Continuous extraction of phenolic compounds from pomegranate peel using high voltage electrical discharge

Green valorization of Chaenomelis Fructus agro-industrial by-products as a source of phenolics: Ultrasound-assisted extraction, adsorptive enrichment and quality control

This study aimed to develop a green and efficient strategy for the recovery of bioactive phenolics from agro-industrial by-products (AIBPs) derived from Chaenomelis Fructus (CF). The peel of Chaenomelis Fructus (CFP) has a higher phenolic content compared to its leaves and seeds. The ultrasound-assisted extraction process for CFP total phenolics (CFPTP) was optimized using response surface methodology, achieving a yield of 216.27 ± 1.04 mg/g. ADS-17 resin exhibited higher adsorption-desorption capacity for CFPTP and was selected as the optimal resin. Studies on adsorption behavior confirmed adherence to pseudo-second order and Langmuir models, characterized by exothermicity, spontaneity, and entropy reduction. A chromatography enrichment process employing ADS-17 resin yielded a CFPTP-rich extract with a purity of 84.22 ± 1.57 %. Additionally, a UPLC-QqQ-MS/MS method was developed to simultaneously measure eight main phenolic compounds in CFPTP extracts. This study contributes to the transformation of CF AIBPs into valuable products rich in phenolics.

Latest Advances in Green Extraction of Polyphenols from Plants, Foods and Food By-Products

Phenolic compounds present in plants and foods are receiving increasing attention for their bioactive and sensory properties, accompanied by consumers' interest in products with health benefits derived from natural rather than artificial sources. This, together with the sustainable development goals for the 21st century, has driven the development of green extraction techniques that allow obtaining these compounds with the safety and quality required to be applied in the food, cosmetic and pharmaceutical industries. Green extraction of natural products involves practices aiming at reducing the environmental impact of the preparation processes, based on using natural or less-polluting solvents, lower energetic requirements and shorter extraction times, while providing greater efficiency in the recovery of target compounds. In this article, the principles of sustainable extraction techniques and the advances produced in recent years regarding green isolation of polyphenols from plants, food and food waste are reviewed.

Optimization of ultrasonic-assisted extraction of total flavonoids from Oxalis corniculata by a hybrid response surface methodology-artificial neural network-genetic algorithm (RSM-ANN-GA) approach, coupled with an assessment of antioxidant activities

The objective of this research endeavor is to refine the ultrasonic-assisted extraction technique for total flavonoids from Oxalis corniculata (TFO), utilizing a synergistic approach combining response surface methodology (RSM) and artificial neural network integrated with genetic algorithm (RSM-ANN-GA). The optimized extraction parameters determined through RSM yielded a TFO concentration of 13.538 mg g-1 under the following conditions: an ethanol concentration of 61.95%, a liquid-solid ratio of 41.06 mL g-1, an ultrasonic power setting of 351.57 W, and an ultrasonic exposure duration of 58.95 minutes. Conversely, the RSM-ANN-GA approach identified an even more refined set of conditions, achieving a TFO concentration of 13.7844 mg g-1, with an ethanol concentration of 58.93%, a liquid-solid ratio of 41.16 mL g-1, an ultrasonic power of 350.22 W, and an ultrasonic exposure time of 58.18 minutes. These findings underscore the superior predictive accuracy and enhanced extraction efficiency offered by the RSM-ANN-GA model over the conventional RSM method. Furthermore, the study demonstrated that TFO possesses a potent antioxidant effect, as evidenced by its ability to scavenge DPPH, hydroxyl, and superoxide anion free radicals in vitro, highlighting its potential as a valuable source of natural antioxidants.

An innovative technique for the extraction and stability of polyphenols using high voltage electrical discharge: HVED-Assisted Extraction of Polyphenols

Polyphenols are the main group of phytochemicals with several biological activities. Due to the adverse effects of conventional solvent extraction methods, innovative extraction techniques have been used as alternatives to overcome these problems. High voltage electric discharge (HVED) is an eco-friendly innovative extraction technique based on the phenomenon of electrical breakdown in water. This technique induces physical and chemical processes, leading to product fragmentation, cellular damage, and liberation of bioactive compounds. HVED treatment can extract polyphenols at lower temperatures and shorter times than the conventional solvent extraction methods. This review summarizes the effect of HVED processing parameters on the recovery and stability of polyphenols from plant sources. Hydroethanolic solutions improve the HVED-assisted extraction of polyphenols compared to water. Moreover, acidic solvents are suitable for the high recovery and protection of polyphenols during electric discharges. This study revealed the efficacy of the HVED technique in extracting polyphenols for their utilization in the food and pharmaceutical industries.

