Green Solvents for Extraction of Natural Food Colorants from Plants: Selectivity and Stability Issues

Consumers associate the color of food with its freshness and quality. More and more attention is being paid to natural colorants that bring additional health benefits to humans. Such natural substances are the carotenoids (yellow to orange), the anthocyanins (red to blue), and the betalains (red and yellow), which are very sensitive to exposure to light, air, high temperatures, and chemicals. Stability and diversity in terms of color can be optimized by using environmentally friendly and selective extraction processes that provide a balance between efficacy, safety, and stability of the resulting extracts. Green solvents like water, supercritical fluids, natural deep eutectic solvents, and ionic liquids are the most proper green solvents when combined with different extraction techniques like maceration, supercritical extraction, and ultrasound-assisted or microwave-assisted extraction. The choice of the right extracting agent is crucial for the selectivity of the extraction method and the stability of the prepared colorant. The present work reviews the green solvents used for the extraction of natural food colorants from plants and focuses on the issues related to the selectivity and stability of the products extracted.

Application of ultrasound technology for the effective management of waste from fruit and vegetable

Food waste presents a continuous challenge for the food industry, leading to environmental pollution and economic issues. A substantial amount of waste, including by-products from fruits and vegetables, non-edible food items, and other waste materials, is produced throughout the food supply chain, from production to consumption. Recycling and valorizing waste from perishable goods is emerging as a key multidisciplinary approach within the circular bio-economy framework. This waste, rich in raw by-products, can be repurposed as a natural source of ingredients. Researchers increasingly focus on biomass valorization to extract and use components that add significant value. Traditional methods for extracting these bio-compounds typically require the use of solvents and are time-consuming, underscoring the need for innovative techniques like ultrasound (US) extraction. Wastes from the processing of fruits and vegetables in the food industry can be used to develop functional foods and edible coatings, offering protection against various environmental factors. This comprehensive review paper discusses the valorization of waste from perishable items like fruits and vegetables using US technology, not only to extract valuable components from waste but also to treat wastewater in the beverage industry. It also covers the application of biomolecules recovered from this process in the development of functional foods and packaging.

Comparative Analysis of Metabolic Variation in Eggplant Fruit of Different Varieties Reveals Metabolites Important for Quality Traits

Eggplant is one of the most important vegetable crops worldwide and has been considered to have great antioxidant activity. However, little information is available about the primary metabolic composition of the nutritional values of eggplant. Using a widely targeted metabolome approach, the current study investigated primary metabolic variation in 13 eggplant varieties with different morphologies. A total of 503 primary metabolites (amino acids, lipids, nucleotides, organic acids, vitamin, saccharides, and alcohols) and 170 phenolic acids were detected, among which 211 metabolites were differently accumulated. Metabolic pathway analysis of the differential metabolites revealed the significant enrichment of phenylpropanoid biosynthesis, arginine biosynthesis, alpha-linolenic acid metabolism, and linoleic acid metabolism. The higher levels of amino acids and lipids were related to the umami, soft, and waxy taste of eggplant fruit. The present work substantially contributes to the knowledge of primary metabolite compositions regarding fruit-eating quality and provides useful information for the future breeding of eggplant.

Exploration of natural colourant of (Solanum melongena L.) brinjal plant residues for fabric dyeing: a novel approach towards textile processing

Natural products have become the main focus of mankind due to increasing environmental pollution. The current study was concerned with brinjal plant residues as a source of bio colourant for cotton dyeing. Various media have been employed for the extraction of colourant. Present studies illustrated that excellent colourant yield was obtained in 4% acidified methanol. Cotton fabric was dyed at 50 °C, for 55 min and showed optimised dyeing conditions. Varying chemicals and bio-mordants have been used to achieve elegant shade. Chemical mordanting results revealed that 2% FeSO4as pre-mordant, and 6% TA as post-mordant while in bio- mordanting, 8% of pomegranate peel extract as pre-mordant and 2% pomegranate peel extract as post-mordant indicated a darker shade to mordanted fabrics. Bio-mordanting gave darker shade, and fastness which revealed that bio-mordants have improved the fastness characteristics. FTIR results revealed the confirmation of flavonoids as a colourant for cotton dyeing.

