Studies On Ovalbumin--Polysaccharide Mixed Gel

By measuring gel strength, gel elasticity and gel transparency, ovalbumin(OVA) mixed with polysaccharide including carrangeenan(Car) and potato starch(PS) were studied to determine the optimal preparation condition for heat-induced mixed gel. This study examined the influence of NaCl, sucrose on the gel properties. To obtain information on molecular forces involved in gelation of mixed system, the effects of denaturant of urea, propylene glycol, 2-mercaptoethanol on properties of the mixed gel of OVA/Car and OVA/PS were investigated. The results indicated that:1) with the total solid concentration of 2%, ratio of protein to Car 1:3, pH 5, heated at 70℃ for 15min, cooled at 0℃, The mixture of OVA/Car form a good gel with a gel strength(GS) of 717g, which is 2.04-fold higher than that of OVA gel.2) With the total solid concentration of 10%, ratio of protein to Car 1:1, pH 4, heated at 80℃ for 30min, cooled at 0℃, The mixture of OVA/PS form a good gel with a gel strength(GS) of 369.92g, which is little higher than that of OVA gel.3) NaCl can enhance the gel strength(GS) of both mixed gel, but decrease the gel elasticity(GE) and gel transparency(GT) at the concentration below the 0.2mol/L. The NaCl has a heavier effect on OVA/Car than OVA/PS.4) CaCl2 can greatly increase the GS of OVA/PS, and decrease GE and GT when the concentration less than 80 mmol/L. At the same condition, it led the OVA/Car unable to form gel.5) Sucrose can enhance the GE and GT of OVA/PS, but decrease GS. At theconcentration less than 5%, it increases the GS, GE and GT of OVA/Car, and the best effect took place at the concentration of 2.5%. When the concentration of sucrose increased, the properties of the mixed gel decreased.6) Fatty acid salts(sodium caprylate, sodium laurate) can enhance the GS, GE and GT of OVA/PS when the concentration more than 1%. It destroies the OVA/Car texture and decrease the gel properties at any concentration. Both the mixed gel system can't form gel in the presence of sodium oleate.7)The mixed gel of OVA/PS is thermo-irreversible, while OVA/Car is thermo -reversible which have lagging temperature phenomenon of 10℃.8)The action of denaturants on mixed gel indicated that hydrogen bonds and disulfide bonds is most important, electrostatic attraction the second place, hydrophobic interactions least in the gel formation of OVA/PS. The OVA/Car form mixed gel with contribution of hydrogen bonds first, then electrostatic attraction and hydrophobic interactions, disulfide bonds the last.