Comparison of Different Green Extraction Techniques Used for the Extraction of Targeted Flavonoids from Edible Feijoa (Acca sellowiana (O.Berg) Burret) Flowers.

This study aimed to investigate the effect of four green extraction techniques (ultrasound-assisted extraction, UAE; supercritical fluid extraction, SFE; subcritical water extraction, SWE; and extraction using deep eutectic solvents, DES) on the extraction of targeted flavonoids from edible feijoa flowers. The bioactive components in the obtained extracts were quantified by High-Performance Liquid Chromatography-Photodiode Array Detector (HPLC-PDA). Moreover, total polyphenol content and antioxidant activity by DPPH•, ABTS•+, FRAP, and CUPRAC assays were investigated. UAE generally gave the highest yields for isoquercitrin and quercetin content (18.36-25.33 and 10.86-16.13 µg/g), while DES extraction with choline chloride:lactic acid (1:2) and H2O content of 50% gave the highest yield of chrysanthemin (90.81 µg/g). The highest yield of flavone (12.69 mg/g) was obtained with supercritical CO2 at 300 bar. Finally, UAE gave the highest total polyphenol content (ca. 64 mg GAE/g) and antioxidant activity at 70 °C during 30 min with 40% (0.84 mmol TEAC/g and 2.25 mmol Fe2+/g, for ABTS•+ and CUPRAC, respectively) and 60% ethanol-water solution (0.49 mmol TEAC/g and 2.09 mmol Fe2+/g, for DPPH• and FRAP, respectively). The eco-friendly extraction techniques resulted in selective methods capable of extracting targeted bioactive compounds from edible feijoa flowers.

Bioprospecting of Targeted Phenolic Compounds of Dictyota dichotoma, Gongolaria barbata, Ericaria amentacea, Sargassum hornschuchii and Ellisolandia elongata from the Adriatic Sea Extracted by Two Green Methods.

The content of bioactive compounds in four brown and one red algae from the Adriatic Sea (Dictyota dichotoma, Gongolaria barbata, Ericaria amentacea, Sargassum hornschuchii and Ellisolandia elongata) is explored. The efficiency of two different extraction methods viz. ultrasound-assisted extraction (UAE) and matrix solid-phase dispersion (MSPD) to obtain the extracts rich in phenolic compounds was compared. The effect of the extraction solvent to modulate the phenolic profile was assessed. In general, the mixture ethanol/water in an isovolumetric proportion showed the best results. The total phenolic content (TPC) and antioxidant activity (AA), as well as the individual polyphenolic profile, were evaluated for five target algae. TPC values ranged between 0.2 mg GAE/g (for E. elongata) and 38 mg GAE/g (for S. hornschuchii). Regarding the quantification of individual polyphenols by liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis, the presence of a high number of hydroxybenzoic acid derivatives (mainly of 3- and 4-hydroxybenzoic acids) in all species was noted. In G. barbata their concentrations reached up to 500 mg/kg. IC50 values (ABTS assay) ranged between 44 mg/L (for S. hornschuchii) and 11,040 mg/L (for E. elongata). This work contributes to the in-depth characterization of these little-explored algae, showing their potential as a natural source of phenolic compounds.

Optimization of MAE for the Separation of Nicotine and Phenolics from Tobacco Waste by Using the Response Surface Methodology Approach.

This study intends to valorize by-products of the industrial processing of tobacco to obtain nicotine and phenolics as value-added compounds. Three influential parameters of the microwave-assisted extraction-MAE (temperature, treatment time, and solvent/solid ratio) were studied for the optimization of the extraction protocol for tobacco leaves and three types of waste-scrap, dust, and midrib, respectively. Nicotine was the dominant bioactive compound in all extracts, ranging from 1.512 to 5.480% in leaves, 1.886 to 3.709% in scrap, 2.628 to 4.840% dust, and 0.867 to 1.783% in midrib extracts. Five phenolic compounds were identified and quantified, predominated by chlorogenic acid and rutin. Additionally, total phenol content and antioxidant activity were determined using spectrophotometric assays. Optimization was performed in two aspects: to obtain a maximum extraction yield with minimum nicotine content and to obtain a maximum extraction yield with maximum nicotine content. These findings demonstrate that tobacco waste is a valuable source of bioactive compounds and MAE can be a promising alternative technique to obtain extracts rich in targeted bioactive compounds, especially nicotine.