Ultrasonic Extraction of Phenolic Compounds from Eggplant Peel and Formulation of Eggplant Peel Extract-Enriched Ice-Cream

In this study, ultrasound-assisted extraction (UAE) was used for the extraction of bioactive compounds from eggplant peels (EPP) and conditions were optimized by using response surface methodology (RSM). Methanol concentrations (60%, 70%, and 80%), time (30 min, 45 min, and 60 min), and temperature (30°C, 45°C, and 60°C) were selected as independent extraction parameters, whereas total anthocyanin content (TAC), DPPH inhibition, and total phenolic content (TPC) were response variables. The optimal extraction was at 45°C for 45 min of extraction time with 70% solvent which corresponded to TAC, TPC, and DPPH inhibition values of 7.94 mg/g, 7.03 mg GAE/g, and 94.8%, respectively. The optimized EPP extract was chemically characterized by a Fourier-transform infrared spectrometer (FTIR), high-performance liquid chromatography (HPLC), and a gas chromatography mass spectrometer (GCMS). The optimized extract was further evaluated for antioxidant and anticancer potential. For antioxidant and anticancer potential, the corresponding IC50 values of the EPP extract were 243.2 μg/ml and 1.52–1.99 mg/ml, respectively. Furthermore, the EPP extract significantly inhibited the migratory ability of cancer cells in a dose-dependent manner. Major components identified in the EPP extract were chlorogenic acid (261.76 mg/kg), benzoic acid (184.41 mg/kg), syringic acid (78.48 mg/kg), p-coumaric acid (49.59 mg/kg), cinnamic acid (32.17 mg/kg), quercetin (5.24 mg/kg), sinapic acid (5.14 mg/kg), and gallic acid (4.34 mg/kg). The EPP extract-enriched ice-cream showed high antioxidant potential and consumer acceptability than the blank ice-cream formulation. The EPP extract, due to its antioxidant and anticancer potential, can be used in the formulation of functional food products.

Anthocyanins from Agro-Industrial Food Waste: Geographical Approach and Methods of Recovery-A Review

Drastic growth in the amount of global food waste produced is observed every year, not only due to incessant population growth but also economic growth, lifestyle, and diet changes. As a result of their increasing health awareness, people are focusing more on healthy diets rich in fruits and vegetables. Thus, following worldwide fruit and vegetable consumption and their processing in various industries (juice, jams, wines, preserves), significant quantities of agro-industrial waste are produced (pomace, peels, seeds) that still contain high concentrations of bioactive compounds. Among bioactive compounds, anthocyanins have an important place, with their multiple beneficial effects on health; therefore, their extraction and recovery from food waste have become a topic of interest in recent years. Accordingly, this review aims to summarize the primary sources of anthocyanins from food waste and the novel eco-friendly extraction methods, such as pulsed electric field extraction, enzyme-assisted extraction, supercritical fluid extraction, pressurized liquid extraction, microwave-assisted extraction, and ultrasonic-assisted extraction. The advantages and disadvantages of these techniques will also be covered to encourage future studies and opportunities focusing on improving these extraction techniques.

Effects of Botanical Ingredients Addition on the Bioactive Compounds and Quality of Non-Alcoholic and Craft Beer

Special beers, known as artisanal, are progressively gaining consumer preference, opening up competition, and acquiring more space in the market. Considering that, exploration for new formulations is justified and plants represent a source of novel compounds with promising antioxidant activity for this beer segment. This paper aims to evaluate the current knowledge on the role of botanical ingredients on the final yield of bioactive compounds in special beer, and how these molecules generally affect the sensory profile. Furthermore, the estimated difficulties of implementation, taking into account the new processes and the relative cost, are discussed. The addition of plants to beer could serve the interests of both the industry and consumers, on one hand, by improving the functional properties and offering a unique flavor, and on the other hand by adding variety to the craft beer landscape. This paper provides guidance and future directions for the development of new products to boost the brewing industry. Brewing processes might affect the valuable compounds, especially the phenolic content. Consequently, future studies need to identify new methods for protecting the level of bioactive compounds in special beer and increasing the bio-accessibility, along with optimization of the sensory and technological properties.

