Green and Sustainable Separation of Natural Products from Agro-Industrial Waste: Challenges, Potentialities, and Perspectives on Emerging Approaches

Bioactive Compounds from Organic Waste

The reuse and reincorporation of waste are the principles of circular economies. Compost, biofuels, animal feed, dyes, and bioactive compounds can be obtained from the revaluation of organic waste. Research on this subject is scarce and limited to specific sectors, such as agriculture and agroindustry, leaving aside others that generate large quantities of organic waste, such as floriculture. The remains of these sectors have a low decomposition rate compared to other organic wastes. They are a source of bioactive compounds (e.g., essential oils, pigments, phenols) that can be reincorporated into the production chain of various industries. This review describes the composition of waste from agroindustry, agriculture, and floriculture, analyzing their potential revalorization as a source of bioactive compounds and an alternative supply source.

Plant-Based Biostimulants for Seeds in the Context of Circular Economy and Sustainability

Plant-based biostimulants (PBs), agents rich in bioactive compounds, are emerging as key players able to sustainably improve plant growth and crop productivity to address food security. PBs are generally applied as foliar spray or soil irrigation, while more recently, the application as seed priming treatments is being envisaged as a highly sustainable method to also improve seed quality and germination. Therefore, this review proposes to explore the use of PBs for the seeds industry, specifically discussing about the relevance of product market values, sustainable methods for their production, why and how PBs are used for seed priming, and pinpointing specific strengths and challenges. The collected research studies indicate that PBs applied to seeds result in improved germination, seedling growth, and stress tolerance, although the molecular mechanisms at work are still largely overlooked. The high variability of bioactive molecules and used sources point towards a huge reservoir of nature-based solutions in support of sustainable agriculture practices.

Intracellular Synthesis of Indoles Enabled by Visible-Light Photocatalysis

Performing abiotic synthetic transformations in live cell environments represents a new, promising approach to interrogate and manipulate biology and to uncover new types of biomedical tools. We now found that photocatalytic bond-forming reactions can be added to the toolbox of bioorthogonal synthetic chemistry. Specifically, we demonstrate that exogenous styryl aryl azides can be converted into indoles inside living mammalian cells under photocatalytic conditions.

Blueberry Pruning Wastes: From an Undervalued Agricultural Residue to a Safe and Valuable Source of Antioxidant Compounds for the Food Industry

Blueberry fruits have been widely explored for their rich composition of bioactive compounds with recognized health benefits. In contrast, blueberry pruning waste (BPW), generated during the pruning stages of blueberries, has been typically overlooked, even though it can represent a potential source of natural antioxidants. This study aims to characterize the value-added compounds extracted from BPW using green techniques, namely microwave-assisted and subcritical water extraction. The total phenolic content ranged from 157 ± 5 to 335 ± 12 mg GAE/g dw, while the radical scavenging activity determined by a DPPH assay varied from 223 ± 21 to 453 ± 21 mg Trolox equivalents/g dw. Additionally, to ensure the safe application of BPW and its extracts, a screening of pesticides and several environmental contaminants was conducted. Chlorpyrifos-methyl was quantified at a concentration of 4.27 µg/kg in a Bluecrop variety collected in 2019; however, none of the studied compounds were found in the extracts. Despite the presence of a pesticide, this level was below the maximum residue limits for blueberry crops. The results of this study demonstrated the potential of this agro-industrial residue as a natural source of bioactive compounds with high antioxidant activity for food industry applications.

Background and Perspectives on the Utilization of Canes' and Bunch Stems' Residues from Wine Industry as Sources of Bioactive Phenolic Compounds

Viticulture activity produces a significant amount of grapevine woody byproducts, such as bunch stems and canes, which constitute potential sources of a wide range of phenolic compounds (PCs) with purported applications. Recently, the study of these byproducts has been increased as a source of health-promoting phytochemicals. Antioxidant, antimicrobial, antifungal, and antiaging properties have been reported, with most of these effects being linked to the high content of PCs with antioxidant properties. This Review summarizes the data related to the qualitative and quantitative composition of PCs recovered from canes and bunch stems side streams of the wine industry, the influence that the different environmental and storage conditions have on the final concentration of PCs, and the current reported applications in specific technological fields. The objective is to give a complete valuation of the key factors to consider, starting from the field to the final extracts, to attain the most suitable and stable characterized product.

Genotoxicity Assessment of Nutraceuticals Extracted from Thinned Nectarine (Prunus persica L.) and Grape Seed (Vitis Vinifera L.) Waste Biomass

Agri-food by-products represent a considerable portion of the waste produced in the world and especially when incorrectly disposed of, contribute to air, soil, and water pollution. Recently, recycling of food waste has proven to be an attractive area of research for pharmaceutical companies, that use agri-food by-products (leaves, bark, roots, seeds, second-best vegetables) as alternative raw material for the extraction of bioactive compounds. Developers and producers are however, advised to assess the safety of nutraceuticals obtained from biowaste that, in virtue of its chemical complexity, could undermine the overall safety of the final products. Here, in compliance with EFSA regulations, we use the Ames test (OECD 471) and the micronucleus test (OECD 487) to assess the mutagenicity of two nutraceuticals obtained from food waste. The first consists of grape seeds (Vitis vinifera L.) that have undergone a process of food-grade depolymerization of proanthocyanidins to release more bioavailable flavan-3-ols. The second nutraceutical product consists of thinned nectarines (Prunus persica L. var nucipersica) containing abscisic acid and polyphenols. The results presented here show that these products are, before as well as after metabolization, non-mutagenic, up to the doses of 5 mg and 100 μg per plate for the Ames and micronucleus test, respectively, and can be thus considered genotoxically safe.

