Green technologies for the extraction of bioactive compounds in fruits and vegetables

A metabolomics approach to evaluate the effect of lyophilization versus oven drying on the chemical composition of plant extracts

Lyophilization is the “gold standard” for drying plant extracts, which is important in preserving their quality and extending their shelf-life. Compared to other methods of drying plant extracts, lyophilization is costlier due to equipment, material and operational expenses. An alternative method is post-extraction oven-drying, but the effects of this process on extract quality are unknown. In this study, crude extracts from Arthrocnemum macrostachyum shoots were compared using three post-extraction drying methods (lyophilization and oven drying at 40 and 60 °C) and two extraction solvents (water and aqueous 50% ethanol). Untargeted metabolomics coupled with chemometrics analysis revealed that post extraction oven-drying resulted in the loss of up to 27% of molecular features when compared to lyophilization in water extracts only. In contrast, only 3% of molecular features were lost in aqueous 50% ethanol extracts when subjected to oven drying. That is to say, ethanol used as a solvent has a stabilizing effect on metabolites and enhances their resistance to thermal transformation in the oven. Collectively, oven-drying of extracts was as effective as lyophilization in preserving metabolites in extracts only when 50% ethanol was used as a solvent. The results presented in this paper demonstrate the value of selecting solvent-appropriate post-extraction drying methods.

Antioxidant Activity of Different Extracts from Black Alder (Alnus glutinosa) Bark with Greener Extraction Alternative

Phenolic compounds isolated from plant biomass consist of bioactive components showing a wide range of benefits for humans, including antioxidant, antimicrobial or anti-inflammatory effects. This paper presents the potential value of black alder (Alnus glutinosa (L.) Gaertn. (Betulaceae)) bark for the production of biologically active substances, despite its current use as a low value fuel source. Most of the extraction methods employ neat organic solvents to obtain extracts with a high antioxidant potential from biomass. The aim of this work is to show the advantages and disadvantages of the extraction process by taking into account the principles of 'green chemistry' and replacing the organic solvents with 'green' solvent water. Using the advantages of accelerated solvent extraction (ASE), it has been shown that the use of deionized water has the prospect of replacing organic solvents. In the case of the one-step water extraction, the total polyphenol content (TPC) varies from 0.55 to 0.62 Gallic acid equivalent (GAE) g/g in the extracts, depending on the temperature, whereas with the result of the sequential extraction with the organic solvents, the TPC content of the 40% (v:v) ethanol extracts ranges from 0.39 to 0.61 GAE g/g, depending on the temperature. The influence of the total polyphenol content and the total proanthocyanidin content on the antioxidant activity is shown. The antioxidant activity (IC₅₀, mg/L) of the extracts obtained with the organic solvents in the (2,2-diphenyl-1-picrylhydrazyl) DPPH^• test varies from 4.05 to 9.58, depending on the temperature in the range of 70-150 °C, respectively, while the results obtained with the deionized water showed promising results in the range of 6.33-7.36 in the temperature range of 70-150 °C, respectively. The extraction with the deionized water showed that approximately 90% of the substances in the extracts obtained with the organic solvents by sequential extraction are possible to obtain as deionized water extracts.

Rapid quantification of dissolved solids and bioactives in dried root vegetable extracts using near infrared spectroscopy

Artificial neural networks (ANN) were developed for prediction of total dissolved solids, polyphenol content and antioxidant capacity of root vegetables (celery, fennel, carrot, yellow carrot, purple carrot and parsley) extracts prepared from the (i) fresh vegetables, (ii) vegetables dried conventionally at 50 °C and 70 °C, and (iii) the lyophilised vegetables. Two types of solvents were used: organic solvents (acetone mixtures and methanol mixtures) and water. Near-infrared (NIR) spectra were recorded for all samples. Principal Component Analysis (PCA) of the pre-treated spectra using Savitzky-Golay smoothing showed specific grouping of samples in two clusters (1st: extracts prepared using methanol mixtures and water as the solvents; 2nd: extracts prepared using acetone mixtures as the solvents) for all four types of extracts. Furthermore, obtained results showed that the developed ANN models can reliably be used for prediction of total dissolved solids, polyphenol content and antioxidant capacity of dried root vegetable extracts in relation to the recorded NIR spectra.

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.

Sonication, a Potential Technique for Extraction of Phytoconstituents: A Systematic Review

Traditional extraction techniques have lost their optimum performance because of rising consumer demand and novel technologies. In this regard, several techniques were developed by humans for the extraction of plant materials from various indigenous sources, which are no longer in use. Many of the techniques are not efficient enough to extract maximum plant material. By this time, evolution in extraction has led to development of various techniques including microfiltration, pulsed electric fields, high pressure, microwave assistance, enzyme assistance, supercritical fluid, subcritical fluid and ultrasonication. These innovations in food processing/extraction are known as “Green Food Processing”. These technologies were basically developed by focusing on three universal parameters: simplicity, energy efficiency and economy. These green technologies are practical in a number of different food sectors, mostly for preservation, inhibition of microorganisms, inactivation of enzymes and extraction of plant material. Like the others, ultrasonication could also be used for the said purposes. The primary objective of this review is to confine the potential use of ultrasonication for extraction of oils, pectin and phytochemicals by reviewing the literature systematically.