Nanoencapsulation of Eggplant (Solanum melongena L.) Peel Extract in Electrospun Gelatin Nanofiber: Preparation, Characterization, and In Vitro Release

This study describes the preparation and characterization of eggplant peel extract-loaded electrospun gelatin nanofiber and study of its in vitro release. Results obtained by scanning electron microscopy (SEM) and transmission electronic microscopy (TEM) micrograph revealed that eggplant peel extract-loaded electrospun gelatin nanofiber is in nanometric range with an average diameter 606.7 ± 184.5 and 643.6 ± 186.7 nm for 20 and 33.3 mg mL⁻¹ of extract addition, respectively. Moreover, the incorporation of extract improved morphology by being smooth, homogeneous, and without account formation compared to nanofibers without extract (control). Fourier transform-infrared (FT-IR) spectra indicated that interaction exists between electrospun gelatin nanofiber and eggplant peel extract by hydrogen bond interactions, mainly. Electrospun gelatin nanofibers showed encapsulation efficiency greater than 90% of extract and a maximum release of 95 and 80% for the medium at pH 1.5 and 7.5, respectively. Therefore, the electrospinning technique is a good alternative for the conservation of bioactive compounds present in the eggplant peel through electrospun gelatin nanofiber.

Fruit and Vegetable Peel-Enriched Functional Foods: Potential Avenues and Health Perspectives

Fresh fruit and vegetables are highly utilized commodities by health-conscious consumers and represent a prominent segment in the functional and nutritional food sector. However, food processing is causing significant loss of nutritional components, and the generation of waste is creating serious economic and environmental problems. Fruit and vegetables encompass husk, peels, pods, pomace, seeds, and stems, which are usually discarded, despite being known to contain potentially beneficial compounds, such as carotenoids, dietary fibers, enzymes, and polyphenols. The emerging interest in the food industry in the nutritional and biofunctional constituents of polyphenols has prompted the utilization of fruit and vegetable waste for developing enriched and functional foods, with applications in the pharmaceutical industry. Moreover, the utilization of waste for developing diverse and crucial bioactive commodities is a fundamental step in sustainable development. Furthermore, it provides evidence regarding the applicability of fruit and vegetable waste in different food formulations especially bakery, jam, and meat based products.

Novel Approaches for the Recovery of Natural Pigments with Potential Health Effects

The current increased industrial food production has led to a significant rise in the amount of food waste generated. These food wastes, especially fruit and vegetable byproducts, are good sources of natural pigments, such as anthocyanins, betalains, carotenoids, and chlorophylls, with both coloring and health-related properties. Therefore, recovery of natural pigments from food wastes is important for both economic and environmental reasons. Conventional methods that are used to extract natural pigments from food wastes are time-consuming, expensive, and unsustainable. In addition, natural pigments are sensitive to high temperatures and prolonged processing times that are applied during conventional treatments. In this sense, the present review provides an elucidation of the latest research on the extraction of pigments from the agri-food industry and how their consumption may improve human health.

Ultrasound-Assisted Extraction of Natural Pigments From Food Processing By-Products: A Review

Ultrasound is an emerging technology, which has been highly explored in the food area to improve processes and products. When ultrasound is applied to a product with solid or fluid characteristics, the passage of acoustic waves and acoustic cavitation generates different mechanisms responsible for modifications in the original matrix of the sample. These effects of ultrasound can also be used to take advantage of by-products, for example by extracting compounds of interest, including natural pigments. Natural pigments or colorants are being highly demanded by different industries not only for color purposes but also due to their healthy properties, the greater demands in regulations and new consumer preferences. This review presents an updated critical analysis of the application of ultrasound-assisted extraction (UAE) to obtain natural pigments from food processing by-products. Initially, the ultrasound effects and mechanisms that improve the extraction of natural pigments in a fluid medium, as well as the factors that influence the extraction and the energy consumption of UAE are analyzed and described. Subsequently, the UAE application to obtain pigments belonging to the groups of carotenoids, chlorophyll, anthocyanins and betalains is evaluated. These sections detail the processing conditions, positive and negative effects, as well as possible applications of the extracted pigments. This review presents relevant information that may be useful to expand and explore new applications of ultrasound technology as well as promote the revaluation of by-products to obtain pigments that can be used in food, pharmaceutical or cosmetic industries.

