乳化剂对鲜湿面货架期内水分迁移及热力学影响

为探析乳化剂对鲜湿面货架期内水分迁移及热力学特性的影响，利用低场核磁共振仪、扫描电子显微镜和差示扫描量热（differential scanning calorimeter，DSC）仪，检测硬脂酰乳酸钠（sodium stearyl lactate，SSL）添加组、β-环糊精（beta-cyelodextrin，β-CD）添加组及空白（control check，CK）组鲜湿面货架期内水分迁移、微观结构和热力学特征。结果表明：贮藏7?d，鲜湿面结合水含量A21和不易流动水含量A22逐渐减少，自由水含量A23逐渐增大；SSL和β-CD均增大了鲜湿面A21和A22（P＜0.05），且减小了A23（P＜0.05），增大了贮藏前期结合水弛豫时间T21和不易流动水弛豫时间T22，其大小均为：SSL＞β-CD＞CK（P＜0.05）；2?种乳化剂使得贮藏7?d的鲜湿面弛豫时间T2减小（P＜0.05），且SSL和β-CD的影响效果有显著差异（P＜0.05）；贮藏7?d鲜湿面的重结晶融化温度Tp和T0及老化焓ΔH越来越大；SSL和β-CD减缓了Tp、T0和ΔH的增加速率（P＜0.05），SSL和β-CD分别使CK组ΔH从（1.81±0.05）J/g减小到（1.37±0.12）J/g和（1.31±0.04）J/g；SSL和β-CD使得鲜湿面微观结构表面光滑，水分分布均匀，面筋结构稳定，且SSL和蛋白连接紧密，β-CD和淀粉形成了包裹结构。?

Effects of Emulsifiers on Moisture Migration and Thermodynamics in Fresh Noodles during Shelf Life

In order to explore the effects of different emulsifiers on moisture migration and thermodynamics in fresh noodles during shelf-life, fresh noodles with sodium stearyl lactate (SSL), β-cyelodextrin (β-CD) and no emulsifier (control) were examined for water distribution and migration, microstructure and thermodynamic properties by low-field nuclear magnetic resonance (LF-NMR), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The results showed that the bound water content (A21) and immobilized water content (A22) of fresh noodles diminished, while the free water content (A23) increased during 7 d of storage at 4 ℃. The addition of SSL and β-CD increased A21 and A22 (P < 0.05), decreased A23 (P < 0.05) and elevated the T21 (bound water) and T22 (immobilized water) relaxation time compared with the control group; SSL showed a greater increase in both T21 and T22 than β-CD. Both emulsifiers decreased the T2 relaxation time in fresh noodles after 7 d storage (P < 0.05) and their effects were significantly different (P < 0.05). The recrystallization melting onset temperature (T0), peak temperature (Tp) and aging enthalpy (ΔH) increased during the 7 d storage period. The emulsifiers slowed the rate of increase in T0, Tp and ΔH (P < 0.05), and they decreased ΔH from (1.81 ± 0.05) J/g to (1.37 ± 0.12) and (1.31 ± 0.04) J/g, respectively. Noodles with SSL and β-CD showed a smooth microstructure and a uniform water distribution, and exhibited more stable gluten structure than the control group. SSL was closely bound to protein, and β-CD was incorporated into starch.