Penicillium chrysogenum as a fungal factory for feruloyl esterases

Plant biomass is a promising substrate for biorefinery, as well as a source of bioactive compounds, platform chemicals, and precursors with multiple industrial applications. These applications depend on the hydrolysis of its recalcitrant structure. However, the effective biological degradation of plant cell walls requires several enzymatic groups acting synergistically, and novel enzymes are needed in order to achieve profitable industrial hydrolysis processes. In the present work, a feruloyl esterase (FAE) activity screening of Penicillium spp. strains revealed a promising candidate (Penicillium rubens Wisconsin 54-1255; previously Penicillium chrysogenum), where two FAE-ORFs were identified and subsequently overexpressed. Enzyme extracts were analyzed, confirming the presence of FAE activity in the respective gene products (PrFaeA and PrFaeB). PrFaeB-enriched enzyme extracts were used to determine the FAE activity optima (pH 5.0 and 50-55 °C) and perform proteome analysis by means of MALDI-TOF/TOF mass spectrometry. The studies were completed with the determination of other lignocellulolytic activities, an untargeted metabolite analysis, and upscaled FAE production in stirred tank reactors. The findings described in this work present P. rubens as a promising lignocellulolytic enzyme producer. KEY POINTS: • Two Penicillium rubens ORFs were first confirmed to have feruloyl esterase activity. • Overexpression of the ORFs produced a novel P. rubens strain with improved activity. • The first in-depth proteomic study of a P. rubens lignocellulolytic extract is shown.

A Real-World Scenario of Citizens' Motivation and Engagement in Urban Waste Management Through a Mobile Application and Smart City Technology

Circular bioeconomy is a key socioeconomic model for advancing the United Nations Global Sustainability Goals and promoting environmental and resource sustainability. However, circular bioeconomy concepts are unknown to most people and politicians worldwide who still have a fragmented picture of sustainability. Common perception of waste needs a cultural shift from "disposable" to commodity. This can happen with effective communication, active citizens' education, and awareness and engagement in core bioeconomy experiences and activities, like urban waste management and environmental sustainability. Citizen engagement methodologies are multiple. This paper proposes the combined use of Information and Communication Technologies (ICTs), citizens' hands-on project involvement, and a direct rewarding system. Similar European examples are displayed, while our key case study is the bitter orange waste problem in the metropolitan region of Attica in Greece, where approximately 40,000 tons of bitter oranges per year remain unmanageable and unexploited, causing serious problems. The Bitter Orange Project aims to educate citizens on bioeconomy and biomass value, hopefully changing the perception of urban waste through their rewarded engagement in fruit collection to produce high added value materials. This can be a versatile platform for urban waste management projects through citizen science regardless of the type of biomass. The project aims to engage all possible local society stakeholders to multiply awareness. The target of this paper is to highlight that environmental problems related to biomass misuse are closer than the average citizen experiences, and that active involvement of society through rewarding can help raise awareness.

Sustainable Approaches Using Green Technologies for Apple By-Product Valorisation as A New Perspective into the History of the Apple

The apple has been recognised as the most culturally important fruit crop in temperate land areas. Centuries of human exploitation and development led to the production of thousands of apple cultivars. Nowadays, the apple represents the third most widely cultivated fruit in the world. About 30% of the total production of apples is processed, being juice and cider the main resulting products. Regarding this procedure, a large quantity of apple by-product is generated, which tends to be undervalued, and commonly remains underutilised, landfilled, or incinerated. However, apple by-product is a proven source of bioactive compounds, namely dietary fibre, fatty acids, triterpenes, or polyphenols. Therefore, the application of green technologies should be considered in order to improve the functionality of apple by-product while promoting its use as the raw material of a novel product line. The present work provides a holistic view of the apple’s historical evolution, characterises apple by-product, and reviews the application of green technologies for improving its functionality. These sustainable procedures can enable the transformation of this perishable material into a novel ingredient opening up new prospects for the apple’s potential use and consumption.

Ionic liquids vs. ethanol as extraction media of algicidal compounds from mango processing waste

The race for environmentally-safe pesticides and biocides has been showing solutions ranging from pest-pathologic microorganisms to safer botanical extracts that can be incorporated in several formulations. Often linked to high biological activities, fruit residues can be recovered from food processing factories to obtain complex extracts enriched with several bioactive chemicals. Mango (Mangifera indica) fruits are processed into food products in high volumes across the globe and generate a consistent residue that contains, among others, the xanthonoid mangiferin and the flavonoid hyperoside. Both compounds have been linked to several pharmacological and pesticidal activities, although not yet studied for algicidal applications, a current concern specially for antifouling and harmful algae blooms control products. The challenge lies, however, not only on the degree of activity of the natural compounds, but also on the processes necessary to separate, isolate and formulate the bioactive compounds in order to obtain an effective final product. The solvent choice plays an important part regarding the selectivity of the separation and isolation of the main bioactive compounds from the solid waste matrix. Ethanolic mixtures in water have been consolidated recently as a promising extraction medium for flavonoids and xanthonoids, although hindered by solubility limitations. In this paper, aqueous solutions of ionic liquids (ILs) were tested, screened and optimized using Box-Behnken design and Response Surface Methodology to obtain mangiferin and hyperoside-enriched extracts. Results showed a greater concentration of mangiferin and hyperoside with 1-octyl-3-methylimidazolium chloride ([C8MIm] Cl), when compared to choline acetate and ethanolic extracts using optimized parameters. In terms of sufficiency, solvent selection between ILs and ethanolic extraction media was discussed considering economic and environmental factors. Ethanol/water mango waste extracts were then studied for their activity against Raphidocelis subcapitata microalgae, which showed a higher growth inhibition in comparison to standard solutions of mangiferin and hyperoside, either individually and in a 1:1 mixture. A EC50 value was found in relative low concentrations of mangiferin and hyperoside (0.015 mg L−1) detected in the extract, showcasing a promising approach to the direct use of residuary plant extracts in biocidal formulations.

Functional proteins through green refining of seafood side streams

Scarcity of nutritive protein is a major global problem, the severity of which is bound to increase with the rising population. The situation demands finding additional sources of proteins that can be both safe as well as acceptable to the consumer. Food waste, particularly from seafood is a plausible feedstock of proteins in this respect. Fishing operations result in appreciable amounts of bycatch having poor food value. In addition, commercial processing results in 50 to 60% of seafood as discards, which consist of shell, head, fileting frames, bones, viscera, fin, skin, roe, and others. Furthermore, voluminous amounts of protein-rich effluents are released during commercial seafood processing. While meat from the bycatch can be raw material for proteinous edible products, proteins from the process discards and effluents can be recovered through biorefining employing upcoming, environmental-friendly, low-cost green processes. Microbial or enzyme treatments release proteins bound to the seafood matrices. Physico-chemical processes such as ultrasound, pulse electric field, high hydrostatic pressure, green solvent extractions and others are available to recover proteins from the by-products. Cultivation of photosynthetic microalgae in nutrient media consisting of seafood side streams generates algal cell mass, a rich source of functional proteins. A zero-waste marine bio-refinery approach can help almost total recovery of proteins and other ingredients from the seafood side streams. The recovered proteins can have high nutritive value and valuable applications as nutraceuticals and food additives.