Application of Natural Functional Additives for Improving Bioactivity and Structure of Biopolymer-Based Films for Food Packaging: A Review

The global trend towards conscious consumption plays an important role in consumer preferences regarding both the composition and quality of food and packaging materials, including sustainable ones. The development of biodegradable active packaging materials could reduce both the negative impact on the environment due to a decrease in the use of oil-based plastics and the amount of synthetic preservatives. This review discusses relevant functional additives for improving the bioactivity of biopolymer-based films. Addition of plant, microbial, animal and organic nanoparticles into bio-based films is discussed. Changes in mechanical, transparency, water and oxygen barrier properties are reviewed. Since microbial and oxidative deterioration are the main causes of food spoilage, antimicrobial and antioxidant properties of natural additives are discussed, including perspective ones for the development of biodegradable active packaging.

Trends in extracting Agro-byproducts' phenolics using non-thermal technologies and their combinative effect: Mechanisms, potentials, drawbacks, and safety evaluation

The agro-food industries generate significant waste with adverse effects. However, these byproducts are rich in polyphenols with diverse bioactivities. Innovative non-thermal extraction (NTE) technologies (Naviglio extractor®, cold plasma (CP), high hydrostatic pressure (HHP), pulse-electric field (PEF), ultrasound-assisted extraction (UAE), etc.) and their combinative effect (integrated UAE + HPPE, integrated PEF + enzyme-assisted extraction, etc.) could improve polyphenolic extraction. Hence, this article comprehensively reviewed the mechanisms, applications, drawbacks, and safety assessment of emerging NTE technologies and their combinative effects in the last 5 years, emphasizing their efficacy in improving agro-byproduct polyphenols' extraction. According to the review, incorporating cutting-edge NTE might promote the extraction ofmore phenolic extractfrom agro-byproducts due to numerous benefits,such as increased extractability,preserved thermo-sensitive phenolics, and low energy consumption. The next five years should investigate combined novel NTE technologies as they increase extractability. Besides, more research must be done on extracting free and bound phenolics, phenolic acids, flavonoids, and lignans from agro by-products. Finally, the safety of the extraction technology on the polyphenolic extract needs a lot of studies (in vivo and in vitro), and their mechanisms need to be explored.

Enhancement of the bioavailability of phenolic compounds from fruit and vegetable waste by liposomal nanocarriers

Fruits and vegetables are one of the most consumed and processed commodities globally and comprise abundant phenolic compounds, one of the main nutraceuticals in the food industry. Comparably elevated rates of these compounds are found in waste (peel, seeds, leaf, stem, etc.) in the food processing industry. They are being investigated for their potential use in functional foods. However, phenolic compounds' low bioavailability limits their application, which can be approached by loading the phenolic compounds into an encapsulation system such as liposomal carriers. This review aims to elucidate the recent trend in extracting phenolic compounds from the waste stream and the means to load them in stable liposomes. Furthermore, the application of these liposomes with only natural extracts in food matrices is also presented. Many studies have indicated that liposomes can be a proper candidate for encapsulating and delivering phenolic compounds and as a means to increase their bioavailability.

Food Service Kitchen Scraps as a Source of Bioactive Phytochemicals: Disposal Survey, Optimized Extraction, Metabolomic Screening and Chemometric Evaluation

Untargeted metabolomics is a powerful tool with high resolution and the capability to characterize a wide range of bioactive natural products from fruit and vegetable by-products (FVB). Thus, this approach was applied in the study to evaluate the phenolic compounds (PC) by metabolomic screening in five FVB after optimizing their extraction. The total phenolic content and antioxidant activity analyses were able to select the best extractor (SM) and ultrasonication time (US) for each FVB; methanol was used as a control. Although ultrasonication yielded a lower number of PC identifications (84 PC), the US extract was the most efficient in total ionic abundance (+21% and +29% compared to the total PC and SM extracts, respectively). Ultrasonication also increased the phenolic acid (+38%) and flavonoid classes (+19%) extracted compared to SM, while the multivariate analyses showed the control as the most dissimilar sample. FVB extracted from the same parts of the vegetable/fruit showed similarities and papaya seed presented the most atypical profile. The application of the metabolomics approach increased the knowledge of the bioactive potential of the evaluated residues and possibilities of exploring and valorizing the generated extracts.

