Extraction of phenolic compounds from rice husk via ethanol-water-modified supercritical carbon dioxide

Biological Activities and Phytochemical Profile of Hawm Gra Dang Ngah Rice: Water and Ethanolic Extracts

Hawm Gra Dang Ngah rice (HDNR) is a red rice variety cultivated in Thailand's southern border region, yet its biological properties have not been extensively studied. This study investigates the effects of HDNR extracts on bioactive constituents, spectral fingerprints, and antioxidant capacities. We evaluated the inhibitory effects of aqueous (HDNR-W) and ethanolic (HDNR-E) extracts on monoamine oxidase (MAO), α-glucosidase, and HMG-CoA reductase activities, as well as their cytotoxicity in normal and cancer cells. The results demonstrated that HDNR-E contained significantly higher concentrations of phenolic compounds, flavonoids, and anthocyanins compared to HDNR-W. In contrast, HDNR-W exhibited greater amino acid content than HDNR-E. FT-IR analysis revealed solvent-specific interactions that influenced compound solubility, highlighting distinct extraction efficiencies. Antioxidant assays showed HDNR-E to be markedly more potent, with superior performance in DPPH, ABTS, metal chelation, and FRAP assays, as evidenced by its lower IC50 values relative to HDNR-W. Furthermore, HDNR-E displayed significantly stronger inhibitory activity against both MAO and α-glucosidase compared to HDNR-W. Conversely, HDNR-W demonstrated greater inhibitory efficacy toward HMG-CoA reductase than HDNR-E. Furthermore, HDNR-E exhibited significant antiproliferative effects against A549 lung cancer and MCF-7 breast cancer cells without affecting normal cells. These results highlight the potential of HDNR-E as a valuable source of bioactive compounds and underscore the importance of solvent selection in enhancing the health benefits of rice extracts.

Optimizing Ethanol-Water Cosolvent Systems for Green Supercritical Carbon Dioxide Extraction of Muscadine Grape Pomace Polyphenols

This study evaluated the ethanol-water modified (50%, v/v) supercritical carbon dioxide (SC-CO2) for the extraction of polyphenols from muscadine grape (Vitis rotundifolia Michgx.) pomace and compared with conventional solvent extractions (ethanol-water and HCl-methanol). The process was optimized with a central composite response surface design consisting of three levels of three independent variables: pressure (20-40 MPa), temperature (40-60 °C), and cosolvent concentration (5-15%) to maximize three responses: total phenolic content (TPC), total flavonoid content (TFC), and resveratrol yields. The optimal conditions were determined as 20 MPa, 60 °C, and 15% cosolvent concentration with TPC, TFC, and resveratrol yields of 2491 mg/100 g, 674 mg/100 g, and 1.07 mg/100 g, respectively. The surface plots indicated that a 15% cosolvent concentration maximized extraction efficiency, producing red-brown colored extracts. In contrast, a 5% cosolvent resulted in poor extractions, yielding yellow-green extracts under all conditions. The yields increased with higher temperatures (i.e., 60 °C) and lower pressures (i.e., 20 MPa). TPC and TFC obtained through cosolvent-modified SC-CO2 were similar to those obtained through conventional extractions. Moreover, the resveratrol yield was lower than the HCl-methanol extraction, even though it was not different from any ethanol-water extractions at any solvent-to-solute ratios. The analysis of antioxidants indicated that the ABTS values of the cosolvent-modified SC-CO2 extract were lower than those of the HCl-methanol extract. However, there were no significant differences in the DPPH values between the two extracts. Thus, this study optimized the sustainable technology of SC-CO2 extraction by employing only food-grade cosolvents-ethanol and water-as a more environmentally friendly method for isolating polyphenols from the underutilized waste product of muscadine grape pomace utilizing statistical methodologies in the extraction process.

Rice husk-fortified beef sausages: Cholesterol oxidation products, physicochemical properties, and sensory attributes

The effect of rice husk flour (RHF) supplementation on the physicochemical properties, oxidative stability, and sensory attributes of beef sausages was examined. Beef sausages were formulated with either 0 % RHF + 15 % wheat flour (WF), RHF-0; 5 % RHF + 10 % WF, RHF-5; 10 % RHF + 5 % WF, RHF-10, or 15 % RHF + 0 % WF, RHF-15, and cooked at 200 °C for 20 min. RHF supplementation significantly increased dietary fiber while decreasing moisture content (P < 0.05). Beef sausages with RHF had lower L*, a*, TBARS, carbonyl content, hardness, chewiness, and gumminess, and a higher pH (P < 0.05). RHF-10 and RHF-15 sausages exhibited greater cook loss compared to other formulations (P < 0.05). The levels of 7-ketocholesterol decreased with increasing RHF levels, while 7α-hydroxycholesterol and 7-hydroperoxycholesterol were higher in RHF-0 and RHF-10 sausages compared to RHF-5 and RHF-15 sausages (P < 0.05). In addition, RHF improved the taste, juiciness, appearance, and overall acceptance of beef sausages. These findings suggest that RHF can be a valuable ingredient in beef sausages by increasing fiber content, reducing oxidative degradation, and maintaining sensory quality despite some moisture loss.

