Untargeted metabolomics, optimization of microwave-assisted extraction using Box-Behnken design and evaluation of antioxidant, and antidiabetic activities of sugarcane bagasse.

INTRODUCTION: The fruit wastes, in particular agricultural wastes, are considered potential and inexpensive sources of bioactive compounds. OBJECTIVE: The current study was aimed at the preparation of an optimized extract of sugarcane bagasse using microwave-assisted extraction (MAE) technology and comparative evaluation of chemical composition, antioxidant, and antidiabetic activities with extract prepared through maceration technique. METHODOLOGY: Box-Behnken Design (BDD) with response surface methodology was applied to observe interactions of three independent variables (ethanol concentrations [%], microwave power [W], and extraction time [min]) on the dependent variables (total phenolic content [TPC] and antioxidant status via 2,2-diphenyl-1-picrylhydrazyl [DPPH] to establish optimal extraction conditions. The ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS) analysis was applied for untargeted metabolite profiling, and in vitro assays were used for evaluation of the antidiabetic and antioxidant potential of the extract. Moreover, an in silico study was used to predict the interaction of five dominant compounds from the UHPLC-Q-TOF-MS profile against the dipeptidyl peptidase-IV (DPP-IV) enzyme. RESULTS: The optimal conditions for the extraction were established at 60% (v/v) ethanol, 500 W microwave power, and 5 min time with TPC 12.83 ± 0.66 mg GAE/g d.w. and DPPH 45.09 ± 0.07%. The UHPLC-Q-TOF-MS analysis revealed the presence of a total of 106 compounds in the extract. Moreover, the extract prepared through MAE technology presented higher TPC and DPPH findings than the extract prepared through maceration. Similarly, the extract was also found with good antidiabetic activity by inhibiting the DPP-IV enzyme which was also rectified theoretically by a molecular docking study. CONCLUSION: The current study presents a sustainable and an optimized approach for the preparation of sugarcane bagasse extract with functional phytoconstituents and higher antidiabetic and antioxidant activities.

Recovery of Cembratrien-Diols from Waste Tobacco (Nicotiana tabacum L.) Flowers by Microwave-Assisted Deep Eutectic Solvent Extraction: Optimization, Separation, and In Vitro Bioactivity.

Deep eutectic solvents (DESs) are novel solvents with physicochemical properties similar to those of ionic liquids, and they have attracted extensive attention for the extraction of bioactive compounds from different plant materials in the context of green chemistry and sustainable development. In this study, seven DESs with different polarities were explored as green extraction solvents for cembratrien-diols (CBT-diols) from waste tobacco flowers. The best solvent, DES-3 (choline chloride: lactic acid (1:3)), which outperformed conventional solvents (methanol, ethanol, and ethyl acetate), was selected and further optimized for microwave-assisted DES extraction using the response surface methodology. The maximum yield of CBT-diols (6.23 ± 0.15 mg/g) was achieved using a microwave power of 425 W, microwave time of 32 min, solid/liquid ratio of 20 mg/mL, and microwave temperature of 40 °C. Additionally, the isolated CBT-diols exhibited strong antimicrobial activity against Salmonella, Staphylococcus aureus, Escherichia coli, Bacillus subtilis, and Pseudomonas aeruginosa and antitumor activity in the human liver cancer HepG2 and SMMC-7721 cell lines. This study highlights the feasibility of recovering CBT-diols from tobacco flower waste using DESs and provides opportunities for potential waste management using green technologies.

Sustainable and Biomimetic Methodology for Extraction of High-Value-Added Compounds in Almond Hulls.