A Systematic Review on Waste as Sustainable Feedstock for Bioactive Molecules—Extraction as Isolation Technology

In today’s linear economy, waste streams, environmental pollution, and social–economic differences are increasing with population growth. The need to develop towards a circular economy is obvious, especially since waste streams are composed of valuable compounds. Waste is a heterogeneous and complex matrix, the selective isolation of, for example, polyphenolic compounds, is challenging due to its energy efficiency and at least partially its selectivity. Extraction is handled as an emerging technology in biorefinery approaches. Conventional solid liquid extraction with organic solvents is hazardous and environmentally unfriendly. New extraction methods and green solvents open a wider scope of applications. This research focuses on the question of whether these methods and solvents are suitable to replace their organic counterparts and on the definition of parameters to optimize the processes. This review deals with the process development of agro-food industrial waste streams for biorefineries. It gives a short overview of the classification of waste streams and focuses on the extraction methods and important process parameters for the isolation of secondary metabolites.

Cereal Waste Valorization through Conventional and Current Extraction Techniques-An Up-to-Date Overview

Nowadays, in the European Union more than 100 million tons of food are wasted, meanwhile, millions of people are starving. Food waste represents a serious and ever-growing issue which has gained researchers’ attention due to its economic, environmental, social, and ethical implications. The Sustainable Development Goal has as its main objective the reduction of food waste through several approaches such as the re-use of agro-industrial by-products and their exploitation through complete valorization of their bioactive compounds. The extraction of the bioactive compounds through conventional methods has been used for a long time, whilst the increasing demand and evolution for using more sustainable extraction techniques has led to the development of new, ecologically friendly, and high-efficiency technologies. Enzymatic and ultrasound-assisted extractions, microwave-assisted extraction, membrane fractionation, and pressure-based extraction techniques (supercritical fluid extraction, subcritical water extraction, and steam explosion) are the main debated green technologies in the present paper. This review aims to provide a critical and comprehensive overview of the well-known conventional extraction methods and the advanced novel treatments and extraction techniques applied to release the bioactive compounds from cereal waste and by-products.

Microwave hydrodiffusion and gravity model with a unique hydration strategy for exhaustive extraction of anthocyanins from strawberries and raspberries

This study aimed to verify if microwave hydrodiffusion and gravity (MHG) could efficiently extract anthocyanins from strawberries and raspberries with low environmental impact and costs. Our findings revealed that it was possible to extract 69 and 64% anthocyanins from the strawberries and raspberries in a single extraction step, respectively. When the co-product (product remaining after extracting in natura fruits) was hydrated with green solvents and subjected to re-extraction, it was possible to exhaustively extract the anthocyanins from both fruits. Using the Green Analytical Procedure Index (GAPI), the MHG proved to cause low environmental impact due to the solvents used, enabling the reuse of the co-product for food and pharmaceutical products application. Moreover, the MHG was economically viable, and the sample pretreated with distilled water was the most indicated re-extraction method. The MHG process proved to be exhaustive for strawberry and raspberry anthocyanins, thus demonstrating to be an excellent alternative for sustainable extraction.

Pigment of Ceiba speciosa (A. St.-Hil.) Flowers: Separation, Extraction, Purification and Antioxidant Activity

In this work, the extraction procedure of a natural pigment from the flower of Ceiba speciosa (A. St.-Hil.) was optimized by response surface methodology. It is the first time that the extraction of the flower pigment of C. speciosa (FPCS) has been reported, along with an evaluation of its stability and biological activity under various conditions, and an exploration of its potential use as a food additive and in medicine. Specifically, the effects of ethanol concentration, solid-liquid ratio, temperature and time on the extraction rate of FPCS were determined using a Box-Behnken design. The optimum extraction conditions for FPCS were 75% ethanol with a solid-liquid ratio of 1:75 mg/mL) at 66 °C for 39 min. The purification of FPCS using different macroporous resins showed that D101 performed best when the initial mass concentration of the injection solution was 1.50 mg/mL, resulting in a three-fold increase in color value. The yield of dry flowers was 9.75% of fresh petals and the FPCS extraction efficiency was 43.2%. The effects of light, solubility, pH, temperature, sweeteners, edible acids, redox agents, preservatives and metal ions on FPCS were also investigated. Furthermore, the characteristics of FPCS were determined by spectrophotometry at a specific wavelength using the Lambert-Beer law to correlate the mass of FPCS with its absorbance value. An acute toxicological test performed according to Horne's method showed that FPCS is a non-toxic extract and thus may be used as a food additive or in other ingestible forms. Finally, western blotting showed that FPCS prevents lipopolysaccharide-induced hippocampal oxidative stress in mice. The study suggests that FPCS may function as an antioxidant with applications in the food, cosmetics and polymer industries.

