Studies of Rheological Properties of Chitosan and its Interaction with Myofibrillar Proteins as Influenced by Chitosan''s Degree of Deacetylation、Concentration and pH

• Main Authors: Ying-Chou Chen, 陳盈州
• Other Authors: Kuo-Wei Lin
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/21105741353533772742

碩士 === 靜宜大學 === 食品營養學系 === 89 === Rheological and thermal gelation characteristics of different degree of deacetylation (dd 50, dd 75, dd85, dd 99), concentration (0.5%, 1.0%, 1.5%) or pH (3, 5) of chitosan solution (in 1% lactic acid) and the mixture of chitosan and myofibrillar proteins were evaluated. Interactions of chitosan with myofibrillar proteins through SDS-PAGE during heating were also demonstrated. Thermal gelation processes of porcine salt-soluble proteins (SSP) extracted from tenderloin could be separated into the low temperature zone (< 50℃) and high temperature zone (> 50℃). No apparent rheological changes were noticed for chitosan/SSP mixture in the low temperature zone, but incorporation of chitosan reduced complex moduli (G*) of SSP in the high temperature zone. This result suggested that SSP thermal gelation be possibly interfered by the positive charges of amino group of chitosan molecule. Regardless of degree of deacetylation, increasing chitosan concentration caused stronger interference on SSP gelation and lowered G*. The tan δ (loss tangent) of chitosan/SSP gel decreased with increasing heating temperature. At the end of heating cycle (75℃), tan δ of chitosan/SSP gel was higher than that of SSP alone. Higher level (1.5%) of dd 99 chitosan, low in amount of acetyl amino group, had the lowest G* which possibly resulted from the ionic interaction with SSP. Increased viscosity was noted for chitosan solution adjusted to pH 3 comparing with chitosan solution prior to pH adjustment. Higher chitosan concentration (at pH 3) resulted in higher G* or gel elasticity of chitosan/SSP mixture. This could be probably attributed to increased ionic interaction between chitosan and SSP, thus enhanced thermal gelation in low temperature zone. Therefore, higher numbers of positive charge for dd 99 chitosan (at pH 3) was shown to have stronger ionic interaction and gel elasticity. Viscosity of chitosan solution at pH 5 was shown to be lower than that of chitosan solution before adjusting pH. Regarding the same degree of deacetylation, increased chitosan level (at pH 5) reduced G* of chitosan/SSP mixture. Contrast to chitosan solution at pH 3, dd 99 possessed less amounts of positive charge which interfered SSP thermal gelation at high temperature zone through the formation of hydrogen bonding. SDS-PAGE results from chitosan/SSP gel following 8M urea treatment revealed large protein molecule (> 200 KDa) aggregation in the stacking gel, which indicated formation of new covalent linkages between chitosan and SSP into chitosan/SSP polymer. Electrophretogram from dd 50 also showed disappearing myosin heavy chain (MW 200 KDa) and actin (MW 45 KDa) protein bands that resulted from formation of chitosan/SSP polymer. Intensities or concentration of large chitosan/protein polymers for chitosan solution at either pH 3 or 5 were less, due to changes in the numbers of positive charge, than that of chitosan solution before pH adjustment. Key words：