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Fe-bentonite is used as a catalyst for the alkylation of phenol using tert-butanol. Bentonite was modified by loading with the known concentrations of Fe/Zn/Zr. Series of catalysts such as Fe-bentonite, Zn-bentonite and Zr-bentonite were prepared by ion-exchange method and were used for the synthesis of p-tert-butylphenol (PTBP) by alkylation of phenol with tert-butylalcohol (TBA) in a batch process. Fe-bentonite was found to be an excellent catalyst with 100% TBA conversion and 81% selectivity for PTBP at 80°C. All the catalysts have been analyzed by different characterization methods, FTIR, XRD, TEM, SEM, and BET. The effect of various parameters like catalyst screening, reaction time, temperature, and the molar ratio of the reagents have been tested to obtain the best conversion and selectivity for the desired product.

Conventional methods of extracting bioactive molecules are gradually losing pace due to their numerous disadvantages, such as product degradation, lower efficiency, and toxicity. Thus, in light of the rising demand for these bioactive, enzymes have garnered much attention for their efficiency in extraction. However, enzyme-assisted extraction is also plagued with a high capital cost that cannot justify the extraction yields obtained. In order to mitigate these problems, enzyme-assisted extraction can be consorted with non-conventional methods. This review includes current progress concerning the combined approaches while converging the recent advancements in the field that outperformed conventional extraction processes. It also highlights the design of biocatalyst and key parameters involved in the effective extraction of bioactive molecules. An integrated approach for efficiently extracting polyphenols, essential oils, pigments, and vitamins has been comprehensively reviewed. Furthermore, the different immobilization strategies have been discussed for large-scale implementation of enzymes for extraction. The integration of advanced non-conventional methods with enzyme-assisted extraction will open new avenues to enhance the overall extraction efficiency.

The production of xylanase from Lechevalieria aerocolonigenes using reetha seed waste as substrate was studied using sequential optimization of fermentation parameters by response surface methodology. Five different lignocellulosic agricultural wastes as a substrate were studied to replace commercially available xylan, amongst which reetha seed waste was found to be the most suitable substrate for xylanase production. A sequential two-stage optimization strategy was used for the fermentation parameter optimization. The Plackett-Burman design was first employed for screening the 6 different physicochemical parameters affecting xylanase production (inoculum concentration, substrate concentration, temperature, pH, media volume, and agitation). The significant factors affecting the xylanase yield were further optimized by Box-Behnken Design in order to obtain the values contributing the highest enzyme yield. Three parameters, namely, temperature, inoculum concentration, and substrate concentration, can be interpreted as the most significant parameters based on the results of Plackett-Burman design. The optimum values by Box-Behnken Design (BBD) are 35 °C temperature, 3 g/L substrate concentration, and inoculum concentration of 4% (v/v) that resulted in maximum xylanase productivity of 5.75 IU/mL at 24 h of the incubation period. Sequential optimization strategy enhanced the xylanase yield by 4.8 fold to that of an unoptimized process.

The majority of the naturally occurring antioxidants are obtained from plant sources. The antioxidant activity is mostly exhibited by polyphenols present in the plant cells. Azadirachta Indica (Neem) leaves are renowned for their medicinal applications due to their anti-inflammatory, antimalarial, antifungal, antibacterial, antiviral, antioxidant, and anticarcinogenic properties. This work aims to optimize the extraction of Azadirachta Indica (Neem) leaf antioxidants using three-phase partitioning (TPP). The optimized conditions are operating time 15 minutes, slurry ratio 1:30 (g/mL), salt concentration 30% (w/v), aqueous to solvent ratio 1:1.5 (v/v), and stirring speed 400 rpm that infer 74.66% extraction yield. Additionally, ultrasonic pretreatment was also employed to increase the extraction yield up to 86.61%. Sonication pretreatment for 4 min operated at 30 W power, and 75% duty cycle was observed to offer maximum antioxidant extraction about 3.3 mg/g.