Polyelectrolyte Precipitation: A New Green Chemistry Approach to Recover Value-Added Proteins from Different Sources in a Circular Economy Context

Proteins have always been vital biological molecules used for industrial purposes, human nutrition and health. Nowadays, seeking new alternatives and sources of these biomolecules is becoming an increasing research trend derived from the present consumer awareness between food consumption and health promotion, but also on environmental sustainability. Although there are different consolidated/traditional downstream processes to obtain proteins, such as chromatography tools, alkali hydrolysis, precipitation by inorganic salts and organic solvents, their industrial-scale application still demands urgent innovation due to the poor recovery yields, high costs and time-consuming steps, environmental impact as well as some toxic concerns. Polyelectrolyte precipitation represents a green, innovative alternative for protein recovery; however, there are reduced data regarding its pilot or industrial-scale application. In this literature work, the action mechanism and principles with regards to its functionality and insights for its application on a big scale are reviewed. Overall, this review discusses the novelty and sustainability of protein precipitation by polyelectrolytes from different sources against traditional techniques as well as highlights the relationship between protein source, production relevance and bioactive properties that are key factors to maximize the application of this extractive method on a circular economy context.

Influence of Cotton Pre-Treatment on Dyeing with Onion and Pomegranate Peel Extracts

In this paper the possibility of applying natural dyes on cellulose fibres were researched with respect to the impact of cotton material pre-treatment (scouring, chemical bleaching, mercerization and mordanting), using renewable sources of natural dyes (waste as a source). As mordants, metal salts of copper, aluminium and ferrum were used, and the influence on colour change as well as on fastness properties were analysed. The natural dyes were extracted from onion peel (Allium cepa L.) and pomegranate peel (Punica granatum L.). In spectrophotometric analysis performed of the plant extracts, the onion extract has peaks at 400 and 500 nm, resulting in red-orange colourations and the pomegranate extract shows a maximum at 400 nm, i.e., in the yellow region, which is characteristic of punicalin. Results show significant influence of cotton pre-treatments on colour appearance and fastness properties, caused by pre-treatments affecting the properties and structure of the cotton itself. The positive effect of mercerization on dye absorption and bonding is confirmed. For wash and light fastness properties, more satisfactory results have been obtained for yarns dyed with pomegranate peel natural dye, and the key importance of mordants for fastness properties has been confirmed.

Increasing the added value of vine-canes as a sustainable source of phenolic compounds: A review

Grapes represent one of the most produced fruit crops around the world leading to the generation of large amounts of vine-canes as a side product, with no current economically profitable application. However, vine-canes have been demonstrated to be natural sources of phenolic compounds with numerous health benefits associated, with several potential applications. Therefore, new ambitious applications focused on their re-use are needed, targeting a sustainable process that simultaneous produces functional products and mitigates the waste generation. This review gives to the readers a complete summary about the state of the art regarding the vine-canes extracts research. Vine-canes phenolic composition is addressed and related to the health benefits exhibited. This review comprises studies from the past two decades reporting the extraction processes to recover vine-cane phenolic compounds, including conventional and environmentally friendly technologies and discussing their advantages and disadvantages. The conditions that favour the extraction process for vine-cane polyphenols for each technique were also deeply explored for the first time, enabling to the reader apply only the best parameters to achieve the highest yields without huge investment in optimizations procedures. Furthermore, a correlation between the bioactive properties of the vine-cane extracts and their applications in multiple fields is also critically presented.

Extraction of Polyphenolic Antioxidants from Red Grape Pomace and Olive Leaves: Process Optimization Using a Tailor-Made Tertiary Deep Eutectic Solvent

In the framework of introducing green strategies for food processing, the industrial orientation has shifted towards the replacement of conventional petroleum-based solvents with alternative eco-friendly ones. On this basis, the objective of this study was to synthesize a novel, tertiary, food-grade deep eutectic solvent, composed of glycerol, citric acid, and L-proline (GL-CA-Pro), and to test it as a solvent for the extraction of polyphenols from agri-food waste biomass. After an initial screening on various common residual materials (apple peels, lemon peels, orange peels, red grape pomace, olive leaves), evidence emerged that indicated GL-CA-Pro was more effective than other DESs commonly used for polyphenol extraction. Furthermore, extracts from red grape pomace (RGP) and olive leaves (OLL) were shown to contain higher level of total polyphenols and increased antioxidant activity. Process optimization for those two materials with the response surface methodology revealed that the major difference pertained to the extraction time. In addition, for both materials, GL-CA-Pro was shown to provide higher total polyphenol yields (53.25 and 42.48 mg gallic acid equivalents per g of dry mass, respectively) compared to water and 60% aqueous ethanol. However, the chromatographic analyses for OLL suggested aqueous ethanol was a more suitable solvent for some principal polyphenolic constituents. The RGP extract produced with GL-CA-Pro exhibited significantly stronger antioxidant effects compared to the aqueous and hydroethanolic extracts, but the outcome for the OLL extracts was diversified. It was concluded that GL-CA-Pro is a very efficient solvent for RGP polyphenols, but its efficiency regarding OLL was comparable to that of aqueous ethanol.

Polysaccharides in Agro-Industrial Biomass Residues

The large-scale industrial use of polysaccharides to obtain energy is one of the most discussed subjects in science. However, modern concepts of biorefinery have promoted the diversification of the use of these polymers in several bioproducts incorporating concepts of sustainability and the circular economy. This work summarizes the major sources of agro-industrial residues, physico-chemical properties, and recent application trends of cellulose, chitin, hyaluronic acid, inulin, and pectin. These macromolecules were selected due to their industrial importance and valuable functional and biological applications that have aroused market interests, such as for the production of medicines, cosmetics, and sustainable packaging. Estimations of global industrial residue production based on major crop data from the United States Department of Agriculture were performed for cellulose content from maize, rice, and wheat, showing that these residues may contain up to 18%, 44%, and 35% of cellulose and 45%, 22%, and 22% of hemicellulose, respectively. The United States (~32%), China (~20%), and the European Union (~18%) are the main countries producing cellulose and hemicellulose-rich residues from maize, rice, and wheat crops, respectively. Pectin and inulin are commonly obtained from fruit (~30%) and vegetable (~28%) residues, while chitin and hyaluronic acid are primarily found in animal waste, e.g., seafood (~3%) and poultry (~4%).