Almond trees are the most cultivated nut tree in the world. The production of almonds generates large amounts of by-products, much of which goes unused. Herein, this study aimed to develop a green chemistry approach to identify and extract potentially valuable compounds from almond by-products. Initially, a screening was performed with 10 different Natural Deep Eutectic Solvents (NADESs). The mixture lactic acid/glycerol, with a molar ratio 1:1 (1:50 plant material to NADES (w/v) with 20% v/v of water) was identified as the best extraction solvent for catechin, caffeoylquinic acid, and condensed tannins in almond hulls. Subsequently, a method was optimized by a Design of Experiment (DoE) protocol using a miniaturized extraction technique, Microwave-Assisted Extraction (MAE), in conjunction with the chosen NADESs. The optimal conditions were found to be 70 °C with 15 min irradiation time. The optimal extraction conditions determined by the DoE were confirmed experimentally and compared to methods already established in the literature. With these conditions, the extraction of metabolites was 2.4 times higher, according to the increase in total peak area, than the established literature methods used. Additionally, by applying the multiparameter Analytical Greenness Metric (AGREE) and Green Analytical Process Index (GAPI) metrics, it was possible to conclude that the developed method was greener than the established literature methods as it includes various principles of green analytical chemistry.

Effect of microwave-assisted drying and extraction of 6-Shogaol from Zingiber officinale Roscoe.

Ginger (Zingiber officinale Roscoe, Zingeberaceae) is a medicinal plant widely used as food, spice, or flavoring agent worldwide. 6-Shogaol is a compound of prime interest in exhibiting anti-inflammatory, antioxidant and chemopreventive effects. The objective of the study is to investigate the effect of microwave-assisted drying (MAD) followed by microwave-assisted extraction (MAE) so as to produce 6-Shogaol enriched Ginger with improved therapeutic benefits. Various drying techniques viz. shade drying, tray drying, microwave-assisted drying and osmotic dehydration as a pretreatment were used for drying Ginger rhizomes. The dried rhizomes were extracted by conventional solvent extraction and microwave-assisted extraction techniques and tested for content of 6-Shogaol using the newly developed HPLC method whereas total flavonoid and polyphenol content were determined using the UV spectrophotometric method. Subjecting the microwave dried Ginger to microwave-assisted extraction for 45 min at constant power level of 284 W resulted in a significant rise in the extractability of 6-Shogaol (1.660 ± 0.018), total polyphenols (855.46 ± 5.33) and flavonoids (617.97 ± 6.40) compared to the conventional method of extraction. The proposed Ginger processing method of microwave drying followed by microwave extraction outperforms traditional methods in terms of speed, convenience, and performance thus can be scaled up to industrial levels.

Comparative Study of Microwave, Pulsed Electric Fields, and High Pressure Processing on the Extraction of Antioxidants from Olive Pomace.

Olive oil production is characterized by large amounts of waste, and yet is considerably highly valued. Olive pomace can serve as a cheap source of bioactive compounds (BACs) with important antioxidant activity. Novel technologies like Pulsed Electric Fields (PEF) and High Pressure (HP) and microwave (MW) processing are considered green alternatives for the recovery of BACs. Different microwave (150-600 W), PEF (1-5 kV/cm field strength, 100-1500 pulses/15 µs width), and HP (250-650 MPa) conditions, in various product/solvent ratios, methanol concentrations, extraction temperatures, and processing times were investigated. Results indicated that the optimal MW extraction conditions were 300 W at 50 °C for 5 min using 60% v/v methanol with a product/solvent ratio of 1:10 g/mL. Similarly, the mix of 40% v/v methanol with olive pomace, treated at 650 MPa for the time needed for pressure build-up (1 min) were considered as optimal extraction conditions in the case of HP, while for PEF the optimal conditions were 60% v/v methanol with a product/solvent ratio of 1:10 g/mL, treated at 5000 pulses, followed by 1 h extraction under stirring conditions. Therefore, these alternative extraction technologies could assist the conventional practice in minimizing waste production and simultaneously align with the requirements of the circular bioeconomy concept.

Structural Characterization and Antioxidant Activity of ß-Glucans from Highland Barley Obtained with Ultrasonic-Microwave-Assisted Extraction.