Volatile organic compounds of tobacco leaves versus waste (scrap, dust, and midrib): extraction and optimization.

BACKGROUND: Volatile organic compounds are present at very low concentration but exhibit an important influence on flavor and aroma of tobacco leaves and products. During tobacco processing, at different stages, tobacco wastes occur. Since they are delivered directly from the tobacco plant, they are expected to have a similar aroma profile. RESULTS: The volatile composition of three types of tobacco waste (scrap, dust, and midrib) was characterized for the first time and compared with tobacco leaves' volatile composition. Ultrasound-assisted extraction with hexane followed by gas chromatography-mass spectrometry was successfully applied. Different ultrasound-assisted extraction parameters (temperature, time, and solvent:solid ratio) showed a significant influence on the volatile profiles of the extracts obtained. The most important compounds in tobacco leaves, scrap, and dust with the highest abundance were nicotine (up to 87.5%), 4,8,13-duvatriene-1,3-diol (up to 16.2%), and neophytadiene (up to 9.4%). In midrib, only nicotine was present in all extracts. The most abundant compounds in the extracts were quantified and subjected to optimization using response surface methodology. CONCLUSION: Regression analysis showed that 83-98% of the variation was explained by the models obtained. The experimentally obtained values agreed with those predicted, thus indicating the suitability of the model employed and the success of response surface methodology in optimizing the extraction conditions. © 2020 Society of Chemical Industry.

Carbohydrates-Key Players in Tobacco Aroma Formation and Quality Determination.

Carbohydrates are important compounds in natural products where they primarily serve as a source of energy, but they have important secondary roles as precursors of aroma or bioactive compounds. They are present in fresh and dried (cured) tobacco leaves as well. The sugar content of tobacco depends on the tobacco variety, harvesting, and primarily on the curing conditions (temperature, time and moisture). If the process of curing employs high temperatures (flue-curing and sun-curing), final sugar content is high. In contrast, when air curing has a lower temperature, at the end of the process, sugar level is low. Beside simple sugars, other carbohydrates reported in tobacco are oligosaccharides, cellulose, starch, and pectin. Degradation of polysaccharides results in a higher yield of simple sugars, but at the same time reduces sugars oxidization and transfer into carbon dioxide and water. Loss of sugar producers will compensate with added sugars, to cover undesirable aroma properties and achieve a better, pleasant taste during smoking. However, tobacco carbohydrates can be precursors for many harmful compounds, including formaldehyde and 5-hydroxymethylfurfural. Keeping in mind that added sugars in tobacco production are unavoidable, it is important to understand all changes in carbohydrates from harvesting to consuming in order to achieve better product properties and avoid the formation of harmful compounds. This review summarizes current knowledge about tobacco carbohydrates, including changes during processing with special focus on carbohydrates as precursors of harmful compounds during smoking.

Optimization of Ultrasound-Assisted Extraction of Some Bioactive Compounds from Tobacco Waste.

This is the first study on ultrasound-assisted extraction (UAE) of bioactive compounds from different types of tobacco industry wastes (scrap, dust, and midrib). The obtained results were compared with starting raw material (tobacco leaves) to see the changes in bioactive compounds during tobacco processing. Results suggested that tobacco waste extracts possess antioxidant activity and considerable amounts of targeted bioactive compounds (phenolics and solanesol). The content of chlorogenic acid varied between 3.64 and 804.2 µg/mL, caffeic acid between 2.34 and 10.8 µg/mL, rutin between 11.56 and 93.7 µg/mL, and solanesol between 294.9 and 598.9 µg/mL for waste and leaf extracts, respectively. There were noticeable differences between bioactive compounds content and antioxidant activity in extracts related to applied UAE conditions and the used type of tobacco waste. Results show that optimal UAE parameters obtained by response surface methodology (RSM) were different for each type of material, so process optimization proved to be necessary. Considering that tobacco waste is mostly discarded or not effectively utilized, the results clearly show that tobacco waste could be used as a potential source of some bioactive compounds.