Recovery Of Pigments Research Articles

Greener technologies in agri-food wastes valorization for plant pigments: Step towards circular economy

The need for food has drastically increased with the world population's unprecedented growth, which consequently raised agricultural production. The increased agricultural and food production as a whole has resulted in the generation of enormous amounts of food waste, which is now posing a threat to both the environment and humanity. To address these issues, it is now crucial to persuade people to use promising green technologies to manage and valorize agri-food waste into valuable food additives. The recovery of value-added pigments from agri-food waste as natural food colorants is one of the new business prospects being created by approaches influenced by the circular economy model that have been continuously growing globally. These natural pigments are expected to substantially impact the development of functional foods and offer a wealth of bio-therapeutic potential. The production of naturally safe food pigments from the agri-food waste offers a greener approach within circular economy concept while avoiding the use of synthetic-petro-based colourants from the food chain. This also promotes the incorporation of natural food pigments obtained through sustainable resources. This state-of-the-art graphical review focused on the recent advances in green valorization technologies of agri-food waste to exploit natural plant pigments and their relation to sustainable food production and green circular economy.

Pressurized Liquid Extraction of Polyphenols and Anthocyanins from Saffron Processing Waste with Aqueous Organic Acid Solutions: Comparison with Stirred-Tank and Ultrasound-Assisted Techniques

Fοllow up with our previous study on the extraction of saffron processing waste polyphenols using deep eutectic solvents, the objective of this examination was a comparative evaluation of pressurized liquid extraction (PLE), stirred-tank extraction (STE) and stirred-tank extraction with ultrasonication pretreatment (STE/UP) with respect to the recovery of pigments and antioxidant polyphenols from saffron processing waste. Aqueous solutions of citric and lactic acids at two different concentrations were used as green solvents. The extracts obtained under the specified conditions were analyzed for total pigment and total polyphenol yields as well as for their ferric-reducing power and antiradical activity. Furthermore, each produced extract was analyzed with liquid chromatography–mass spectrometry to profile its analytical polyphenolic composition. In all cases, PLE provided inferior results compared to the two other techniques, producing extracts with lower polyphenolic concentration and weaker antioxidant properties. On the other hand, no specific pattern was detected concerning the effect of ultrasonication, acid type and acid concentration. Hierarchical cluster analysis indicated that stirred-tank extraction with 1% (w/v) lactic acid and ultrasonication pretreatment might be the highest-performing combination, providing extracts with increased polyphenol and pigment concentration; however, it also enhanced antioxidant activity. It was also concluded that the significantly shorter extraction time when using PLE might be an important element in further optimizing the process, buttressing the use of this technique for the establishment of innovative and sustainable-by-design extraction methodologies.

Development of a Green Methodology for Simultaneous Extraction of Polyphenols and Pigments from Red Winemaking Solid Wastes (Pomace) Using a Novel Glycerol-Sodium Benzoate Deep Eutectic Solvent and Ultrasonication Pretreatment

In this examination, two glycerol-based deep eutectic solvents (DESs) were tested for their efficiency in the recovery of antioxidant polyphenols and anthocyanin pigments from red grape pomace (RGP). The two DESs synthesized had sodium acetate and sodium benzoate as hydrogen bond acceptors, to test the role of the hydrogen bond acceptor polarity on the extraction performance. Furthermore, the process was enhanced by an ultrasonication pretreatment stage. After initial testing with respect to water content, ultrasonication power and liquid-to-solid ratio, the DES composed of glycerol and sodium benzoate (GL-SBz) was shown to be significantly more efficient than the one made of glycerol and sodium acetate (GL-SAc). Further optimization of the extraction with regard to time and temperature demonstrated GL-SBz to be a highly effective solvent for the production of RGP extracts rich in polyphenols including gallic acid, catechin and quercetin, and pigments including malvidin 3-O-glucoside p-coumarate and malvidin 3-O-glucoside. The extracts produced also had significantly higher antiradical activity and reducing power compared to those generated with aqueous ethanol or water. From this study, evidence emerged regarding the role of the hydrogen bond acceptor nature in the extraction efficiency of polyphenols. The process developed is proposed as a green, high-performing methodology for the production of RGP extracts with enhanced polyphenolic content and antioxidant activity.