A Critical Review on Pulsed Electric Field: A Novel Technology for the Extraction of Phytoconstituents

Different parts of a plant (seeds, fruits, flower, leaves, stem, and roots) contain numerous biologically active compounds called “phytoconstituents” that consist of phenolics, minerals, amino acids, and vitamins. The conventional techniques applied to extract these phytoconstituents have several drawbacks including poor performance, low yields, more solvent use, long processing time, and thermally degrading by-products. In contrast, modern and advanced extraction nonthermal technologies such as pulsed electric field (PEF) assist in easier and efficient identification, characterization, and analysis of bioactive ingredients. Other advantages of PEF include cost-efficacy, less time, and solvent consumption with improved yields. This review covers the applications of PEF to obtain bioactive components, essential oils, proteins, pectin, and other important materials from various parts of the plant. Numerous studies compiled in the current evaluation concluded PEF as the best solution to extract phytoconstituents used in the food and pharmaceutical industries. PEF-assisted extraction leads to a higher yield, utilizes less solvents and energy, and it saves a lot of time compared to traditional extraction methods. PEF extraction design should be safe and efficient enough to prevent the degradation of phytoconstituents and oils.

Recent advances in extraction technologies for recovery of bioactive compounds derived from fruit and vegetable waste peels: A review

Fruits and vegetables are the most important commodities of trade value among horticultural produce. They are utilized as raw or processed, owing to the presence of health-promoting components. Significant quantities of waste are produced during fruits and vegetables processing that are majorly accounted by waste peels (∼90-92%). These wastes, however, are usually exceptionally abundant in bioactive molecules. Retrieving these valuable compounds is a core objective for the valorization of waste peel, besides making them a prevailing source of beneficial additives in food and pharmaceutical industry. The current review is focused on extraction of bioactive compounds derived from fruit and vegetable waste peels and highlights the supreme attractive conventional and non-conventional extraction techniques, such as microwave-assisted, ultrasound assisted, pulsed electric fields, pulsed ohmic heating, pressurized liquid extraction, supercritical fluid extraction, pressurized hot water, high hydrostatic pressure, dielectric barrier discharge plasma extraction, enzyme-assisted extraction and the application of "green" solvents say as well as their synergistic effects that have been applied to recover bioactive from waste peels. Superior yields achieved with non-conventional technologies were identified to be of chief interest, considering direct positive economic consequences. This review also emphasizes leveraging efficient, modern extraction technologies for valorizing abundantly available low-cost waste peel, to achieve economical substitutes, whilst safeguarding the environment and building a circular economy. It is supposed that the findings discussed though this review might be a valuable tool for fruit and vegetable processing industry to imply an economical and effectual sustainable extraction methods, converting waste peel by-product to a high added value functional product.

Impact of Extraction Process in Non-Compliant ‘Bravo de Esmolfe’ Apples towards the Development of Natural Antioxidant Extracts

The ‘Bravo de Esmolfe’ apple (BE) is rich in antioxidants and represents one of the most important traditional cultivars in Portugal. A large amount of non-compliant BE, with no market value, it is generated every year. Thus, an effort to find value-added solutions is of utmost importance. For the first time, green extraction (microwave-assisted-extraction (MAE) and ultrasound-assisted-extraction (UAE)) were compared against conventional extraction (with (CET) and without temperature (CE)) to select the most efficient process to produce a natural antioxidant extract from non-compliant BE. The results showed that MAE and CET are good methodologies for developing a BE antioxidant extract. However, MAE is more sustainable than CET, requiring less time to reach high temperatures. The MAE-extract showed great antioxidant activity (14.80 ± 0.70 mg TE/g DE by ORAC, 3.92 ± 0.25 mg AAE/g DE by ABTS, and 5.11 ± 0.13 mg TE/g DE by DPPH). This extract revealed high amount of chlorogenic acid (0.48 ± 0.07 mg/g DE), (−)-epicatechin (0.30 ± 0.02 mg/g DE) and phloridzin (0.13 ± 0.01 mg/g DE). This study shows that non-compliant BE is a useful source of antioxidants, being a sustainable way for the recovery of value-added compounds from the rejected fruit in line with sustainable and circular bioeconomy principles.

Bioactive components from Moringa oleifera seeds: production, functionalities and applications - a critical review