In order to efficiently extract ß-glucan from highland barley (HBG) and study its structural characterization and antioxidant activity, ultrasonic-microwave-assisted extraction (UME) was optimized by the response surface method (RSM). Under the optimal extraction conditions of 25.05 mL/g liquid-solid ratio, 20 min ultrasonic time, and 480 W microwave intensity, the DPPH radical scavenging activity of HBG reached 25.67%. Two polysaccharide fractions were purified from HBG, namely HBG-1 and HBG-2. Structural characterization indicated that HBG-1 and HBG-2 had similar functional groups, glycosidic linkages, and linear and complex chain conformation. HBG-1 was mainly composed of glucose (98.97%), while HBG-2 primarily consisted of arabinose (38.23%), galactose (22.01%), and xylose (31.60%). The molecular weight of HBG-1 was much smaller than that of HBG-2. Both HBG-1 and HBG-2 exhibited concentration-dependent antioxidant activity, and HBG-1 was more active. This study provided insights into the efficient extraction of HBG and further investigated the structure and antioxidant activities of purified components HBG-1 and HBG-2. Meanwhile, the results of this study imply that HBG has the potential to be an antioxidant in foods and cosmetics.

Valorization of pineapple rind for bromelain extraction using microwave assisted technique: optimization, purification, and structural characterization.

Huge amount of waste is generated by the pineapple processing industries which raises concerns regarding its safe disposal into the environment. This ever-increasing problem of waste management can be solved by the valorization of pineapple by-products to high-value compounds. The extraction of proteolytic enzyme, bromelain from pineapple rind using green techniques can help to overcome the drawbacks associated with conventional methods. In the present study, the extraction of bromelain from pineapple rind using microwave assisted technique resulted in considerable amount of proteolytic activity (127.8 U/mL) and protein content (2.55 mg/mL). The optimized extraction conditions were found as 200 W microwave power, 1:5 solid/ liquid ratio and after treatment time of 10 min. Highest specific activity (512 U/mg) of bromelain was obtained after using gel filtration chromatography. FTIR result confirmed the presence of functional groups in bromelain, whereas, XRD analysis indicated the semi-crystalline nature of bromelain. The results indicated MAE as an effective green technique for the extraction of bromelain from pineapple rind. The proteolytic action of the extracted bromelain makes it a suitable functional ingredient for its applications in bakery, dairy, and seafood processing industries.

Advanced methods of algal pigments extraction: A review.

Algae are exclusively aquatic photosynthetic organisms that are microscopic or macroscopic, unicellular or multicellular and distributed across the globe. They are a potential source of food, feed, medicine and natural pigments. A variety of natural pigments are available from algae including chlorophyll a, b, c d, phycobiliproteins, carotenes and xanthophylls. The xanthophylls include acyloxyfucoxanthin, alloxanthin, astaxanthin, crocoxanthin, diadinoxanthin, diatoxanthin, fucoxanthin, loroxanthin, monadoxanthin, neoxanthin, nostoxanthin, perdinin, Prasinoxanthin, siphonaxanthin, vaucheriaxanthin, violaxanthin, lutein, zeaxanthin, ß-cryptoxanthin, while carotenes include echinenone, α-carotene, ß-carotene, γ-carotene, lycopene, phytoene, phytofluene. These pigments have applications as pharmaceuticals and nutraceuticals and in the food industry for beverages and animal feed production. The conventional methods for the extraction of pigments are solid-liquid extraction, liquid-liquid extraction and soxhlet extraction. All these methods are less efficient, time-consuming and have higher solvent consumption. For a standardized extraction of natural pigments from algal biomass advanced procedures are in practice which includes Supercritical fluid extraction, Pressurized liquid extraction, Microwave-assisted extraction, Pulsed electric field, Moderate electric field, Ultrahigh pressure extraction, Ultrasound-assisted extraction, Subcritical dimethyl ether extraction, Enzyme assisted extraction and Natural deep eutectic solvents. In the present review, these methods for pigment extraction from algae are discussed in detail.

A cross talk based critical analysis of solvent free microwave extraction to accentuate it as the new normal for extraction of essential oil: an attempt to overhaul the science of distillation through a comprehensive tutelage.

