Abstract:Carotenoids are natural pigments found in plants, and their degradation products, such as ionone and β-cyclocitral, exhibit characteristics such as low threshold values and high-quality aroma, which contribute to the characteristic flavors of food and tobacco products. In this study, β?-carotene-degrading strains were screened using selective media, and volatile components were detected using headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HP-SPME-GC-MS). The primary components of the activity ingredients were analyzed by high performance liquid chromatography-mass spectrometry (HPLC-MS). The degradation mechanism of β-carotene by the strain was investigated using molecular docking and hydrolyzed amino acid spectroscopy. The basic properties of the active components were analyzed using a spectrophotometer. A high-efficiency β-carotene-degrading bacterium, L-4, was isolated from rice wine koji and identified as Bacillus cereus. The optimal degradation conditions were a 3% inoculum volume fraction, a cultivation temperature of 37 ℃, and a pH of 7.0. The primary degradation products included β-ionone, formed by cleavage at the C9—C10 double bond of β-carotene, and β-cyclocitral, produced by cleavage at the C7—C8 double bond of β?-carotene. The active component FS1 is predominantly composed of four peptides: RF1 (ALTFR), RF2 (VYHYVTYQPPG), RF3 (WYMCC), and RF4 (KKPVLLHA). Hydrophobic amino acids in these peptides play a crucial role in the degradation of β-carotene. Bacillus cereus L-4 effectively degrades β-carotene by secreting hydrophobic peptides that destabilize the β-carotene emulsion, promoting double bond cleavage and decolorization through the action of amino acid residues in FS1 and metal ions. The carotenoid-degrading microbial resources identified in this study have significant implications for the food and tobacco industries.
