Rapid and Green Analytical Method for the Determination of Quinoline Alkaloids from Cinchona succirubra Based on Microwave-Integrated Extraction and Leaching (MIEL) Prior to High Performance Liquid Chromatography

Quinas contains several compounds, such as quinoline alkaloids, principally quinine, quinidine, cinchonine and cichonidine. Identified from barks of Cinchona, quinine is still commonly used to treat human malaria. Microwave-Integrated Extraction and Leaching (MIEL) is proposed for the extraction of quinoline alkaloids from bark of Cinchona succirubra. The process is performed in four steps, which ensures complete, rapid and accurate extraction of the samples. Optimal conditions for extraction were obtained using a response surface methodology reached from a central composite design. The MIEL extraction has been compared with a conventional technique soxhlet extraction. The extracts of quinoline alkaloids from C. succirubra obtained by these two different methods were compared by HPLC. The extracts obtained by MIEL in 32 min were quantitatively (yield) and qualitatively (quinine, quinidine, cinchonine, cinchonidine) similar to those obtained by conventional Soxhlet extraction in 3 hours. MIEL is a green technology that serves as a good alternative for the extraction of Cinchona alkaloids.     

A remarkable influence of microwave extraction: Enhancement of antioxidant activity of extracted onion varieties

Four (red, yellow, white and grelot onion) varieties of Allium cepa, a rich source of quercetin (flavonol) glycosides, were studied for their total content of reducing compounds (TCRC), flavonol content and antioxidant activity evaluation. Extracts obtained by solvent free microwave hydrodiffusion and gravity (MHG) technique and conventional solvent extraction (CSE) were analysed with high performance liquid chromatography (HPLC) for quantification of flavonoids. Three different methods were selected for evaluating the antioxidant capacity of the different onion varieties (after the determination of their phenolic content by the Folin–Ciocalteu method): the reduction of the stable DPPH (2,2-diphenyl-1-picrylhydrazyl) radical, the ORAC (oxygen radical absorbance capacity) method, and the inhibition of the AAPH-induced peroxidation of linoleic acid in SDS micelles. The highest antioxidant capacity was observed for red onion, followed by yellow, white and grelot onion. In spite of the low recovery of extractable flavonoids (quercetin 3,4′-diglucoside, 4′-glucoside and 3-glucoside), MHG remained the preferred extraction method in comparison to the conventional method, as all the samples obtained under microwave-assisted extraction (MAE) exhibited the highest antioxidant activities in all the tests. Also the microscopic observations of extracted tissues showed that at cellular level, microwaves induced disruptions of vacuoles and cell walls thus promoting the effectiveness of this method.     

A bittersweet symphony: Systematically modulating the taste of food by changing the sonic properties of the soundtrack playing in the background

We report an experiment designed to investigate the consequences of manipulating the pitch of the background auditory stimulation on the taste of food. The participants in the present study evaluated four pieces of cinder toffee while listening to two auditory soundtracks, presented in a random order. One soundtrack was designed to be more crossmodally (or “synaesthetically”) congruent with a bitter-tasting food whereas the other soundtrack was designed to be more congruent with a sweet-tasting food instead. The participants rated each sample using three computer based line scales: One scale was anchored with the words bitter and sweet. The second scale required participants to localize the taste/flavour percept elicited by the food (at the front vs. back of their mouth). The third scale involved participants giving a hedonic evaluation of the foodstuff. As expected, the cinder toffee samples tasted while listening to the presumptively ‘bitter’ soundtrack were rated as tasting significantly more bitter than when exactly the same foodstuff was evaluated while listening to the ‘sweet’ soundtrack instead. These results provide the first convincing empirical demonstration that the crossmodal congruency of a background soundtrack can be used to modify the taste (and presumably also flavour) of a foodstuff.     

An Improved Ultrasound Clevenger for Extraction of Essential Oils

A new process employing ultrasound technology to improve hydrodistillation extraction was designed and developed. The extraction process (sono-Clevenger) was performed under simultaneous sonication using an ultrasonic horn in situ to provide rapid and complete recovery of analytes from the matrix. The extraction of essential oil from orange peels with conventional Clevenger extraction was compared with the sono-Clevenger process using physicochemical characterization and gravimetric analysis. The new procedure provided a substantial reduction in the extraction time when compared to conventional process without interfering on composition of target compounds.     

