This study aimed to investigate the impact of the addition of rice flour (RF) and glutinous rice flour (GRF) in comparison with tapioca starch (TS) on the emulsion stability, water states, protein secondary structure, and microstructure of an emulsion-type cooked sausage. Their incorporation significantly increased the cooking yield and moisture retention of cooked sausages (p < 0.05). RF and GRF significantly decreased the fat loss and total fluid release of the cooked sausage compared to control (p < 0.05). However, RF and GRF functional effects on these parameters remained lower compared to TS (p < 0.05). Among these functional ingredients, TS had a significantly higher emulsion stability and cooking yield and generated a firmer and more uniform gel network structure. The transverse relaxation time T2 results revealed four categories of water population (T2b1, T2b2, T21, and T22) with particular mobility. TS immobilized a greater proportion of water molecules within the myofibrils (T21 population). All three ingredients increased the emulsion stability of the emulsion-type cooked sausages by decreasing the fat globule mobility and binding more water molecules. Raman spectra (400-3600 cm-1) showed that the incorporation of RF, GRF, or TS did not affect the β-sheet and α-helix protein structure. However, TS presented significantly higher contents of the random coil structure. These findings provide a good insight into the effects of RF and GRF as functional ingredients to manufacture emulsified meat products with good quality and improved nutritional values.
Keywords: cereal products; meat emulsion; microstructure; sausage; starch.