Current Status and Future Perspectives on Therapeutic Potential of Apigenin: Focus on Metabolic-Syndrome-Dependent Organ Dysfunction

Metabolic syndrome and its associated disorders such as obesity, insulin resistance, atherosclerosis and type 2 diabetes mellitus are globally prevalent. Different molecules showing therapeutic potential are currently available for the management of metabolic syndrome, although their efficacy has often been compromised by their poor bioavailability and side effects. Studies have been carried out on medicinal plant extracts for the treatment and prevention of metabolic syndrome. In this regard, isolated pure compounds have shown promising efficacy for the management of metabolic syndrome, both in preclinical and clinical settings. Apigenin, a natural bioactive flavonoid widely present in medicinal plants, functional foods, vegetables and fruits, exerts protective effects in models of neurological disorders and cardiovascular diseases and most of these effects are attributed to its antioxidant action. Various preclinical and clinical studies carried out so far show a protective effect of apigenin against metabolic syndrome. Herein, we provide a comprehensive review on both in vitro and in vivo evidence related to the promising antioxidant role of apigenin in cardioprotection, neuroprotection and renoprotection, and to its beneficial action in metabolic-syndrome-dependent organ dysfunction. We also provide evidence on the potential of apigenin in the prevention and/or treatment of metabolic syndrome, analysing the potential and limitation of its therapeutic use.

Recovery of Chlorogenic Acids from Agri-Food Wastes: Updates on Green Extraction Techniques

The agri-food sector produces a huge amount of agri-food wastes and by-products, with a consequent great impact on environmental, economic, social, and health aspects. The reuse and recycling of by-products represents a very important issue: for this reason, the development of innovative recovery and extraction methodologies must be mandatory. In this context of a circular economy, the study of green extraction techniques also becomes a priority in substitution of traditional extraction approaches. This review is focused on the recovery of chlorogenic acids from agri-food wastes, as these compounds have an important impact on human health, exhibiting several different and important healthy properties. Novel extraction methodologies, namely microwave and ultrasound-assisted extractions, supercritical fluid extraction, and pressurized-liquid extraction, are discussed here, in comparison with conventional techniques. The great potentialities of these new innovative green and sustainable approaches are pointed out. Further investigations and optimization are mandatory before their application in industrial processes.

Green Aspects in Molecularly Imprinted Polymers by Biomass Waste Utilization

Molecular Imprinting Polymer (MIP) technology is a technique to design artificial receptors with a predetermined selectivity and specificity for a given analyte, which can be used as ideal materials in various application fields. In the last decades, MIP technology has gained much attention from the scientific world as summarized in several reviews with this topic. Furthermore, green synthesis in chemistry is nowadays one of the essential aspects to be taken into consideration in the development of novel products. In accordance with this feature, the MIP community more recently devoted considerable research and development efforts on eco-friendly processes. Among other materials, biomass waste, which is a big environmental problem because most of it is discarded, can represent a potential sustainable alternative source in green synthesis, which can be addressed to the production of high-value carbon-based materials with different applications. This review aims to focus and explore in detail the recent progress in the use of biomass waste for imprinted polymers preparation. Specifically, different types of biomass waste in MIP preparation will be exploited: chitosan, cellulose, activated carbon, carbon dots, cyclodextrins, and waste extracts, describing the approaches used in the synthesis of MIPs combined with biomass waste derivatives.

In vitro fermentability of a broad range of natural ingredients by fecal microbiota from lean and obese individuals: potential health benefits

The prevalence of obesity and related complications is continuously increasing while the gut microbiota might have a significant role to address this challenge. In this context, the food industry generates large amounts of residues that could be likely revalorised as functional ingredients. Hence, we evaluated the fermentability of food skins, husks, shells, trimming residues, mosses and mushrooms, which were subjected to in vitro fermentation with faecal microbiota from lean and obese adults. We demonstrated for the first time that pumpkin skin is highly fermented by human faecal microbiota showing pH-lowering effects and promoting gas and SCFA production. Furthermore, brewers' spent grain generated an inulin-like SCFA profile after microbial fermentation, whereas Irish moss, plum skin, quinoa husk and mushrooms, including Armillaria mellea and Boletus edulis, showed high fermentation rates. Remarkably, although propionate production was significantly higher in obese individuals, the fermentability of the ingredients was similar between lean and obese conditions.

Use of Polyphenols as Modulators of Food Allergies. From Chemistry to Biological Implications

The multifactorial process of aging predisposes humans to infections and inflammatory disorders, thus affecting their quality of life and longevity. Given this reality, the need to increase the consumption of bioactive compounds, like dietary polyphenols emerges in our daily basis mostly due to their health related effects in slowing-down the incidence of chronic and degenerative diseases and even food allergy, which has been growing rapidly in prevalence currently affecting 5% of adults and 8% of children. Polyphenols embrace a large family of secondary metabolites from plant-derived foods and food wastes and are considerable of interest since they have attracted special attention over the years because of their reported anti-inflammatory and antimicrobial properties along with their high antioxidant capacity. These compounds are claimed as nutraceuticals with protective effect in offsetting oxidant species over-genesis in normal cells, and with the potential ability to stop or reverse oxidative stress-related diseases. Plant-derived foods represent a substantive portion of human diet containing a significant amount of structurally diverse polyphenols. There is a need to understand the polyphenolic composition of plant-derived foods mainly because of its chemistry, which discloses the bioactivity of a plant extract. However, the lack of standardized methods for analysis and other difficulties associated to the nature and distribution of plant polyphenols leads to a high variability of available data. Furthermore, there is still a gap in the understanding of polyphenols bioavailability and pharmacokinetics, which clearly difficult the settlement of the intake needed to observe health outcomes. Many efforts have been made to provide highly sensitive and selective analytical methods for the extraction (liquid-liquid; solid-liquid; supercritical-fluid), separation (spectrophotometric methods) and structural identification (chromatographic techniques, NMR spectroscopy, MS spectrometry) of phenolic and polyphenolic compounds present in these extracts. Liquid chromatography coupled to mass spectrometry (LC-MS) has been a fundamental technique in this area of research, not only for the determination of this family of compounds in food matrices, but also for the characterization and identification of new polyphenols classified with nutraceutical interest. This review summarizes the nature, distribution and main sources of polyphenols, analytical methods from extraction to characterization to further evaluate the health effects toward immune reactions to food.

