Proteolysis of Defatted Rice Bran Using Commercial Proteases and Characterization of Its Hydrolysates

탈지미강 단백질의 가수분해 및 분해물의 특성 연구

  • Kim, Chang-Won (Department of Food Science and Biotechnology, Institute of Life Science Resources, Kyung Hee University) ;
  • Kim, Hyun-Seok (Department of Food Science & Biotechnology, Andong National University) ;
  • Kim, Byung-Yong (Department of Food Science and Biotechnology, Institute of Life Science Resources, Kyung Hee University) ;
  • Baik, Moo-Yeol (Department of Food Science and Biotechnology, Institute of Life Science Resources, Kyung Hee University)
  • 김창원 (경희대학교 생명과학대학 식품공학과) ;
  • 김현석 (안동대학교 식품생명공학과) ;
  • 김병용 (경희대학교 생명과학대학 식품공학과) ;
  • 백무열 (경희대학교 생명과학대학 식품공학과)
  • Received : 2010.11.16
  • Accepted : 2011.02.11
  • Published : 2011.02.28

Abstract

The defatted rice bran (DRB) was enzymatically hydrolyzed using eight commercial proteases for 4hr at optimum pH and temperature. Proteolytic hydrolysates were examined in supernatant and precipitate using lowry, semimicro kjeldahl and gravimetric method using weight difference before and after enzymatic hydrolysis. In lowry and kjeldahl protein assay method, two proteases (Alcalase and Protease N) were found to be the most effective enzymes. In gravimetric method, 60.6~118.3 mg protein/g DRB was hydrolyzed after eight commercial proteases treatments. Similar to lowry and kjeldahl method, 118.3 and 107.1 mg protein/g DRB were hydrolyzed after Alcalase and Protease N treatments, respectively. When two or three effective proteases (Protamex, Alcalase and Protease N) were applied at one time to obtain synergistic effect, significant increase (P<0.05) was observed when three proteases were applied at one time (63.4 mg protein/g DRB in lowry method and 204.5 mg protein/g DRB in gravimetric method). This result suggests that Alcalase and Protease N were the most effective enzymes for proteolysis of DRB and three commercial enzymes (Protamex, Alcalase and Protease N) showed the synergistic effect on the hydrolysis of DRB.

쌀부산물인 탈지미강을 상업적으로 사용되는 8가지 protease를 최적화된 조건에서 단일 혹은 혼합 처리하여 수용성 단백질을 분리하였다. 이렇게 분리된 단백질을 Lowry, Kjeldahl 그리고 Gravimetric method 등 총 3가지 방법으로 분석을 한 결과 Protamex, Alcalase, Protease N이 가장 높은 분해율을 나타냈다. 3가지 방법에서 모두 Protamex, Alcalase, Protease N이 가장 높은 분해율을 나타내었고, Gravimetric method의 경우 다른 두 분석방법인 Lowry, Kjeldahl method에 비해 더 높은 단백질 함량을 보였다. 또한 위의 단일처리결과를 바탕으로 3가지 protease를 혼합하여 처리하였을 때 단일효소처리에 비해 상승효과가 나타나는 것을 알 수 있었는데, 이것은 protease의 경우 가수분해 할 수 있는 특정 peptide 혹은 amino acid가 있는데 각각의 protease가 분해하지 못하는 peptide 혹은 amino acid를 서로 분해해줌으로써 상승효과가 나타난 것으로 생각된다. 효소처리를 하여 얻어진 단백질의 사이즈를 알아보기 위해 SDS PAGE를 한 결과 어떠한 밴드도 형성이 되지 않았고 이는 분해된 단백질이 marker의 최소 사이즈인 15 kDa보다 작기때문인 것으로 생각된다. 따라서 일반 단백질보다 사이즈가 작은 polypeptide나 amino acid로써 분해된 것을 뜻하고 실제로 섭취하였을 때는 신체에서 생성되는 단백질 분해효소인 trypsin이나 chymotrypsin의 분해 없이도 쉽게 흡수 할 수 있을 것이라 판단된다. 또한 효소의 종류가 많을수록 총 아미노산의 함량이 높아짐으로써 식품첨가물로써 활용도가 높은 단백질가수분해물로 분해되었음을 확인할 수 있었다.

Keywords

Acknowledgement

Supported by : 농림수산식품부

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