Bee Bread: Physicochemical Characterization and Phenolic Content Extraction Optimization

Beebread or ambrosia is a unique product for humans and bees, which is the result of lactic fermentation on pollen in honeycombs. Bee bread is a rich source of nutrients (proteins, vitamins) and polyphenols (such as flavonoids, flavonols, phenolic acids). This study aimed to characterize bee bread in terms of physicochemical properties: pH, free acidity, glucose, fructose, sucrose, raffinose and melesitose content, total phenolic content (TPC), total flavones content (TFC), fatty acids and individual phenolics (gallic acid, protocatechiuc acid, p-hydroxybenzoic acid, caffeic acid, vanillic acid, chlorogenic acid, p-coumaric acid, rosmarinic acid, myricetin, luteolin, quercetin and kaempferol). The main phenolic compound identified in the bee bread was kaempferol, followed by myricetin and luteolin. The TPC, TFC and extraction yield were optimized in function of ultrasonic amplitude, temperature and time and the suitable conditions for achieving the maximum level were 87.20% amplitude of ultrasonic treatment, 64.70 °C and 23.10 min, respectively for reaching 146.2 mg GAE/L of TPC, 1231.5 mg QE/g of TFC and a 5.72% extraction yield. The most abundant fatty acids were C18:3 (all-cis-9,12,15) octadeca-6,9,15-trienoic acid, followed by C16:1 (9Z)-hexadec-9-enoic acid, C21:0 heneicosanoic acid and C18:2 (all-cis-9,12) (9Z,12Z)-octadeca-9,12-dienoic acid, respectively.

Green Extraction of Antioxidant Polyphenols from Green Tea (Camellia sinensis)

In this study, the feasibility of improving the extraction yield of green tea antioxidant polyphenols by the combination of ultrasound-assisted extraction (UAE) and deep eutectic solvents (DESs) was investigated. Choline chloride (ChCl)-glycerol was selected as the best DES among 12 ChCl-based DESs to extract tea antioxidant polyphenols. Subsequently, the influences of extraction parameters on total phenolic content (TPC) values were investigated, and liquid/solid ratio, ultrasonic power, and ultrasonic time were optimized based on the response surface methodology. The optimal extraction conditions were a liquid to solid ratio of 36:1 (mL/g), ultrasonic power of 461.5 W, and ultrasonic time of 21 min, with the highest TPC value of 243 ± 7 mg gallic acid equivalent (mg GAE)/g dry weight (DW), which was 13% higher than that before optimization. In addition, under the optimal extraction conditions, tea polyphenolic extract exhibited higher antioxidant activity compared with conventional extraction methods. Four major catechins in the green tea extracts, including (−)-epicatechin (EC), (−)-epigallocatechin (EGC), (−)-epicatechin gallate (ECG) and (−)-epigallocatechin gallate (EGCG) were identified and quantified by high-performance liquid chromatography. In addition, scanning electron microscopy (SEM) analysis revealed that UAE-DES effectively disrupted the green tea leaf cells, thereby improving tea polyphenol yield. In summary, UAE-DES is an ideal green extraction method for the extraction of tea antioxidant polyphenols.

