bir yaklaşımla araştırılmıştır. Çiğ ve ön ısıl işlem görmüş örnekler (80 oC/ 5 minutes), tgaz ile 1:10 ve 1:20 olmak üzere iki farklı enzim: protein oranında 4 saate kadar 3 farklı inkübasyon sıcaklığında inkübe edilmiştir (4, 30 and 42 oC). Tgazın doğal serum proteinleri üzerine etkisi olmadığı ortaya konulmuştur. Isıl işlem görmüş ve görmemiş yağsız süt örneklerinde, en yüksek reaksiyon hız sabiti κ-kazein için bulunmuştur; bunu sırasıyla β-kazein ve α-kazein izlemiştir. κ-kazein için çapraz bağlanma reaksiyonunun 42 oC’de ilk 5 dakikada neredeyse tamamlanmıştır. β-kazein için Ea değeri (aktivasyon enerjisi) (29 kj/mol), α-kazeininkinden (45 kj/mol) daha düşük bulunmuştur. Diğer taraftan, bu kinetik parametreler değerlendirildiğinde, tgazın peynir üretimi (30 oC, 1:10 E:P oranında) ve yoğurt üretimi (42 oC, 1:20 E:P oranında) için kullanılabileceği ortaya konulmuştur. Bu yaklaşım, daha sonra yapılacak bir çalışma ile değerlendirilmeye alınacaktır.

Keywords

• süt, proteinler, transglutaminaz, çapraz bağlanma       　　

References

1. Motoki M, Seguro K. 1998. Transglutaminase and Its Use For Food Processing. Trends Food Sci Tech., 9: 204-210.
2. Traore F, eunier JC. 1992. Cross-linking activity of placen- tal F XIIIa on whey proteins and caseins. J Agric Food Chem, 40: 399-402.
3. Han XQ, Damodaran S. 1996. Thermodynamic compati- bility of substrate proteins affects their cross-linlinking by transglutaminase. J Agric Food Chem, 44: 1211-1217.
4. Dickinson E, YamamotoY. 1996. Rheology of milk prote- in gels and protein-stabilized emulsion gels cross-linked with transglutaminase. J Agric Food Chem, 44: 1371-1377.
5. Faegermand M, Quvist KB. 1997. Transglutaminase: effect on rheological properties, microstructure and permeability of set style acid milk gel. Food Hydrocolloid, 11: 287-292.
6. Lorenzen PC. 2000. Renneting properties of transglutaminase-treated milk. Milchwissenschaft, 55: 433- 437.
7. Lorenzen PC. 2000. Techno-functional properties of transglutaminase-treated milk proteins. Milchwissenschaft, 55: 667-670.
8. Nio N, Motoki M, Takinami K. 1986. Gelation mecanism of protein emulsion by transglutaminase. Agr Biol Chem, 50: 1409-1412.

9. Ikura K, Goto M, Hoshikawa M, Sasaki R, Chiba H. 1984. Use of transglutaminase: reversible blocking of amino groups in substrate proteins for a high yield of spesific products. Agr Biol Chem, 48: 2347-2354.
10. Gauche C, Vieira JTC, Ogliari PJ, Bordignon-Luiz MT. 2008. Crosslinking of milk whey proteins by transglutamina- se. Process Biochem, 43: 778-794.
11. Schorsch C, Carrie H, Norton IT. 2000. Crosslinking Ca- sein micelles by a Microbial Transglutaminase: Influence of Crosslinks in Acid-induced Gelation. Int Dairy J, 10: 529-539. 12. Sharma R, Lorenzen PC, Qvist KB. 2001. Influence of transglutaminase treatment of skim milk on the formation of Є-(γ-glutamyl)lysine and the susceptibility of individual pro- teins towards crosslinking. Int Dairy J, 11: 785-793.
12. O’Connell JE, de Kruif CG. 2003. β-casein micelles; cross- linking with transglutaminase. Colloids and Surfaces A: Physicochem. Eng Aspects, 216: 75-81.
13. Faegermand M, Murray BS, Dickonson E, Quvist KB. 1999. Cross-linking of adsorbed casein films with transgluta- minase. Int Dairy J, 9: 343-346.