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Synthesis of ethyl acetate (EA) using lipase as a catalyst, as an environmentally-friendly process, has attracted considerable attention. However, the slow rate of enzymatic reaction and higher cost limit its applications. Ultrasound irradiation (UI) is known as an effective tool for accelerating the rate of enzymatic reaction under mild conditions. To attain maximum yield, it is crucial to understand the effect of UI on EA synthesis and the underlying mechanism. Therefore, the present study investigated the effect of UI on lipase-catalyzed ethyl acetate synthesis. The results clearly demonstrated that UI could remarkably accelerate the process of lipase-catalyzed synthesis of ethyl acetate compared with mechanical shaking. The optimal conditions of ultrasound-assisted reaction by using Novozyme 435® were 6% enzyme loading, 4:1 molar ratio of ethanol to acetic acid, 150 W & 28 kHz ultrasonic power and frequency, respectively. Bi-bi ping-pong model was employed to give a deep insight into the underlying mechanism of the beneficial effect of UI. It was found that Vmax under UI was elevated by 143% compared with that under mechanical shaking. Application of UI could decrease Kacetic acid and Ki ethanol while increase Kethanol and Ki acetic acid. In conclusion, the present study addresses that UI could remarkably accelerate the process of lipase-catalyzed synthesis of EA compared with mechanical shaking, and kinetic model results explained why ultrasound can significantly speed up lipase catalyzed synthesis of ethyl acetate, which may help to improve the industrial application potential of ethyl acetate biosynthesis.

In this study, biodiesel was produced from high free fatty acid (FFA) oil obtained from waste olives, whose food quality deteriorated by falling from the tree to the ground. The FFA value of the oil obtained from waste olives was determined as 23% by titration method. In order to produce biodiesel with high conversion efficiency, esterification process was carried out to reach at least 1% FFA value in the first stage of the study. Acid esterification experiments were designed according to Taguchi's L-16 (4(2) 2(1)) orthogonal array. The amount of sulfuric acid catalyst, methanol ratio, and mixing speed were taken as the test variables for the esterification process. For the lowest FFA value, optimum test parameters were determined using the signal-to-noise (S/N) ratio. In the biodiesel production stage, ultrasound-assisted transesterification method was preferred in terms of high conversion efficiency and short reaction duration. According to the results, it was determined that the optimum reaction conditions in the esterification process were 25% by weight acid catalyst (according to the weight of the FFA in the oil), 22:1 methanol molar ratio in terms of fatty acids, and 400 rpm mixing speed. At these reaction conditions, the FFA of the oil was reduced from 23 to 0.608% in a single step. In the ultrasound-assisted process, Waste olive oil methyl ester (WOOME) conversion yield of 98.7% was achieved in a reaction time of 10 min. The fuel properties of WOOME (also called biodiesel) were determined to be within the EN 14214 standard. As a result, optimization was made to minimize the use of alcohol and catalyst in the acid esterification process. Also, time and energy savings were achieved in biodiesel production with ultrasound-assisted.

The preparation and characterization of biodegradable films based on starch-PVA-nanoclay by solvent casting are reported in this study. The films were prepared with a relation of 3:2 of starch:PVA and nanoclay (0.5, 1.0, and 1.5% w/v), and glycerol as plasticizer. The nanoclays before being incorporated in the filmogenic solution of starch-PVA were dispersed in two ways: by magnetic stirring and by sonication. The SEM results suggest that the sonication of nanoclay is necessary to reach a good dispersion along the polymeric matrix. FTIR results of films with 1.0 and 1.5% w/v of sonicated nanoclay suggest a strong interaction of hydrogen bond with the polymeric matrix of starch-PVA. However, the properties of WVP, tensile strength, percentage of elongation at break, and Young’s modulus improved to the film with sonicated nanoclay at 0.5% w/v, while in films with 1.0 and 1.5% w/w these properties were even worse than in film without nanoclay. Nanoclay concentrations higher than 1.0 w/v saturate the polymer matrix, affecting the physicochemical properties. Accordingly, the successful incorporation of nanoclays at 0.5% w/v into the matrix starch-PVA suggests that this film is a good candidate for use as biodegradable packaging.

