Impact of ultrasound on solid-liquid extraction of phenolic compounds from maritime pine sawdust waste. Kinetics, optimization and large scale experiments

Chemical composition and radical scavenging activity of Amygdalus pedunculata Pall leaves' essential oil

The main objective of the current study was to investigate the components and radical scavenging activity of essential oil from Amygdalus pedunculata Pall leaves (APEO) extracted by an ultrasound-assisted method. Thirty-eight chemical components were identified in APEO using gas chromatography-mass spectrometry (GC-MS). APEO primarily consisted of alcohols (36.82%), esters (28.81%), ketones (1.47%), alkanes (18.61%) and phenols (8.93%). The most abundant compound was n-hexanol (33.49%). The antioxidant activity of APEO was characterized for 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, hydroxyl radical (OH·), hydrogen peroxide (H₂O₂), and superoxide anion radical (O₂·^-) scavenging and Fe³⁺ reduction, and the IC₅₀ values were 2.32, 2.65, 2.42, 5.24 and 4.19 mg/mL, respectively. The IC₅₀ values for H₂O₂ scavenging and Fe³⁺ reduction of APEO were less than those of ascorbic acid (Vc; 3.15 and 5.13 mg/mL). The results showed that APEO has a high radical scavenging activity.

Study of a laboratory-scaled new method for the accelerated continuous ageing of wine spirits by applying ultrasound energy

During the ageing of brandies, many physicochemical processes take place involving the distilled spirit and the wood of the casks. Because of these reactions, the polyphenolic content of brandies and their content of organic acids increase with the ageing. These reactions are slow, and the ageing of high-quality brandies takes several years. In this paper, the development of a system that uses the circulation of the wine distillate through encapsulated American oak chips and the application of ultrasound energy with the aim of producing aged wine spirits has been carried out, and the influences of the operation variables over the characteristics of the produced drink have been measured. With that proposal, the influence of different powers of ultrasound, and also the influence of the movement of the liquor through oak chips, was determined first. This way, the results show that higher powers of ultrasound, of nearly 40W/L, in addition with the movement of the spirit, improve the extraction of phenolic compounds in a 33.94%, after seven days of ageing. Then, applying Youden and Steiner's experimental design, eight experiments of ageing were performed, and the samples obtained by this new method were analysed to obtain information related to their physicochemical and oenological characterisation in order to determine the experimental conditions that produce the best ageing results. This way, the best spirit produced by this new method of ageing is obtained with a high alcoholic strength of the distilled wine and a high quantity of oak chips, and with room temperature and high flow rate. In addition, the presence of oxygen in the sample and the absence of light increase the quality of the produced spirit. Finally, the application of ultrasound energy in large pulses is related with the improvement of two important ageing markers: the intensity of the colour and the TPI. As a last experiment, we applied this ageing method to five varietal spirits. The sensorial analysis of aged samples showed the aged spirits had better ratings than the initial distilled wine.

Kinetics of ultrasound-assisted extraction of antioxidant polyphenols from food by-products: Extraction and energy consumption optimization

Ultrasound-assisted extraction (UAE) of antioxidant polyphenols from chicory grounds was studied in order to propose a suitable valorization of this food industry by-product. The main parameters influencing the extraction process were identified. A new mathematical model for multi-criteria optimization of UAE was proposed. This kinetic model permitted the following and the prediction of the yield of extracted polyphenols, the antioxidant activity of the obtained extracts and the energy consumption during the extraction process in wide ranges of temperature (20-60°C), ethanol content in the solvent (0-60% (vol.) in ethanol-water mixtures) and ultrasound power (0-100W). After experimental validation of the model, several simulations at different technological restrictions were performed to illustrate the potentiality of the model to find the optimal conditions for obtaining a given yield within minimal process duration or with minimal energy consumption. The advantage of ultrasound assistance was clearly demonstrated both for the reduction of extraction duration and for the reduction of energy consumption.

Ultrasound induced green solvent extraction of oil from oleaginous seeds

Ultrasound-assisted extraction of rapeseed oil was investigated and compared with conventional extraction for energy efficiency, throughput time, extraction yield, cleanness, processing cost and product quality. A multivariate study enabled us to define optimal parameters (7.7 W/cm(2) for ultrasonic power intensity, 40 °C for processing temperature, and a solid/liquid ratio of 1/15) for ultrasound-assisted extraction of oil from oilseeds to maximize lipid yield while reducing solvent consumption and extraction time using response surface methodology (RSM) with a three-variable central composite design (CCD). A significant difference in oil quality was noted under the conditions of the initial ultrasound extraction, which was later avoided using ultrasound in the absence of oxygen. Three concepts of multistage cross-current extraction were investigated and compared: conventional multistage maceration, ultrasound-assisted maceration and a combination, to assess the positive impact of using ultrasound on the seed oil extraction process. The study concludes that ultrasound-assisted extraction of oil is likely to reduce both economic and ecological impacts of the process in the fat and oil industry.