Valorisation of food wastes to produce natural pigments using non‐thermal novel extraction methods: a review

SummaryWaste or by‐products produced during food processing can be used as a potential source of bioactive compounds including natural pigments. Natural pigments/colourants have numerous health benefits whereas the synthetic colourants have many negative effects on human health. Thus, there is a considerable interest worldwide in pigments extraction from natural sources. Conventional extractions such as soxhlet extraction, water distillation, and solvent extraction have many limitations such as large solvent consumption, long extraction time, and low extraction yields. Therefore, novel techniques such as high pressure, ultrasound, negative pressure and electric field have been employed to assist the pigment extraction process. The novel extraction methods are being developed with the primary aim of higher pigment yield, lower solvent consumption, minimised environmental effects and the convenience of extraction. With this perspective, the present review provides recent insights into the recovery of natural pigments from food wastes/by‐products and the application of novel non‐thermal technologies for their recovery.

Eurasian water milfoil: Composition, recovery of phenolics and anthocyanins, and saccharification

AbstractEurasian water milfoil (Myriophyllum spicatum; EWM) is an invasive aquatic weed that has spread worldwide but remains unstudied as a potential source of bioenergy and valuable chemicals. In this study, the composition of EWM biomass is characterized by determining the monosugar and lignin content, ash, and extractives. EWM extractives contain beneficial phenolic compounds, among them anthocyanin pigments. Following the biorefinery concept, a stepwise treatment of this aquatic plant was carried out toward integrating the extraction of phenolics with the saccharification of carbohydrates for viable biomass utilization. The recovery of phenolics and anthocyanin pigments was studied, in which different extracting compositions and conditions were applied. The antioxidant capacity of the extracts was evaluated. Saccharification was carried out using autoclaving, followed by hydrolysis using common cellulase enzyme. Different media were studied. Under the best condition, the carbohydrates contained were hydrolyzed to reducing sugars, and the conversion rate to glucose reached 90%. The yield of glucose was 0.245 g g−1 dried plant. This study demonstrates the potential of EWM as a source of antioxidants comparable to some phenolics‐rich algae, and as a bioenergy resource comparable with other sugar‐rich macrophytes.

\u03b2-Carotene extraction from Dunaliella salina by supercritical CO2

This paper reports the results of supercritical carbon dioxide (scCO2) extraction of β-carotene from Dunaliella salina as potential alternative to conventional organic solvent extraction. In pilot-scale scCO2 experiments, the pressure, temperature, and co-solvent concentration were varied. The supercritical extraction at 500 bar, 70 °C, and 10 wt% ethanol as co-solvent yielded in the highly efficient pigment recovery of over 90%. Techno-economic assessment demonstrated higher energy consumption for the scCO2 extraction that was compensated by lower solvent costs. Thus, comparable pigment production costs to the reference extraction with n-hexane were estimated for the scCO2 process. Due to the green solvent properties of scCO2 and ethanol, this approach is highly promising for extraction of algal biomass in industrial scale.

A Novel Process for the Recovery of Betalains from Unsold Red Beets by Low-Temperature Enzyme-Assisted Extraction.

Food waste management plays a central role in the circular economy. To our knowledge, only a few studies have investigated the use of unsold fruit and vegetables from supermarkets as a substitute source for the extraction of natural colorants. Thus, the aim of this paper was to suggest a green, tailored protocol that avoids the use of organic solvents for the recovery of betalains from unsold red beets for use as a food colorant. The recovery of such pigments was carried out by a tailored enzymatic mix, blended considering the polysaccharide composition of the beetroot cell wall; thus, it consisted of: cellulase (37%), xylanase (35%), and pectinase (28%). The enzyme-assisted extraction protocol was optimized, and the most suitable conditions (in terms of pigment yield and color attributes) for the recovery of betalains from unsold beets appeared to be: 25 U/g total dose of enzymatic mix, temperature 25 °C, and processing time 240 min.