Development of New Extracts of Crocus sativus L. By-Product from Two Different Italian Regions as New Potential Active Ingredient in Cosmetic Formulations

This project aimed to apply eco-friendly extraction methods to Crocus sativus L. by-product (flowers without stigmas i.e., tepals composed of petals and sepals) to recover extracts with high antioxidant capacity and polyphenol content, to be used in cosmetic products. Flowers grown in two different Italian regions (Sample 1—Alba in Piemonte, north of Italy and Sample 2—Sibillini in Marche, centre of Italy) were subjected for the first time to different eco-friendly microwave-mediated green solvents extractions (MGSE) andquali-quantitative determination in antioxidant molecules. Firstly, the extracts from Sample 1 were selected according to their total phenol content (TPC) by Folin–Ciocalteu’s assay and antioxidant capacity (AC) by spectrophotometric assays. Then, according to preliminary results, MGSE carried out in ethanol 70°, water, and glycerin were selected as the most performing methods and applied to both Samples 1 and 2. The best results were obtained using green solvents, such as water or ethanol 70°, for the samples coming from Marche. The identification and quantification of phenolic compounds, belonging to anthocyanins and flavonols classes, was performed by using UPLC-DAD-ESI-MS. Concerning flavonols content, the most abundant analyte is kaempferol 3-O-sophoroside and the extract in water from Sample 1 showed the higher amount of flavonols, reaching the concentration of 25.35 mg of kaempferol 3-O-glucoside equivalent per gram of tepals DW of raw material. Among anthocyanins, the most abundant was delphinidin 3,5-O-diglucoside and the high concentration of anthocyanin was detected in water and ethanol extract. Two new compounds, myricetin-di-glucoside and primflasine, were identified for the first time in Crocus sativus L. by-product by high-resolution mass spectrometry (HRMS). The green batches obtained by extraction were thus characterized and evaluated for their biological potential and safety in keratinocyte HaCaT cells. The extracts were not cytotoxic up to 0.03 mg/mL. The water and ethanol 70° extracts were the most effective in counteracting oxidative stress induced by H2O2 and UVA exposure and reduced cytotoxicity induced by UVB exposure. The water extract was also able to significantly reduce cytotoxicity induced by sodium dodecyl sulphate-induced damage. Taken together, these results suggest a potential use of these waste materials as cosmeceutical preparations such as antiaging, and as anti-skin irritation formulation by-products.

Valorization of Bio-Residues from the Processing of Main Portuguese Fruit Crops: From Discarded Waste to Health Promoting Compounds

Food processing generates a large amount of bio-residues, which have become the focus of different studies aimed at valorizing this low-cost source of bioactive compounds. High fruit consumption is associated with beneficial health effects and, therefore, bio-waste and its constituents arouse therapeutic interest. The present work focuses on the main Portuguese fruit crops and revises (i) the chemical constituents of apple, orange, and pear pomace as potential sources of functional/bioactive compounds; (ii) the bioactive evidence and potential therapeutic use of bio-waste generated in the processing of the main Portuguese fruit crops; and (iii) potential applications in the food, nutraceutical, pharmaceutical, and cosmetics industries. The current evidence of the effect of these bio-residues as antioxidant, anti-inflammatory, and antimicrobial agents is also summarized. Conclusions of the revised data are that these bio-wastes hold great potential to be employed in specific nutritional and pharmaceutical applications.

Recent developments in sustainably sourced protein-based biomaterials

Research into the development of sustainable biomaterials is increasing in both interest and global importance due to the increasing demand for materials with decreased environmental impact. This research field utilises natural, renewable resources to develop innovative biomaterials. The development of sustainable biomaterials encompasses the entire material life cycle, from desirable traits, and environmental impact from production through to recycling or disposal. The main objective of this review is to provide a comprehensive definition of sustainable biomaterials and to give an overview of the use of natural proteins in biomaterial development. Proteins such as collagen, gelatin, keratin, and silk, are biocompatible, biodegradable, and may form materials with varying properties. Proteins, therefore, provide an intriguing source of biomaterials for numerous applications, including additive manufacturing, nanotechnology, and tissue engineering. We give an insight into current research and future directions in each of these areas, to expand knowledge on the capabilities of sustainably sourced proteins as advanced biomaterials.

Machine learning prediction of cellulose-rich materials from biomass pretreatment with ionic liquid solvents

Ionic liquid solvents (ILSs) have been effectively utilized in biomass pretreatment to produce cellulose-rich materials (CRMs). Predicting CRM properties and evaluating multi-dimensional relationships in this system are necessary but complicated. In this work, machine learning algorithms were applied to predict CRM properties in terms of cellulose enrichment factor (CEF) and solid recovery (SR), using 23-feature datasets from biomass characteristics, operating conditions, ILSs identities, and catalyst. Random forest algorithm was found to have the highest prediction accuracy with RMSE and R² of 0.22 and 0.94 for CEF, as well as 0.07 and 0.84 for SR, respectively. Highly influential features on making predictions were mainly from biomass characteristics andILS treatment'soperating conditions, totally contributed 80% on CEF and 60% on SR. One- and two-way partial dependence plots were used to explain/interpret the multi-dimensional relationships of the most important features. Our findings could be applied in designing new ILSs and optimizing the process conditions.