Ultrasound-Assisted Extraction of Polyphenols From Crude Pollen

The aim of this study was to evaluate the extraction efficiency of polyphenols from crude pollen by an ultrasonic process. Prior to the polyphenols extraction, the crude pollen was defatted. The extraction from defatted pollen was carried out by varying four extraction parameters: ultrasonic amplitude (20%, 60% and 100%), solid/liquid ratio (10 g/L, 20 g/L and 30 g/L), temperature (35, 50 and 65 °C) and time (10, 20 and 30 min). The extracts were analyzed in terms of extraction yield (%), total phenolic content (TPC) and total flavones content (TFC). The extracted oil was analyzed in terms of fatty acids composition; myristic acid (159.1 µg × g^-1) and cis-14-pentadecenoic acid (106.6 µg·g^-1) were found in the highest amount in the pollen oil. The optimum conditions of extraction were determined and were, as follows: 100% amplitude of ultrasonic treatment, 30 g/L solid/liquid ratio, 40.85 °C and 14.30 min, which led to the extraction of 366.1 mg GAE/L of TPC and 592.2 mg QE/g of TFC, and also to an extraction yield of 1.92%.

Value-Added Lager Beer Enriched with Eggplant (Solanum melongena L.) Peel Extract

Manufacturing beer with a high biological value requires identifying new methods for increasing the health-enhancing compounds level. The aim of this study was to increase the biological value of beer by adding antioxidant-rich eggplant (Solanum melongena L.) peel extract (EPE). The total phenolic content (TPC), total flavonoid content (TFC), and total monomeric anthocyanin content (TMA) were determined. Moreover, the antioxidant activity was evaluated by different radical scavenging assays. The addition of different levels of EPE resulted in a significant increase of TPC and TFC of beer samples from 0.426 to 0.631 mg GAE/mL, and from 0.065 to 0.171 mg CE/mL, respectively. The EPE-supplemented beer samples developed a reddish color because of the presence of anthocyanin pigments. The TMA content of beer varied from 0.011 to 0.083 mg D3G/mL with the level of added EPE. The HPLC analysis indicated that the anthocyanins prevailing in the eggplant peels were delphinidin-3-rutinoside, delphininidin-3-glucoside and delphinidin-3-rutinoside-5-glucoside. The radical scavenging assays indicated a linear increase of the antioxidant activity following EPE addition, without altering the physicochemical parameters of the beer. These results are promising for using the EPE as a functional ingredient for beer production.

Ultrasonic Treatment Increases Extraction Rate of Common Bean (Phaseolus vulgaris L.) Antioxidants

The feasibility of improving the extraction rate of common bean antioxidants by ultrasonic treatment was investigated. Scanning electron microscopy (SEM) and spectrum Fourier transform infrared spectrophotometer (FT-IR) analysis revealed that ultrasonic treatment substantially altered the cellular structure of common bean seed, resulting in increased surface area, eroded cell walls, and greater exposure of cellulose and hemicellulose. The highest antioxidant activity was obtained at optimal extraction conditions (68 min, 55% acetone, 36:1 liquid to solid ratio, 30 ℃, and 480 W) which were optimized by response surface methodology. In terms of the extraction rate of common bean antioxidants, ultrasound-assisted extraction (UAE) exhibits about seven-fold higher extraction efficiency than conventional solvent extraction (CSE). In addition, 10 phenolic compounds in the common bean extracts were detected and quantified by high performance liquid chromatography (HPLC), including protocatechuic acid, catechin, chlorogenic acid, epicatechin, ferulic acid, coumarin, rutin, myricetin, cinnamic acid, and genistein. In summary, ultrasonic treatment is an ideal candidate methodology for improving the extraction rate of common bean antioxidants.

Metabolism of anthocyanins and consequent effects on the gut microbiota

Anthocyanins are natural water-soluble polyphenols present in fruits and vegetables. Health-promoting effects attributed to anthocyanins are mainly associated with oxidative stress inhibition and gut microbiota modulation. Dietary anthocyanins undergo a complex metabolism after ingestion and interact with endogenous and microbial enzymes, leading to the production of a large number of circulating and excreted anthocyanin metabolites and catabolic products. To date, the bioavailability and health benefits of anthocyanins have been widely documented. Although there are several papers that illustrated the metabolism of anthocyanins, the effects of dietary anthocyanins on the modulation of the gut microbial ecology and on the growth of certain microbial species are still poorly understood. The present paper summarizes the recent data on the absorption of anthocyanins in the upper gastrointestine and the metabolism of anthocyanins by gut microbiota. The modulatory effects of anthocyanins from different sources on gut microbiota are also discussed.