Recovery of Red Pigments from Monascus purpureus FTC 5357 by Extraction of Fermented Solids: Operational Conditions and Kinetics

HIGHLIGHTS Red pigment of Monascus purpureus effectively extracted from dried fermented oil palm frond (OPF) using 60% ethanol. Maximum pigment recovery was obtained at 30 (C, 180 rpm agitation speed, 16 h, ratio of 1:60 solid to solvent and pH 6 of 60% ethanol. Peleg’s model proved to be the best for describing solid-liquid extraction of the pigments under the above specified conditions.

Pilot-scale phycoremediation using Muriellopsis sp. for wastewater reclamation in the Atacama Desert: microalgae biomass production and pigment recovery.

Municipal wastewater phycoremediation represents a promising circular economy-based process for wastewater reclamation used to recover water and produce biomass. This study aimed to evaluate a pilot-scale phycoremediation system, using the most efficient strain of microalgae for wastewater reclamation in the Atacama Desert. Nitrogen and phosphorus removal, as well as biomass growth, were compared in different microalgae treatments, namely Muriellopsis sp., Scenedesmus almeriensis, Chlamydomonas segnis, Chlorella pyrenoidosa and Chlorella vulgaris. The most efficient treatments, Muriellopsis sp. and S. almeriensis, were scaled up to 20-L bubble column reactors to evaluate nutrient removal and biomass biochemical profile for potential biotechnological application. Finally, Muriellopsis sp. was selected for a pilot-scale phycoremediation experiment (800-L raceway), which removed 84% of nitrogen, 93% of phosphorus and other chemical compounds after 4 days of treatment to meet most of the Chilean standards for irrigation water (NCh. 1333. DS. MOP No. 867/78). Faecal coliforms count was reduced by 99.9%. Furthermore, biomass productivity reached 104.25 mg·L-1·day-1 value with 51% protein, and pigment content of 0.6% carotenoid, with 0.3% lutein. These results indicate the potential of wastewater phycoremediation at an industrial scale for the production of irrigation water and carotenoid using Muriellopsis sp.

Recovery of pigments from Ulva rigida

Pigments, such as chlorophylls and carotenoids, have important applications in various fields, such as colorants in food, cosmetic or textile industries and in biomedical applications. Both pigments have an important role in the photosynthetic process and can be found in the marine green macroalgae genus Ulva. In this work, an integrated downstream process was developed to extract chlorophylls and carotenoids from those macroalgae. The solid-liquid extraction was optimized. For that, several conditions were tested, namely the use of different mechanical processes (maceration, microwave- or ultrasound- assisted extraction), type of solvent, number of consecutive extractions, solid-liquid ratio, and the design of the extraction process using a mechanical treatment. Using the extract obtained, a liquid-liquid extraction system composed of ethanol, hexane, and water was then studied. Different mixture points within the biphasic region were tested in terms of their ability to selectively separate chlorophylls and xanthophylls to opposite phases in a single step. The optimization and implementation of a simple, fast and efficient downstream process to separate both classes of pigments such as chlorophylls and xanthophylls from green macroalgae is reported. It could be applied to fractionate other extracts with similar compositions obtained from other natural sources.

Recovery of Crocins From Floral Tissue of Gardenia jasminoides Ellis.

In this research, a novel source of phytopigment crocins from fully open mature flowers of cape jasmine (Gardenia jasminoides) is introduced. Methanol and deionized water were appropriate solvents for pigment recovery with maximum yields of at least 17% from the floral tissue. Pigment separation by thin layer chromatography also confirmed the presence of the carotenoids, which dissolved well in these high-strength polar solvents, in fruit, flower, and leaf materials. The spectral patterns of the extracts from ultraviolet and nuclear magnetic resonance showed maximum absorption at ~420 nm and the chemical shift values were similar to those of crocetin aglycones (crocins) in the methanol extracts of a commercial source of yellow gardenia (fructus or fruit of Gardenia florida). Chemical compositions were then evaluated using aqueous-phase capillary electrophoresis of the methanol extracts. The methanolic extracts of the flowers and fruit had 11 principal ingredients in common. Among these, crocetin and crocin 2 belong to the crocin group and are known to be the major components of commercial yellow Gardenia. This research not only demonstrates a sustainable means of raw material utilization for natural product recovery, but also encourages a movement toward an edible landscape for the community.

