Structure and functionality of oat protein extracted by choline chloride‒dihydric alcohol deep eutectic solvent and its water binary mixtures

Toward Diverse Plant Proteins for Food Innovation

This review highlights the development of plant proteins from a wide variety of sources, as most of the research and development efforts to date have been limited to a few sources including soy, chickpea, wheat, and pea. The native structure of plant proteins during production and their impact on food colloids including emulsions, foams, and gels are considered in relation to their fundamental properties, while highlighting the recent developments in the production and processing technologies with regard to their impacts on the molecular properties and aggregation of the proteins. The ability to quantify structural, morphological, and rheological properties can provide a better understanding of the roles of plant proteins in food systems. The applications of plant proteins as dairy and meat alternatives are discussed from the perspective of food structure formation. Future directions on the processing of plant proteins and potential applications are outlined to encourage the generation of more diverse plant-based products.

Deep eutectic solvent: Synthesis, classification, properties and application in macromolecular substances

Deep eutectic solvent (DES) is a kind of solvent prepared by mixing hydrogen bond donors and hydrogen bond acceptors, and have become a hot topic in ecological civilization construction due to its low toxicity and sustainability. Its excellent properties such as low volatility, thermal stability and biodegradability make it stand out among many organic solvents and widely used in fields including medicine, chemical industry and agriculture, with broad development prospects. In recent years, the application of DES in the food field has mostly focused on the extraction of small molecular substances, and there are few summaries on the application of DES in macromolecular substances. In this review, we introduced the synthesis, classification and properties of DES, and summarized the application of DES in the food industry for macromolecular substances, including the extraction of macromolecular substances such as chitosan and pectin, as well as the preparation of related macromolecular substrate films. At the same time, we analyzed the characteristics of DES and its advantages and limitations in application, and provided prospects for future development.

Glucomannan isolation from porang (Amorphophallus muelleri Blume) flour using natural deep eutectic solvents and ethanol: A comparative study

Ethanol is a common solvent to isolate glucomannan from porang (Amorphophallus muelleri Blume) flour (NPF). This study investigated the use of natural deep eutectic solvents (NADESs) in glucomannan isolation from NPF. NADESs formed by the hydrogen bond acceptors (choline chloride and betaine) and the hydrogen bond donors (glycerol, 1,2-propanediol, formic acid, and acetic acid) in varying molar ratios of 1:2, 1:3, and 1:4 were characterized to optimize glucomannan isolation. The results showed that higher molar ratios of NADES tended to yield porang glucomannan flour (PGF) with higher glucomannan content and viscosity. The gel of PGF exhibited pseudoplastic behavior. The FTIR spectra indicated that betaine-based NADES removed the acetyl groups from glucomannan chains. The PGF obtained from NADESs with a molar ratio of 1:4 was comparable to those obtained from ethanol with a glucomannan content of 87.34 %-93.28 % and a weight-average molecular weight of 9.12 × 105-1.20 × 106 g/mol.

Deep eutectic solvents: Preparation, properties, and food applications

Deep Eutectic Solvents (DESs) emerge as innovative 21st-century solvents, supplanting traditional ones like ethanol and n-hexane. Renowned for their non-toxic, biodegradable, and water-miscible nature with reduced volatility, DESs are mostly synthesized through heating and stirring method. Physicochemical properties such as polarity, viscosity, density and surface tension of DESs influenced their application. This review paper gives the overview of application of eco-benign DESs in fruits, vegetables, cereals, pulses, spices, herbs, plantation crops, oil seed crops, medicinal and aromatic plants, seaweed, and milk for the extraction of bioactive compounds. Also, it gives insight of determination of pesticides, insecticides, hazardous and toxic compounds, removal of heavy metals, detection of illegal milk additive, purification of antibiotics and preparation of packaging film. Methodologies for separating bioactive compounds from DESs extracts are systematically examined. Further, safety regulations of DESs are briefly discussed and reviewed literature reveals prevalent utilization of DES-based bioactive compound rich extracts in cosmetics, indicating untapped potential of their application in the food industry.

