Deep Eutectic Solvent Choline Research Articles

Selective Leaching of Cadmium from Cold Filter Cake Using Green Deep Eutectic Solvent Choline Chloride-Oxalic Acid

Selective Leaching of Cadmium from Cold Filter Cake Using Green Deep Eutectic Solvent Choline Chloride-Oxalic Acid

Simultaneous extraction and derivatization of biogenic amines during in-situ deep eutectic solvent-based liquid phase extraction from Doogh samples prior to HPLC analysis

A simple and efficient microwave-assisted extraction method using deep eutectic solvent was developed for the simultaneous analysis of four biogenic amines (putrescine, tyramine, cadaverine and histamine) in Doogh (yogurt-based beverage) samples. Important parameters like precipitating agent volume, vortexing time, microwave power, and exposure time were optimized. Zinc sulfate was utilized for proteins precipitation prior to extraction of analytes with the deep eutectic solvent choline chloride/p-anisidine. The analytes were derivatized with dansyl chloride and analyzed by HPLC-DAD. The method showed good linearity (r2 ≥ 0.994) over wide ranges with low limits of detection (0.52–0.78 ng mL−1) and quantification (1.7–2.5 ng mL−1). Extraction recoveries ranged from 68–72 % and relative standard ≤8.1 %. Negligible matrix effects were observed. When the method was applied to real Doogh samples and several biogenic amines were detected. The developed method provided reliable results in terms of sensitivity and selectivity.

Pressure-driven membrane processes for the recovery and recycling of deep eutectic solvents: A seaweed biorefinery case study.

Deep eutectic solvents (DES) are green alternatives for conventional solvents. They have gained attention for their potential to extract valuable compounds from biomass, such as seaweed. In this framework, a case study was developed to assess the feasibility of pressure-driven membrane processes as an efficient tool for the recovery of deep eutectic solvents and targeted biomolecules. For this purpose, a mixture composed of the DES choline chloride – ethylene glycol (ChCl-EG) 1:2, water and alginate was made to mimic a DES extraction from seaweed. An integrated separation process design was proposed where ultrafiltration-diafiltration-nanofiltration (UF-DF-NF) was coupled. UF and DF were found to be effective for the separation of alginate with an 85 % yield. DES was likewise recovered by 93 %, proving the membrane filtrations’ technical feasibility. The NF performance to separate the DES from the water, for its recycling, laid by a 45 %-50 % retention and a final concentrated DES solution of 18 %(v/v).

The Properties of Xylan Extracted from Corncob Using Deep Eutectic Solvent

Abstract Corncob is an abundant agricultural biomass that is generally underutilized and discarded. It has potential to be a resource for high-value products due to its cellulose and hemicellulose content. Xylan, which is the primary constituent of hemicellulose, can serve as a raw material or intermediary in both non-food and food industry. This research aims to study the extraction of xylan from corncob using deep eutectic solvent (DES) for clean processing and analyzes the characteristics of corncob xylan. DES comprises choline chloride and acetic acid with a molar ratio of 1:2. Xylan was extracted from corncobs by immersion in aqueous DES (70% and 90%) and heating using an autoclave at 105°C for 15 minutes. FT-IR and NMR characterized the chemical structures of xylan, while FE-SEM observed the surface. The FT-IR result showed that xylan had a peak range of 1041 cm−1, which is attributed to the glycosidic bond. A delignification process seems to have occurred as indicated by the absorption peak at 1475-1477 cm−1, indicating the presence of lignin in xylan and solid residue. Both types of extracted xylan had similar NMR spectra in the 3-4.3 ppm range, which indicates that they contained xylose. The solid residue structure obtained from extracting two DES concentrations shows the difference in the extraction process. However, the surface morphology of the two types of extracted xylan had a similar irregular shape and roughness. The use of the DES choline chloride-acetic acid could lead to the extraction and separation of xylan from lignocellulosic corncob.

Influence of Choline Chloride/Urea and Glycerol Plasticizers on the Mechanical Properties of Thermoplastic Starch Plastics.