Microwave-assisted extraction (MAE) is a sustainable non-contact heating source and has been extensively researched for extraction of plant bioactives. There are various derivatives or modules available for MAE and solvent free microwave extraction (SFME) is one of them where by operational aspects of MAE have been maneuvered to make it compatible for extraction of essential oil (EO). This article makes an attempt to overhaul the science of distillation by revisiting SFME and trying to learn through a comprehensive tutelage comprising of 20 years of published literature in Web of Science so that a shrewd decision can be obtained through a cross talk based critical analysis on the science SFME. A total of 312 articles within the time frame of 2001-2020 were extracted from WOS and critically analyzed. Considering the various uncertainties involved with SFME the articles establishes some global working standards and tries to explore the dynamic relationship between plant part/genus and microwave power, microwave power and time, microwave power and extracted volatile principles, prioritizes plant family selection and also presents a research blueprint of SFME. A techno-commercial feasibility study has been presented for smooth industrial transition of SFME. The tutelage presented decodes the publication trends and SFME blueprint.

Microwave-assisted extraction in closed vessel in food analysis.

Microwave-assisted extraction (MAE) is an important technique in analytical chemistry. It offers several advantages over traditional extraction methods, such as improved extraction efficiency, shorter extraction times, reduced solvent consumption, and enhanced analyte recovery. Using microwaves, heat is directly applied to the sample, leading to rapid and efficient extraction of target compounds by enhancing the solubility and diffusion of the target compounds, thus requiring lower solvent volume. Therefore, MAE can be considered a more environmentally friendly and cost-effective option facilitating the transition toward greener and more sustainable analytical chemistry workflows. This contribution systematically reviews the application of MAE to a selection of target compounds/compounds classes of relevance for food quality and safety assessment. As inclusion criteria, MAE active temperature control and molecularly-resolved characterization of the extracts were considered. Contents include a brief introduction of the principles of operation, available systems characteristics, and key parameters influencing extraction efficiency and selectivity. The application section covers functional food components (e.g., phenols, diterpenes, and carotenoids), lipids, contaminants (e.g., polycyclic aromatic hydrocarbons and mineral oil hydrocarbons), pesticides, veterinary drug residues, and a selection of process contaminants and xenobiotics of relevance for food safety.

Development of deep eutectic solvent-based microwave-assisted extraction combined with temperature controlled ionic liquid-based liquid phase microextraction for extraction of aflatoxins from cheese samples.

In this study, for the first time, a deep eutectic solvent-based microwave-assisted extraction was combined with ionic liquid-based temperature controlled liquid phase microextraction for the extraction of several aflatoxins from cheese samples. Briefly, the analytes are extracted from cheese sample (3 g) into a mixture of 1.5 mL choline chloride:ethylene glycol deep eutectic solvent and 3.5 mL deionized water by exposing to microwave irradiations for 60 s at 180 W. The liquid phase was taken and mixed with 55 µL 1-hexyl-3-methylimidazolium hexafluorophosphate. By cooling the solution in the refrigerator centrifuge, a turbid state was obtained and the analytes were extracted into the ionic liquid droplets. The analytes were determined by high-performance liquid chromatography equipped with fluorescence detector. Low limits of detection (9-23 ng kg-1 ) and quantification (30-77 ng kg-1 ), high extraction recovery (66%-83%), acceptable enrichment factor (40-50), and good precision (relative standard deviations ≤ 5.2%) were obtained using the offered approach. These results reveal the high extraction capability of the method for determination of aflatoxins in the cheese samples. In this method, there was no need for organic solvents and it can be considered as green extraction method.

Emerging Technologies to Extract Fucoxanthin from Undaria pinnatifida: Microwave vs. Ultrasound Assisted Extractions.

Macroalgae are an extensive resource for the obtention of bioactive compounds, mainly phenolic compounds, phlorotannins, and pigments. Fucoxanthin (Fx) is the most abundant pigment present in brown algae and has shown several useful bioactivities that can be used to fortify products in the food and cosmetic industries. Nevertheless, to date, there is still insufficient literature reporting on the extraction yield of Fx from U. pinnatifida species from green technologies. In this regard, the present study aims to optimize the extraction conditions to obtain the highest Fx yield from U. pinnatifida through emerging techniques, namely microwave-assisted extraction (MAE) and ultrasound-assisted extraction (UAE). These methods will be compared with the conventional methodologies of heat-assisted extraction (HAE) and Soxhlet-assisted extraction (SAE). According to our results, even though the extraction yield could be slightly higher when using MAE than UAE, the Fx concentration obtained from the alga was double when using UAE. Thus, the Fx ratio in the final extract reached values of 124.39 mg Fx/g E. However, the optimal conditions should also be considered since UAE needed 30 min to perform the extraction, whereas MAE was able to obtain 58.83 mg Fx/g E in only 3 min and 2 bar, meaning less energy expenditure and minimum cost function. To our knowledge, this study obtains the highest concentrations of Fx ever reported (58.83 mg Fx/g E for MAE and 124.39 mg Fx/g E for UAE), with low energy consumption and short times (3.00 min for MAE and 35.16 min for UAE). Any of these results could be selected for further experiments and proposed for industrial scaling-up.