Accelerated Solvent Extraction as a Green Tool for the Recovery of Polyphenols and Pigments from Wild Nettle Leaves

This study aimed to investigate the performance of accelerated solvent extraction (ASE) as a green approach for the recovery of polyphenols and pigments from wild nettle leaves (NL). ASE was operated at different temperatures (20, 50, 80 and 110 °C), static times (5 and 10 min) and cycle numbers (1–4) using ethanol (96%) as an extraction solvent. In order to compare the efficiency of ASE, ultrasound assisted extraction (UAE) at 80 °C for 30 min was performed as a referent. Polyphenol and pigment analyses were carried out by HPLC and antioxidant capacity was assessed by ORAC. Seven polyphenols from subclasses of hydroxycinnamic acids and flavonoids, along with chlorophylls a and b and their derivatives and six carotenoids and their derivatives were identified and quantified. Chlorogenic acid was the most abundant polyphenol and chlorophyll a represented the dominant pigment. ASE conditions at 110 °C/10 min/3 or 4 cycles proved to be the optimal for achieving the highest yields of analyzed compounds. In comparison with UAE, ASE showed better performance in terms of yields and antioxidants recovery, hence delivering extract with 60% higher antioxidant capacity. Finally, the potential of NL as a functional ingredient from natural sources can be successfully accessed by ASE.

Natural Pigments and Biogas Recovery from Microalgae Grown in Wastewater.

This study assessed the recovery of natural pigments (phycobiliproteins) and bioenergy (biogas) from microalgae grown in wastewater. A consortium of microalgae, mainly composed by Nostoc, Phormidium, and Geitlerinema, known to have high phycobiliproteins content, was grown in photobioreactors. The growth medium was composed by secondary effluent from a high rate algal pond (HRAP) along with the anaerobic digestion centrate, which aimed to enhance the N/P ratio, given the lack of nutrients in the secondary effluent. Additionally, the centrate is still a challenging anaerobic digestion residue since the high nitrogen concentrations have to be removed before disposal. Removal efficiencies up to 52% of COD, 86% of NH4+-N, and 100% of phosphorus were observed. The biomass composition was monitored over the experimental period in order to ensure stable cyanobacterial dominance in the mixed culture. Phycocyanin and phycoerythrin were extracted from harvested biomass, achieving maximum concentrations of 20.1 and 8.1 mg/g dry weight, respectively. The residual biomass from phycobiliproteins extraction was then used to produce biogas, with final methane yields ranging from 159 to 199 mL CH4/g VS. According to the results, by combining the extraction of pigments and the production of biogas from residual biomass, we would not only obtain high-value compounds, but also more energy (around 5–10% higher), as compared to the single recovery of biogas. The proposed process poses an example of resource recovery from biomass grown in wastewater, moving toward a circular bioeconomy.

Coral Bleaching Susceptibility Is Predictive of Subsequent Mortality Within but Not Between Coral Species

Marine heat waves instigated by anthropogenic climate change are causing increasingly frequent and severe coral bleaching events that often lead to widespread coral mortality. While community-wide increases in coral mortality following bleaching events have been documented on reefs around the world, the ecological consequences for conspecific individual colonies exhibiting contrasting phenotypes during heat stress (e.g. bleached vs. not bleached) are not well understood. Here we describe the ecological outcomes of the two dominant reef-building coral species in Kāneʻohe Bay, Hawaiʻi, Montipora capitata and Porites compressa, by monitoring the fates of individuals that exhibited either a bleaching susceptible phenotype (bleached) or resistant phenotype (non-bleached) following the second of two consecutive coral bleaching events in Hawaiʻi in 2015. Conspecific pairs of adjacent bleaching susceptible vs. resistant corals were tagged on patch reefs in two regions of Kāneʻohe Bay with different seawater residence times and terrestrial influence. The ecological consequences (symbiont recovery and mortality) were monitored for two years following the peak of the bleaching event. Bleaching susceptible corals suffered higher partial mortality than bleaching resistant corals of the same species in the first 6 months following heat stress. Surprisingly, P. compressa had greater resilience following bleaching (faster pigment recovery and lower post-bleaching mortality) than M. capitata, despite having less resistance to bleaching (higher bleaching prevalence and severity). These differences indicate that bleaching susceptibility of a species is not always a good predictor of mortality following a bleaching event. By tracking the fate of individual colonies of resistant and susceptible phenotypes, contrasting ecological consequences of heat stress were revealed that were undetectable at the population level. Furthermore, this approach revealed individuals that underwent particularly rapid recovery from mortality, including some colonies over a meter in diameter that recovered all live tissue cover from >60% partial mortality within just one year. These coral pairs (44 pairs of each species) continue to be maintained and monitored in the field, serving as a “living library” for future investigations on the ecology and physiology of coral bleaching.