Bio-based plastics made of food-safe compostable materials, such as thermoplastic starch (TPS), can be designed into films that have potential to replace many non-biodegradable single-use plastic (SUP) items. TPS film characteristics, such as elongation at break and tensile strength, are largely affected by the choice of the plasticizers used in formulation. Our work identifies the mechanical properties and the chemical structural differences between TPS films made with two different plasticizer mixtures that have not yet been compared alongside one another: deep eutectic solvent choline chloride/urea (1:2) (CC:U) and glycerol with an acetic acid catalyst (AA:G). Potato-based TPS samples were formed by mixing each plasticizer with a consistent amount of potato starch and distilled water with heat. After gelation formation, the viscous TPS mixture was centrifuged to degas and extruded. Films were dried at controlled room temperature. Characterization included the tensile testing of coupons according to ASTM (American Society of Testing and Materials) standard D638, attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy, X-ray diffraction (XRD), melting point (MP), and scanning electron microscopy (SEM). The AA:G films displayed significantly higher tensile strength (M = 2.04 ± 1.24 MPa) than the CC:U films (M = 0.18 ± 0.08 MPa); however, the CC:U films had higher elongation at break (M = 47.2 ± 3.6%) than the AA:G films (M = 31.1 ± 12.6%). This can be explained by the difference in functional groups, composition, and the degree of crystallinity evidenced by the FTIR, XRD, MP, and SEM results. Our findings suggest that potato-based TPS films with an AA:G plasticizer mixture hold promise for SUP applications that require more strength, while CC:U films may be more suited for wraps and bags that require flexibility. These innovations can aid to mitigate the environmental impact of harmful plastic waste.

Continuous Purification of Biodiesel with Deep Eutectic Solvent in a Laboratory Karr Column

Following the trend of transport decarbonization, biodiesel has become a promising alternative fuel option. Its production includes multiple steps, all of which can be time-consuming and energy intensive. Improving any of these steps could bring considerable environmental and economic benefits. The utilization of deep eutectic solvents (DESs) for glycerol extraction from crude biodiesel has predominantly been explored as a batch process. This work provides insight into continuous column extraction. Different waste cooking oils were used to produce biodiesel via transesterification with methanol, and the selective solvent for purification was DES choline chloride–ethylene glycol (1:2.5, mol.). A laboratory Karr column at different pulsation frequencies and DES to biodiesel mass ratio was used for extraction. Plate material (steel and 3D printed PETG) and geometry influence on the efficiency of extraction were investigated. Contact angle measurement was used to measure the surface free energy of steel and PETG and the spreading ability of biodiesel and DESs on both materials. Extraction efficiency was analyzed by several analytical techniques. Higher efficiency was observed with steel plates of a triangular pitch hole arrangement. Increasing the mixing intensity and DES to biodiesel mass ratio further increased the efficiency of extraction.

Integrated understanding of acidic deep eutectic solvent choline chloride: Oxalic acid pretreatment to enhance the enzymatic hydrolysis of rape straw

Using choline chloride (ChCl) as hydrogen-bonded-acceptor (HBA) and oxalic acid (OA) as hydrogen-bonded-donor (HBD), deep eutectic solvents (DESs) with different HBD-to-HBA molar ratios were synthesized to pretreat rape straw (RS). The influence of DES treatment on the RS chemical composition, structure change, and enzymatic saccharification were explored. DESs with low molar ratio of HBD-to-HBA exhibited low viscosity, which enhanced the pretreatment efficiency. When HBA-to-HBD molar ratio was 1:3, the delignification and enzymatic digestion efficiency were only 60.6% and 41.8%. As the molar ratio of OA decreased, delignification and enzymatic digestion efficiency increased to 83.6% and 96% (ChCl:OA = 3:1, mol/mol). After pretreatment (severity factor LogR0 =2.66), the cellulose accessibility and crystallinity increased from 353.0 to 691.1 mg/g and 35.4–64.2%, respectively. The lignin surface area decreased from 596.3 to 201.9 m2/g. The significant increase in cellulose accessibility and the decrease in lignin surface area explained the efficient enzymatic hydrolysis efficiency.