Antioxidant Activity and Chemical Characteristics of Supercritical CO2 and Water Extracts from Willow and Poplar

Renewable feedstock from perennial industrial crops, including those cultivated on marginal land in a short-rotation coppice system, could be an important contribution to the bioeconomy. The majority of data available on the topic are limited to the production of bioenergy from this type of biomass. According to the concept of bioeconomy, biomass-based bioproducts have priority over energy production. This paper characterizes the chemical composition and antioxidant activity of extracts from bark (b), wood (w) or a mixture of bark and wood (b + w) from Salix purpurea, Salix viminalis and Populus nigra obtained using supercritical carbon dioxide (scCO₂), scCO₂ and water (1%, w/w) or only water. Generally, a high concentration of polyphenols was obtained after extraction with scCO₂ and water, while the lowest concentration was found in extracts obtained with scCO₂. The highest concentration of polyphenols (p < 0.05) was obtained in an extract from P. nigra (b) (502.62 ± 9.86 mg GAE/g dry matter (d.m.)) after extraction with scCO₂ and water, whereas the lowest polyphenol concentration was observed in an scCO₂ extract from S. purpurea (b) (6.02 ± 0.13 mg GAE/g d.m.). The flavonoids were effectively separated by extraction with scCO₂ (0.88-18.37 mg QE/g d.m.). A positive linear relationship between the antioxidant activity determined by DPPH and ABTS assays and the concentration of polyphenols was demonstrated, R² = 0.8377 and R² = 0.9568, respectively. It is most probable that the concentration of flavonoids, rather than the concentration of polyphenols, determines the chelating activity of Fe²⁺. The Fe²⁺-chelating activity of scCO₂ extracts ranged from 75.11% (EC₅₀ = 5.41 mg/cm³, S. purpurea, b + w) to 99.43% (EC₅₀ = 0.85 mg/cm³, P. nigra, b + w). The lowest chelating activity was demonstrated by the extracts obtained with scCO₂ and water (maximum 26.36%, S. purpurea, b + w). In extracts obtained with scCO₂ and water, p-hydroxybenzoic acid (210-428 µg/g), p-coumaric acid (56-281 µg/g), saligenin (142-300 µg/g) and salicortin (16-164 µg/g) were the dominant polyphenols. All of these chemical compounds occurred mainly in the free form. The S. purpurea, S. viminalis and P. nigra biomass proved to be an attractive source of biologically active compounds for various possible applications in food, drugs or cosmetics. These compounds could be extracted using an environmentally friendly method with scCO₂ and water as a co-solvent.

Valorization of Tropical Biomass Waste by Supercritical Fluid Extraction Technology

The inception of sustainable and cleaner extraction technology has paved the way for the innovative development of nonconventional extractions, such as supercritical fluid extraction, apart from conventional extraction counterparts. The concept of biomass waste-to-wealth for the conversion of biomass waste or by-products into value-added products for diversified applications had piqued the prominent interest of researchers and industry players, especially with the abundance of biomass resources readily available in tropical regions that have yet to be tapped into to reach their full potential. In this paper, a critical review of the developments of supercritical fluid technology from its initial inception up to commercialized scalability, including its limitations, extraction of potential tropical biomass wastes for various types of applications, such as biopesticides, bio-repellents, phenolics, and lipids for biofuel, and its role in circular bioeconomy and sustainable development approaches, are discussed in detail.

Development and application of green and sustainable analytical methods for flavonoid extraction from Passiflora waste

Brazilian biodiversity and favourable environmental conditions open up possibilities not yet explored, showing potential to shift the country's monochromatic economy into an emancipated, diversified and sustainable economic environment. This can be made possible through the integral use of its resources, exploring every functional fraction to create novel solutions to modern problems. Biorefineries present an interesting strategy to fully use the potential of agricultural feedstocks and together with green separation methods can contribute to the generation of sustainable processes and products. Passion Fruit (Passiflora edulis Sims f. flavicarpa Deg species) is produced on a large scale in Brazil and in other tropical countries, and its processing plants generate tons of residues that basically consist of peel, seeds and bagasse, which account for around 75% of its mass. These fractions of P. edulis can contain significant amounts of flavonoids, secondary metabolites that are the main compounds responsible for the fruit's bioactivity (antioxidant, anti-inflammatory, pesticide and biocide, in general). Therefore, this work aims to develop, apply and compare the best conditions for the extraction of isoorientin, orientin and isovitexin from passion fruit applying solid-liquid methodologies, followed by analyte quantification using UHPLC-PDA. Homogenizer-assisted (HAE), ultrasound-assisted (UAE) and microwave-assisted (MAE) extraction techniques were used, as well as a full factorial design to reach optimal parameters concerning the extraction yield and energy and solvent efficiencies. According to the results, the procedure based on HAE presented the best conditions for the extraction of selected flavonoids (1.07, 0.90 and 0.33 mg g-1 of isoorientin, orientin and isovitexin, respectively) and was considered the best method according to the green and sustainable described factors.

Biorefinery Approach for Aerogels

According to the International Energy Agency, biorefinery is "the sustainable processing of biomass into a spectrum of marketable bio-based products (chemicals, materials) and bioenergy (fuels, power, heat)". In this review, we survey how the biorefinery approach can be applied to highly porous and nanostructured materials, namely aerogels. Historically, aerogels were first developed using inorganic matter. Subsequently, synthetic polymers were also employed. At the beginning of the 21st century, new aerogels were created based on biomass. Which sources of biomass can be used to make aerogels and how? This review answers these questions, paying special attention to bio-aerogels' environmental and biomedical applications. The article is a result of fruitful exchanges in the frame of the European project COST Action "CA 18125 AERoGELS: Advanced Engineering and Research of aeroGels for Environment and Life Sciences".

Revalorization of bioactive compounds from tropical fruit by-products and industrial applications by means of sustainable approaches

Tropical fruits trade is on the rise due to the claimed health benefits related with their consumption. Functional activities are exerted by the presence of bioactive compounds which could be used for prevention or amelioration diseases. However, the occurrence of bioactive compounds is found mainly in non-edible fraction of tropical fruits which are usually discarded. Therefore, the revalorization of tropical fruits by-products as source of functional compounds is on the cutting-edge research. The implementation of this challenge not only allows the enhancement of the tropical fruits by-products management, but also the production of value-added products. This review compiles the latest comprehensive information about the revalorization of bioactive compounds from tropical fruits by-products. A revision of the sustainable green technologies used for the isolation of valuable compounds has been carried out as well as the current food, functional, cosmeceutical and bioenergetics industrial applications of bioactive compounds extracted from tropical fruits by-products.

