Effects of ultrasonic-assisted extraction on bioactive compounds,volatile flavors and antioxidant activities of vine tea water extracts

Background:Ampelopsis grossedentata,vine tea,which is the tea alternative beverages in China.In vine tea processing,a large amount of broken tea is produced,which has low commercial value.Methods:This study investigates the influence of different extraction methods(room temperature water extraction,boiling water extraction,ultrasonic-assisted room temperature water extraction,and ultrasonic-assisted boiling water extraction,referred to as room temperature water extraction(RE),boiling water extraction(BE),ultrasonic assistance at room temperature water extraction(URE),and ultrasonic assistance in boiling water extraction(UBE))on the yield,dihydromyricetin(DMY)content,free amino acid composition,volatile aroma components,and antioxidant properties of vine tea extracts.Results:A notable influence of extraction temperature on the yield of vine tea extracts(P<0.05),with BE yielding the highest at 43.13±0.26%,higher than that of RE(34.29±0.81%).Ultrasound-assisted extraction significantly increased the DMY content of the extracts(P<0.05),whereas DMY content in the RE extracts was 59.94±1.70%,that of URE reached 66.14±2.78%.Analysis revealed 17 amino acids,with L-serine and aspartic acid being the most abundant in the extracts,nevertheless ultrasound-assisted extraction reduced total free amino acid content.Gas chromatography-mass spectrometry analysis demonstrated an increase in the diversity and quantity of compounds in the vine tea water extracts obtained through ultrasonic-assisted extraction.Specifically,69 and 68 volatile compounds were found in URE and UBE extracts,which were higher than the number found in RE and BE extracts.In vitro,antioxidant activity assessments revealed varying antioxidant capacities among different extraction methods,with RE exhibiting the highest DPPH scavenging rate,URE leading in ABTS•+free radical scavenging,and BE demonstrating superior ferric ion reducing antioxidant activity.Conclusion:The findings suggest that extraction methods significantly influence the chemical composition and antioxidant properties of vine tea extracts.Ultrasonic-assisted extraction proved instrumental in elevating the DMY content in vine tea extracts,thereby enriching its flavor profile while maintaining its antioxidant properties.

Preparation and chemical characterization of banana/orange composite wine

Banana/orange composite wine was brewed in the lab by liquid fermentation using angel yeast and lactic acid bacteria as the fermentation strains,and characterized by chemical analyses.It was found that the best ratio of banana juice to navel orange juice was 1:2,and the optimum alcohol fermentation parameters were as follows:28~30℃,22%initial sugar content,6%yeast,and 6 days of fermentation to reach an alcohol concentration of 11.63%v/v.The free amino acids in the composite wines were tested by automatic amino acid analyzer,and the flavor components of the composite wine were determined and analyzed by gas chromatography-mass spectrometry(GC-MS).Seven types of trace elements in the composite wine were measured by atomic absorption spectrometry.Results showed that there were 17 free amino acids,and their total concentration was up to 897.6 mg/L.A total of 16 key compounds were identified in the composite wine,11 of which were ester,4 of which were alcohols and 1 of which was acid.Magnesium,iron,copper and manganese elements were relatively rich in the wine,while lead was extremely low.