In order to extract antioxidant phenolic compounds from spent grain (SG) two extraction methods were studied: the ultrasound-assisted method (US) and the Ultra-Turrax method (high stirring rate) (UT). Liquid to solid ratios, solvent concentration, time, and temperature/stirring rate were optimized. Spent grain extracts were analyzed for their total phenol content (TPC) (0.62 to 1.76 mg GAE/g SG DW for Ultra-Turrax pretreatment, and 0.57 to 2.11 mg GAE/g SG DW for ultrasound-assisted pretreatment), total flavonoid content (TFC) (0.6 to 1.67 mg QE/g SG DW for UT, and 0.5 to 1.63 mg QE/g SG DW for US), and antioxidant activity was measured using 2,2-diphenyl-2-picrylhydrazyl (DPPH) free radical (25.88% to 79.58% for UT, and 27.49% to 78.30% for UT). TPC was greater at a high stirring rate and high exposure time up to a certain extent for the Ultra-Turrax method, and at a high temperature for the ultrasound-assisted method. P-coumaric acid (20.4 ± 1.72 mg/100 SG DW for UT, and 14.0 ± 1.14 mg/100 SG DW for US) accounted for the majority of the phenolic found compounds, followed by rosmarinic (6.5 ± 0.96 mg/100 SG DW for UT, and 4.0 ± 0.76 mg/100 SG DW for US), chlorogenic (5.4 ± 1.1 mg/100 SG DW for UT, and non-detectable for US), and vanillic acids (3.1 ± 0.8 mg/100 SG DW for UT, and 10.0 ± 1.03 mg/100 SG DW for US) were found in lower quantities. Protocatechuic (0.7 ± 0.05 mg/100 SG DW for UT, and non-detectable for US), 4-hydroxy benzoic (1.1 ± 0.06 mg/100 SG DW for UT, and non-detectable for US), and caffeic acids (0.7 ± 0.03 mg/100 SG DW for UT, and non-detectable for US) were present in very small amounts. Ultrasound-assisted and Ultra-Turrax pretreatments were demonstrated to be efficient methods to recover these value-added compounds.

This study aimed to determine optimal extraction parameters by using response surface methodology, examining the effect of microencapsulation on crocin retention, and evaluating the temperature and pH stability of crocin microcapsules. The effect of process variables on the crocin yield was successfully determined by quadratic models (R 2 > 0.99 and adj R 2 > 0.98). All variables significantly affected the crocin yield (P < 0.1). The process parameters, namely extraction time (4.40 min), temperature (55 °C), amplitude level (94%), and liquid to solid ratio (L/S) (1000) were determined as optimum extraction points. Safranal was shown to be a compound with major volatility in both the saffron and microcapsule extracts. Safranal, 2,4,4-trimethyl-3-carboxaldehyde-5-hydroxy-2,5-cyclohexadiene-1-one, 4-hydroxy-2,6,6-trimethyl-1-cyclohexene-1-carboxaldehyde (HTCC), and isophorone were other major volatile compounds of saffron extract. The encapsulation process affected volatile percentage distribution insignificantly (P > 0.05). The thermal and pH stability of the crocin was determined at different temperatures (60, 70, 80, and 90 °C) and pH levels (2, 4.5, and 6). The crocin degradation showed first order kinetic, and degradation rate constant (k) were significantly affected by pH and temperature (P < 0.05). A high temperature and low pH showed higher degradation (k) in crocin content. This study suggested that crocin from saffron stigmas should be preserved by spray drying encapsulation and should only be used as a natural food colorant in low or moderate acid food. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.

Ultrasound-assisted melt-extrusion method (USME) is a high-quality process used to produce polymeric compounds with an adequate homogeneous dispersion. This study evaluates white-color films of linear low-density polyethylene (LLDPE) prepared using TiO2 masterbatch obtained by ultrasound-assisted melt-extrusion at variable frequencies (USME-VF). LLDPE with three different melt-flow indices (2, 20 and 50 g/10 min) were used as the polymer matrix. The films were obtained from the dilution of masterbatches of LLDPE (melt-flow index = 2) at a concentration of 7 wt% TiO2. The morphology, pigmentation, TiO2 reactivity, and the mechanical stability of the films were assessed. The masterbatch compounds were evaluated by melt-flow index (MFI) and scanning electron microscopy (SEM). The contrast ratio, yellowness index and mechanical properties of films were also measured. The properties of whiteness and elongation at break improved in the films prepared using masterbatches with higher dispersion. Though the reactivity of the TiO2 particles increased during accelerated aging, it did not affect the elongation to rupture. The yellowness index was moderately affected in films that included TiO2 particles processed using USME-VF.