Isolation of detoxified cassava (Manihot esculenta L.) leaf protein by alkaline extraction-isoelectric precipitation: Optimization and its characterization

The cassava leaves protein isolate extraction and optimization were investigated using response surface methodology, where the maximum protein content (21.83 ± 0.41 g/100 g dm), extraction yield (18.31 ± 0.53%), and protein recovery yield (69 ± 1.31%) were obtained at optimal conditions: 114 min extraction time, 46 °C extraction temperature, 23.5 mL/g solvent/solute ratio and pH 11.0 value. The presence of toxicant (Cyanide) and anti-nutrient (tannin) in cassava leaves reduced the bio-accessibility of its protein isolate, strictly prohibiting its consumption. Therefore, detoxification was applied to diminish cyanide and tannin to 85% and 69% in leaves, respectively, where the protein content was reduced to 9.7%. However, detoxified cassava leaf protein isolate exhibited changes in the compositional, structural, morphological, molecular, and thermal characteristics compared to the controlled one. Moreover, the functional properties in protein isolate improved after detoxification at different pH conditions, which can be used as an active ingredient in various foods.

Characterisation of the Enzymatically Extracted Oat Protein Concentrate after Defatting and Its Applicability for Wet Extrusion

An oat protein concentrate (OC1) was isolated from oat flour through starch enzymatic hydrolysis, by subsequent defatting by ethanol and supercritical fluid extraction (SFE) reaching protein concentrations of 78% and 77% by weight in dry matter, respectively. The protein characterisation and functional properties of the defatted oat protein concentrates were evaluated, compared and discussed. The solubility of defatted oat protein was minor in all ranges of measured pH (3-9), and foamability reached up to 27%. Further, an oat protein concentrate defatted by ethanol (ODE1) was extruded by a single screw extruder. The obtained extrudate was evaluated by scanning electron microscope (SEM), texture and colour analysers. The extrudate's surface was well formed, smooth, and lacking a tendency to form a fibrillar structure. Textural analysis revealed a non-unform structure (fracturability 8.8-20.9 kg, hardness 26.3-44.1 kg) of the oat protein extrudate.

Evaluating the status quo of deep eutectic solvent in food chemistry. Potentials and limitations

Conventional organic solvents (e.g., methanol, ethanol, ethyl acetate) are widely used for extraction, reaction, and separation of valuable compounds. Although these solvents are effective, they have disadvantages, including flammability, toxicity, and persistence in the environment. Deep eutectic solvents (DESs) are valued for their biodegradability/low impact on the environment, low cost, and ease of manufacture. The objective of this review was to provide an overview of applications of DES in food chemistry, specifically in regard of extraction of polyphenols (e.g., anthocyanin, rutin, kaempferol, quercetin, resveratrol), protein, carbohydrates (e.g., chitin, pectins), lipids and lipid-soluble compounds (e.g., free fatty acids, astaxanthin, β-carotene, terpenoids), biosensor development, and use in food safety (pyrethroids, Sudan I, bisphenol A, Pb²⁺, Cd²⁺, etc.) over the past five years. A comprehensive analysis and discussion of DES types, preparation, structures, and influencing factors is provided. Furthermore, the potential and disadvantages of using DESs to extract biomolecules were assessed. We concluded that DES is a viable alternative for extracting polyphenols, carbohydrates, and lipids as well as use in food safety monitoring and biosensor development. However, more work is needed to address shortcomings, and determine whether using compounds extracted with DES can be consumed safely.

Extraction and purification of phycobiliproteins from algae and their applications

Microalgae, macroalgae and cyanobacteria are photosynthetic microorganisms, prokaryotic or eukaryotic, living in saline or freshwater environments. These have been recognized as valuable carbon sources, able to be used for food, feed, chemicals, and biopharmaceuticals. From the range of valuable compounds produced by these cells, some of the most interesting are the pigments, including chlorophylls, carotenoids, and phycobiliproteins. Phycobiliproteins are photosynthetic light-harvesting and water-soluble proteins. In this work, the downstream processes being applied to recover fluorescent proteins from marine and freshwater biomass are reviewed. The various types of biomasses, namely macroalgae, microalgae, and cyanobacteria, are highlighted and the solvents and techniques applied in the extraction and purification of the fluorescent proteins, as well as their main applications while being fluorescent/luminescent are discussed. In the end, a critical perspective on how the phycobiliproteins business may benefit from the development of cost-effective downstream processes and their integration with the final application demands, namely regarding their stability, will be provided.

Enabling Sustainable Chemistry with Ionic Liquids and Deep Eutectic Solvents: A Fad or the Future?

Ionic liquids (ILs) and deep eutectic solvents (DESs) debuted with a promise of a superior sustainability footprint due to their low vapor pressure. However, their toxicity and high cost compromise this footprint, impeding their real-world applications. Fortunately, their property tunability through a rational selection of precursors, including bioderived ones, provides a strategy to ameliorate toxicity, lower cost, and endow new functions. This Review discusses whether ILs and DESs are sustainable solvents and how they contribute to sustainable chemical processes.