Solid-phase extraction based on PDMS/ionic liquid sponge followed by gas chromatography-mass spectrometry for rapid and sensitive determination of volatile components in lavender.

INTRODUCTION: Due to the complexity and the low concentrations of volatile components in aromatic plants, sample pretreatment is an important step in the whole analytical procedure. OBJECTIVE: This study aimed to propose a novel, sensitive and fast approach to determine the volatile components in lavender. METHODS: The 1-butyl-3-(propyltrimethoxysilane)imidazolium chloride ([BPtmsim]Cl) ionic liquid was introduced onto the surface of polydimethylsiloxane (PDMS) to prepare a novel PDMS/[BPtmsim]Cl sponge with large surface area, good sorption performance, and reusability. A solid-phase extraction method was developed based on PDMS/[BPtmsim]Cl sponge combined with gas chromatography-mass spectrometry (GC-MS). RESULTS: The effects of the various experimental parameters on the extraction efficiency were investigated. The optimal conditions were [BPtmsim]Cl amount of 0.3 g, 1:4 as the mass ratio of PDMS/[BPtmsim]Cl to lavender sample, microwave power of 700 W, microwave time of 10 min, and n-hexane as the desorption solvent. The method validation results showed good linearity (10-800 µg/ml), high correlation coefficient (R2 ≥ 0.9991), low limits of detection (1.73-2.50 ng/µl), and limits of quantification (4.10-5.11 ng/µl). The interday and intraday precision with relative standard deviation (RSD) values were below 1.93% and 4.71%, respectively. Under the optimal extraction conditions, 16 lavender samples from three different species were analysed and a total of 57 volatile compounds were identified. The correlation between different species of lavender and volatile components was explored using principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA). CONCLUSION: The results showed that PDMS/[BPtmsim]Cl extraction is a rapid, highly efficient, and sensitive technique for the determination of volatile components in complex plant samples.

Aligned with sustainable development goals: microwave extraction of astaxanthin from wet algae and selective cytotoxic effect of the extract on lung cancer cells.

Astaxanthin is one of the most attractive carotenoid in the cosmetic, food, pharmaceutical, and aquaculture industries due to its strong bioactive properties. Among the various sources, several algae species are considered as rich sources of astaxanthin. Downstream processing of algae involves the majority of the total processing costs. Thus, elimination of high energy involved steps is imperative to achieve cost-effective scale in industry. This study aimed to determine operation conditions for astaxanthin extraction from wet Haematococcus pluvialis using microwave-assisted extraction. The isolated astaxanthin extract was evaluated for cytotoxicity on human lung cancer cells. The microwave-assisted extraction process at 75 °C under the power of 700 Watt for 7 min gave the highest astaxanthin yield (12.24 ± 0.54 mg astaxanthin/g wet cell weight). Based on MTT cell viability and Hoechst 33342 nuclear staining assays on A549 lung cancer cells, astaxanthin inhibited cell growth in dose- and time-dependent manners, where IC50 value was determined as 111.8 ± 14.8 µg/mL and apoptotic bodies were observed along with positive control group at 72 hr. These results showed that the treatment with astaxanthin extracted from wet H. pluvialis by microwave-assisted extraction exhibited anti-cancer activity on lung cancer cells indicating a newly potential to be utilized in industry.

Microwave-Assisted Extraction Optimization and Effect of Drying Temperature on Catechins, Procyanidins and Theobromine in Cocoa Beans.