The current research work focuses on the conventional bio-catalysed synthesis of amyl levulinate with immobilized Candida antarctica lipase B in the absence of a toxic solvent. The green catalyst and solvent free system offered considerable benefits like mild and gentle condition requirement, lesser-energy demand, easy down-streaming and reusability of the biocatalyst. The process parameters were examined, and the maximum conversion (73.2%) was obtained under the optimum condition of 50℃ temperature, 1:3 molar ratio of levulinic acid to amyl alcohol using 0.8% (w/v) biocatalyst at 250 rpm speed. The immobilized lipase was characterized by SEM, BET, XRD, FTIR and amyl levulinate was characterized by FTIR and GC-MS analysis. The enzyme lipase was effectively reused till 5 cycles for the formation of ester. The thermodynamic parameters (ΔH, ΔG, and ΔS) and energy of activation (Ea) were determined for the assessment of energy requirement. The activation energy was determined to be 48.42 kJ/mol. The research protocol strikes the development of biocatalytic synthetic route of amyl levulinate without using any toxic solvent, which may contribute to green chemistry approach.

The ultrasound-assisted extraction of Total Phenolic Content from Sesbania grandiflora L. leaves and its optimization with kinetics is dealt with in this study. The effect of extraction of solvents...

Diabetes is one of the leading causes of morbidity and mortality worldwide. Replacement of the chemically synthesized medicines with phytomedicines is of great importance. Syzygium cumini fruit has around 30% hard seed kernel part that is considered solid waste and can be a good source of bioactive phenolic compounds. Thus, this work was performed to valorize Syzygium cumini kernels powder (SCKP) using a three-phase partitioning technique (TPP) and evaluate in vitro antioxidant and hypoglycemic activities. The extraction yield of catechin, gallic acid, TFC, and TPC obtained through TPP was 0.52, 33.24 mg/g, 7.78 mg CE/g, and 82.66 mg GAE/g, respectively, in 45 min, 40% ammonium sulfate, 1:1 (V/V) extraction slurry to t-butanol, 30 ± 2 °C temperature, pH 4, 1:20 (g/mL) SCKP to water and SCKP size 106 µm. IC50 values 12.15, 9.33, and 7.55 in µg/mL for TPP extract were obtained from DPPH, α-amylase, and α-glucosidase in vitro assays, respectively. TPP for extraction of bioactive compounds was found superior over traditional extraction techniques (devoid of t-butanol and ammonium sulfate). The extract obtained shows enormous antioxidant and hypoglycemic potential for use in nutraceutical and pharmaceutical industries.HighlightsFirst report on three-phase partitioning (TPP) extraction of catechin and gallic acid from SCKP.Effective extraction of total phenolic and flavonoid compounds.Proved the enormous antioxidant and hypoglycemic potential of SCKP's TPP extract.TPP extraction, the selective, efficient, and economically viable option.

Natural Deep Eutectic Solvents (NADESs) have attracted growing interest in the scientific community as an alternative to conventional organic solvents and are exclusively made up of naturally occurring non-toxic, environment friendly compounds. In the present study, NADESs based on choline chloride and carboxylic acids are presented as new and green extraction media for glycyrrhizic acid (GA) extraction from Glycyrrhiza glabra. Initial solvent screening indicated that the highest extraction yield was achieved using choline chloride-lactic acid mixture at mole ratio 1:1. Various extraction conditions were optimized, such as 30 % water in choline chloride:lactic acid NADES, liquid/solid ratio 40:1 (v/w, mL/g), temperature 40℃, agitation speed 400 rpm, and extraction time 30 min yielding 53.72 ± 0.57 mg/g GA. The NADES extraction method successfully provided enhanced yield and improved in-vitro anti-inflammatory activity, which was assessed using human red blood cell membrane stabilization method. In addition, it was found to be energy efficient and economical compared to conventional extraction techniques. SEM was performed to study the surface morphology of Glycyrrhiza glabra powder before and after extraction. Also, FTIR was used to provide information about hydrogen bonding in NADES. The results presented valuable information towards NADES implementation for designing of extraction process for bioactive compounds.