A readily distinguishable and indigenous member of the plant kingdom in the Indian subcontinent is the 'drumstick tree', i.e. Moringa oleifera Lam. In addition to India, this drought-tolerant and rapidly evolving tree is currently extensively disseminated across the globe, including subtropical and tropical areas. The plant boasts a high nutritional, nutraceutical and therapeutic profile, mainly attributing to its significant repertoire of the biologically active components in different parts: protein, flavonoids, saponins, phenolic acids, tannin, isothiocyanate, lipids, minerals, vitamins, amongst others. M. oleifera seeds have been shown to elicit a myriad of pharmacological potential and health benefits, including: antimicrobial, anticancer, antidiabetic, antioxidant, antihypertensive, anti-inflammatory and cardioprotective properties. Additionally, the seed cakes obtained from post-extraction process are utilized for: coagulation, flocculation and sedimentation purposes, benefiting effluent management and the purification of water, mainly because of their capability in eliminating microbes and organic matter. Despite the extraordinary focus on other parts of the plant, especially the foliage, the beneficial aspects of the seeds have not been sufficiently highlighted. The health benefits of bioactive components in the seeds are promising and demonstrate enough potential to facilitate the development of functional foods. In this review, we present a critical account of the types, characteristics, production and isolation of bioactive components from M. oleifera seeds. Furthermore, we appraise the: pharmacological activities, cosmetic, biodiesel, lubricative, modern farming, nutritive and wastewater treatment applications of these functional ingredients. We infer that there is a need for further human/clinical studies and evaluation, despite their health benefits. Additionally, the safety issues need to be adequately clarified and assessed, in order to establish a conventional therapeutic profile.

Supercritical Fluid-Based Decellularization Technologies for Regenerative Medicine Applications

Supercritical fluid-based extraction technologies are currently being increasingly utilized in high purity extract products for food industries. In recent years, supercritical fluid-based extraction technology is transformed in biomaterials process fields to be further utilized for tissue engineering and other biomedical applications. In particular, supercritical fluid-based decellularization protocols have great advantage over the conventional decellularization as it may allow preservation of extracellular matrix components and structures. In this review, the latest technological development utilizing the supercritical fluid-based decellularization for regenerative medicine is introduced.

Current trends and possibilities for exploitation of Grape pomace as a potential source for value addition

Grape pomace (GP) is a low-value by-product that contains a significant amount of high value-added products. The huge amount of non-edible residues of GP wastes (seeds, skins, leaves and, stems) produced by wine industries causes' environmental pollution, management issues as well as economic loss. Studies over the past 15-20 years revealed that GP could serve as a potential source for valuable bioactive compounds like antioxidants, bioactive, nutraceuticals, single-cell protein, and volatile organic compounds with an increasing scientific interest in their beneficial effects on human and animal health. However, the selection of appropriate techniques for the extraction of these compounds without compromising the stability of the extracted products is still a challenging task for the researcher. Based on the current scenario, the review mainly summarizes the novel applications of winery wastes in many sectors such as agriculture, pharmaceuticals, cosmetics, livestock fields, and also the bio-energy recovery system. We also summarize the existing information/knowledge on several green technologies for the recovery of value-added by-products. For the promotion of many emerging technologies, the entrepreneur should be aware of the opportunities/techniques for the development of high-quality value-added products. Thus, this review presents systematic information on value-added by-products that are used for societal benefits concerning the potential for human health and a sustainable environment.

Extraction of bioactive compounds from Senecio brasiliensis using emergent technologies

Several plant species synthesize biologically active secondary metabolites. Pyrrolizidine alkaloids are a large group of biotoxins produced by thousands of plant species to protect against the attack of insects and herbivores, but they are highly toxic for humans and animals. In this study, extracts from the aerial part of Senecio brasiliensis were obtained using different technologies: ultrasound-assisted extraction (UAE), pressurized liquid extraction (PLE), and microwave hydrodiffusion and gravity (MHG). The study aimed to evaluate the effectiveness of these technologies for the extraction of chemical compounds found in this plant, focusing on two pyrrolizidine alkaloids: integerrimine and senecionine. Influential parameters on yield and chemical composition were also evaluated: for UAE and MHG, temperature and pressure; for PLE, temperature, and percentage of ethanol. All the extraction techniques were efficient for the extraction of integerrimine and senecionine. The UAE and PLE stood out for the higher yields and number of compounds. The PLE presented a maximum yield of 18.63% for the matrix leaf and the UAE a maximum yield of 11.82% for the same matrix. These two techniques also stood out in terms of the number of compounds, once 36 different compounds were found via PLE and 17 via UAE.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-021-02845-1.

Green non-conventional techniques for the extraction of polyphenols from agricultural food by-products: A review

Food processing industry is accompanied with the generation of a great production of wastes and by-products exceptionally rich in bioactive compounds (especially phenolics), with antioxidant activity. The recovery of these health molecules constitutes a key point for the valorization of by-products, with the possibility of creating new ingredients to be used for the formulation of food and cosmetic products. One of the main limitations to reuse by-products is linked to the high cost to obtain bioactive compounds, consequently in order to exploit these resources commercially valuable it is necessary to develop innovative, economic and environmentally friendly extraction strategies. These extraction methods should be able to reduce petroleum solvents, energy consumption and chemical wastes, protecting both environment and consumers and ensuring safe and high-quality final products. The purpose of this review is to summarize current knowledge and applications of the new extraction techniques such as supercritical fluid extraction, pressurized liquid extraction, ultrasound assisted extraction applied to polyphenols extraction from agricultural food by-products. Particular attention has been paid to theoretical background, highlighting mechanisms and safety precautions. Authors concluded that relevant results of these techniques represent an opportunity to industrial scale-up, improving the extraction yields, minimizing time, costs and environmental impact.

