Abstract:
In this study, to explore the effects of brown rice in different regions on the starch properties and eating quality of instant noodle sheet (NS), refined wheat flour (FD) was blended with six types of brown rice flours from different regions at a ratio of 25%, and the mixtures were processed into instant noodle sheet by extrusion. Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and X-ray diffractometer (XRD) were used to analyze the structural differences of starch. The microstructure of NS was observed by scanning electron microscopy (SEM), and the quality of NS was evaluated by measuring its rehydration and digestion properties. The results showed that the addition of brown rice 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%, 8.73%~10.83%). The starch in NS presented a V-type crystal structure. Due to the high amylose contents (23.67% and 19.90%) and suitable lipid-binding abilities, Jilin-Instant noodle sheet (YZ-NS) and Hubei-Instant noodle sheet (HB-NS) had increased crystallinity (26.16% and 20.61%) and denser microstructures. Jiangsu-Instant noodle sheet (JS-NS) had the highest dietary fiber content (1.78%), resulting in a looser starch gel structure, which shortened the rehydration time of the sample (3.20 min), but had the highest broken noodle rate (19.50%). In contrast, YZ-NS had a rehydration loss rate of 8.17% and a 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 the formation of V-type complexes, while wheat flour-Instant noodle sheet (FD-NS) had the highest digestibility (85%) which was associated with 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 the eating quality of NS by changing the distribution of starch-lipid complexes and dietary fiber. Among them, YZ-NS exhibits better rehydration quality and low digestibility, providing a theoretical basis for the development of nutritious instant noodle sheet.