Custard apple (Annona Squamosa) seed is mainly an agricultural waste generated in many fruit and pulp industries. The seeds are an important source of value added products such as oil, polyphenols, and acetogenins, possessing medicinal properties and having excellent market potential. The current work aims at developing an intensified method to extract volatile and non-volatile components from custard apple seeds using supercritical CO2 extraction (SC−CO2) with detailed process optimization so as to establish conditions for maximum yield. The maximum extraction of non-volatile components was obtained at optimized conditions of 25 MPa pressure, 318 K temperature, and 2.5 mL/min flow rate. The extraction of volatile oils was maximum under conditions of 15 MPa pressure, 308 K temperature, and 1.5 mL/min. The extraction was observed to be complete within 1 h due to an increase in permeability based on the action of high pressure SC−CO2, as also evident from the results of scanning electron microscopy (SEM) imaging. The antibacterial and antifungal properties of the obtained extract were also demonstrated in the work. The total number of energy units required for 1 kg extract production was calculated to be 40.69 kW h.

The present study evaluates the potential use of ultrasound irradiation to synthesize decyl oleate using Fermase CALBTM10000 under the solvent-free system (SFS). The optimal condition to achieve a maximum yield of 97.14% was found to be 1:2 oleic acid:decanol ratio, 1.8% (w/w) enzyme loading, 45°C temperature, 200 rpm agitation speed, 50 W power input, 50% duty cycle, 22 kHz frequency and reaction time of 25 minutes. The thermodynamic study was done to determine the change in entropy, Gibb's free energy, and change in enthalpy at various temperatures. The experimental results and kinetic study showed that the reaction followed ordered bi-bi model with kinetic parameters as rate of reaction (V max ) = 35.02 M/min/g catalyst, Michaelis constant for acid (K A ) = 34.47 M, Michaelis constant for alcohol (K B ) = 3.31 M, Inhibition constant (Ki) = 4542.4 M and sum of square error (SSE) = 0.000334. The application of ultrasound irradiation combined with biocatalyst and the absence of solvent intensified the process compared to the traditional stirring method using hexane as solvent.

Syzygium cumini, owing to higher bioactive constituents, its parts principally kernels are used for the antidiabetic purpose since the olden days. The current manuscript illustrated batch extraction of phenolic compounds from S. cumini using a stirred extractor. The yields 0.61 mg/g, 35.9 mg/g, 79.89 mg GAE/g, and 7.29 mg CE/g of catechin, gallic acid, TPC and TFC, respectively, were obtained in 105 min. at 1:20 SCKP to water, 50 ± 2 °C temperature, 4 pH, at 250 rpm and 106 µm particle size of SCKP. In vitro evaluation of the antioxidant and antidiabetic potential of the obtained aqueous extract was carried out by DPPH, α-amylase, and α-glucosidase inhibitory assays. The IC50 values of SCKP aqueous extract obtained were 12.97, 9.03, and 7.13 µg/mL for DPPH scavenging, inhibition of α-amylase, and α-glucosidase, respectively. The cost required to extract 1 kg of catechin, gallic acid, TPC, and TFC was Rs 6691.6, 113.7, 51.1, and 559.93/-, respectively. Stirred batch extraction technique manifests traditional but simple, ecofriendly, and efficient compared to other traditional techniques. The output of this research bestows support to utilize the SCKP stirred batch extract as a promising source of antioxidant and antidiabetic compounds in ayurvedic formulations.

Aegle marmelos is a prominent tree in Indian Ayurveda and occupies an important place in Ayurvedic, Unani and Siddha system of Indian medicine due to its ethnomedicinal values. The current work dem...

In the present work, ultrasound was combined with three-phase partitioning (UA-TPP) for the extraction of curcuminoids from Curcuma longa. The effect of various process parameters viz. solvents, irradiation time, ammonium sulphate concentration, ratio of turmeric aqueous slurry to t-butanol, turmeric powder to aqueous ratio, and ultrasonic power along with duty cycle on UA-TPP was examined. The yield of 67.15 mg/g was achieved using UA-TPP in 20 min irradiation time at room temperature (30 ± 2 °C) using 30% (w/v) ammonium sulphate saturation, 1:1 (v/v) turmeric aqueous slurry to t-butanol ratio, 1:30 (w/v) turmeric powder to solvent ratio with 22 kHz frequency, 60 W power and 60% (6 sec ON and 4 sec OFF) duty cycle. The comparison study was done based on extraction yields, time, energy requirement and process cost required by UA-TPP, conventional TPP and Soxhlet. UA-TPP found useful not only to enhance the process but also to improve the antioxidant capacity and anti-inflammatory activity of the extract in comparison with TPP.