Development of ANN models based on combined UV-vis-NIR spectra for rapid quantification of physical and chemical properties of industrial hemp extracts

OBJECTIVES

The aim of this study was to develop artificial neural network (ANNs) models for prediction of physical (total dissolved solids, extraction yield) and chemical (total polyphenolic content, antioxidant activity) properties of industrial hemp extracts, prepared by two different extraction methods (solid-liquid extraction and microwave-assisted extraction) based on combined UV-VIS-NIR spectra. Spectral data were gathered for 46 samples per extraction method.

RESULTS

The PCA analysis ensured efficient separation of the samples based on the amount of ethanol in extraction solvent using NIR spectra for both conventional and microwave-assisted extraction.

CONCLUSIONS

Results showed that reliable ANN models (R² >0.7000) for describing physical, chemical, and simultaneously physical and chemical characteristics can be developed based on combined UV-VIS-NIR spectra of industrial hemp extracts without spectra pre-processing.

Green extraction techniques from fruit and vegetable waste to obtain bioactive compounds-A review

Food wastes imply significant greenhouse gas emissions, that increase the challenge of climate change and impact food security. According to FAO (2019), one of the main food wastes come from fruit and vegetables, representing 0.5 billion tons per year, of the 1.3 billion tons of total waste. The wastes obtained from fruit and vegetables have plenty of valuable components, known as bioactive compounds, with many properties that impact positively in human health. Some bioactive compounds hold antioxidant, anti-inflammatory, and anti-cancer properties and they have the capacity of modulating metabolic processes. Currently, the use of fruit and vegetable waste is studied to obtain bioactive compounds, through non-conventional techniques, also known as green extraction techniques. These extraction techniques report higher yields, reduce the use of solvents, employ less extraction time, and improve the efficiency of the process for obtaining bioactive compounds. Once extracted, these compounds can be used in the cosmetic, pharmaceutical, or food industry, the last one being focused on improving food quality.

Innovative Technologies for Extraction and Microencapsulation of Bioactives from Plant-Based Food Waste and their Applications in Functional Food Development

The by-products generated from the processing of fruits and vegetables (F&V) largely are underutilized and discarded as organic waste. These organic wastes that include seeds, pulp, skin, rinds, etc., are potential sources of bioactive compounds that have health imparting benefits. The recovery of bioactive compounds from agro-waste by recycling them to generate functional food products is of increasing interest. However, the sensitivity of these compounds to external factors restricts their utility and bioavailability. In this regard, the current review analyses various emerging technologies for the extraction of bioactives from organic wastes. The review mainly aims to discuss the basic principle of extraction for extraction techniques viz. supercritical fluid extraction, subcritical water extraction, ultrasonic-assisted extraction, microwave-assisted extraction, and pulsed electric field extraction. It provides insights into the strengths of microencapsulation techniques adopted for protecting sensitive compounds. Additionally, it outlines the possible functional food products that could be developed by utilizing components of agricultural by-products. The valorization of wastes can be an effective driver for accomplishing food security goals.

Direct Contact Ultrasound in Food Processing: Impact on Food Quality

Consumers' demand for “minimally processed” products that maintain the “fresh-like” characteristics has increased in recent years. Ultrasound (US) is a non-thermal technology that enhances mass and energy transfer processes resulting in improved food quality. A new method of applying US to food without using a liquid or gaseous medium for the propagation of acoustic waves has recently been under research. It is known as direct contact US, since the food is directly placed on a plate where the transducers are located. In this type of systems, the main effect is not cavitation but acoustic vibration, which encourages mass and energy transfer processes due to the “sponge effect.” Furthermore, as the product is not immersed in a liquid medium, the loss of hydrophilic nutritional compounds is reduced; systems such as these can thus be more easily implemented on an industrial level. Nevertheless, the very few studies that have been published about these systems mainly focus on dehydration and freezing. This article summarizes published research on the impact of direct contact US in nutritional and organoleptic quality of food in order to assess their potential to meet new market trends.

Plant Extracts Obtained with Green Solvents as Natural Antioxidants in Fresh Meat Products

Plants are rich in bioactive compounds (BACs), mainly polyphenols, which are valuable choices to replace synthetic antioxidants in meat products. These natural antioxidants from plants, in the form of extracts and essential oils (EOs), have been obtained from different sources such as fruits (dragon fruit, guarana, pomegranate), vegetables, (cabbage, onion), herbs, and spices (epazote, ginger, rosemary, sage, thyme, turmeric, winter savory) by several extraction processes. However, in the context of current directives there is a notable incentive for “green” solvents to replace organic ones and conventional techniques, in order to avoid harm to the environment, operator, and consumer health. In addition, the recycling of co-products from the processing of these plant materials allow us to obtain valuable BACs from under-exploited materials, contributing to the revalorization of these wastes. The resulting extracts allow us to maintain the quality of meat products, exhibiting similar or better antioxidant properties compared to those shown by synthetic ones. Their incorporation in fresh meat products would maintain the oxidative stability, stabilizing colour parameters, decreasing the formation of metmyoglobin, lipid, and protein oxidation and the generation of lipid-derived volatile compounds, without affecting sensory attributes. In addition, these novel ingredients contribute to improve both technological and functional characteristics, thus diversifying the offer of so-called “wellness foods”. In this review, the application of plant extracts as natural antioxidants in several fresh meat products is presented, showing their efficacy as scavenging radicals and imparting additional health benefits.

