Abstract: To improve the eating quality of whole wheat non-fried instant noodles, this study examined the effects of different levels of NaHCO3 addition (0%, 0.1%, 0.2%, 0.3%, 0.4%, and 0.5%) on their quality and in vitro digestion characteristics by measurement of rehydration properties, texture analysis, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), in vitro digestion simulation, and sensory evaluation. The results indicated that the appropriate addition of NaHCO3 effectively enhanced the foam resistance, texture characteristics, sensory quality and microstructure of the product. Upon the addition of 0.2% NaHCO3, the lowest estimated glycemic index (eGI) of 62.68, and the lowest proportion of random coil (17.23 ± 0.36)% were observed. The proportion of β-sheet in the secondary structure of proteins generally increased, and the proportions of α-helix and β-turn decreased accordingly, indicating improved structural order of proteins. Excessive addition of NaHCO3 resulted in a decline in the water-holding capacity, microstructural compactness, digestive resistance of starch, and order of protein secondary structure in the noodles. Considering all quality indicators, the optimal addition level of NaHCO3 in non-fried whole wheat instant noodles is 0.2%.

Key words: NaHCO3; non-fried whole wheat instant noodles; in vitro digestibility; eating quality