pH 전이로 회수한 근육 단백질의 가열 변성에 따른 이화학적 특성과 가열 젤의 조직
Phycochemical properties of recovered muscle protein by pH shift during heating and texture of heat-induced gel
PH전이 단백질 가열변성 수산가공;
- 원문 URL
The first part of study was conducted to investigate physicochemical properties of recovered muscle protein by pH shift. The effect of pH on recovered proteins was measured by changes of 1-amilino-8-naphtalene sulfurate(ANS) hydrophobicity, surfhydryl (SH) content, hydrogen-bond, degradation of myosin heavy chain and enthalpy. Exposed hydrophobic residue in myofibrillar protein(MF) was the highest around 60℃. The ANS surface hydrophobicity was different between myofibrillar protein and myofibrillar protein including sarcoplasmic protein(SAMF). The peak at 1636cm^(-1) was increased with increase of pH. Results indicate that β-sheet structure by unfolding of fish protein is increased around in alkali pH. Difference of ractive and total SH group at pH 7.0 and 10.0 was relatively high, and decrease of reactive SH group content indicated formation of S-S bonds. Mackerel and frozen croaker showed bands of polymerized myosin heavy chain on SDS-PAGE pattern. In DSC analysis of a recovered protein by alkali processing, transition temperature was 33.1℃, 44.3℃ and 65.5℃. The enthalpy was lower than that of conventional surimi. These results suggest that gelation of a recovered protein by alkali processing occurs in by a increase of β-sheet structure due to unfolding by pH treatment, formation of S-S bonds by oxidation of reactive SH group in heating, polymerization of myosin heavy chain in order. The second part of study investigated gel properties of a recovered protein from mackerel, croaker, chicken breast and pork leg using acid and alkali processing, and optimum blend of them were evaluated. A myofibrillar protein from mackerel by acid processing did not form a heat-induced gel, whereas a recovered protein including sarcoplasmic protein formed heat-induced gel. Breaking force of gel from mackerel processed at pH 10.5 was the lowest. A deformation value of frozen croaker was the highest, followed by chicken breast, pork leg and mackerel. Whiteness of frozen croaker was the highest among heat-induced gel. Breaking force, deformation and whiteness were decreased by adding a recovered protein from mackerel, but price was increased. A breaking force and whiteness of a recovered protein gel from frozen croaker were increased with addition of a recovered protein from chicken breast, and the price was greatly decreased. When the constraint of breaking force, deformation and price of raw material were set up above 110g, 4.5 mm and below 1,940 won/kg, A optimum percentage for blending protein was 36∼50% for frozen croaker, 34∼40% for chicken breast, 14∼25% for pork leg. The recovered protein gel from frozen croaker showed compact structure compared to that of a recovered protein from mackerel. A formulation of chicken breast and pork leg based on croaker can be used in surimi based products having various texture.