Antioxidant Molecules from Plant Waste: Extraction Techniques and Biological Properties

The fruit, vegetable, legume, and cereal industries generate many wastes, representing an environmental pollution problem. However, these wastes are a rich source of antioxidant molecules such as terpenes, phenolic compounds, phytosterols, and bioactive peptides with potential applications mainly in the food and pharmaceutical industries, and they exhibit multiple biological properties including antidiabetic, anti-obesity, antihypertensive, anticancer, and antibacterial properties. The aforementioned has increased studies on the recovery of antioxidant compounds using green technologies to value plant waste, since they represent more efficient and sustainable processes. In this review, the main antioxidant molecules from plants are briefly described and the advantages and disadvantages of the use of conventional and green extraction technologies used for the recovery and optimization of the yield of antioxidant naturals are detailed; finally, recent studies on biological properties of antioxidant molecules extracted from plant waste are presented here.

Impacto de las tecnologías de extracción verdes para la obtención de compuestos bioactivos de los residuos de frutos cítricos

En la actualidad, las técnicas de extracción convencionales como la maceración, soxhlet y el calentamiento-reflujo entre otras, han seguido utilizándose debido a su principal ventaja como procesos de extracción más económicos. Sin embargo, estas metodologías presentan diversas desventajas, como largos tiempos de extracción y requerimiento de altas cantidades de disolventes. Es por lo hasta aquí expuesto que se han implementado metodologías de extracción alternativas que cumplen con los principios de la química verde, como son las extracciones asistidas: por ultrasonido (EAU), microondas (EAM) y con fluidos supercríticos (EAFS). Estos métodos de extracción, alternos a los convencionales, han logrado despertar el interés de los investigadores como futuras perspectivas de aplicación, con altos rendimientos, para la recuperación de compuestos bioactivos de los residuos de frutos cítricos, en menor tiempo de extracción, empleando disolventes verdes. El objetivo de la presente revisión es dar a conocer el impacto de las metodologías de extracción alternativas con un enfoque en el aprovechamiento y revalorización de los residuos de frutos cítricos, debido a que éstos presentan una gran diversidad de compuestos de interés para la industria farmacéutica, alimentaria y biotecnológica.

Avocado fruit and by-products as potential sources of bioactive compounds

The increased demand for avocado, and therefore production and consumption, generate large quantities of by-products such as seeds, peel, and defatted pulp, which account for approximately 30% of fruit weight, and which are commonly discarded and wasted. The present review focuses on various compounds present in avocado fruit and its by-products, with particular interest to those that can be potentially used in different industrial forms, such as nutraceuticals, to add to or to formulate functional foods, among other uses. Main molecular families of bioactive compounds present in avocado include phenolic compounds (such as hydroxycinnamic acids, hydroxybenzoic acids, flavonoids and proanthocyanins), acetogenins, phytosterols, carotenoids and alkaloids. Types, contents, and possible functions of these bioactive compounds are described from a chemical, biological, and functional approach. The use of avocado and its by-products requires using processing methods that allow highest yield with the least amount of unusable residues, while also preserving the integrity of bioactive compounds of interest. Avocado cultivar, fruit development, ripening stage, and processing methods are some of the main factors that influence the type and amount of extractable molecules. The phytochemical diversity of avocado fruit and its by-products make them potential sources of nutraceutical compounds, from which functional foods can be obtained, as well as other applications in food, health, pigment, and material sectors, among others.

Insight into High-Hydrostatic Pressure Extraction of Polyphenols from Tomato Peel Waste

In this paper, high-hydrostatic pressure extraction (HHPE) as an emerging food processing and preservation technique constitutes an alternative to conventional thermal treatment that has been used for extraction of polyphenols from tomato peel waste generated by the canning industry. The impact of time (5 and 10 min), temperature (25, 35, 45 and 55 °C) and solvents (water, 1% HCl, 50 and 70% methanol with and without addition of HCl, and 50 and 70% ethanol), at a constant pressure of 600 MPa, has been evaluated in this paper with respect to polyphenols' yields. The results showed a significant (p < 0.05) variation in the contents of a great number of phenolic compounds in respect of the applied temperatures and solvents. On the other hand, the time invested in HHPE had no effect on polyphenols' yields. Among phenolic compounds, the p-coumaric acid (p-CA) and chlorogenic acid derivative (ChA der) are predominant, i.e., 0.57 to 67.41 mg/kg and 1.29 to 58.57 mg/kg, respectively, depending on the solvents and temperatures used. In particular, methanol (50 and 70%) at temperatures of 45 and 55 °C enhanced the recovery of polyphenols in comparison to other utilised solvents. In conclusion, this paper puts forth the theory that by applying HHPE with minimal expenditure of time, it is possible to achieve efficient production of polyphenols from low-cost tomato peel waste, generating income both for producers and agri-food industries.

