Mid infrared as a tool to study the conformational structure of starch and proteins with oil addition during gelatinization

The impact of varying fat and gelatinization on the starch and protein secondary structures was investigated in slurry and batter systems using mid-infrared (MIR) spectroscopy. Following the addition of both thickening agent and oil, the absorbance ratio R1: 1022 cm−1/995 cm−1 ranged from 0.99 to 1.1 and from 0.85 to 0.89 for slurries and batters, respectively. The level of the β-turn structure decreased for both slurries (from 20.2 to 17.9%) and batters (from 18.8 to 16.4%) with the thickening agent addition. Similarly, oil incorporation reduced the amount of the β-turn structure for both slurries (from 20.2 to 9.1%) and batters (from 18.8 to 16.4%). This result confirms the increase of the hydrophobicity of unfolded proteins, the loss of the β-turn structure and the increase of the β-sheet. The gelatinization increased the level of α-helix structure and reduced the percentage of β-sheet structure for all slurry and batter systems in the Amide III regions.