An Industrial and Sustainable Platform for the Production of Bioactive Micronized Powders and Extracts Enriched in Polyphenols From Olea europaea L. and Vitis vinifera L. Wastes

In the last few years, literature data have reported that health status is related to the consumption of foods rich in polyphenols, bioactive compounds found in the plant world, in particular in vegetables and fruit. These pieces of scientific evidence have led to an increase in the demand for functional foods and drinks enriched in polyphenols, so that plant materials are more and more requested. The availability of food and agricultural wastes has adverse effects on the economy, environment, and human health. On the other hand, these materials are a precious source of bioactive compounds as polyphenols. Their recovery and reuse from wastes are according to the circular economy strategy, which has introduced the “zero waste concept.” However, the process is convenient from an economic and environmental point of view only if the final products are standardized and obtained using sustainable and industrial technologies. In this panorama, this paper describes an industrial and sustainable platform for the production of micronized powders and extracts enriched in polyphenols from Olea europaea L. and Vitis vinifera L. wastes that are useful for food, cosmetics, and pharmaceuticals sectors. The platform is based on drying plant materials, extraction of polyphenols through membrane technologies with water, and, when necessary, the concentration of the final fractions under vacuum evaporation. All powders and extracts were characterized by high-performance liquid chromatography–diode array detector–mass spectrometry analysis to define the qualitative and quantitative content of bioactive compounds and insure their standardization and reproducibility. The chromatographic profiles evidenced the presence of secoiridoids, flavones, flavonols, anthocyanins, hydroxycinnamic acids, catechins, and condensed tannins. An overview of the biological activities of the main polyphenols present in Olea europaea L. and Vitis vinifera L. powders and extracts is reported because of biomedical applications.

Subcritical Methanol Extraction of the Stone of Japanese Apricot Prunus mume Sieb. et Zucc

The pits of Japanese apricot, Prunus mume Sieb. et Zucc., which are composed of stones, husks, kernels, and seeds, are unused by-products of the processing industry in Japan. The processing of Japanese apricot fruits generates huge amounts of waste pits, which are disposed of in landfills or, to a lesser extent, burned to form charcoal. Mume stones mainly consist of cellulose, hemicellulose, and lignin. Herein, we attempted to solubilize the wood-like carapace (stone) encasing the pit by subcritical fluid extraction with the aim of extracting useful chemicals. The characteristics of the main phenolic constituents were elucidated by liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance (NMR) analyses. The degrees of solubility for various treatments (190 °C; 3 h) were determined as follows: subcritical water (54.9%), subcritical 50% methanol (65.5%), subcritical 90% methanol (37.6%), subcritical methanol (23.6%), and subcritical isopropyl alcohol (14.4%). Syringaldehyde, sinapyl alcohol, coniferyl alcohol methyl ether, sinapyl alcohol methyl ether, 5-(hydroxymethyl)-2-furfural, and furfural were present in the subcritical 90% methanol extract. Coniferyl and sinapyl alcohols (monolignols) are source materials for the biosynthesis of lignin, and syringaldehyde occur in trace amounts in wood. Our current findings provide a solubilization method that allows the main phenolic constituents of the pits to be extracted under mild conditions. This technique for obtaining subcritical extracts shows great potential for further applications.

Antioxidant Properties of Agri-food Byproducts |and Specific Boosting Effects of Hydrolytic Treatments

Largely produced agri-food byproducts represent a sustainable and easily available source of phenolic compounds, such as lignins and tannins, endowed with potent antioxidant properties. We report herein the characterization of the antioxidant properties of nine plant-derived byproducts. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing/antioxidant power (FRAP) assays indicated the superior activity of pomegranate peels and seeds, grape pomace and pecan nut shell. An increase in the antioxidant potency was observed for most of the waste materials following a hydrolytic treatment, with the exception of the condensed tannin-rich pecan nut shell and grape pomace. UV-Vis and HPLC investigation of the soluble fractions coupled with the results from IR analysis and chemical degradation approaches on the whole materials allowed to conclude that the improvement of the antioxidant properties was due not only to removal of non-active components (mainly carbohydrates), but also to structural modifications of the phenolic compounds. Parallel experiments run on natural and bioinspired model phenolic polymers suggested that these structural modifications positively impacted on the antioxidant properties of lignins and hydrolyzable tannins, whereas significant degradation of condensed tannin moieties occurred, likely responsible for the lowering of the reducing power observed for grape pomace and pecan nut shell. These results open new perspectives toward the exploitation and manipulation of agri-food byproducts for application as antioxidant additives in functional materials.

Bioactive Phenolic Compounds From Agri-Food Wastes: An Update on Green and Sustainable Extraction Methodologies

Phenolic compounds are broadly represented in plant kingdom, and their occurrence in easily accessible low-cost sources like wastes from agri-food processing have led in the last decade to an increase of interest in their recovery and further exploitation. Indeed, most of these compounds are endowed with beneficial properties to human health (e.g., in the prevention of cancer and cardiovascular diseases), that may be largely ascribed to their potent antioxidant and scavenging activity against reactive oxygen species generated in settings of oxidative stress and responsible for the onset of several inflammatory and degenerative diseases. Apart from their use as food supplements or as additives in functional foods, natural phenolic compounds have become increasingly attractive also from a technological point of view, due to their possible exploitation in materials science. Several extraction methodologies have been reported for the recovery of phenolic compounds from agri-food wastes mostly based on the use of organic solvents such as methanol, ethanol, or acetone. However, there is an increasing need for green and sustainable approaches leading to phenolic-rich extracts with low environmental impact. This review addresses the most promising and innovative methodologies for the recovery of functional phenolic compounds from waste materials that have appeared in the recent literature. In particular, extraction procedures based on the use of green technologies (supercritical fluid, microwaves, ultrasounds) as well as of green solvents such as deep eutectic solvents (DES) are surveyed.

Pecan (Carya illinoinensis (Wagenh.) K. Koch) Nut Shell as an Accessible Polyphenol Source for Active Packaging and Food Colorant Stabilization

Herein, the antioxidant and food stabilizing properties of a pecan nut shell (PNS) hydroalcoholic extract (PNSE) are reported. Chemical degradation of PNSE demonstrated the presence of condensed tannins as the main phenolic components. PNSE showed remarkable antioxidant properties in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay (EC₅₀ = 0.004 mg/mL). PNSE was initially tested as an inhibitor of mushroom tyrosinase, exhibiting a quite low IC₅₀ value (0.055 mg/mL) against the enzyme diphenolase activity, suggesting its use in enzymatic browning inhibition. The anthocyanin stabilization properties were evaluated under accelerated aging conditions of both pure pigments and commercial fruit juices, and PNSE was found to be effective at concentrations (0.05 mg/mL) at which well-known stabilizers such as chlorogenic and ferulic acids proved to fail. PNSE also performed well in the stabilization of spray-dried anthocyanins for use as a food colorant, increasing the half-life of blackberry anthocyanins up to 20%. In order to explore the possibility of using PNSE as a functional additive for active packaging, polylactic acid (PLA) films containing PNSE were prepared by solvent casting, and no substantial alteration of the mechanical properties was found on addition of the extract up to 10% w/w. The films showed remarkable antioxidant properties (DDPH reduction >60% with a 3% w/w loading, at a dose of 1 mg/mL in the DPPH solution) and delayed the onset of browning of apple smoothies (ca. 30% inhibition with a 10% w/w loading). These results highlight the exploitation of PNS as a low-cost polyphenol source for food industry applications.