Pef-assisted Supercritical CO2 Extraction of Pigments from Microalgae Nannochloropsis Oceanica in a Continuous Flow System

This study aimed at evaluating the effect of pulsed electric fields (PEF) pre-treatment on the extractability of pigments (total carotenes, chlorophyll a) from microalgae Nannochloropsis oceanica by supercritical CO2 (scCO2) extraction. Aqueous microalgal suspensions (1% w/w) added with 10% ethanol were treated in a continuous flow unit with either PEF at different field strengths (10–30 kV/cm) and total specific energy inputs (20–100 kJ/kg), or scCO2 at different pressures (8-20 MPa), with fixed temperature (35°C), CO2/biomass ratio (53.3 kgCO2/kgDW) and contact time (7 min). Extracts from conventional solvent extraction process and PEF-assisted scCO2 extraction were analyzed and compared with those achieved upon the application of single PEF and scCO2 extraction processes. Results showed that in PEF-assisted extraction the recovery yield of the target compounds significantly increased with increasing the treatment severity, even though the effect of the field strength appeared less important than the energy input. After PEF treatment at 10 kV/cm and 100 kJ/kg, the extraction yield for total carotenes and chlorophyll a increased by 1.6 and 1.4 times, respectively. During single scCO2 extraction process at 14 MPa the extraction yield for total carotenes and chlorophyll a increased up to 10.3 and 13.6 times, respectively, as compared to the untreated samples. The use of PEF prior to scCO2 extraction remarkably increased the extractability of the two pigments showing a clear synergistic effect. The results obtained in this work suggested that the application of PEF prior to scCO2 extraction could represent a suitable approach for the efficient recovery of pigments from microalgal biomass.

Modeling the Dynamics of Pigment Content in Cells of Dunaliella Salina Teod. Unicellular Alga at the Stage of Carotenogenesis

The work is focused on modeling of chlorophyll and carotenoids content dynamics in the in cells of the unicellular algae D. salina, living in salt water, at carotenogenesis induction phase. A mathematical model of pigments content in microalgae cells, which experience excess of light energy and the limit of nutrient medium mineral components, is proposed. The model is based on assumption, that observed rate of variation in pigment concentration is an algebraic sum of the rates of synthesis, photodestruction and partial recovery of photo-oxidized pigments. The rate of secondary carotenoids synthesis does not depend on external conditions and is determined by the quantity of key enzyme complex and its turnover rate. The rate of secondary carotenoids and chlorophyll photodestruction depends on the effective light intensity and is proportional to the amount of absorbed photosynthetically active radiation energy. The verification of the derived equations was conducted in the course of D. salina cultivation at the carotenogenesis stage. The specific rate of chlorophyll a photodestruction was determined, which resulted in 0.12 days–1. The secondary carotenoids concentration increases up to the maximum value, which is determined by the ratio of synthesis and photodestruction specific rates, as well as the maximum culture density. Under conditions of natural light in the Sevastopol region, the maximum concentration of carotenoids was 18.33 mg/l or 0.73 g/m2.

Influence of long term nitrogen limitation on lipid, protein and pigment production of Euglena gracilis in photoheterotrophic cultures.