Ecological Synthesis of CuO Nanoparticles Using Punica granatum L. Peel Extract for the Retention of Methyl Green

The aqueous extract from the bark of Punica granatum L. was invested to generate CuO nanoparticles from CuSO4 using a green, economical, ecological, and clean method. The synthesized nanoparticles were characterized and were successfully used as adsorbents for methyl green retention of an absorptive capacity amounting to 28.7 mg g−1. Methyl green equilibrium adsorption data were correlated to the Langmuir model following the pseudo-second order kinetics model. This study clearly corroborates that copper nanoparticles exhibit a high potential for use in wastewater treatment.

Chemical, Antioxidant, and Antimicrobial Properties of the Peel and Male Flower By-Products of Four Varieties of Punica granatum L. Cultivated in the Marche Region for Their Use in Cosmetic Products

We are now seeing an increase in the production of agri-food waste, which is an essential resource for the recovery of bioactive compounds that may be employed as innovative natural ingredients in cosmetics. To date, the approach to cosmetics preservation has seen a significant shift in the search for biological components that give healthier alternatives for customers and help businesses operate in an environmentally friendly manner. To achieve this goal, we studied pomegranate extracts using the peel and, for the first time, extracts from the male flowers of a wide pomegranate variety cultivated in the Marche region, specifically, the Wonderful, Mollar de Elche, Parfianka, and less-studied G1 varieties. We studied the phenol compounds profile, antioxidant capacity, antimicrobial activity, and cell viability of the obtained pomegranate extracts. The identification and quantification of phenol compounds belonging to different classes, such as hydrolysable tannins, hydroxybenzoic acid, hydroxycinnamic acid, dihydroflavonol, gallocatechin, and anthocyanins, were performed using UPLC-ESI-MS/MS. Punicalagin isomers and punicalin resulted in the most abundant polyphenols found in the peel and male flower extracts. Mollar de Elche 2020 peel extract revealed a high concentration of punicalagin A and B (7206.4 mg/kg and 5812.9), while the content of gallic acid revealed high results in the G1 and Parfianka varieties. All extracts were spectrophotometrically analysed to determine their total phenol content (TPC) using the Folin–Ciocalteu method and their antioxidant capacity (AC). In terms of the total phenol obtained by the Folin–Ciocalteu colorimetric method, Mollar de Elche 2020 extracts reported the highest TPC content of 12.341 µmol GAE/g. Results revealed that the Mollar de Elche and Wonderful 2020 peel extracts demonstrated the highest TPC and AC. Furthermore, AC results indicated that the peel extracts displayed higher AC than the male flower extract due to the high punicalagin content detected by UPLC analysis. The antimicrobial activity testing revealed that the Wonderful and G1 2020 peel extracts resulted active against Escherichia coli, while all extracts exhibited promising anticandidal activity. Additionally, the cytocompatibility was evaluated in keratinocytes HaCaT cells by testing concentrations of pomegranate extracts ranging from 0.15 to 5.00 mg/mL. Extracts were non-toxic for the cells in the tested concentration range. The acquired results may help exploit pomegranate agri-food waste products provided by the Marche region’s short supply chain for their use as an antimicrobial and antioxidant booster in the formulation of cosmetic products.

Phenolic Compounds and Bioactivities from Pomegranate (Punica granatum L.) Peels

Pomegranate peels, which are normally processed as the main byproduct of pomegranate juice production, are worthy of being researched and utilized for the aim of economic and environmental benefits. In a phytochemical investigation of the peels of Punica granatum L., 10 phenolic compounds containing a common hexahydroxy diphenol moiety were isolated. Three of them were identified for the first time and named as pomegranatins A-C, and from the other seven known ones, two of them were obtained from pomegranate peels for the first time. Their structures were determined via extensive spectroscopic analysis. Besides, for the sake of preliminarily comprehending their biological activities, in vitro antimicrobial, antioxidant, as well as antitumor assays were detected. In the DPPH antioxidant assay, six compounds presented significant free radical scavenging ability. Two compounds exhibited moderate antimicrobial activities against Candida albicans; one compound could inhibit the proliferation of both C. albicans and Escherichia coli within limits. Four compounds possessed weak antitumor activity toward the Hela cell line without taking into account the bioavailability of ellagitannins. Overall, these results provided further information on the structural diversity of bioactive compounds present in pomegranate peels, as well as on their biological activities.

