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

Öz

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.

Anahtar Kelimeler

• milk, proteins, transglutaminase, cross-linking

Transglutaminaz ile İnek Sütü Protein Sisteminin Modifikasyonu (İngilizce)

Öz

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.

Anahtar Kelimeler

• süt, proteinler, transglutaminaz, çapraz bağlanma       　　

Kaynakça

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