Abstract: 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.

Key words: fresh noodle, SSL, β-CD, moisture migration, SEM