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.

Co-Treatment of EFF and 1-MCP for Enhancing the Shelf-Life and Aroma Volatile Compounds of Oriental Sweet Melons(Cucumis melo var.makuwa Makino)

Compared to other melon types, oriental sweet melon （Cucumis melo var. makuwa Makino） is quite a different species with a shorter shelf-life due to its typical climacteric behavior and thin pericarp. The purpose of this experiment is to explore the effects of co- treatment of enhanced freshness formulation （EFF） and 1-methylcyclopropene （1-MCP） on physiological changes and the content of aroma volatile compounds introduced by them of two oriental sweet melon cultivars （Yumeiren and Tianbao） during storage. The melons were stored in incubators with temperature of 15~C and a relative humidity of 85% for 24 d during which fruit quality and related physiological index were measured. Compared to the control, both treatments delayed fruit weight loss rate and kept the fruit firmness, water content and soluble solids content. Ascorbate peroxidase （APX） and phenylalanine ammonia lyase （PAL） activities showed fluctuations in treated melons, while lipoxygenase （LOX） activity （P〈0.01） and malondialdehyde （MDA） content （P〈0.05） decreased compared to control. During the early stage of storage, alcohols and aldehydes were the main volatile compounds, and esters gradually increased during storage. Of all the esters, acetic esters were the main components, followed by oxalic acid esters and other esters. The total content of aroma volatile compounds, esters, alcohols and aldehydes of co-treated melons were all higher than those of 1-MCP treated and control melons. In addition, the aroma volatile peak of co-treated melons occurred later than that of 1-MCP treated and control melons. In summary, co-treatment of EFF and 1-MCP was more beneficial than 1-MCP treatment to delay ripening and senescence, maintain fruit quality, enhance shelf-life and improve levels of aroma volatile compounds.

Analysis of Aroma Volatile Compounds in Fuji Apple Using SPME with Different Fiber Coatings

The aroma volatile compounds in Fuji apple were isolated by solid-phase microextraction( SPME),and detected by gas chromatography-mass spectrometry( GC-MS). The results showed that the optimal retention time of the heating up of capillary columns was 5 min. Of the seven fibers used in this work,DVB/CAR/PDMS was found to be the most suitable to extract the aroma volatile compounds in Fuji apple. A total number of 43 volatile compounds were identified according to their retention time on capillary columns and their mass spectra,including eleven esters,ten alcohols,ten aldehydes,seven alkenes,two anhydrides,one ketone,one phenol and one ether. This detection method will provide a new foundation for analysis of volatile compounds in apple were identified.

GC-MS Analysis of Volatile Components in ‘Changping 8’ Apple Fruit

Solid-phase and micro-extraction combined with GC/MS(SPME-GC-MS) were employed to detect main aroma components in ‘Changping 8’ apple fruit. The results showed that, 29 kinds of compounds were identified from the aroma components in ‘Changping 8’ apple fruit, and they were aldehydes, alcohols, esters, ketones, etc. The main aroma components of apple fruits were acetic acid, hexyl ester, acetic acid, butyl ester,(E)-2-hexenal, 1-butanol, hexanal, and 1-hexanol.

Lycopene Accumulation Affects the Biosynthesis of Some Carotenoid-related Volatiles Independent of Ethylene in Tomato

For elucidating the regulatory mechanism of ethylene on carotenoid-related volatiles （open chain） compounds and the relationship between lycopene and carotenoid-related volatiles, transgenic tomato fruits in which ACC synthase was suppressed were used. The transgenic tomato fruit showed a significant reduction of lycopene and aroma volatiles with low ethylene production. 6-methyl-5-hepten-2-one, 6-methyl-5-hepten-2-ol and geranylacetone, which were suspected to be lycopene degradation products, were lower than those in wild type tomato fruits. In order to identify whether lycopene accumulation effects the biosynthesis of some carotenoid-related volatiles independent of ethylene in tomato or not, the capability of both wild type and transgenic tomato fruits discs to convert lycopene into carotenoid-related volatiles was evaluated. The data showed that external lycopene could convert into 6-methyl-5-hepten-2-one and 6-methyl-5-hepten-2-ol in vivo, indicating that the strong inhibition of ethylene production had no effect on enzymes in the biosynthesis pathway of some carotenoid-related volatUes. Therefore, in ACS-suppression transgenic tomato fruits, the low levels of 6-methyl- 5-hepten-2-one, 6-methyl-5-hepten-2-ol was due to decreased lycopene accumulation, not ethylene production. Ethylene only affected the accumulation of lycopene, and then indirectly influenceed the level of lycopene-related volatiles.

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.

Comparative Analysis of Three Types of Peaches:Identification of the Key Individual Characteristic Flavor Compounds by Integrating Consumers' Acceptability with Flavor Quality

In order to recognize the key flavor compounds influencing the consumers' choice for honey peach, nectarine, and flat peach and provide important information for orientation breeding, sugars, organic acids, and aroma volatiles in 3 types of peaches were examined by high performance liquid chromatography(HPLC) and gas chromatography–mass spectrometry(GC–MS) and their key individual characteristic flavor compounds were identified by multivariate analysis integrated with consumers' evaluation. No significant differences in sugar and organic acid were observed between 3 types of peaches. In hierarchical clustering analysis(HCA) and principal component analysis(PCA)models, 3 types of peaches could not be differentiated by sugars or organic acids, but could be identified completely by aroma volatiles or by flavor compounds. A partial least squares regression(PLSR) model revealed that the key individual characteristic volatiles in nectarine, honey peach, and flat peach are C9 compounds and terpenic compounds, norisoprenoids and C6 compounds, and benzaldehyde, γ-decalactone, andδ-dodecalactone, respectively. These results suggest that sugars and organic acids form the background flavor of peach fruit and lactones shape the typical peach aroma. However, the individual aroma volatiles play the decisive role in unique flavor determination of different types of peaches.