Abstract: This study investigated the effects of yeast polysaccharides on the pasting properties of wheat flour, as well as the textural properties, cooking characteristics, starch relative crystallinity, short-range ordered structure, and microstructure of hot dry noodles. The mechanism underlying the quality improvement of hot dry noodles by adding yeast polysaccharides was also explored. The results showed that when the addition level of yeast polysaccharides was 0.6%, the hardness of the noodles reached a maximum of 2 689 g, and the elasticity and chewiness increased to 0.85 and 1 487 g, respectively. Meanwhile, the water absorption rate significantly increased to 26.21%, while the cooking loss rate decreased to 1.04%. The analysis of pasting characteristics indicated that with increasing addition of yeast polysaccharides (from 0.2% to 0.8%), the peak viscosity, breakdown value, and setback value exhibited a decreasing trend. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy analysis indicated that the incorporation of yeast polysaccharides increased the relative crystallinity of starch in the noodles from 19.81% to 30.16%, the degree of short-range order (DO) value to 1.542, and the double helix content (DD) to 0.774, indicating significantly enhanced short-range ordered structure of starch without altering its V-type crystalline pattern. Raman spectroscopy further confirmed that yeast polysaccharides promoted the ordered arrangement of starch molecules, as evidenced by the decreased full width at half maximum at 480 cm–1. Scanning electron microscopy (SEM) demonstrated that the noodles incorporated with 0.6% yeast polysaccharides exhibited the most compact and uniform cross-sectional structure, with starch granules fully embedded in a continuous gluten network. In conclusion, an appropriate amount of yeast polysaccharides can fill the gluten network through hydrogen bonding, enhance starch structural order, and improve the microstructure, thereby imparting favorable mechanical properties and processing quality to hot dry noodles.

Key words: yeast polysaccharides; hot dry noodles; texture; microstructure; quality improvement