The immobilization of enzyme with enhanced catalytic activity is the major challenge. In this work, we have activated the lipase in the presence of proline and successfully immobilized into zeolitic imidazolate framework (ZIF)-8 by biomineralization method. The prepared lipase-proline MOF exhibited 135% enhanced catalytic activity as compared to free counterpart. Further, it exhibited four-fold improved thermal stability with respect to native enzyme after immobilization. In Michaelis-Menten kinetic studies, Km values for lipase-proline MOF were found to be lower, whereas, it exhibited higher Vmax than lipase-MOF and free lipase. The lipase-MOF and lipase-proline MOF were showed 56% and 72% residual activity, respectively after six cycles of reuse.

Aqueous two-phase extraction of wedelolactone from Eclipta alba was studied using the polymer-salt system. The system consisted of polyethylene glycol (PEG) as a top phase (polymer) and sodium citr...

The present study focuses on ultrasound assisted enzyme catalysed synthesis of pleasing flavour and fragrances ester product from caprylic acid and butanol with immobilised Novozym 435 as a catalys...

In this work, a novel approach was developed to synthesis advance magnetic nano-catalyst; Fe3O4@Chitosan –AgNP nanocomposite. It is made up of chitosan (fish industry-waste) doped onto the magnetic core with active silver nanoparticles on the exterior shell using NaBH4 as reductant and total soluble solids (dairy effluent-waste) as a stabilizing agent. TEM images confirm the average mean diameter of composed nanocatalyst about 8 ± 2.2 nm. SEM images, EDX spectra, and ICP-MS data confirmed the co-presence of Ag, Fe, C, and O elements with a calculated percentage weight of Ag as 8.15%. XRD patterns revealed the product was chitosan doped iron oxide with surfaced silver nanoparticles. XPS and FTIR confirm composition, elemental electronic state, and binding energy. Additionally, it is utilized as an effective solid-phase catalyst for the reduction of anthropogenic pollutant p-nitrophenol to p-aminophenol. It has a very convenient magnetic separability. ICP-Ms data for cumulative silver release shows prepared nanocatalyst remains active and stable even after recycled for more than 15 times. Also, an excellent antifungal activity was observed against the agricultural pathogens such as Colletotrichum coccodes, Aspergillus niger, and Pyricularia sp. Thus, functionalized nanostructures Fe3O4@Chitosan –AgNP magnetic nanocomposite can probably hold greater potential in catalysis and agriculture applications.

The porous material has been considered as a potential candidate for immobilizing enzymes. Recently, metal organic framework (MOF) has been emerged as a hybrid organic inorganic material with unique intrinsic properties such as well-defined pore structure, excellent chemico-thermal stability, and extremely high surface areas which make them as a suitable scaffold for enzyme immobilization. The outstanding improvement in catalytic performance, high enzyme loading capacity, remarkable interaction between enzyme and MOF are the key features of the novel enzyme-MOF biocomposites. Amongst different immobilization approaches of enzyme-MOF composite development, de novo strategy received immense attention due to rapid, facile, mild immobilization procedure which exhibits potentially superior catalytic activity and extraordinary operational stability. This review presents a holistic insight of two different de novo strategies i.e. co-precipitation and biomineralization with state-of-art examples. Further, the recent developments in enzyme-MOF composites along with their potential features and characteristics are exploited in terms of catalytic activity, thermal/chemical stability, Michaelis-Menten kinetics, recyclability and storage stability. The advanced de novo strategies such as multi-enzyme catalytic system and magnetic enzyme-MOF are explored in the latter part of highlights.

