Effect of duck egg white addition on textural properties and microstructure of rice noodles.
The textural properties and microstructure of freshly cooked rice noodles with different fractions of duck egg white (0-50% w/w) were investigated. The tensile strength and firmness of rice noodle increased with increasing egg white proportion. The addition of egg white 1030% increased the breaking distance (extensibility), however, higher proportion of egg white (40and50%) decreased the extensibility of the noodles. The microstructure of noodle with 0% egg white revealed smooth and compact structure of gelatinized rice starch granules under scanning electron microscope. Addition of egg white resulted in rough and less compact structure of mixed rice starch-egg white protein gels. The continuity of protein matrix observed in noodles with 30% egg white indicated the net work of rice proteins and egg white proteins, distinguished by FITC and Rhodamine B staining, as illustrated under confocal laser scanning microscope. Protein matrix provides an explanation for increasing strength of rice noodles with added egg white.