Nitrogen limitation is considered a good strategy for enhancement of algal lipid production while conversely N repletion has been shown to result in biomass rich in proteins. In this study, the influence of long-term N limitation on Euglena gracilis fatty acid (FA), protein, chlorophyll a, and carotenoid concentrations was studied in N limited cultures. Biomass composition was analyzed from three-time points from N starved late stationary phase cultures, exposed to three different initial N concentrations in the growth medium. Total lipid content increased under N limitation in ageing cultures, but the low N content and prolonged cultivation time resulted in the formation of a high proportion of saturated FAs. Furthermore, growth as well as the production of proteins, chlorophyll a and carotenoids were enhanced in higher N concentrations and metabolism of these cellular components stayed stable during the stationary growth phase. Our findings showed that a higher N availability and a shorter cultivation time is a good strategy for efficient E. gracilis biomass production, regardless of whether the produced biomass is intended for maximal recovery of polyunsaturated FAs, proteins, or photosynthetic pigments. Additionally, we showed an increase of neoxanthin, β-carotene, and diadinoxanthin as a response to higher N availability.

Pigments and vitamins from plants as functional ingredients: Current trends and perspectives.

The food manufacturing industry has increasingly focused in the development of wholesome and safer products, including certified labeled "super foods," "healthy foods" and "functional foods," which are currently under great demand worldwide. Plant pigments and vitamins are amidst the most common additives incorporated to foodstuff, not only for improving their nutritional status but also for coloration, preservation, and even therapeutic purposes. The recovery of pigments from agro industrial wastes using green emerging approaches is a current trend and clearly the best alternative to ensure their sustainable obtainment and make these ingredients more popular, although still full of challenging aspects. Stability and bioavailability limitations of these active molecules in food matrices have been increasingly studied, and a number of methods have been proposed to minimize these issues, among which the incorporation of a co-pigment, exclusion of O2 during processing and storage, and above all, microencapsulation and nanoencapsulation techniques. The most recent advances and challenges in the application of natural pigments and vitamins in functional foods, considering only reports of the last 5 years, were the focus of this chapter.

Solid phase fractionation techniques for segregation of red cabbage anthocyanins with different colorimetric and stability properties

Red cabbage anthocyanin extract contains cyanidin derivatives as various non-, mono-, and di-acylated forms capable of expressing various colors from red to blue. The objective of this study was to develop a simple solid phase extraction (SPE) method to fractionate and segregate di-acylated anthocyanins which have greater stability and more desirable blue colorimetric properties. Two different sorbents with different separation chemistries: SCX (Strong Cation Exchange) and C18 sorbents were evaluated. Red cabbage anthocyanins were fractionated and eluted from the SCX cartridge using combinations of different buffers (pH 6–8) and MeOH (20–70%) or eluted from the C18 cartridge using different percentages of acidified (0.01% HCl) MeOH (30–100%) or EtOH (10–100%). With SCX SPE, washing the loaded pigments with a mixture of buffer pH 6 + 20% MeOH followed by elution with buffer pH 8 + 70% MeOH proved most effective in segregating the di-acylated pigments; however, some anthocyanins were permanently retained by the sorbent. When using the C18 cartridge, washing bound pigments with 32% MeOH or 18.5% EtOH and eluting with 100% alcohol respectively resulted in high (> 93%) recovery of di-acylated pigments. The C18 cartridge with MeOH eluent was the most effective for isolating the target di-acylated red cabbage anthocyanins that produced desirable blue colors with increased stability.

Simultaneous decoloration and purification of crude oligosaccharides from pumpkin (Cucurbita moschata Duch) by macroporous adsorbent resin.

This study investigated an efficient and recyclable approach for purification of crude pumpkin oligosaccharide (POS) by macroporous resins. Five resins with different physical and chemical properties were tested for decoloration of POS. In virtue of its higher decoloration ratio (92.6%) and POS recovery ratio (81.3%), the macroporous resin DM28 was considered to a better selection. Depending on the changes of molecular weight, part of the monosaccharides in crude POS were removed simultaneously after decoloration by DM28. Operating conditions were also determined by the dynamic breakthrough and desorption curves. Moreover, UV/vis spectroscopy and Fourier transform infrared results revealed that most of the colored impurities and proteins can be removed, but the characteristic groups of the POS exhibited no significant difference. Compared with traditional methods, DM28 resin is superior in decoloration efficiency, pigment recovery and oligosaccharide recovery. This research contributes to further exploration on the structure and function of POS.