Extraction Methods for Obtaining Natural Blue Colorants

Background:

Blue is a color not often present in food. Even so, it is especially attractive to children. Today, most blue coloring agents used by the food industry are synthetic. With increasing health issues concern by the scientific community and the general population, there is a trend to look for natural alternatives to most synthetic products. There only exist few natural blue colorants, which are presented in a literature survey, along with the methods currently used for their recovery from natural sources. The best extraction methods and process parameters for the extraction of blue anthocyanins, iridoids and phycocyanin are discussed.

Methods:

A literature survey was conducted to detect the main sources of blue colorants found in nature. The focus was on the extraction methods used to recover such molecules, with the objective of finding efficient and environmentally safe techniques for application at industrial level, and, thus, allowing the production of natural blue colorants at scale high enough for food industry consumption.

Results:

The main natural blue colorants found in literature are anthocyanins, phycocyanin, and genipin. While anthocyanins can be recovered from a variety of plants, the source of phycocyanin are algae, and genipin can be obtained specifically from Gardenia jasminoides Ellis and Genipa americana L. Several extraction techniques have been applied to recover blue colorants from such sources, from classical methods using organic solvents, to more sophisticated technologies as ultrasoundassisted extraction, supercritical fluid extraction, pressurized liquid extraction, high-pressure extraction, and enzyme-assisted extraction.

Conclusion:

There is great potential for anthocyanins, phycocyanin and genipin use as natural food additives with health benefits, besides imparting color. However, the technologies for the colorants recovery and application are not mature enough. Therefore, this area is still developing, and it is necessary to evaluate the economic feasibility of the proposed extraction processes, along with the safety and acceptance of colored food using these additives.

Dietary Fiber from Underutilized Plant Resources—A Positive Approach for Valorization of Fruit and Vegetable Wastes

Agri-food industries generate enormous amounts of fruit and vegetable processing wastes, which opens up an important research area aimed towards minimizing and managing them efficiently to support zero wastes and/or circular economy concept. These wastes remain underutilized owing to a lack of appropriate processing technologies vital for their efficient valorization, especially for recovery of health beneficial bioactives like dietary fibers. Dietary fiber finds wide applications in food and pharmaceutical industries and holds high promise as a potential food additive and/or as a functional food ingredient to meet the techno-functional purposes important for developing health-promoting value-added products. Based on this, the present review has been designed to support ‘zero waste’ and ‘waste to wealth’ concepts. In addition, the focus revolves around providing updated information on various sustainability challenges incurred towards valorization of fruit and vegetable wastes for extraction of health promoting dietary fibers.

Green and Sustainable Valorization of Bioactive Phenolic Compounds from Pinus By-Products

In Europe, pine forests are one of the most extended forests formations, making pine residues and by-products an important source of compounds with high industrial interest as well as for bioenergy production. Moreover, the valorization of lumber industry residues is desirable from a circular economy perspective. Different extraction methods and solvents have been used, resulting in extracts with different constituents and consequently with different bioactivities. Recently, emerging and green technologies as ultrasounds, microwaves, supercritical fluids, pressurized liquids, and electric fields have appeared as promising tools for bioactive compounds extraction in alignment with the Green Chemistry principles. Pine extracts have attracted the researchers’ attention because of the positive bioproperties, such as anti-inflammatory, antimicrobial, anti-neurodegenerative, antitumoral, cardioprotective, etc., and potential industrial applications as functional foods, food additives as preservatives, nutraceuticals, pharmaceuticals, and cosmetics. Phenolic compounds are responsible for many of these bioactivities. However, there is not much information in the literature about the individual phenolic compounds of extracts from the pine species. The present review is about the reutilization of residues and by-products from the pine species, using ecofriendly technologies to obtain added-value bioactive compounds for industrial applications.

Distillery Stillage: Characteristics, Treatment, and Valorization

Distilleries are among the most polluting industries because ethanol fermentation results in the discharge of large quantities of high-strength liquid effluents with high concentrations of organic matter and nitrogen compounds, low pH, high temperature, dark brown color, and high salinity. The most common method of managing this wastewater (distillery stillage) is to use it for soil conditioning, but this requires thickening the wastewater and may cause soil pollution due to its high nitrogen content. Therefore, treatment of distillery stillage is preferable. This review discusses individual biological and physico-chemical treatment methods and combined technologies. In addition, special attention is paid to valorization of distillery stillage, which is a valuable source of polysaccharides and volatile fatty acids (VFAs), as well as natural antioxidants, including polyphenols and other bioactive compounds of interest to the pharmaceutical, cosmetic, and food industries. New directions in improvement of valorization technologies are highlighted, including the search for new eutectic solvents for extracting these compounds. Such technologies are essential for sustainable development, which requires the use of management and valorization strategies for recovery of valuable compounds with minimal disposal of waste streams.

