Study on the Nutritional Characteristics and Flavor of De-Anthocyanidin Black Rice Fermented by Multiple Compound Lactobacillus.

De-anthocyanin black rice (DBR) is a residue generated after the industrial extraction of anthocyanins; it retains considerable polysaccharides and other bioactives but remains largely underutilized. In this study, DBR underwent co-fermentation using a 2:1 (v/v) mixture of Lactiplantibacillus plantarum and Lactobacillus delbrueckii subsp. bulgaricus at 30°C for 39 h. This mixed lactic acid bacteria (LAB) fermentation led to a marked drop in pH, a rise in titratable acidity, and a final LAB viable count reaching 9.47 Log CFU/mL. Total phenolic content rose by 24.60% to 18.23 mg GAE/mL, and both total flavonoids and DPPH/ABTS radical-scavenging activities increased markedly. Fermentation led to the formation of 19 additional volatile compounds as identified by HS-SPME-GC-MS. Increased concentrations of alcohols, esters, and short-chain fatty acids (predominantly acetic acid) were linked to desirable fruity aromas. In the fermented matrix, lactic acid was the major total organic acid, but it is non‑volatile. Consequently, acetic acid became the main component of the volatile acidic profile. These findings demonstrate that mixed LAB fermentation substantially improves the nutritional, antioxidant, and flavor properties of DBR, supporting its potential application as a functional beverage base.