Synergetic effect of hydrothermal and deep eutectic solvents (DES) pretreatments on Robinia wood fractionation for the manufacture of bioethanol and cellulose nanocrystals

This study dealt with the use of environmentally friendly processes based on microwave-assisted autohydrolysis (MAA) and deep eutectic solvents (DES) for the selective fractionation of Robinia pseudoacacia wood (RW) within a biorefinery approach. MAA enabled the recovery of 76% of hemicelluloses in the form of oligomers. Afterwards, different conditions were assessed for the optimal delignification of RW with the DES choline chloride combined with lactic acid reaching delignification ratios up to 86%. Two different methods were accomplished to valorize the cellulosic-rich solid fraction after delignification: (i) bioethanol via enzymatic-fermentative pathway (attaining 53.3 g ethanol/L, about 83% of ethanol yield), and (ii) cellulose nanocrystals (length of 27–550 nm, width of 2–12 nm). Hence, this study presents a novel multiproduct biorefinery to selectively separate the main components of RW and valorize its cellulosic fraction using eco-friendly procedures.

Synthesis of furoic acid from biomasses by sequential catalysis with fish scale-rice husk-based heterogeneous chemocatalyst and dehydrogenase biocatalyst

In this work, furfural was effectively converted to furoic acid (FCA) by using biological macromolecules as raw materials in tandem reaction with chemical biological catalysts. Firstly, a biochar-based heterogeneous catalyst Sn-FS-RH was prepared using equal mass of fish scale (FS) and rice husk (RH) as carriers. Different biomasses (such as poplar wood, winter bamboo shoot shell, corn cob, corn straw, reed leaf, peanut shell, rape straw, and potato shell) were transformed into furfural with Sn-FS-RH in deep eutectic solvent choline chloride:Maleic acid (ChCl:MLA)-H2O (10:90, v/v; 170 °C), and the furfural yield from corn cob-derived xylose reached the highest (70.5% yield, based on xylose) after 15 min of catalysis. The mechanism of Sn-FS-RH-catalyzed the transformation of lignocellulose to furfural was interpreted in ChCl:MLA-H2O. One liter of xylose-hydrolysate was obtained after acid hydrolysis of biomass. The preparation of FUR was generally carried out in a 10 liter of autoclave reactor containing 75 g biomass, 36 g Sn-FS-RH catalyst, 100 g ChCl:MLA, and 20 g ZnCl2. The reactor was stirred at 170 ℃ for 15 min at 500 rpm. It was observed that the by-products (formic acid, levulinic acid, and 5-hydroxymethylfurfural) formed in the transformation of lignocellulose to furfural had somewhat inhibitory effect on the formation of furoic acid from furfural bioconversion. After 24–72 h, Escherichia coli HMFOMUT cells containing dehydrogenase could transform fully furfural derived from different biomass (30–90 mM) into furoic acid. This two-step chemoenzymatic strategy was an efficient way to transform biomacromolecules into biofurans in a sustainable medium.

Efficient synthesis of furfural from waste biomasses by sulfonated crab shell-based solid acid in a sustainable approach

As one of key biobased chemicals, furfural can be manufactured from the hydrothermal transformation of hemicelluloses in biomass, which is widely utilized in manufacturing furans, plastics, polymers, rubbers, resins, synthetic fibers, medicine, biofuels and other additives. In this work, one eco-friendly and sustainable approach for transforming waste lignocellulosic biomass to furfural was established in one-pot reaction manner. Crab shells (CRSs), which are derived from discarded seafood bio-waste, are known as one kind of naturally renewable and abundant bioresource. Using the pretreated CRS as support, a biobased heterogeneous chemocatalyst Sn-CFCRS was successfully prepared by carbonization followed by sulfonation, which was utilized to transform waste lignocellulosic biomass into furfural. The structure and morphology of the as-prepared chemocatalyst was examined and the acidity was measured. Deep eutectic solvent choline chloride:malic acid (DES ChCl:MA) (pKa=3.46) was chosen to assist Sn-CFCRS for catalysis of biomass. The catalytic performances were evaluated by one-pot transformation of various biomasses to furfural. Sn-CFCRS (2.4 wt%) transformed 75 g/L corncob into 117.1 mM furfural (65.6% yield) at 180 °C after 10 min in ChCl:MA−water (1:9, v/v) containing 50 mM CaCl2. This established sustainable process shows high potential application for valorization of biomass into furfural by utilizing biobased chemocatalyst in a benign reaction medium.