Effect of Extraction Method on the Bioactive Composition, Antimicrobial Activity and Phytotoxicity of Pomegranate By-Products

Pomegranate by-products can be an asset to the food industry due to the richness in bioactive and antimicrobial compounds. This work studied the influence of conventional solvent and sonication-assisted extraction methods on the bioactive profile, antimicrobial properties, and phytotoxicity effect of the peels and seeds extracts from Acco, Big Full, and Wonderful pomegranate cultivars. The bioactive composition of the extracts was evaluated for the content of total phenolics, total flavonoids, and antioxidant activity (expressed as the half-maximal inhibitory concentration—IC₅₀) by spectrophotometric methods, while the tannins were determined by titration and the anthocyanins were estimated by the pH-differential method. For the evaluation of the antimicrobial activity, the disk diffusion method of Kirby-Bauer was adapted through inhibition halos against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus cereus, and Yarrowia lipolytica. The extracts’ phytotoxicity was evaluated in vitro on garden-cress seeds. Extracts from conventional extraction were richer in total phenolics, expressed as gallic acid equivalents (0.16–0.73 mg GAE/mg extract), while those from sonication-assisted extraction had higher contents of total flavonoids, expressed as catechin equivalents (0.019–0.068 mg CATE/mg extract); anthocyanins, expressed as cyanidin-3-glucoside (0.06–0.60 µg C3G/mg, dry basis); and antioxidant activity (IC₅₀, 0.01–0.20 mg/mL). All extracts were more effective against Gram-positive bacteria and yeasts than Gram-negative bacteria. In general, the sonication-assisted extracts led to higher inhibition halos (8.7 to 11.4 mm). All extracts presented phytotoxicity against garden-cress seeds in the tested concentrations. Only the lowest concentration (0.003 mg/mL) enabled the germination of seeds and root growth, and the sonication-assisted extracts showed the highest Munoo-Liisa vitality index (51.3%). Overall, sonication-assisted extraction obtained extracts with greater bioactive and antimicrobial potential and less phytotoxicity.

Infrared assisted extraction of bioactive compounds from plant materials: Current research and future prospect

The extraction of bioactive compounds from plant materials has attracted much attention due to their potential therapeutic effects. This article reviews the basic principles, characteristics, and recent applications of infrared assisted extraction (IAE) of bioactive compounds from plant materials. The advantages and disadvantages of IAE are considered, and operation mode and technological improvements, processes, solvents used and other future developments are identified. The review indicated that IAE was a simple, rapid, and cost-effective technique with the capacity for industrial scale application. Future research should focus on energy consumption reduction, green chemistry extraction processes, simplified operation steps, intelligent extraction process, and the establishment of kinetic and thermodynamic models. This article provides a comprehensive understanding of the principles and applications of IAE for the preparation of bioactive compounds, which will be of benefit to researchers and users of the technology.

Bio Discarded from Waste to Resource

The modern linear agricultural production system allows the production of large quantities of food for an ever-growing population. However, it leads to large quantities of agricultural waste either being disposed of or treated for the purpose of reintroduction into the production chain with a new use. Various approaches in food waste management were explored to achieve social benefits and applications. The extraction of natural bioactive molecules (such as fibers and antioxidants) through innovative technologies represents a means of obtaining value-added products and an excellent measure to reduce the environmental impact. Cosmetic, pharmaceutical, and nutraceutical industries can use natural bioactive molecules as supplements and the food industry as feed and food additives. The bioactivities of phytochemicals contained in biowaste, their potential economic impact, and analytical procedures that allow their recovery are summarized in this study. Our results showed that although the recovery of bioactive molecules represents a sustainable means of achieving both waste reduction and resource utilization, further research is needed to optimize the valuable process for industrial-scale recovery.

Emerging Green Techniques for the Extraction of Antioxidants from Agri-Food By-Products as Promising Ingredients for the Food Industry

Nowadays, the food industry is heavily involved in searching for green sources of valuable compounds, to be employed as potential food ingredients, to cater to the evolving consumers’ requirements for health-beneficial food ingredients. In this frame, agri-food by-products represent a low-cost source of natural bioactive compounds, including antioxidants. However, to effectively recover these intracellular compounds, it is necessary to reduce the mass transfer resistances represented by the cellular envelope, within which they are localized, to enhance their extractability. To this purpose, emerging extraction technologies, have been proposed, including Supercritical Fluid Extraction, Microwave-Assisted Extraction, Ultrasound-Assisted Extraction, High-Pressure Homogenization, Pulsed Electric Fields, High Voltage Electrical Discharges. These technologies demonstrated to be a sustainable alternative to conventional extraction, showing the potential to increase the extraction yield, decrease the extraction time and solvent consumption. Additionally, in green extraction processes, also the contribution of solvent selection, as well as environmental and economic aspects, represent a key factor. Therefore, this review focused on critically analyzing the main findings on the synergistic effect of low environmental impact technologies and green solvents towards the green extraction of antioxidants from food by-products, by discussing the main associated advantages and drawbacks, and the criteria of selection for process sustainability.

