摘要
Citrus reticulata peels,often discarded,are crucial sources of bioactive compounds with significant antioxidant capacities.Biotechnological processes such as ultrasonication and solid-state fermentation(SSF)have shown promise in enhancing bioactive,but research on their synergistic effects is limited.Therefore,this research studied the influence of ultrasound pretreatment on antioxidant accumulation in Citrus reticulata peel powder(CRPP)during SSF with Aspergillus niger.Ultrasound pretreatment of A.niger inoculum before SSF,under optimal conditions of 270 W power,20 min duration,30℃ temperature,and 20/40/60 kHz frequency,maximized the total phenolic content(TPC),total flavonoid content(TFC),and antioxidant activities(2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulphonic acid(ABTS)and 2.2-diphenyl 1-pycrilhydrazyl(DPPH)scavenging capacity)by 29.6%,31.2%,48.2%,and 71.8%,respectively,compared to nonfermented CRPP(NF-CRPP).Further optimization of ultrasound parameters(28℃,a solid-to-liquid ratio of 100 mg/mL,210 W,and 39 min)for CRPP substrate pretreatment led to significant antioxidant accumulation.Compared to NF-CRPP,TPC,TFC,ABTS,and DPPH scavenging capacities of CRPP fermented with both ultrasound-pretreated inoculum and substrate(UISCRPP)increased by 1.38-,1.33-,1.55-,and 1.73-fold,respectively.Additionally,these values were 9.83%,4.92%,6.38%,and 10.16%higher than those obtained from CRPP fermented with A.niger without ultrasound pretreatment(F-CRPP).High-performance liquid chromatography analysis revealed significant increases in chlorogenic acid by 220.6%and 240.4%in CRPP fermented with ultrasound-pretreated inoculum(UI-CRPP)and UIS-CRPP,respectively,compared to NF-CRPP.This study highlights the potential of ultrasound-assisted SSF as an effective strategy for valorizing citrus by-products with enhanced bioactive properties.
基金
supported by the Jiangsu Specially Appointed Professor Program under grant number zk20190386,awarded to X.Chen.