Supercritical fluid extraction and encapsulation of Rivas (Rheum ribes) flower: Principal component analysis (PCA)

Supercritical CO2 modified by polar solvents can extract a wide variety of polar and non-polar chemical components compared to conventional methods. The current study aims to extract Rivas (Rheum ribes) flower using the ethanol modified supercritical CO2 (SCO2-EOH) method; analyze its chemical compounds and bioactivity, encapsulate the extract in maltodextrin, gum-Arabic (GA), and their combination (GA + MD) using the spray drying method and investigate the differences among microparticles using Principal Component Analysis (PCA). The Rivas extract obtained by the SCO2-EOH method was a rich source of unsaturated fatty acids (mainly linoleic acid: 57.58 %), phytosterols (mainly sitosterol: 197.02 and campesterol: 144.47 mg/100g), terpenoids (mainly camphor: 17.52 %; and 1,8-cineol: 10.91 %) and phenolics (mainly m-coumaric acid: 48.22; luteolin: 38.07 and gallic acid: 26.25 mg/g). The yield of Rivas extract was 1.62 ± 0.27 %. The extract bioactivity was as follows: antioxidant activity of 89.6 ± 1.39 %; total phenolic content of 306.19 ± 13.59 mg GAE/g; total flavonoid content of179.84 ± 5.77 mg QE/g and a comparable antimicrobial effect to synthetic antimicrobials against E. coli, L. monocytogenes, and A. fumigatus. The encapsulation efficiency of microparticles was 90.53 % for MD to 93.23 % for GA + MD (P < 0.05). The microparticles had irregular semi-spherical shapes with wrinkled surfaces. According to the PCA, MD showed the best solubility and the lowest price, making it a cost-effective ingredient to improve the nutritional-value of food formulations. If the stability of bioactive compounds is more important, GA + MD will be the best choice.

Using the TOPSIS method to select the best low-toxicity organic cosolvent for rice-based toxicity tests

The application of low-toxicity cosolvents in phytotoxicity tests is a common technique to enhance the distribution of non-water-soluble organic pollutants in the aqueous phase. In this study, the physiological and biochemical responses of rice seedlings to four commonly used organic solvents i.e., dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), pyridine, and Tween-80 were investigated using 16 parameters to assess their impacts on rice plants. Results from phytotoxicity tests indicated that these organic solvents caused varying toxic responses in rice plants and significantly affected the uptake and distribution of mineral nutrients within rice tissues. In order to select the best organic solvent for rice-based toxicity tests among the four solvents with optimal concentrations, the technique for order preference by similarity to ideal solution (TOPSIS) was employed to minimize the variations across different treatment groups. Three different weighting coefficients, namely entropy weight coefficients (EWCs), contribution factor coefficients (CFCs), and combination effective coefficients (CECs) were adopted to calibrate the initially created evaluation matrices. All estimations were judged by the relative closeness coefficients, in which the higher relative closeness value means the better solution to the optimal result. Among the four organic solvents evaluated by TOPSIS, pyridine at 1.24 mmol/L emerged as the most effective solution for rice-based phytotoxicity tests. Overall, this study represents the first attempt to comprehensively evaluate the toxic responses of cosolvents to rice plants using the TOPSIS method. It also offers valuable insights into a number of ecotoxicological applications like the analysis of solvent-generated extracts of environmental matrices from soils and sediments, or the detection of organic compounds induced toxicity with cosolvents.

In vitro digestion of starch and protein aerogels generated from defatted rice bran via supercritical carbon dioxide drying

This study investigated the in vitro digestibility of starch and protein aerogels produced from defatted rice bran (DRB), an underutilized rice processing byproduct, using supercritical carbon dioxide (SC-CO2) drying. The extracted starch (i.e., purified starch), crude starch, and proteins were used for the aerogel formation at 15% (w/w) concentration and further characterized. All aerogels exhibited three-dimensional open porous structures with high surface areas of 36-47 m2/g, densities lower than 0.3 g/cm3, and porosities higher than 84%. The starch hydrolyses in starch and crude starch aerogels were 86 and 73%, respectively, while the protein hydrolysis in protein aerogels reached up to 82% after sequential oral, gastric, and intestinal digestion. Thus, the hydrolysis rates achieved in simulated digestions suggest that the developed aerogels from DRB have the potential to serve as vehicles for delivering bioactive compounds and add value to the underutilized DRB.