Novel trends in extraction and optimization methods of bioactives recovery from pomegranate fruit biowastes: Valorization purposes for industrial applications

Pomegranate biowastes present potential economic value worldwide owing to their several health benefits mediated by a complex mixture of unique bioactives. The exploitation of these bioactives has motivated the exploration of eco-friendly, efficient, and cost-effective extraction techniques to maximize their recovery. The current review aims to provide updated technical information about bioactives extraction mechanisms from pomegranate wastes (seeds and peel), their advantages and disadvantages, and factors towards optimization. A comparative overview of the modern green extraction techniques viz., supercritical fluid extraction, ultrasound-assisted extraction, microwave-assisted extraction, pressurized liquid extraction, and eutectic solvent mixture as alternatives to conventional extraction methods for seeds and peel is presented. Approaches focused on biowastes modification for properties improvement are also discussed. Such comprehensive review shall provide the best valorization practices of pomegranate biowastes and its application in food and non-food areas focusing on original methods, innovation, protocols, and development to be considered for other fruit biowastes.

Physical Properties of Chitosan Films Containing Pomegranate Peel Extracts Obtained by Deep Eutectic Solvents

Pomegranate peel is a byproduct of pomegranate juice production, and is rich in polyphenol compounds. The objective of this study was to investigate the incorporation of pomegranate peel extract in chitosan films. Green deep eutectic solvents (DESs) were used as extraction solvents. Choline chloride (ChCl) and glycerol (Gly) were used as the hydrogen bond acceptor and hydrogen bond donor, respectively; the molar ratio of the DES ingredients, ChCl:Gly, was 1:11. The extraction process was optimized by deploying response surface methodology. Under the optimized conditions, the extraction yield in total polyphenols amounted to 272.98 mg of gallic acid equivalents per g of dry matter and, for total flavonoids, 20.12 mg of quercetin equivalents per g of dry matter, with a liquid to solid ratio of 47 mL g⁻¹, time of 70 min, and 30% (v/v) water concentration in the DES. Afterwards, composite chitosan films were prepared by using five different formulations; the DES containing extract was incorporated as a plasticizer in the chitosan films. Specimens of every recipe were submitted to large deformation tensile testing in Texture Analyzer. Furthermore, water sorption behavior and color parameters of the films were determined.

Intensification of bio-actives extraction from pomegranate peel using pulsed ultrasound: Effect of factors, correlation, optimization and antioxidant bioactivities

Pomegranate peel (PP) is one of the interesting agri-food by-products because of its abundant bioactive phytochemicals. However, the bioactivity of valuable compounds is affected due to the extraction method used. A pulsed ultrasound-assisted extraction (PUAE) was carried out to intensify the extraction efficacy with reduced power and time. Influence of several process variables viz. peel solids/ solvent ratio, sonication power, duty cycle, and extraction time was studied using empirical quadratic models followed by multicriterial numerical optimization with respect to face-centered composite design. Power-duty cycle combination was found to be most significant (p < 0.05) for process intensification. The optimal process conditions of 2.17 g/100 mL S/S ratio at 116 W power with 80% duty cycle for 6 min resulted into 0.48 g/g yield, 177.54 mg GAE/g total phenolics content, 35.71 mg QE/g total flavonoids, 160.54 mg GAE/g antioxidant capacity, 21.65 mg cyn-3-glc/100 g anthocyanin content with 54.92 browning index in dry pomegranate peel. Significant Pearson correlation analysis was established in all responses with potent phenols and flavonoid relation with highest coefficient (r) 0.931. All response models were significantly validated with regression coefficient (R2) above 0.965. Remarkable antioxidant bioactivities were recorded for the resultant peel extract. Hence, it is strongly recommended that PUAE could be successfully applied for the intensification of the extraction process of bioactive from any peel and or plant systems with minimal process time and power consumption with a green label.