Switchable product selectivity in dehydration of N-acetyl-d-glucosamine promoted by choline chloride-based deep eutectic solvents

Herein, we report choline chloride-based deep eutectic solvents (DESs) promoted conversion of N-acetyl-d-glucosamine (GlcNAc) into nitrogen-containing compounds, i.e., 3-acetamido-5-(1',2'-dihydroxyethyl) furan (Chromogen III) and 3-acetamido-5-acetylfuran (3A5AF). The binary deep eutectic solvent choline chloride-glycerin (ChCl-Gly), was found to promote the dehydration of GlcNAc to form Chromogen III, which reaches a maximum yield of 31.1%. On the other hand, the ternary deep eutectic solvent, choline chloride-glycerol-B(OH)3 (ChCl-Gly-B(OH)3), promoted the further dehydration of GlcNAc into 3A5AF with a maximum yield of 39.2%. In addition, the reaction intermediate, 2-acetamido-2,3-dideoxy-d-erythro-hex-2-enofuranose (Chromogen I), was detected by in situ nuclear magnetic resonance (NMR) techniques when promoted by ChCl-Gly-B(OH)3. The experimental results of the 1H NMR chemical shift titration showed ChCl-Gly interactions with α-OH-3 and α-OH-4 of GlcNAc, which is responsible for promoting the dehydration reaction. Meanwhile, the strong interaction between Cl- and GlcNAc was demonstrated by 35Cl NMR.

Valorization of Avocado Seed Wastes for Antioxidant Phenolics and Carbohydrates Recovery Using Deep Eutectic Solvents (DES).

Avocado seeds represent the chief waste produced in avocado processing, leading not only to environmental problems regarding its elimination but to a loss of economic profitability. In fact, avocado seeds are known as interesting sources of bioactive compounds and carbohydrates, so their utilization may reduce the negative effect produced during the industrial manufacture of avocado-related products. In this sense, deep eutectic solvents (DES) are a novel greener alternative than organic solvents to extract bioactive polyphenols and carbohydrates. The study was based on a Box-Behnken experimental design to study the effect of three factors, temperature (40, 50, 60 °C), time (60, 120, 180 min) and water content (10, 30, 50% v/v) on the responses of total phenolic (TPC) and flavonoid content (TFC), antioxidant capacity (measured as ABTS and FRAP) and xylose content in the extract. The DES Choline chloride:glycerol (1:1) was used as solvent on avocado seed. Under optimal conditions, TPC: 19.71 mg GAE/g, TFC: 33.41 mg RE/g, ABTS: 20.91 mg TE/g, FRAP: 15.59 mg TE/g and xylose: 5.47 g/L were obtained. The tentative identification of eight phenolic compounds was assayed via HPLC-ESI. The carbohydrate content of the solid residue was also evaluated, and that solid was subjected to two different processing (delignification with DES and microwave-assisted autohydrolysis) to increase the glucan susceptibility to enzymes, and was also assayed reaching almost quantitative glucose yields. These results, added to the non-toxic, eco-friendly, and economic nature of DES, demonstrate that these solvents are an efficient alternative to organic solvents to recover phenolics and carbohydrates from food wastes.

Encapsulated deep eutectic solvent and carbonic anhydrase jointly by microfluidics for high capture performance of carbon dioxide

Excessive carbon dioxide (CO2) emissions from fossil fuel combustion have a profound impact on environment, leading to different associated climate disasters. Although deep eutectic solvents (DES) have the advantage of high absorption capacity of CO2, their high viscosities sharply decrease absorption performance due to the low absorption rates. Herein, one of DES choline chloride / urea (CU) and carbonic anhydrase (CA) was encapsulated jointly by microfluidics and crosslinked thermally (microcapsule@(CU + CA)), which was designed for high capture performance of CO2. The absorption abilities of microcapsules have been significantly improved by the increase of specific surface area, in which the absorption capacity and absorption rate of microcapsule@(CU + CA) were 74 times and 253 times higher than that of neat CU. In addition, the selectivity of CO2/CH4 also increased 62 times via encapsulation. The high cyclic performance of microcapsule@(CU + CA) was achieved for its high absorption performance and high ability to desorb CO2 from microcapsule. DES and CA encapsulated jointly by microfluidics can realize high absorption capacity, high absorption rate and high absorption selectivity simultaneously, and it also provides a potential pathway for the efficient capture of various gases.

Phytantriol phase behaviour in choline chloride urea and water mixtures.