Optimization of Ultrasonic-Assisted Extraction of Phenolic Compounds and Antioxidant Activity from Araticum Peel Using Response Surface Methodology

The peel represents a significant portion of the araticum fruit (about 40%), which becomes waste after its consumption or processing. Previous studies have shown that the araticum peel is rich in phenolic compounds; however, little is known about the ideal conditions for recovering these compounds. Therefore, response surface methodology, using a central composite rotatable design, was employed to optimize the extraction process to maximize the total phenolic compounds (TPCs) and enhance the Trolox equivalent antioxidant capacity (TEAC) from araticum peel. The variables optimized were ethanol concentration (EC; 20-80%, v/v), extraction time (ET; 5-45 min), and solid-solvent ratio (SSR; 10-100 mg/mL). Additionally, condensed tannins, antioxidant capacity against synthetic free radicals (TEAC and FRAP) and reactive oxygen species (ROS), and the phenolic compounds profile, were evaluated. Optimum extraction conditions were 50% (v/v) ethanol concentration, 5 min of extraction time, and 10 mg/mL solid-solvent ratio. Under these conditions, experimental TPCs and TEAC values were 70.16 mg GAE/g dw and 667.22 µmol TE/g dw, respectively, comparable with predicted models (68.47 mg GAE/g dw for TPCs and 677.04 µmol TE/g dw for TEAC). A high condensed tannins content (76.49 mg CE/g dw) was also observed and 12 phenolic compounds were identified, predominantly flavonoids (97.77%), including procyanidin B2, epicatechin, and catechin as the major compounds. Moreover, a potent antioxidant activity was observed against synthetic free radicals and ROS, especially in scavenging peroxyl and hydroxyl radicals. From this study, we obtained the ideal conditions for recovering phenolic compounds from araticum peel using a simple, fast, sustainable, and effective method, offering a promising opportunity for the management of this plant byproduct.

Application of supercritical carbon dioxide to enhance the aroma of whole sorghum flour for use in 3D printing of sorghum cookies

Sorghum is a promising ingredient for new food products due to its high fiber content, slow digestibility, drought resistance, and gluten-free nature. One of the main challenges in sorghum-based products is the unpleasant aroma compounds found in grain sorghum. Therefore, in this study, sorghum flour was treated via supercritical carbon dioxide (SC-CO2) to remove undesired aroma compounds. The resulting SC-CO2-treated flours were used to generate dough for 3D food printing. At the optimized conditions, sorghum cookies were 3D-printed using 60 % water and a nozzle diameter of 1.5 mm. All dough samples produced with untreated and SC-CO2-treated sorghum flours exhibited shear-thinning behavior. Changing the treatment pressure (8-15 MPa) or temperature (40-60 °C) did not significantly affect the viscosity of the dough samples. Moreover, the sorghum cookie doughs had higher G' and G″ values after the SC-CO2 treatments (G' > G″). Doughs generated from flours treated at 15 MPa - 40 °C and 8 MPa - 60 °C showed lower adhesiveness compared to the ones produced from untreated flour, whereas 15 MPa - 60 °C treatment did not affect the adhesiveness. After baking, the 3D-printed cookies from SC-CO2-treated flour exhibited significantly lower redness (a*), but the hardness of the cookies was not affected by SC-CO2 treatment. Overall, the SC-CO2 treatment of sorghum flour did not negatively affect the quality parameters of the 3D-printed cookies while enhancing the aroma of the flour.

Artemisia herba-alba: antioxidant capacity and efficacy in preventing chronic arthritis in vivo

Arthritis is a debilitating condition impacting the quality of life for millions worldwide, characterized by pain and inflammation. Understanding the mechanisms of arthritis and developing effective treatments are crucial. This study investigated the hydroethanolic extract of Artemisia herba-alba for its protective potential against arthritis hallmarks, oxidative stress, and lipid peroxidation in vitro. It also assessed its in vivo anti-arthritic activity. The phytochemical analysis identified various compounds within the extract, with high concentrations of polyphenols and flavonoids. These compounds are associated with numerous health benefits, making A. herba-alba a potential source of valuable phytochemicals. A. herba-alba demonstrated a notable effect in body weight loss, paw edema, and arthritic severity. Histopathological examination revealed structural improvements in bone and muscle tissues, emphasizing its therapeutic potential in managing chronic arthritis. Furthermore, while these findings are promising, further studies are necessary to delve deeper into the mechanisms underlying the observed hematological changes and to gain a more comprehensive understanding of the in vivo results. This research sets the stage for continued exploration, ultimately aiming to unlock the full potential of A. herba-alba in addressing chronic arthritis and enhancing the lives of those affected by this condition.