Lab and pilot-scale ultrasound-assisted water extraction of polyphenols from apple pomace

Apple pomace, a residue from juice or cider production, shows high content of exploitable polyphenols. In this work, apple pomace was submitted to an Ultrasound-Assisted Extraction (UAE) in order to produce extracts rich in antioxidants. After a preliminary study, a solid/liquid ratio of 150 mg of dry material per mL was used, and optimized conditions obtained by response surface methodology for polyphenols water-extraction were 40 °C, 40 min and 0.764 W/cm². A comparison showed Total Phenolics Content (TPC) obtained by UAE was 30% higher than the content obtained by Conventional Extraction (CE)(555 and 420 mg of catechin equivalent per 100 g of dry weight, respectively) and both methods presented the same extraction kinetics. Furthermore, extracts obtained by ultrasound showed higher antioxidant activity, which was confirmed by HPLC analysis, that revealed main polyphenols were not degraded under the applied conditions. The large scale experiments of this ultrasound procedure showed a potential industrial application.     

Microwave steam diffusion for extraction of essential oil from orange peel: Kinetic data,extract’s global yield and mechanism

The microwave steam diffusion (MSDf) apparatus for extraction of essential oils from orange peel (by-products) was studied. MSDf has been compared with conventional steam diffusion (SDf). A response surface methodology (RSM) was realised to investigate the influence of process variables by a central composite design (CCD) approach. The statistical analysis revealed that the optimal conditions for the extraction of orange essential oil were a steam mass flow rate of 25 g min⁻¹ and a microwave power of 200 W. Cytohistological investigations using light microscopy provided evidences for rapid and pronounced cell and tissue alterations of oil glands with MSDf in comparison with SDf. The essential oils extracted by MSDf for 12 min were quantitatively (yield) and qualitatively (aromatic profile) similar to those obtained by SDf for 40 min. Extraction of essential oils from orange peel with MSDf was better than SDf in terms of energy saving, cleanliness and reduced waste water.     

Ultrasound-assisted extraction of polyphenols (flavanone glycosides) from orange (Citrus sinensis L.) peel

The present study reports on the extraction of polyphenols especially flavanones from orange (Citrus sinensis L.) peel by using ethanol as a food grade solvent. After a preliminary study showing that the best yield of extraction was reached for a particle size of 2 cm², a response surface methodology (RSM) was launched to investigate the influence of process variables on the ultrasound-assisted extraction (UAE) followed by a central composite design (CCD) approach. The statistical analysis revealed that the optimised conditions were a temperature of 40 °C, a sonication power of 150 W and a 4:1 (v/v) ethanol:water ratio. The high total phenolic content (275.8 mg of gallic acid equivalent/100 g FW), flavanone concentrations (70.3 mg of naringin and 205.2 mg of hesperidin/100 g FW) and extraction yield (10.9 %) obtained from optimised UAE proved its efficiency when compared with the conventional method. Furthermore, the antioxidant activity determined by the DPPH and ORAC tests confirmed the suitability of UAE for the preparation of antioxidant-rich plant extracts.     

The impact of pleasantness ratings on crossmodal associations between food samples and musical notes

Although several crossmodal associations involving taste and olfaction have been reported recently, the mechanism(s) by which they operate are still poorly understood. In the present study, we explored the role of a single parameter that has been suggested to play an important role in taste/flavour-musical note association, namely pleasantness. Chocolate was chosen as a stimulus as it elicits a wide range of pleasantness ratings (especially in the case of dark chocolate). Participants tasted three types of chocolate (dark, milk, and marzipan-filled) and had to match their flavour with a musical note (choosing both the pitch and the instrument playing the note). The results demonstrated that, while there was an overall correlation between pleasantness ratings and the chosen pitch, it disappeared when a single stimulus was considered in isolation, suggesting that pleasantness is not solely responsible for the associations between tastes/flavours and pitch. By contrast, pleasantness affects the choice of instrument even when a single stimulus is considered. The role of pleasantness in driving associations between tastes/flavours and musical notes, while important in the choice of instrument, is thus not as essential for the choice of pitch as has been suggested previously.     

First investigation on ultrasound-assisted preparation of food products: sensory and physicochemical characteristics

This paper presents a comparison between manufactured food products using conventional and ultrasound-assisted procedures. Three different foam-type products, chocolate Genoise, basic sponge cake, and chocolate mousse were prepared using both methods with subsequent evaluation of the samples using both sensory and physicochemical methods. Ultrasound-assisted preparations were considered superior according to the sensory analysis, and physicochemical data confirmed this finding. This approach of applying an emerging piece of equipment, with potential industrial application to assist food preparation, consists of a new technique that could be of great interest for the development of not only other food products created by molecular gastronomy but also for practical work carried out by students.