Cocoa beans (Theobroma cacao L.) are an important source of polyphenols. Nevertheless, the content of these compounds is influenced by post-harvest processes. In this sense, the concentration of polyphenols can decrease by more than 50% during drying. In this study, the process of procyanidins extraction was optimized and the stability of catechins, procyanidins, and theobromine to different drying temperatures was evaluated. First, the effectiveness of methanol, ethanol, acetone, and water as extract solvents was determined. A Box-Behnken design and response surface methodology were used to optimize the Microwave-Assisted Extraction (MAE) process. The ratios of methanol-water, time, and temperature of extraction were selected as independent variables, whereas the concentration of procyanidins was used as a response variable. Concerning the drying, the samples were dried using five temperatures, and a sample freeze-dried was used as a control. The quantitative analyses were carried out by HPLC-DAD-ESI-IT-MS. The optimal MAE conditions were 67 °C, 56 min, and 73% methanol. Regarding the drying, the maximum contents of procyanidins were obtained at 40 °C. To our knowledge, this is the first time that the stability of dimers, trimers, and tetramers of procyanidins on drying temperature was evaluated. In conclusion, drying at 40 °C presented better results than the freeze-drying method.

Optimization of Ultrasound- and Microwave-Assisted Extraction for the Determination of Phenolic Compounds in Peach Byproducts Using Experimental Design and Liquid Chromatography-Tandem Mass Spectrometry.

The conversion of plant byproducts, which are phenolic-rich substrates, to valuable co-products by implementing non-conventional extraction techniques is the need of the hour. In the current study, ultrasound- (UAE) and microwave-assisted extraction (MAE) were applied for the recovery of polyphenols from peach byproducts. Two-level screening and Box-Behnken design were adopted to optimize extraction efficiency in terms of total phenolic content (TPC). Methanol:water 4:1% v/v was the extraction solvent. The optimal conditions of UAE were 15 min, 8 s ON-5 s OFF, and 35 mL g-1, while MAE was maximized at 20 min, 58 °C, and 16 mL g-1. Regarding the extracts' TPC and antioxidant activity, MAE emerged as the method of choice, whilst their antiradical activity was similar in both techniques. Furthermore, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated to determine chlorogenic acid and naringenin in byproducts' extracts. 4-Chloro-4'-hydroxybenzophenone is proposed as a new internal standard in LC-MS/MS analysis in foods and byproducts. Chlorogenic acid was extracted in higher yields when UAE was used, while MAE favored the extraction of the flavonoid compound, naringenin. To conclude, non-conventional extraction could be considered as an efficient and fast alternative for the recovery of bioactive compounds from plant matrices.

Enhanced Recovery of Natural Antioxidants from Grape Waste Using Natural Eutectic Solvents-Based Microwave-Assisted Extraction.

The evaluation of sustainable solvents as alternatives to more harmful conventional solvents combined with intensification techniques to recover phenolic compounds from agri-food waste is in the spotlight. The wine industry generates large amounts of waste as a consequence of grape processing operations, which can be revalued by solvent extraction of valuable antioxidants for food and fine chemical applications. Therefore, the present study focuses on the use of natural eutectic solvents (NAESs) with benign environmental, health, and safety profiles, for valorization of grape waste in the context of a circular economy. Herein, up to 15 NAESs consisting of combinations of three hydrogen bond acceptors (choline chloride, L-proline, and betaine) and four hydrogen bond donors (1,2-propanediol, glycerol, and 1,2- and 1,3-butanediol) were evaluated for antioxidant recovery. After an initial screening of the performance of NAESs by conventional extraction, the process was intensified by microwave-assisted extraction (MAE). The extracts were analyzed by UV/VIS spectrophotometric and HPLC methods. Promising results were obtained with the solvent betaine, 1,2-butanediol [1:4], using MAE at 100 °C for 3 min. Overall, the proposed NAESs-based MAE method was successfully applied to recover target compounds from grape waste, with great prospects for the antioxidants market and sustainable development for the winery sector.

Sustainable Recovery of Phenolic Compounds from Distilled Rosemary By-Product Using Green Extraction Methods: Optimization, Comparison, and Antioxidant Activity.