Application of deep eutectic solvents in protein extraction and purification

Deep eutectic solvents (DESs) are a mixture of hydrogen bond donor (HBD) and hydrogen bond acceptor (HBA) molecules that can consist, respectively, of natural plant metabolites such as sugars, carboxylic acids, amino acids, and ionic molecules, which are for the vast majority ammonium salts. Media such as DESs are modular tools of sustainability that can be pointed toward the extraction of bioactive molecules due to their excellent physicochemical properties, their relatively low price, and accessibility. The present review focuses on the application of DESs for protein extraction and purification. The in-depth effects and principles that apply to DES-mediated extraction using various renewable biomasses will be discussed as well. One of the most important observations being made is that DESs have a clear ability to maintain the biological and/or functional activity of the extracted proteins, as well as increase their stability compared to traditional solvents. They demonstrate true potential for a reproducible but more importantly, scalable protein extraction and purification compared to traditional methods while enabling waste valorization in some particular cases.

Deep Eutectic Solvent as Green Solvent in Extraction of Biological Macromolecules: A Review

Greater awareness of environmental sustainability has driven many industries to transition from using synthetic organic solvents to greener solvents in their manufacturing. Deep eutectic solvents (DESs) have emerged as a highly promising category of green solvents with well-demonstrated and wide-ranging applications, including their use as a solvent in extraction of small-molecule bioactive compounds for food and pharmaceutical applications. The use of DES as an extraction solvent of biological macromolecules, on the other hand, has not been as extensively studied. Thereby, the feasibility of employing DES for biomacromolecule extraction has not been well elucidated. To bridge this gap, this review provides an overview of DES with an emphasis on its unique physicochemical properties that make it an attractive green solvent (e.g., non-toxicity, biodegradability, ease of preparation, renewable, tailorable properties). Recent advances in DES extraction of three classes of biomacromolecules-i.e., proteins, carbohydrates, and lipids-were discussed and future research needs were identified. The importance of DES's properties-particularly its viscosity, polarity, molar ratio of DES components, and water addition-on the DES extraction's performance were discussed. Not unlike the findings from DES extraction of bioactive small molecules, DES extraction of biomacromolecules was concluded to be generally superior to extraction using synthetic organic solvents.

A Green Method of Extracting and Recovering Flavonoids from Acanthopanax senticosus Using Deep Eutectic Solvents

In recent years, green extraction of bioactive compounds from herbal medicines has generated widespread interest. Deep eutectic solvents (DES) have widely replaced traditional organic solvents in the extraction process. In this study, the efficiencies of eight DESs in extracting flavonoids from Acanthopanax senticosus (AS) were compared. Response surface methodology (RSM) was employed to optimize the independent variable including ultrasonic power, water content, solid-liquid ratio, extraction temperature, and extraction time. DES composed of glycerol and levulinic acid (1:1) was chosen as the most suitable extraction medium. Optimal conditions were ultrasonic power of 500 W, water content of 28%, solid-liquid ratio of 1:18 g·mL⁻¹, extraction temperature of 55 °C, and extraction time of 73 min. The extraction yield of total flavonoids reached 23.928 ± 0.071 mg·g⁻¹, which was 40.7% higher compared with ultrasonic-assisted ethanol extraction. Macroporous resin (D-101, HPD-600, S-8 and AB-8) was used to recover flavonoids from extracts. The AB-8 resin showed higher adsorption/desorption performance, with a recovery rate of total flavonoids of up to 71.56 ± 0.256%. In addition, DES solvent could efficiently be reused twice. In summary, ultrasonic-assisted DES combined with the macroporous resin enrichment method is exceptionally effective in recovering flavonoids from AS, and provides a promising environmentally friendly and recyclable strategy for flavonoid extraction from natural plant sources.

One-step extraction of oat protein by choline chloride-alcohol deep eutectic solvents: Role of chain length of dihydric alcohol

The aim of this study is to investigate the effect of dihydric alcohol chain length (1,2-ethanediol, 1,3-propanediol, and 1,4-butanediol) on the structure of deep eutectic solvents (DESs) and the properties of the extracted oat proteins. Herein, five anhydrous and nine hydrated DESs were successfully prepared by mixing choline chloride, dihydric alcohol, and/or water in a heating method. The structures of DESs were confirmed by FTIR and 1H NMR. Among them, only four anhydrous and six hydrated DESs were able to extract oat proteins from flours by one-step extraction. SDS-PAGE and FTIR analyses indicated that the structural properties of the oat proteins were highly reliant on the composition of the DESs; while physicochemical properties were primarily ruled by the environmental pH. Overall, the hydrated DES composing of all food-grade compounds, including choline chloride, 1,3-propanediol, and water at a molar ratio of 1:3:1, demonstrated its great potential for one-step biorefinery of oat proteins.