The current work investigates biodiesel synthesis from the cheaper source- palm fatty acid distillate (PFAD) using HClSO3–ZrO2 acid catalyst. The effect of various physicochemical parameters such as molar ratio, catalyst loading, temperature, molecular sieves addition, and agitation speed was studied. The maximum conversion of 91.5% and yield of 90.2% was achieved in 150 min under the reaction conditions of molar ratio 8:1, amount of catalyst 3.5 wt%, 60 °C, agitation speed 250 rpm, and molecular sieves 5 wt%. While comparing the catalytic activity with Amberlyst-15 in converting PFAD to FAME, it was found that HClSO3–ZrO2 gave 7.2 times more conversion as compared to Ambetlyst-15 for similar reaction conditions. Catalyst reusability was also tested and showed a negligible decrease in the conversion at least for three cycles. The kinetics and thermodynamics properties were investigated with the help of Arrhenius equation and Eyring reaction rate theory. The physicochemical properties of the purified PFAD biodiesel were compared with the petroleum diesel and also matched with American Society for Testing and Materials (ASTM) standards and found within the limit.

Biological molecules are widely produced by fermentation technology using bacteria, fungi or yeast. Fermentation is a biochemical process wherein the rate of bioconversion is governed by the organisms involved. The growth of the organism is mainly limited by mass transfer rates of nutrients and gases that directly affect the product formation in fermentation. Attempts have been made to enhance the growth rate and yield using mutational, recombinant strain development approach at microbial level as well as fed batch and continuous processing approach at bioprocess level in the past. The growth rate of microbes can be accelerated by increased mass transfer rates and cell wall permeability with the use of controlled low frequency ultrasound irradiation. The present review provides insights into the application of acoustic cavitation in process intensification of fermentation approaches and the role of various factors involved are highlighted with typical examples.

The detailed optimization study for the ultrasound assisted lipase catalyzed synthesis of cinnamyl butyrate under solvent free conditions was described using central composite rotatable design and response surface methodology. The statistical analysis shows that three out of the four variables tested, i.e. molar ratio (A), enzyme loading (B), and ultrasound intensity (D) are found to be statistically significant. The mutual interactions between molar ratio-enzyme loading (AB) and temperature-ultrasound intensity (CD) are also found to be significant along with quadratic interactions of all the parameters (A2, B2, C2, D2). The maximum conversion of 93% was obtained at optimal conditions; molar ratio 2.5 (cinnamyl alcohol:butyric acid); enzyme loading 2.8% of the total mass of reactants; reaction temperature 46 °C and ultrasound intensity 105 W (ultrasound intensity is 7412.68 W/m2). Additionally, hydrodynamic parameters have been determined to estimate the effect of external and intraparticle mass transfer diffusion, which do not show any significant influence on the reaction rate. Reusability study of biocatalyst shows that it can be used up to three cycles with minimal loss of its enzymatic activity.

The 2-ethylhexyl stearate is used as a bio-lubricant in various cosmetic products. The present study is focused on the biocatalyzed esterification of 2-ethylhexanol and stearic acid to form 2-ethylhexyl stearate catalyzed by Fermase CALB 10000 in the presence of ultrasound treatment. The maximum conversion (95.87%) was obtained at molar ratio of 2-ethylhexanol to stearic acid 2:1, enzyme amount of 2 % (w/w), power 80 W, duty cycle 50 % and temperature 50°C in comparatively short reaction time (3 h) in the presence of Fermase as a catalyst. At optimum conditions, it is observed that in the presence of ultrasound; the reaction time minimizes up to 4 h as compared to mechanical stirring method (7 h). The physiochemical properties for the 2-ethylhexyl palmitate were also evaluated.

This work aims to minimise the gel layer formation over the membrane surface and subsequently attempts to recover the glycyrrhizic acid (GA) from the licorice root extract. Various experimental par...

The conventional flavor synthesis method suffers from low yields, time inefficiency, and extreme reaction conditions. Therefore, there is a necessity for the green and novel synthesis approach to overcome these limitations. The current review presents a holistic insight into different aspects associated with the synthesis of flavor esters using the immobilized enzyme. The application of process intensification tools such as ultrasound and microwave irradiation can enhance the reaction efficiency because of higher product recovery, less formation of by-products, and decreased energy consumption. This review presents the process intensification of value-added flavor esters synthesis and the mechanism of ultrasound and microwave action on the enzyme to enhance the enzyme activity and increase the reaction rate. It also summarizes the role of process intensification in enzymatic flavor ester synthesis, followed by specific examples as reported in the literature.