Effects of yeast fermentation on the quality characteristics and in vitro starch digestibility of fried-free instant noodles with rapid rehydration

This study aimed to enhance the rehydration properties of fried-free instant noodles (FFNs) using a fermentation method with yeast, thereby improving their quality. The iodine contrast index (ICI), rapid visco analyzer (RVA), scanning electron microscopy (SEM) and confocal laser scanning microscope (CLSM) analysis indicated that fermentation by yeast significantly improved the degree of gelatinization and porosity of FFNs. Fermentation by yeast for 60 min greatly enhanced the rehydration and digestive properties of FFNs, and reduced the cooking loss of FFNs. Compared with that of the unfermented and naturally fermented FFNs, the rehydration time of the yeast-fermented FFNs were reduced by 32.75% and 32.20%, respectively, and the cooking loss were decreased by 31.31% and 23.08%, respectively, with the porosity increasing by 63.53% and 61.37%, respectively. It was confirmed that the formation of multi-hole structure and high degree of gelatinization were crucial factors affecting the rapid rehydration ability of FFNs. Thus, yeast fermentation has been demonstrated to be an effective method for improving the quality of FFNs, especially their rehydration properties. The study provides an innovative approach for improving the quality of instant noodles.