硫酸盐对玉米淀粉糊化性与成膜性影响

Effect of Sulfate on Maize Starch Gelatinization and Filming Properties

玉米淀粉糊化过程中,硫酸盐能够影响玉米淀粉糊化与成膜性能。分别添加亚硫酸钠、硫代硫酸钠0,0.05,0.1,0.2,0.4和0.8 g至5 g/100 mL淀粉悬液中,90℃糊化40 min,测定糊化性指标;添加同水平硫酸盐制备玉米淀粉-甘油-海藻酸钠复合膜,测定膜机械性能、透明度、水溶性,并用DSC,SEM检测膜热稳定性与形貌表征。结果表明:亚硫酸钠的添加使淀粉膨胀度由9.56(g/g)增加至15.53(g/g),溶解度由0.07(g/g)增加至0.45(g/g),凝沉性减弱,无水析出。硫代硫酸钠的添加未改变淀粉膨胀度,溶解度由0.07(g/g)增加至0.34(g/g),凝沉率由7%增加至12%。DSC分析表明:两种膜热稳定性好;SEM显示膜较粗糙,表面结晶减少。两种硫酸盐的添加使淀粉溶解性、透光率、吸水性及膜水溶性、断裂伸长率增加,膜透明度降低。

The effects of two sulfates on the gelatinization of corn starch were examined. Sodium sulfite and sodium thiosulfate were separately added to gelatinizing corn starch in concentration of 0, 0.05, 0.1, 0.2, 0.4, 0.8 and 5 g/100 mL, with 90 ℃ and 40 min. With same levels above, then those were processed to corn starch-glycerol-sodium alginate composites films. The mechanical properties, transparency and water solubility of the composite films were detected, and thermal stability and morphology were characterized by DSC and SEM. The results showed that the swelling degree of starch increased from 9.56 （g/g） to 15.53 （g/g）, the solubility increased from 0.07 （g/g） to 0.45 （g/g） with the added of sodium sulfite; Adding of sodium thiosulfate didn＇t change the swelling degree of the starch, coagulation weakened, anhydrous precipitation, the solubility increased from 0.07 （g/g） to 0.34 （g/g）, and the rote of coagulation increased from 7% to 12%. DSC analysis showed that the films had good thermal stability. SEM showed that the film surface became rough and crystallization reduced. The addition of the two sulphates increased the starch solubility, light transmittance, water absorption and films water solubility, elongation at break and reduced film＇s transparency.