Techniques and modeling of polyphenol extraction from food: a review

There is a growing demand for vegetal food having health benefits such as improving the immune system. This is due in particular to the presence of polyphenols present in small amounts in many fruits, vegetables and functional foods. Extracting polyphenols is challenging because extraction techniques should not alter food quality. Here, we review technologies for extracting polyphenolic compounds from foods. Conventional techniques include percolation, decoction, heat reflux extraction, Soxhlet extraction and maceration, whereas advanced techniques are ultrasound-assisted extraction, microwave-assisted extraction, supercritical fluid extraction, high-voltage electric discharge, pulse electric field extraction and enzyme-assisted extraction. Advanced techniques are 32-36% more efficient with approximately 15 times less energy consumption and producing higher-quality extracts. Membrane separation and encapsulation appear promising to improve the sustainability of separating polyphenolic compounds. We present kinetic models and their influence on process parameters such as solvent type, solid and solvent ratio, temperature and particle size.

Application of Raw and Modified Pomegranate Peel for Wastewater Treatment: A Literature Overview and Analysis

The use of renewable substrates as biosorbents has a great attention in wastewater treatment. The pomegranate peel (PGP) constitutes one of these substrates. A review is carried out to investigate the potential of pomegranate peel (PGP) for wastewater treatment. Physical and chemical PGP properties are presented and compared to those of Tunisian pomegranate peel (El Gabsi). Raw and modified PGP performance and sorption capacity for metals, dyes, and organic pollutants are evaluated. Different experimental sorption conditions such as concentration, contact time, pH, temperature, and adsorbent dose used in the literature are illustrated. Studied and best-fitted kinetics and isotherm models to experimental data and thermodynamic parameters are compared. The effects of activating physical and/or chemical conditions on the activated PGP properties are presented. This paper reveals noteworthiness properties of raw PGP for wastewater treatment compared to this activated form. The comparison between activated and raw PGP morphology exhibits that the activation does not necessarily improve the PGP adsorption capacity. Despite a limited research carried out on the raw PGP biosorbent, it appears from this study that it has very good adsorption properties, making it a serious and low-cost renewable substrate toward practical applications in wastewater treatment compared to various other waste agricultural biomass.

Shelf life extension of apricot fruit by application of nanochitosan emulsion coatings containing pomegranate peel extract

The effect of nanochitosan coating containing pomegranate peel extract (PPE) at concentrations 0.5, 0.75 and 1% (w/v) on postharvest quality of apricot fruit was studied during storage at 4 °C for 30 days. Nanoemulsions showed significant increase in droplet diameter 275-400 nm, decrease in zeta potential -30-23 mV and viscosity 90-76 mPas^-1 with increase in PPE concentration. Results confirmed that apricot fruit treated with chitosan and 1% PPE showed significantly reduced decay percentage, weight loss, effectively retained DPPH radical scavenging activity, ascorbic acid, kept titratable acidity and firmness at high level than untreated fruit. Color attributes showed decrease in L*, a* values and significant increase in b* value. Nanochitosan containing 1% PPE significantly inhibited total psychrophilic bacterial count, yeast and mold count during storage. Our results suggest that chitosan coatings enriched with pomegranate peel extract has the potential to preserve the quality and extend shelf life of apricot.

Evaluation of Cellulolytic Enzyme-Assisted Microwave Extraction of Punica granatum Peel Phenolics and Antioxidant Activity

Conventional techniques for phenolics extraction from pomegranate (Punica granatum) peel (PP) have several insufficiencies like longer time duration, bioactive degradation, excess use of harmful chemicals and solvents. In the present study, we established the synergistic use of two non-conventional extraction strategies i.e., enzyme-assisted extraction (EAE) using a cellulolytic enzyme preparation (Viscozyme) followed by microwave-assisted extraction (MAE) for efficient recovery of phenolics from PP. This optimized method was individually compared with EAE, MAE, and conventional solvent extraction (CSE) methods for recovering PP phenolics with maximum antioxidant activity (AOA). Extracts were analyzed for AOA using ferric reducing antioxidant power (FRAP) and cupric reducing AOA (CUPRAC) methods. Response surface methodology (RSM), was used as an optimization tool to achieve maximum yield of phenolics and with highest AOA at power 443.5 W, time 131.0 min, and solvent-to-solid ratio 23.6:1. The predicted values for maximum phenolics and AOA obtained through RSM were 305 mg GAE/g, 1788 μmol TE/g (FRAP) and 2641 μmol TE/g (CUPRAC), respectively. Phenolic contents of only 94.6, 165.46, and 197.6 mg GAE/g were achieved through CSE, EAE and MAE, respectively. Here we substantiate the auxiliary role of Viscozyme and microwave treatment in achieving high phenolic content and AOA from PPs. Phenolic rich extracts are known to act as multi-target ligands that inhibit various enzymes involved in diseases like Alzheimer's, Parkinson's, and diabetes mellitus. The extract can be commercially exploited for the development of functional foods, supplements, and natural preservatives.