Deep eutectic solvents (DES) are tailorable non-aqueous solvents with promising properties for a range of applications, from industrial dissolution of plant products to biomedicine. They are mixtures of hydrogen bond donors and acceptors with low melting points that can be tailored to specific applications, and many support the self-assembly of amphiphilic molecules into lyotropic liquid crystal phases. Self-assembled lipid structures have potential for numerous applications, including drug delivery. These ordered structures can act as carriers, slow-release vehicles, or microreactors. Lipid self-assembly in non-aqueous solvents, such as deep eutectic solvents, is important for applications at extreme temperatures, or involving water-insoluble or water sensitive components. However, lipid self-assembly in these solvents remains largely unexplored. In this paper, we have examined the self-assembly of phytantriol, a non-ionic lipid, at 10 and 30 wt% in the deep eutectic solvent choline chloride:urea, with and without water. Self-assembly was assessed using small angle X-ray scattering and cross polarised optical microscopy at temperatures from 25-66 °C. We found that pure choline chloride:urea supports a Pn3m cubic phase similar to that formed in water. However, mixtures of the DES with water resulted in phytantriol forming an inverse hexagonal phase and influenced the phase transition temperatures. These results demonstrate that choline chloride:urea can support diverse phase behaviour, and also provides a mechanism for tailoring the phase for particular applications simply by controlling the amount of water in the solvent. In the future this could lead to methods of triggered release of drugs and biomolecules by the simple addition of water which could be critical for drug delivery applications.

Insights into the Effect of Lithium Doping on the Deep Eutectic Solvent Choline Chloride:Urea.

Choline-based deep eutectic solvents (DESs) are potential candidates to replace flammable organic solvent electrolytes in lithium-ion batteries (LIBs). The effect of the addition of a lithium salt on the structure and dynamics of the material needs to be clarified before it enters the battery. Here, the archetypical DES choline chloride:urea at 1:2 mole fraction has been added with lithium chloride at two different concentrations and the effect of the additional cation has been evaluated with respect to the non-doped system via multinuclear NMR techniques. 1H and 7Li spin-lattice relaxation times and diffusion coefficients have been measured between 298 K and 373 K and revealed a decrease in both rotational and translational mobility of the species after LiCl doping at a given temperature. Temperature dependent 35Cl linewidths reflect the viscosity increase upon LiCl addition, yet keep track of the lithium complexation. Quantitative indicators such as correlation times and activation energies give indirect insights into the intermolecular interactions of the mixtures, while lithium single-jump distance and transference number shed light into the lithium transport, being then of help in the design of future DES electrolytes.

Chemoenzymatic catalytic synthesis of furfurylamine from hemicellulose in biomasses

Recently, efficient synthesis of furan-based chemicals from biomacromolecule via chemoenzymatic approaches have been widely recognized. In this work, an efficient conversion of biomacromolecule (e.g., xylan in biomass) to furfurylamine (FLA) was developed in a tandem reaction by bridging with chemocatalysis and biocatalysis. Various biomasses (e.g., corncob, bagasse, bamboo shoot shell, corn stalk, rice straw stalk, reed, water bamboo and sunflower stalk) could produce different titer of furfural due to the diverse xylan content in biomass. After being catalyzed by shrimp shell-supported solid acid catalyst (Sn-DAT-SS) in deep eutectic solvent choline chloride:ethylene glycol (ChCl:EG) − water (10:90, v/v) at 170 °C after 30 min, corncob gave the highest furfural yield of 52.4 %. The potential catalytic mechanism for Sn-DAT-SS-catalyzing the conversion of biomass into furfural in ChCl:EG − water was proposed. It was found that by-products (formic acid, levulinic acid, 5-hydroxymethylfurfural) and soluble sugars (glucose, xylose, arabinose, cellobiose) produced during the conversion of biomass to furfural had certain inhibition effects on the biotransamination of furfural to FLA. Biomass-derived furfural (36.7–92.3 mM) could be fully aminated to FLA by E. coli CCZU-XLS160 cells harboring ω-transaminase after 24–72 h. The established chemoenzymatic strategy for converting biomacromolecules into valuable furan-based products was successfully developed in an eco-friendly system.

