Abstract:
To explore the effects of brown rice from different regions on starch properties and eating quality of instant noodle sheets (NS), refined wheat flour (FD) was blended with six types of brown rice flour from different regions at a ratio of 25%, and the mixtures were processed into instant noodle sheets by extrusion. Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and X-ray diffraction (XRD) were used to analyze the structural differences in starch. Microstructure of NS was observed using scanning electron microscopy (SEM), and quality of NS was evaluated by measuring its rehydration and digestion properties. The results showed that brown rice addition significantly increased the dietary fiber content in NS (1.26%~1.78%), while reducing the contents of total starch, amylose, and protein (61.50%~71.43%, 8.64%~23.67%, and 8.73%~10.83%, respectively). Starch in NS exhibited a V-type crystal structure. Owing to the high amylose content (23.67% and 19.90%) and suitable lipid-binding abilities, the Jilin-Instant Noodle Sheets (YZ-NS) and Hubei - Instant Noodle Sheets (HB-NS) had increased crystallinity (26.16% and 20.61%, respectively) and denser microstructures. The Jiangsu-Instant Noodle Sheet (JS–NS) had the highest dietary fiber content (1.78%), resulting in a looser starch gel structure, which shortened the sample rehydration time (3.20 min), but it resulted in the highest broken noodle rate (19.50%). In contrast, YZ-NS had a rehydration loss rate of 8.17% and broken noodle rate of 13.75%, indicating better quality. The digestion results showed that YZ-NS had the lowest
in vitro digestibility due to its high crystallinity (26.16%) and V-type complexes formation, whereas wheat flour-Instant Noodle Sheet (FD–NS) had the highest digestibility (85%) owing to its high amylose content (37.72%) and low dietary fiber content (0.67%). In conclusion, the addition of brown rice affects the starch properties and eating quality of NS by changing the distribution of starch-lipid complexes and dietary fiber. Among them, YZ-NS exhibited the best rehydration quality and lowest digestibility, providing a theoretical basis for the development of nutritious instant noodle sheets.