Ultrasound-assisted aqueous two-phase extraction of total flavonoids from Tremella fuciformis and antioxidant activity of extracted flavonoids.

Here, the extraction of total flavonoids from Tremella fuciformis (TF) by aqueous two-phase extraction combined with ultrasound is presented. The extraction was optimized via a single-variable approach using the variables of mass fraction of ethanol and NaH2PO4, ultrasonication time, and TF sample amount. Response surface methodology (RSM) was then applied to determine the best conditions for extraction using the following three key parameters: ultrasonication time, ethanol mass fraction, and NaH2PO4 mass fraction. The optimum conditions were as follows: an aqueous two-phase system of ethanol/NaH2PO4, an ethanol mass fraction of 23%, a NaH2PO4 mass fraction of 27.18%, and an extraction time of 8.25 min. Under these conditions, the maximum extraction rate of total flavonoids was 0.158 mg/g. The scavenging rates for superoxide anion and hydroxyl radical, as well as the antioxidant activity of total flavonoids in TF, were studied. Total flavonoids from TF showed some scavenging ability, but the scavenging effects were lower than those of vitamin C (Vc) at the same concentrations. Nevertheless, ultrasound-assisted two-phase extraction was considered an efficient and rapid method that can be used to extract total flavonoids from TF.

Secretome of Aspergillus oryzae in Shaoxing rice wine koji.

Shaoxing rice wine is the most famous and representative Chinese rice wine. Aspergillus oryzae SU16 is used in the manufacture of koji, the Shaoxing rice wine starter culture. In the current study, a comprehensive analysis of the secretome profile of A. oryzae SU16 in Shaoxing rice wine koji was performed for the first time. The proteomic analysis for the identification of the secretory proteins was done using two-dimensional electrophoresis combined with matrix-assisted laser desorption/ionization-tandem time of flight mass spectrometry based on the annotated A. oryzae genome sequence. A total of 41 unique proteins were identified from the secretome. These proteins included 17 extracellular proteins following the classical secretory pathway, and 10 extracellular proteins putatively secreted by the non-classical secretory pathway. The present secretome profile greatly differed from previous reports on A. oryzae growing in other solid-state nutrient sources. Several new secretory or putative secretory proteins were also found. These proteomic data will significantly aid the advancement of research on the secretome of A. oryzae, especially in solid-state cultures, and in elucidating the production process mechanism of Shaoxing rice wine koji. The findings may promote the technological development and innovation of the Shaoxing rice wine industry.