Inoculation of Aspergillus strain OA3 enhances aflatoxin B1 and ochratoxin a degradation and improves quality of Fu tea

Aspergillus strain OA3 raised OTA/AFB 1 degradation to 95.56%/90.38%. • Inoculation elevated sweet/umami amino acids by 7.4%–42.1% vs. natural fermentation. • 93 volatiles with 40 odor activity values >0.1 dynamically rebuilt flavor profiles. • Inoculation enriched flavonoid biosynthesis (13vs.5)/degradation (7vs.3) vs. natural. • OA3-inoculated final product raised ABTS + · 25.1%, DPPH 5.7%, FRAP 6.8% vs. natural. This study compared Aspergillus strain OA3 inoculated fermentation and natural fermentation of Fu tea for safety, composition, flavor and metabolism. The OA3-inoculated group exhibited superior safety, with ochratoxin A and aflatoxin B 1 degradation rates reaching 95.56 ± 1.32% and 90.38 ± 3.48%, far higher than 68.93 ± 0.78% and 56.11 ± 3.48% in natural fermentation. Physicochemical components changed regularly during fermentation, with more flavor amino acids retained and stronger antioxidant activity in inoculated samples. Gradually accumulated ketones, esters and alcohols formed the characteristic flavor of Fu tea. Metabolomic analysis identified 158 metabolites throughout fermentation, with a more complex metabolic network at the late stage. Pathways of flavonoid degradation and flavone and flavonol biosynthesis were significantly enriched in OA3-fermented samples. Correlation analysis confirmed altered flavonoid levels closely correlated with improved antioxidant capacity. Aspergillus strain OA3 fermentation is an effective way to produce safer, high-quality Fu tea and facilitates targeted process optimisation. Download: Download high-res image (250KB) Download: Download full-size image