Green Extraction Methods for Extraction of Polyphenolic Compounds from Blueberry Pomace

In this study, green extraction methods—high voltage electrical discharges (HVED), pulsed electric field (PEF), and ultrasound-assisted extraction (UAE)—were compared in terms of extraction yield of total and individual polyphenolic compounds, as well as the antioxidant capacity of blueberry pomace extracts. All extractions were performed with methanol- and ethanol-based solvents. The highest total polyphenols content (TPC) (10.52 mg of gallic acid equivalent (GAE) per g of dry weight (dw)) and antioxidant activity (AA) (0.83 mmol TE/g dw) were obtained by PEF-assisted extraction in the ethanol-based solvent after 100 pulses and 20 kV/cm, which corresponds to an energy input of 41.03 kJ/kg. A total of eighteen individual polyphenols were identified in all investigated blueberry pomace extracts by high-performance liquid chromatography with the diode-array detector (HPLC-DAD) and liquid chromatography electrospray ionization tandem mass spectrometric (LC-(HESI)-MS/MS). The highest anthocyanin (1757.32 µg/g of dw) and flavanol (297.86 µg/g of dw) yields were obtained in the methanol-based solvent, while the highest phenolic acid (625.47 µg/g of dw) and flavonol (157.54 µg/g of dw) yields were obtained in the ethanol-based solvent by PEF-assisted extraction at the energy input of 41.03 kJ/kg. These results indicated that PEF is a promising green extraction method which can improve the blueberry pomace’s polyphenol extraction yield.

A Glimpse into the Extraction Methods of Active Compounds from Plants

Naturally active compounds are usually contained inside plants and materials thereof. Thus, the extraction of the active compounds from plants needs appropriate extraction methods. The commonly employed extraction methods are mostly based on solid-liquid extraction. Frequently used conventional extraction methods such as maceration, heat-assisted extraction, Soxhlet extraction, and hydrodistillation are often criticized for large solvent consumption and long extraction times. Therefore, many advanced extraction methods incorporating various technologies such as ultrasound, microwaves, high pressure, high voltage, enzyme hydrolysis, innovative solvent systems, adsorption, and mechanical forces have been studied. These advanced extraction methods are often better than conventional methods in terms of higher yields, higher selectivity, lower solvent consumption, shorter processing time, better energy efficiency, and potential to avoid organic solvents. They are usually designed to be greener, more sustainable, and environment friendly. In this review, we have critically described recently developed extraction methods pertaining to obtaining active compounds from plants and materials thereof. Main factors that affect the extraction performances are tuned, and extraction methods are chosen in line with the properties of targeted active compounds or the objectives of extraction. The review also highlights the advancements in extraction procedures by using combinations of extraction methods to obtain high overall yields or high purity extracts.

High Voltage Electrical Discharges as an Alternative Extraction Process of Phenolic and Volatile Compounds from Wild Thyme (Thymus serpyllum L.): In Silico and Experimental Approaches for Solubility Assessment

The objective of this study was to evaluate the potential of green solvents for extractions of bioactive compounds (BACs) and essential oils from wild thyme (Thymus serpyllum L.) using theoretical and experimental procedures. Theoretical prediction was assessed by Hansen solubility parameters (HSPs) and conductor-like screening model for realistic solvents (COSMO-RS), to predict the most suitable solvents for extraction of BACs. An experimental procedure was performed by nonthermal technology high voltage electrical discharge (HVED) and it was compared with modified conventional extraction (CE). Obtained extracts were analyzed for chemical and physical changes during the treatment. Theoretical results for solution of BACs in ethanol and water, as green solvents, were confirmed by experimental results, while more accurate data was given by COSMO-RS assessment than HSPs. Results confirmed high potential of HVED for extraction of BACs and volatile compounds from wild thyme, in average, 2.03 times higher yield of extraction in terms of total phenolic content was found compared to CE. The main phenolic compound found in wild thyme extracts was rosmarinic acid, while the predominant volatile compound was carvacrol. Obtained extracts are considered safe and high-quality source reach in BACs that could be further used in functional food production.