Effects of Mixed‐Culture Fermentation on Quality of Non‐Fried Buckwheat Instant Noodles

Non-fried buckwheat instant noodles are known to be low-fat and low-glycemic-index products but suffer from poor dough processing and poor rehydration. The study aims to improve the rehydration and flavor of non-fried buckwheat noodles by co-fermenting yeast and lactic acid bacteria (Lactobacillus bulgaricus and Streptococcus thermophilus). Non-fried buckwheat instant noodles were evaluated for rehydration, cooking tolerance, texture, digestibility, microstructure, and volatile aroma compounds. Co-fermentation significantly reduced rehydrating time by 15.20% from 342 to 290 s. With mixed culture, the sample with 1% yeast and 0.075% lactic acid bacteria provided excellent cooking tolerance and a good rehydration rate. It also had a low expected glycemic index (45.96-50.74) in digestion assays. The scanning electron microscope showed uniformly distributed pores and a dense gluten network with 1% yeast addition. Electronic nose data indicated that the groups of samples had similar odor characteristics. The gas chromatography-mass spectrometry, combined with principal component analysis and optimal aroma response values, suggested that key aroma compounds (trans-2-nonenal, decanal, 2-pentylfuran, and geranyl acetone) contributed to the unique flavor of non-fried buckwheat noodles. The co-fermentation with yeast and lactic acid bacteria improved the gluten network and quality of non-buckwheat noodles, particularly enriching their volatile compounds. The optimal formulation was 1% yeast with 0.75% lactic acid bacteria. PRACTICAL APPLICATIONS: Compound bacteria fermentation improved the quality of buckwheat instant noodles. Rehydration time was shortened due to the formation of a porous structure. More volatile flavor substances were produced during fermentation. The eGI value was held in 45.96-50.74.