On the Enhanced Accuracy of Kinetic Curve Building in Supercritical Fluid Extraction from Aroma Plants Using a New 3D-Printed Extract Collection Device

Accurate collection of extracted material represents a technical problem in supercritical fluid extraction because trapping should be performed in severe conditions of rapidly moving and freezing expanded fluid. We have developed a simple device for effective sample collection in analytical-scale supercritical fluid extraction. The device consists of a cyclone separator equipped with a spray trap and a heated check valve. The cyclone separator and spray trap are manufactured from a light polymer via 3D printing and are quick-detachable, which encourages its use in applications where mass yield measurements are required. The device was compared to a standard tubing-and-vial approach in the task of building kinetic curves for the extraction from two aroma plants, namely, laurel and rosemary. The new device showed almost two-fold increase in extraction trapping, most probably due to better collection of volatile compounds. A curious effect of the number of mass measurement points per curve on apparent yield was observed. An increase in the number of points led to an increase in yield, probably due to the effect of the static-dynamic extract regime posed by the manner in which the device is used.

Innovation and strategic orientations for the development of advanced biorefineries

Advanced biorefineries, which aim at valorizing biomass (from agriculture, forestry, aquaculture, among others) into a wide spectrum of products and bioenergy, are seen today as key to implement a sustainable biobased economy. Although different concepts of biorefinery are currently under development, further research and improvement are still required to obtain environmentally friendly and economically feasible commercial scale biorefineries. Valorization of all biomass components and integration of different disciplines are some of the strategies that have been considered to improve the economic and environmental performance. This paper summarizes and discusses the most recent innovations and strategic orientations for the development of advanced biorefineries. Focus is given on the valorization of non-carbohydrate components of biomass (protein, acetic acid and lignin), on-site and tailor-made production of enzymes, big data analytics, and interdisciplinary efforts. The idea is to provide new insights and directions to support the development and large-scale implementation of biorefineries.

Viticultural wood waste as a source of polyphenols of interest: Opportunities and perspectives through conventional and emerging extraction methods

Viticultural waste has been widely demonstrated to contain high-added value compounds named the stilbenes. Among them, trans-resveratrol (Rsv) and trans-ε-viniferin (Vf) are the most abundant in particular in grape canes. Various emerging methods such as ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE) or pressurized solvent extraction (PSE) have been studied to recover Rsv and Vf from grape canes in order to enhance their extraction. This paper gives a critical overview of the techniques used to this end, integrating conventional and non-conventional methods investigated in the literature as well as those used in industrial processes. It finally highlights that the unconventional technics are usually less time-consuming than conventional extraction ones but further investigations for the discussed compounds and biomass are needed to optimize and understand the influence of the individual parameters of each extraction process.

Bioadhesive Polymeric Films Based on Red Onion Skins Extract for Wound Treatment: An Innovative and Eco-Friendly Formulation

The onion non-edible outside layers represent a widely available waste material deriving from its processing and consumption. As onion is a vegetable showing many beneficial properties for human health, a study aiming to evaluate the use of extract deriving from the non-edible outside layers was planned. An eco-friendly extraction method was optimized using a hydroalcoholic solution as solvent. The obtained extract was deeply characterized by in vitro methods and then formulated in autoadhesive, biocompatible and pain-free hydrogel polymeric films. The extract, very soluble in water, showed antioxidant, radical scavenging, antibacterial and anti-inflammatory activities, suggesting a potential dermal application for wounds treatment. In vitro studies showed a sustained release of the extract from the hydrogel polymeric film suitable to reach concentrations necessary for both antibacterial and anti-inflammatory activities. Test performed on human keratinocytes showed that the formulation is safe suggesting that the projected formulation could be a valuable tool for wound treatment.

Cellulose-based polyacetals by direct and sensitized photocationic ring-opening polymerization of levoglucosenyl methyl ether

Polyacetal homopolymers and block copolymers are produced by photochemically initiated cationic ring-opening polymerization (CROP).

Grape Seeds: Chromatographic Profile of Fatty Acids and Phenolic Compounds and Qualitative Analysis by FTIR-ATR Spectroscopy

The primary product of the oenological sector is wine. Nonetheless, the grape processing produces large amounts of by-products and wastes, e.g., the grape seeds. In the context of a sustainable production, there is a strong push towards reutilizing these by-products and waste for making useful derivatives since they are rich of bioactive substances with high additional value. As it is true for the wine itself, bringing these by-products derivatives to the market calls for quality measures and analytical tools to assess quality itself. One of the main objectives is to collect analytical data regarding bioactive compounds using potentially green techniques. In the present work, the profile of fatty acids and the main phenolic compounds were investigated by conventional methods. The qualitative analysis of the main functional groups was carried out by Fourier Transform Infrared (FTIR) spectroscopy. Moreover, the successful use of FTIR technique in combination with chemometric data analysis is shown to be a suitable analytical tool for discriminating the grape seeds. Grape seeds of different origin have different content of bioactive substances, making this technique useful when planning to recover a certain substance with specific potential application in health area as food supplement or nutraceutical. For example, Cesanese d’Affile seeds were found to have a rather high fat content with a significant fraction of unsaturated fatty acids. On the other hand, the seeds of Nero d’Avola exhibit the highest amount of phenolic compounds.

Agricultural waste

The management of agricultural waste has become very important because the inappropriate disposal yields negative effects on the environment. The resource recovery from agricultural waste which converts waste into available resources can reduce the waste and new resource consumption. This review summarizes the 2018 researches of over three hundred scholar papers from several aspects: agricultural waste, and, waste chemical characterization, agricultural waste material, adsorption, waste energy, composting, waste biogas, agricultural waste management, and others.