Are Ionic Liquids Better Extracting Agents Than Toxic Volatile Organic Solvents? A Combination of Ionic Liquids, Microwave and LC/MS/MS, Applied to the Lichen Stereocaulon glareosum

We report a green strategy for the extraction of lichen substances from Stereocaulon glareosum. This sustainable alternative does not use volatile toxic organic solvents, but it is assisted by microwave and is checked by UHPLC/ESI/MS/MS. Ionic liquids may provide a better alternative in the extraction of natural products from lichens.

Preliminary Testing of Ultrasound/Microwave-Assisted Extraction (U/M-AE) for the Isolation of Geraniin from Nephelium lappaceum L. (Mexican Variety) Peel

The rambutan peel (RP) is a relevant source of bioactive molecules, which could be used for application in cosmetics, food, and pharmaceutical areas. Total soluble polyphenol content was extracted from Mexican variety rambutan peels using an emergent ultrasound/microwave-assisted extraction (U/M-AE) technology. Five extractions were performed using different mass/volume and ethanol/water ratios; 1:16-0; 1:16-70; 1:8-0; 1:8-70; 1:12-30. Condition 1:16-0 was defined as the best extraction condition with 0% ethanol percentage (only water). The content of total soluble polyphenols was 307.57 mg/g. The total bound polyphenol content was 26.53 mg/g. Besides, two separation processes were made with the soluble fraction; the first one was performed using Amberlite XAD-16 (Sigma-Aldrich, Saint Louis, MO, USA), and seven polyphenolic compounds were obtained. The second one was performed using a preparative HPLC (Varian, Palo Alto, CA, USA) equipment obtained fraction where three compounds were obtained: geraniin (main compound), ellagic acid, and ellagic acid pentoside. The major compound isolated in the two separations was geraniin, according to HPLC/ESI/MS (High Performance Liquid Chromatography/ElectroSpray Ionization/Mass) analysis.

Stabilization of betalains by encapsulation-a review

Betalains are pigments that have properties that benefit health, such as antioxidant, anticancer, and antimicrobial activity, and they also possess a high ability to provide color. However, these pigments, although used as colorants in certain foods, have not been able to be potentialized to diverse areas such as pharmacology, due to their instability to physicochemical factors such as high temperature, pH changes and high water activity. For this reason, different stabilization methods have been reported. The method that has presented best results for diversifying the use of betalains has been encapsulation. Encapsulation is a method of entrapment where the objective is to protect a compound utilizing more stable matrices from encapsulation technologies. This method has been employed to provide greater stability to betalains, using different matrices and encapsulation technologies. However, a review does not exist, to our knowledge, which analyzes the effect of matrices and encapsulation technologies on betalains stabilization. Therefore, the objective of this review article was to evaluate the different matrices and encapsulation techniques that have been employed to stabilize betalains, in order to arrive at specific conclusions concerning the effect of encapsulation on their stabilization and to propose new techniques and matrices that could promote their stabilization.

Selective pressurized hot water extraction of nutritious macro-nutrients vs. micro-nutrients in Moringa oleifera leaves-a chemometric approach

Moringa oleifera leaves are widely used in traditional medicine as a food supplement because they are high in essential and nutritious content. Pressurized hot water extraction (PHWE), which is a green approach, was used for the recovery of the macro-nutrient and micro-nutrient elements from dried leaf powder of Moringa oleifera. In this study, response surface methodology was applied to assess the influence of temperature (50-200 °C) and time (5-60 min) on the extractability pattern of macro-nutrient and micro-nutrient elements from the leaves of Moringa oleifera when processed by PHWE. The quantification of macro-nutrient elements such as Ca, K and Mg and micro-nutrient elements like Al, Co, Cr, Cu, Fe, Ni and Zn from the leaves was determined using inductively coupled plasma optical emission spectroscopy (ICP-OES). Obtained results revealed that the extraction of macro-nutrient elements from the Moringa oleifera leaves was enhanced by increasing the extraction time more than the extraction temperature. On the contrary, the amounts of extractable micro-nutrient elements were increased by increasing the extraction temperature. Hence, the recovery for macro-nutrient elements ranged from 88 to 98% while for micro-nutrients it ranged from 21 to 46%. This implies that macro-nutrient elements are extracted with relatively high selectivity in relation to micro-nutrient elements in Moringa dried leaf powder using the PHWE technique.

A Combination of Aqueous Extraction and Polymeric Membranes as a Sustainable Process for the Recovery of Polyphenols from Olive Mill Solid Wastes

Polyamide commercial membranes in flat-sheet configuration and with molecular weight cut-off (MWCO) in the range of ultrafiltration (UF) to nanofiltration (NF) were tested for the recovery of phenolic compounds from clarified olive mill solid waste (OMSW) aqueous extracts. The performance of selected membranes was evaluated in terms of productivity (permeate flux) and selectivity towards biologically active compounds (such as phenolic compounds, flavanols, and hydroxycinnamic acids derivatives) and total antioxidant activity (TAA) as a function of transmembrane pressure (TMP). NF membranes produced higher permeate fluxes and a lower fouling index in comparison with UF membranes. Retention of bioactive compounds was also significantly higher for NF membranes than for UF membranes. In particular, membranes with MWCO in the range 150–500 Da showed rejection towards flavanols and hydroxycinnamic acid derivatives of about 100%. On the other hand, the rejection towards TAA and total polyphenols was of about 90% and 72%, respectively. Therefore, NF retentate fractions appear of practical interest for the production of food additives and food supplements due to their high antioxidant activity.

