DOI QR코드

DOI QR Code

Electron Microscopical Characteristics of Transglutaminase-treated Raw Skim Milk After pH Adjustment

pH조정후 트랜스글루타미나제로 처리한 탈지 원유의 전자현미경적 특성

  • Moon, Jeong-Han (Dept. of Food and Nutrition, Human Ecology Research institute, and BioFood Research Center, Chonnam National University) ;
  • Hong, Youn-Ho (Dept. of Food and Nutrition, Human Ecology Research institute, and BioFood Research Center, Chonnam National University)
  • 문정한 (전남대학교 식품영양학과 생활과학연구소 바이오식품연구센타) ;
  • 홍윤호 (전남대학교 식품영양학과 생활과학연구소 바이오식품연구센타)
  • Published : 2005.12.01

Abstract

In order to develop novel food products or additives using transglutaminase (TGase), some physicochemical and morphological understandings are needed. Raw skim milk was adjusted to pH 5.5, 7.0, and 8.5, and each was treated with microbial TGase for 0, 1, 2, 4, and 8 hours, for the protein structure observation using scanning electron microscope (SEM), The particles of untreated raw skim milk were small and evenly associated. After adjustment of pH to 5.5 and treatment of TGase for 1-hour, the protein particles aggregated widely in a bigger form than that of control. Under the same condition for 2 hours, the particles associated and clustered. The particles gathered widely and became a number of small spherical forms after 4 hours. After 8 hours, they made larger forms than the result of 1-hour treatment, and the aggregation broadened. Under the pH 7.0 and 8.5 conditions with TGase-treatment, the protein Particles fractionated and associated into the bigger masses at 1 hour point, but each piece slowly became smaller and more fractionated until treated time reached 4 hours. After 8 hours, the fragmented protein particles aggregated into larger forms as those on the pH 5.5 condition. In general, the electron microscopical forms of the samples adjusted to pH 5.5 showed smaller than those of pH 7.0 or pH 8.5, It is suggested that the protein particles and textural behavior were influenced by pH, TGase, and reaction time.

원유에서 지방을 제거한 탈지유의 pH를 5.5, 7.0, 8.5로 조정한 다음 TGase를 첨가하여 0, 1, 2, 4, 8시간 반응시킨 후 동결 건조하여 조직의 성상을 주사 전자 현미경을 이용해 관찰, 비교하였다. pH와 TGase를 처리하지 않은 탈지유는 단백질 입자들이 규칙적으로 회합해 있었다. pH 조정 후 TGase를 처리한 다음 반응시간을 달리한 시료에서는 pH를 5.5로 조정한 경우 현저한 변화가 있었는데, 그 변화 양상은 단백질 입자들이 0시간에서 조각을 이루어 회합되어 있다가 1시간 반응시킨 경우 단백질 입자들이 서로 결합하여 넓게 회합하였다. 2시간 반응시킨 경우 단백질 입자들이 다시 뭉쳐서 회합하였으며 4시간 반응시킨 경우 뭉쳐져 있던 단백질 입자들이 조그만 한 구형 성상으로 넓게 회합하였다. 8시간 반응시킨 시료는 구형 성상으로 회합되어 있던 단백질 입자들이 사라지면서 다시 넓게 회합하는 것을 관찰할 수있었다. pH 7.0과 8.5 조건하에서는 단백질 입자들이 조각 형태를 이루고 있었으며 반응시간이 증가할수록 입자들이 넓게 확대되는 현상을 나타냈다. 전반적으로 현미경적 입자의 형태는 pH 5.5로 조정된 시료가 pH 7.0또는 pH 8.5로 처리된 시료들보다 더작게 관찰되었다. 이와 같은 단백질들의 현미경적 변화 양상은 pH TGase처러 그리고 반응시간에 따라 영향을 받고 있는 것으로 사료된다.

Keywords

References

  1. Icekson I, Apelbaum A. 1987. Evidence for transglutaminase activity in plant tissue. Plant Physiol 84: 972-974 https://doi.org/10.1104/pp.84.4.972
  2. Kuraishi C, Sakamoto J, Soeda T. 1996. The usefulness of transglutaminase for food processing. In Biotechnology for improved foods and flavors. ACS Symposium Series 637. American Chemical Society, Washington, DC. p 29-38
  3. O'sullivan M M, Kelly AL, Fox PF. 2002. Influence of transglutaminase treatment on some physico-chemical properties of milk. J Dairy Res 69: 433-442
  4. Walsh DJ, Cleary D, McCarthy E, Murphy S, FitzGerald RJ. 2003. Modification of the nitrogen solubility properties of soy protein isolate following proteolysis and transglutaminase cross-linking. Food Res Int 36: 677-683 https://doi.org/10.1016/S0963-9969(03)00017-6
  5. Lauber S, Noack I, Klostermeyer H, Henle T. 2001. Stability of Microbial transglutaminase to high pressure treatment. Eur Food Res Technol 213: 273-276 https://doi.org/10.1007/s002170100381
  6. Lee DS, Matsumoto S, Matsumura Y, Mori T. 2002. Identification of the $\varepsilon$-($\gamma$-glutamyl)lysine cross-linking sites in $\alpha$-lactalbumin polymerized by mammalian and Microbial transglutaminases. J Agric Food Chem 50: 7412-7419 https://doi.org/10.1021/jf020529a
  7. Moon JH, Hong YH. 2003. Electron microscopical property of transglutaminase added milk. Korean J Food Sci Ani Resour 23: 350-355
  8. Moon JH, Hong YH. 2004. Electron microscopical observation of transglutaminase-treated ultra high temperature milk sediment. Korean J Food Sci Ani Resour 33: 1359-1366
  9. Flanagan J, FitzGerald RJ. 2003. Functional properties of Bacillus proteinase hvdrolysates of sodium caseinate incubated with transglutaminase pre- and post-hydrolysis. Int Dairy J 13: 135-143 https://doi.org/10.1016/S0958-6946(02)00149-8
  10. Jeong JE, Hong YH. 2005. Electrophoretical properties of transglutaminase treated milk product powders. Korean J Food Sci Technol 37: 345-351
  11. Schorsch C, Carrie H, Norton IT. 2000. Cross-linking casein micelles by a Microbial transglutaminase: influence of cross-links in acid-induced gels. Int Dairy J 10: 529-539 https://doi.org/10.1016/S0958-6946(00)00069-8