In order to develop a rapid and efficient method for the industrial production of rice protein-glucose conjugates, rice protein was extruded and then subjected to the Maillard reaction with glucose. Herein, rice protein was extruded at different temperatures (80, 90, 100, 110, 120 and 130 ℃) and then conjugated with glucose for 30 minutes at pH 10.5. We analyzed the effect of different extrusion temperatures on the functional properties (solubility, emulsification activity index (EAI) and emulsion stability index (ESI)) and structural properties of extruded rice protein and glucose (ERPG) conjugates and characterized ERPG conjugates using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Compared to native rice protein and glucose (NRPG) conjugate, the degree of glycosylation (DG) of ERPG conjugate prepared with rice protein extruded at 90 ℃ was the highest, and the solubility of ERPG conjugates prepared with rice protein extruded at 90–120 ℃ decreased. The EAI, ESI and surface hydrophobicity of ERPG conjugates prepared with rice protein extruded at 80–90 ℃ increased, while those of ERPG conjugates prepared with rice protein extruded at 100–130 ℃ slowly decreased. The FTIR results showed that ERPG conjugate had higher contents of α-helix, β-turn and random coil and a lower content of β-sheet than NRPG. The SDS-PAGE indicated that the protein was aggregated into larger particles by extrusion. Under SEM, ERPG conjugates exhibited more disordered structure with irregular fragments.

In order to improve the quality of pea protein-based meat analog, this study investigated the effect of interaction between sodium carboxymethyl cellulose (CMC) and protein on the quality of extruded pea protein products. CMC and pea protein were employed as raw materials to prepare protein-based meat analog by high-moisture extrusion (HME). Next, the effects of CMC contents (0%, 2%, 4%, 6% and 8%) on the textural properties, color, microstructure and protein-protein interaction forces of meat analog were explored. The correlation of secondary structure content and protein-protein interaction forces with quality attributes (textural properties and color) was established. The results showed that the main interaction force was disulfide bonds. Compared with meat analog without CMC, the addition of 4% CMC promoted the formation of disulfide bonds and increased the hardness of meat analog by 95%. Meanwhile, pea protein-based meat analog exhibited a smooth and homogeneous surface. It was also found that the random coil content increased, and was correlated with higher lightness, indicating that CMC could improve the quality of pea protein-based meat analog.