Recovery of Bioactive Extracts from Olive Leaves Using Conventional and Microwave-Assisted Extraction with Classical and Deep Eutectic Solvents

The recovery of phenolic compounds from olive leaves (Olea europaea L.) has received special attention due to their significant potential for applications in food, nutraceuticals, cosmetics, and pharmaceuticals. In this work, the extraction of the phenolic compounds from olive leaves was examined by means of conventional extraction and microwave-assisted extraction (MAE) using nontoxic common solvents such as ethanol and water as well as using promising environmentally friendly, Deep Eutectic Solvents (DESs) and their mixtures with ethanol or water. The effects of the various parameters that likely govern the extractability of the bioactive compounds of olive leaves (OL), such as the solvent type, temperature, and biomass to solvent mass ratio, were studied and evaluated with regard to the oleuropein and hydroxytyrosol content, antioxidant activity, and total phenolic content of the extracts. The study also explores the effects of the microwave-assisted extraction parameters, namely irradiation power and time, on the total phenolic content and antioxidant activity of the extracts. The findings of this work suggest that among the solvents studied, the solvent mixture consisting of the DES choline chloride:acetic acid with a molar ratio of 1:2 and ethanol (80:20 w/w) is highly effective in recovering extracts rich in phenolic compounds and with significant antioxidant activity. Moreover, it is demonstrated that the MAE method allows for the recovery of bioactive compounds in a very short processing time.

Lithium Salt Effects on the Liquid Structure of Choline Chloride–Urea Deep Eutectic Solvent

Deep eutectic solvents (DESs) added with lithium salts are emerging as alternative electrolytes for lithium-ion batteries (LIBs). Yet, to design, optimize, and develop efficient DES-based electrolytes for LIBs, an in-depth understanding of the role played by the lithium cations in the intermolecular interactions between all species in the mixture is crucial. A joint approach of experimental NMR techniques and polarizable molecular dynamics (MD) simulations is used here to gather a comprehensive picture of the structure and dynamics of the prototypical system composed of the DES choline chloride:urea (ChCl:U, xChCl = 0.33) and the lithium salt containing the same anion, LiCl. Strong coordination of lithium cations by chloride anions, resulting in the formation of LiCl32– units, is revealed. Other species (especially, urea) are present in the second coordination shell of lithium, creating an extensive hydrogen-bond network. The effect of small quantities of water, typically absorbed by DES from air moisture, on the studied properties is discussed.

Derivation of an anti-cancer drug nanocarrier using a malonic acid-based deep eutectic solvent as a functionalization agent

Deep eutectic solvents (DESs) are novel ‘green’ solvents that have recently gained considerable interest from diverse sectors of the scientific community. They are considered biocompatible, chemically stable, biodegradable, low-volatility, and non-flammable. In addition, the physicochemical properties of DESs are highly tunable and can be customized to meet the needs of a particular mission, including for its novel application in drug delivery systems. Here, graphene functionalized with the DES choline chloride:malonic acid was investigated for anti-cancer activity after loading with the drug doxorubicin. The DES-functionalized graphene demonstrated high drug loading efficiency and exhibited destructive effects against cancerous cells. Real-time cell growth analysis confirmed its cytotoxicity against cancerous cells over time. All told, the combination of choline chloride and malonic acid shows great promise as a green functionalizing agent for a nano-drug carrier, owing to its lower cytotoxicity, higher doxorubicin loading capacity, and inhibition of cancer cell growth profile.

Combined microwave‐assisted extraction and headspace gas chromatography for hexanal determination in fat‐rich food

AbstractThe feasibility of a new approach for the determination of volatiles in solid matrices by coupling microwave‐assisted extraction with static headspace gas chromatography has been demonstrated using hexanal as an analyte present in fat‐rich food. Eight polar and low volatility deep eutectic solvents were prepared using microwave heating and examined for hexanal extraction. Choline chloride‐glucose‐water showed the best transition efficiency of hexanal to the headspace and was applied to extract hexanal using microwave‐assisted extraction. Hexanal released from the fat‐rich food is poorly soluble in the hydrophilic deep eutectic solvent choline chloride‐glucose‐water so enters the gas phase and subsequently dissolves in coconut oil fixed above the extraction mixture in a polypropylene capillary. After cooling the capillary was transferred to a headspace vial and headspace gas chromatography was carried out. Under optimized conditions, the limit of detection was 3.1 μg g–1. The developed approach was successfully applied to analyze hexanal in fat‐rich food.