The Impact of Temperature and Ethanol Concentration on the Global Recovery of Specific Polyphenols in an Integrated HPLE/RP Process on Carménère Pomace Extracts

Sequential extraction and purification stages are required to obtain extracts rich in specific polyphenols. However, both separation processes are often optimized independently and the effect of the integrated process on the global recovery of polyphenols has not been fully elucidated yet. We assessed the impact of hot-pressurized liquid extraction (HPLE) conditions (temperature: 90-150 °C; ethanol concentration: 15%-50%) on the global recovery of specific phenolic acids, flavanols, flavonols and stilbenes from Carménère grape pomace in an integrated HPLE/resin purification (RP) process. HPLE of phenolic acids, flavanols and stilbenes were favored when temperature and ethanol concentration increased, except for chlorogenic acid which showed an increment of its Gibbs free energy of solvation at higher ethanol contents. Ethanol concentration significantly impacted the global yield of the integrated HPLE/RP process. The lower the ethanol content of the HPLE extracts, the higher the recovery of phenolic acids, flavanols and stilbenes after RP, except for flavonols which present more polar functional groups. The best specific recovery conditions were 150 °C and ethanol concentrations of 15%, 32.5% and 50% for phenolic acids, flavanols and stilbenes, and flavonols, respectively. At 150 °C and 32.5% of ethanol, the extracts presented the highest total polyphenol content and antioxidant capacity. The integrated HPLE/RP process allows a selective separation of specific polyphenols and eliminates the interfering compounds, ensuring the safety of the extracts at all evaluated conditions.

Strategies for recycling and valorization of grape marc

Grapes are one of the most cultivated fruit crops worldwide. Either for wine or juice production, grape processing generates a large amount of residues that must be treated, disposed of or reused properly to reduce their pollution load before being applied to the soil. In this review, a special focus is given to the treatment and valorization of the winemaking by-product like grape marc via anaerobic digestion, composting and vermicomposting at laboratory, pilot, and industrial scales. The impact of the final products (digestates, composts, and vermicomposts) on soil properties is briefly addressed. Moreover, the role of grape marc and seeds as a valuable source of natural phytochemicals that include polyphenols and other bioactive compounds of interest for pharmaceutical, cosmetic, and food industries is also discussed. This is of paramount importance given the fact that sustainability requires the use of management and valorization strategies that allow the recovery of valuable compounds (e.g. antioxidants) with minimum disposal of waste streams.

Study of Acidified Aqueous Extraction of Phenolic Compounds from Hibiscus sabdariffa L. calyces

Introduction:

Hibiscus calyces are important sources from anthocyanins and pigments. The recovery of these bioactive compounds using non-organic solvents becomes very attractive for the food industry.

Methods:

For this reason, the separation of phenolic compounds by acidified aqueous extraction from hibiscus calyces was studied. The experiments were conducted by a fractional factorial design.

Result and Conclusion:

Four factors were evaluated: temperature, time, stirring speed and enzyme concentration. The extracts produced were subjected to analysis of color (L*,a*,b*andChroma), total monomeric anthocyanins, antioxidant capacity by ABTS and fourteen phenolic compounds were quantified. The results showed that the best condition to obtain hibiscus calyces extract was using an enzyme concentration of 50 µL/1000 g hibiscus extract, 400 rpm of stirring speed at 55 ºC by 4 hours of extraction, that corresponded to concentrations of 17595, 7516, 2568 μg/g, expressed on a dry basis, for total phenolic compounds, delphinidin 3-sambubioside and cyanidin 3-sambubioside, respectively, and antioxidant capacity measured by ABTS of 7.8 µmol of Trolox equivalent per gram.

Optimization of an Ultrasound-Assisted Extraction Condition for Flavonoid Compounds from Cocoa Shells (Theobroma cacao) Using Response Surface Methodology

This study investigates the ultrasound-assisted extraction of flavonoids from Malaysian cocoa shell extracts, and optimization using response surface methodology. There are three variables involved in this study, namely: ethanol concentration (70⁻90 v/v %), temperature (45⁻65 °C), and ultrasound irradiation time (30⁻60 min). All of the data were collected and analyzed for variance (ANOVA). The coefficient of determination (R²) and the model was significant in interaction between all variables (98% and p < 0.0001, respectively). In addition, the lack of fit test for the model was not of significance, with p > 0.0684. The ethanol concentration, temperature, and ultrasound irradiation time that yielded the maximum value of the total flavonoid content (TFC; 7.47 mg RE/g dried weight (DW)) was 80%, 55 °C, and 45 min, respectively. The optimum value from the validation of the experimental TFC was 7.23 ± 0.15 mg of rutin, equivalent per gram of extract with ethanol concentration, temperature, and ultrasound irradiation time values of 74.20%, 49.99 °C, and 42.82 min, respectively. While the modelled equation fits the data, the T-test is not significant, suggesting that the experimental values agree with those predicted by the response surface methodology models.