Enhancement of total phenolic and flavonoids extraction from Rosmarinus officinalis L using electromagnetic induction heating (EMIH) process

Electromagnetic induction heating (EMIH) assisted extraction of phenolic compounds from Rosmarinus officinalis L, and the antioxidant and antimicrobial activities of the plant extract were examined in this study. The extraction yield acquired with this process was found to be 25.1 ± 2%, with maximum amounts of phenolic compounds: 127.87 ± 2.1 mg Gallic acid equivalents per g dry weight and total flavonoids contents 14.48 ± 1.5 mg quercetin equivalents per g dry weight, under optimum extraction conditions (extraction time 2 h, ratio of raw material to liquid 1:2 and 0% of NaCl). The antioxidant activity was assessed by the 1,1-diphenyl-2-picrylhydrazyl (DPPH); 2, 2'-azinobis (3-ethylbenzothiazoline-6- sulfonic acid) radical cation (ABTS⁺) and ferric reducing power (FRAP) methods. The results indicate the extract derived through EMIH showed a strong antioxidant ability (89.25%; EC₅₀ of 0.0148 µg/mL). Besides, the antimicrobial bioassay demonstrated that the extract possessed a good antimicrobial activity against all tested fungi and bacteria.

Diallel genetic analysis for multiple traits in eggplant and assessment of genetic distances for predicting hybrids performance

Evaluation and prediction of the performance of hybrids is important in eggplant (Solanum melongena) breeding. A set of 10 morphologically highly diverse eggplant parents, including nine inbred S. melongena and one weedy S. insanum accessions, were intercrossed according to a half-diallel mating design without reciprocals to obtain 45 hybrids. Parents and hybrids were evaluated for 14 morphological and agronomic conventional descriptors and 14 fruit morphometric traits using Tomato Analyzer. Genetic distances among parents were estimated with 7,335 polymorphic SNP markers. Wide ranges of variation and significant differences were observed in the set of 55 genotypes for all traits, although the hybrids group had significantly higher vigour and yield than parents. General and specific combining abilities (GCA and SCA) were significant for most (GCA) or all (SCA) traits, although a wide variation was obtained for GCA/SCA ratios. Many relevant traits associated to vigour and yield had low GCA/SCA ratios and narrow-sense heritability (h2) values, while the reverse occurred for most fruit shape descriptors. Broad-sense heritability (H2) values were generally high, irrespective of GCA/SCA ratios. Significant correlations were found between traits related to size of leaf, flower and fruit, as well as among many fruit morphometric traits. Genetic distances (GD) among parents were coherent with their phylogenetic relationships, but few significant and generally low correlations were found between GD and hybrid means, heterosis or SCA. The results provide relevant information for developing appropriate strategies for parent selection and hybrid development in eggplant and suggest that GD among parents have limited value to predict hybrid performance in this crop.

Stability of functional compounds and antioxidant activity of fresh and pasteurized orange passion fruit (Passiflora caerulea) during cold storage

This research aimed to evaluate differences in the stability of physicochemical and color parameters, phenolic compounds, flavonoids, carotenoids and antioxidant capacity in fresh and pasteurized juice of orange passion fruit, respectively cold stored (8 °C) during 0-4 or during 0-15 days. The results showed that in the physicochemical analysis, no significant differences were observed comparing pasteurized and fresh juice during storage. The pasteurized juice showed higher concentrations of color parameters, phenolic compounds (15% more of retention for days 0 and 4), epigallocatechin gallate (40% in day 0 and 27% in day 4), lycopene (142% for day 0 and 39% for day 4), total carotenoids (114% in day 0 and 8% in day 4) and antioxidant capacity (12% in day 0 and 7% in day 4).; already fresh juice retained more values of quercetin (79% in day 0 and 245% in day 4), α-carotene (57% in day 4), β-carotene and provitamin A (80% of retention in day 4). Therefore, the pasteurization processing was positive in orange passion fruit juice and improved the accessibility of most bioactive compounds.