Optimization of the extraction process of flavonoids from Trollius ledebouri with natural deep eutectic solvents

In recent years, natural deep eutectic solvents have been favored greatly due to their environment friendly, mild biological toxicity and simple biodegradability. Natural deep eutectic solvents gradually applied for the extracting bioactive compounds from natural products efficiently. In this study, 20 natural deep eutectic solvents were prepared and their physical and chemical properties were tested. The ultrasonic-assisted extraction method was used to extract flavonoids from Trollius ledebouri and high-performance liquid chromatography-ultraviolet was applied to examine two main bioactive flavonoids (orientin and vitexin). Compared with traditional solvents (water and 60% ethanol solution), natural deep eutectic solvents composed of L(-)-proline and levulinic acid (molar ratio 1:2) show a super extraction efficiency. On this basis, the response surface method was used to optimize the extraction temperature, extraction time, water contents, and solid-liquid ratio. As a consequence, the extraction temperature 60℃, extraction time 18 min, water content 14% (v/v), and the solid-liquid ratio 48 mL·g^-1 were chosen as the best extraction process. This study shows that natural deep eutectic solvents can effectively extract flavonoids from T. ledebouri, laying a foundation for the further application of natural deep eutectic solvents to extract bioactive compounds from natural products.

Plant Proteins for Future Foods: A Roadmap

Protein calories consumed by people all over the world approximate 15-20% of their energy intake. This makes protein a major nutritional imperative. Today, we are facing an unprecedented challenge to produce and distribute adequate protein to feed over nine billion people by 2050, in an environmentally sustainable and affordable way. Plant-based proteins present a promising solution to our nutritional needs due to their long history of crop use and cultivation, lower cost of production, and easy access in many parts of the world. However, plant proteins have comparatively poor functionality, defined as poor solubility, foaming, emulsifying, and gelling properties, limiting their use in food products. Relative to animal proteins, including dairy products, plant protein technology is still in its infancy. To bridge this gap, advances in plant protein ingredient development and the knowledge to construct plant-based foods are sorely needed. This review focuses on some salient features in the science and technology of plant proteins, providing the current state of the art and highlighting new research directions. It focuses on how manipulating plant protein structures during protein extraction, fractionation, and modification can considerably enhance protein functionality. To create novel plant-based foods, important considerations such as protein-polysaccharide interactions, the inclusion of plant protein-generated flavors, and some novel techniques to structure plant proteins are discussed. Finally, the attention to nutrition as a compass to navigate the plant protein roadmap is also considered.

A green deep eutectic solvent modified magnetic titanium dioxide nanoparticles for the solid-phase extraction of chymotrypsin

Magnetic titanium dioxide nanoparticles modified with green deep eutectic solvent (DES) composed of choline chloride (ChCl) and xylitol (Xyl) (Fe₃O₄@TiO₂@[ChCl][Xyl]) were synthesized and applied to the solid-phase extraction(MSPE) of chymotrypsin (Chy). The physicochemical properties and morphology of Fe₃O₄@TiO₂@[ChCl][Xyl] was characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), Zeta potential, X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and transmission electron microscope (TEM). The experiment parameters such as initial concentration of Chy, extraction time, pH value, ionic strength, extraction temperature and sample matrix were effectively optimized. Under the optimal experimental conditions, the extraction capacity of Fe₃O₄@TiO₂@[ChCl][Xyl] obtained a significantly improvement after the modification of Fe₃O₄@TiO₂ nanoparticles by [ChCl][Xyl], and reached up to 347.8 mg g^-1. In the elution experiment, 10% sodium dodecyl sulfate-acetic acid (SDS-HAc) was used as eluent, achieving an elution rate of 85.9% for the Chy on Fe₃O₄@TiO₂@[ChCl][Xyl]. And the Fe₃O₄@TiO₂@[ChCl][Xyl] still maintained a good extraction capacity for Chy after six times of reuse. The application result in the extraction of Chy from porcine pancreas crude extract showed a good practical application ability for Chy extraction. All the results indicated that the synthesized Fe₃O₄@TiO₂@[ChCl][Xyl] has good application potential in the extraction of biomolecular molecules such as protein.