Rosemary solid distillation waste (SWR), a by-product of the essential oil industry, represents an important source of phenolic antioxidants. Green technologies such as ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE), and accelerated solvent extraction (ASE) of phenolic compounds from SWR were optimized as valorization routes to maximize yield, rosmarinic acid (RMA), carnosol (CARO) and carnosic acid (CARA) contents. Response surface methodology was used in this context, with ethanol concentration (X1), extraction temperature (X2), and time (X3) being the independent variables. A second-order polynomial model was fitted to the data, and multiple regression analysis and analysis of variance were used to determine model fitness and optimal conditions. Ethanol concentration was the most influential extraction parameter, affecting phenolic compounds, while the influence of other parameters was moderate. The optimized conditions were as follows: X1: 67.4, 80.0, and 59.0%, X2: 70, 51, and 125 °C, and X3: 15, 10, and 7 min for MAE, UAE, and ASE, respectively. A comparison of optimized MAE, UAE, and ASE with conventional Soxhlet extraction techniques indicated that ASE provided a higher extraction yield and content of phenolic compounds. However, UAE represented the best process from an environmental point of view, allowing an improved extraction of phenolics from SWR with high energy efficiency and low energy costs.

Exploring the antioxidant potential of fermented turmeric pulp: effect of extraction methods and microencapsulation.

Curcumin is one of the major constituents of turmeric which possess multifarious therapeutic properties. However, owing of its limited solubility in water its bioavailability is poor. Thus, attempts have been made to increase the solubility of curcumin by fermenting turmeric followed by extraction and encapsulation. Lactobacillus fermentum was used for the fermentation of raw turmeric pulp. The influence of Lactobacillus fermentation and different extraction methods (conventional solvent extraction (CSE), ultrasound (UAE) and microwave-assisted extraction (MAE)) on total phenolic content (TPC), flavonoid content, antioxidant activity and curcumin content were analyzed. Further, to increase the stability of extract, different concentrations of maltodextrin were used to microencapsulate the curcumin extract. The results showed that, Lactobacillus fermentation increased the TPC and antioxidant activity from 5.59 ± 0.20 to 6.27 ± 0.28 mg GAE/g and 67.49 ± 1.51 to 79.00 ± 2.20%, respectively. MAE showed highest TPC (7.88 ± 0.08 mg GAE/g), antioxidant activity (94 ± 1.57%) and curcumin content (0.866 ± 0.05 mg/g) followed by UAE and CSE. Maximum yield of curcumin extract was observed in MAE, UAE and CSE as 59.93, 47.09 and 29.44% respectively, higher than non-fermented turmeric pulp. Maltodextrin percentage showed a significant influence on bio-functional properties of encapsulated powder. However, 20% maltodextrin exhibited better bio-functional properties as compared to other concentrations.

Microwave-assisted valorization and characterization of Citrus limetta peel waste into pectin as a perspective food additive.

Machine learning techniques were employed to evaluate the effect of process parameters viz. microwave power (100 W, 300 W, 600 W); pH (1, 1.5, 2); and microwave time (the 60 s, 120 s, 180 s) on the pectin yield from Citrus limetta peel. A fourth-order polynomial function of 66.60 scales was used by the Support Vector Regression (SVR) model at an epsilon (ε) value of 0.003. The co-efficient of determination (R2) and root mean square error-values for training data and test data were 0.984; 0.77 and 0.993; 0.66 respectively. At optimized conditions, microwave power 600 W, pH 1, and time 180 s the best yield of 32.75% was obtained. The integrity of pectin skeletal was confirmed with FTIR and 1H NMR spectrums. The physicochemical analysis revealed that CLP is a high-methoxyl pectin (HMP) with a 63.20 ± 0.88% degree of esterification, 798.45 ± 26.15 equivalent weight, 8.06 ± 0.62% methoxyl content, 67.93 ± 3.36 AUA content, 6.27 ± 0.27 g water/g pectin WHC, 2.68 ± 0.20 g oil/g pectin OHC, low moisture, ash and protein content of 6.85 ± 0.10%, 3.87 ± 0.10% and 2.61 ± 0.06% respectively, which can be utilized as a food additive. Therefore, pectin extraction from Citrus limetta peel using a greener technique like MAE is an eco-friendly, time-saving approach to transform waste into a versatile food additive.