A facile synthesis of hitherto unreported 3-(2-benzofuroyl)carbazoles 3a–k, 3,6-bis(2-benzofuroyl)carbazoles 5a–k, and naphtho[2,1-b]furoylcarbazoles 3l and 5l is described. The synthesis mainly relies on the ultrasound-assisted Rap–Stoermer reaction of 3-chloroacetyl- (1) or 3,6-dichloroacetyl-9-ethyl-9H-carbazole (4) with various salicylaldehydes 2a–k as well as 2-hydroxy-1-naphthaldehyde (2l) in CH3CN with the presence of PEG-400 as catalyst. The procedure offers easy access to benzofuroylcarbazoles in short reaction times and the products are obtained in moderate to good yields.

© 2015 Elsevier Ltd. Herein, we developed a novel integrated device to perform phase separation based on ultrasound-assisted, salt-induced, liquid-liquid microextraction for determination of five fluoroquinones in meats by HPLC analysis. The novel integrated device consisted of three simple HDPE (high density polyethylene) parts that were used to separate the solvent from the aqueous solution prior to retrieving the extractant. The extraction parameters were optimized using the response surface method based on central composite design: 589μL of acetone solvent, pH2.1, 4.1min extraction time and 3.5g of Na2SO4. The limits of detection were 0.056-0.64μgkg-1 and recoveries were 87.2-110.6% for the five fluoroquinones in muscle tissue from fish, chicken, pork and beef. This method is easily constructed from inexpensive materials, extraction efficiency is high, and the approach is compatible with HPLC analysis. Thus, it has excellent prospects for sample pre-treatment and analysis of fluoroquinones in meat samples.

Background Extraction prior to component analysis is the primary step in the recovery and isolation of bioactive phytochemicals from plant materials. Methods Response surface methodology was applied to optimize ultrasound-assisted extraction conditions followed by ultra high performance liquid chromatography (UHPLC) to achieve high catechin, myricetin, and quercetin contents, and high antioxidant and anticancer activities in the curry leaf extracts. The antioxidant and anticancer activities of the leaf extracts were determined by the 1,1-diphenyl-2-picryl-hydrazyl (DPPH) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays, respectively. The central composite experimental design (3-level, 3-factorial) was employed to consider the effects of ultrasonic power (80–150 W), temperature (40–80°C), and methanol dilution (40–80%) on the properties of the curry leaf extracts. Results It was found that ultrasonic power of 145.49 W at 55.9°C with 80% methanol was the most appropriate set of conditions for the extraction of catechin, myricetin, and quercetin from curry leaves with the consequent high antioxidant activity. Using the optimum extraction conditions, the extraction yields of catechin, myricetin, and quercetin were 0.482, 0.517, and 0.394 mg/g DW, respectively, and the antioxidant activity was enhanced to 83%. The optimized extract showed more distinct anticancer activity against HeLa cancer cells in a concentration of 67.2 μg/mL (P

In this study, the bioactive compounds of loquat fruit (Eriobotrya japonica Lindl.) skin and pulp extracted by two extraction methods (solvent and ultrasound‐assisted) with three solvents (ethanol, water and ethanol–water) were compared to supercritical fluid extraction. The antioxidant activities of skin and pulp extracts were evaluated and compared to tertiary butylhydroquinone (TBHQ) using 2, 2‐diphenyl‐1‐picrylhydrazyl (DPPH˙) radical scavenging, β‐carotene bleaching, and the Rancimat assays. In DPPH assay solvent extracts of skin by ethanol (SSE) and ethanol–water (SSEW) showed strong inhibitory activity. The SSEW also showed the highest inhibition percentage of 85.58% by the β‐carotene bleaching assay and longest induction time of 4.78 h by the Rancimat method. The large amount of tocopherols and phenolics contained in the skin extract may cause its strong antioxidant ability. The results indicated that the solvent extraction with ethanol–water produced the maximum extraction yield of phenolic and tocopherol compounds from loquat fruit skin and pulp. Furthermore, solvent extraction was the most effective in antioxidant activity of the extracts compared to other extraction techniques.