One pot synthesis of furan-modified lignin from agricultural waste via lignin-first approach

This study investigated a lignin-first approach to produce furan-modified lignin from sugarcane bagasse (SB), rice hull (RH), and sunn hemp biomass (SHB) using 5 methylfurfural (MF) and 5 methul-2-furanmethanol (MFM). The reaction time (5 h) was selected based on the delignification of SB using methanol and Ru/C catalyst which yielded the highest hydroxyl content. Delignification of SB with various MF weight ratios (1:1, 1:2, 1:3, 2:1, and 3:1) revealed that 1:1 and 2:1 ratios produced the highest hydroxyl content (7.7 mmol/g) and bio-oil yield (23.2 % wt% total weight). Further exploration identified that RH and MF at 1:1 ratio and SHB and MF at a 2:1 ratio produced the highest hydroxyl content (13.0 mmol/g) and bio-oil yield (31.6 % wt% tot. weight). This study developed a one-step method to extract and modify lignin with furan compounds simultaneously while opening new avenues for developing value-added products.

Agave angustifolia Haw. Leaves as a Potential Source of Bioactive Compounds: Extraction Optimization and Extract Characterization

The leaves of Agave angustifolia Haw. are the main agro-waste generated by the mezcal industry and are becoming an important source of bioactive compounds, such as phenolic compounds, that could be used in the food and pharmaceutical industries. Therefore, the extraction and identification of these phytochemicals would revalorize these leaf by-products. Herein, maceration and supercritical carbon dioxide (scCO2) extractions were optimized to maximize the phenolic and flavonoid contents and the antioxidant capacity of vegetal extracts of A. angustifolia Haw. In the maceration process, the optimal extraction condition was a water-ethanol mixture (63:37% v/v), which yielded a total phenolic and flavonoid content of 27.92 ± 0.90 mg EAG/g DL and 12.85 ± 0.53 µg QE/g DL, respectively, and an antioxidant capacity of 32.67 ± 0.91 (ABTS assay), 17.30 ± 0.36 (DPPH assay), and 13.92 ± 0.78 (FRAP assay) µM TE/g DL. Using supercritical extraction, the optimal conditions for polyphenol recovery were 60 °C, 320 bar, and 10% v/v. It was also observed that lower proportions of cosolvent decreased the polyphenol extraction more than pressure and temperature. In both optimized extracts, a total of 29 glycosylated flavonoid derivatives were identified using LC-ESI-QTof/MS. In addition, another eight novel compounds were identified in the supercritical extracts, showing the efficiency of the cosolvent for recovering new flavonoid derivatives.

Research Progress on Extraction and Detection Technologies of Flavonoid Compounds in Foods

Flavonoid compounds have a variety of biological activities and play an essential role in preventing the occurrence of metabolic diseases. However, many structurally similar flavonoids are present in foods and are usually in low concentrations, which increases the difficulty of their isolation and identification. Therefore, developing and optimizing effective extraction and detection methods for extracting flavonoids from food is essential. In this review, we review the structure, classification, and chemical properties of flavonoids. The research progress on the extraction and detection of flavonoids in foods in recent years is comprehensively summarized, as is the application of mathematical models in optimizing experimental conditions. The results provide a theoretical basis and technical support for detecting and analyzing high-purity flavonoids in foods.

Effect of a novel drying method based on supercritical carbon dioxide on the physicochemical properties of sorghum proteins

The aim of this research was to use supercritical carbon dioxide (SC-CO2) drying as a novel approach for generating sorghum protein concentrates/isolates with enhanced functional properties. Sorghum protein extracts were obtained from white whole-grain sorghum flour and were dried by two methods, namely, freeze-drying and SC-CO2 drying. The collected proteins were characterized for their morphology, color, crystallinity, surface hydrophobicity, emulsifying activity index (EAI), creaming index (CI), foaming capacity (FC), foaming stability (FS), protein solubility, chemical interactions, and viscosity. The SC-CO2-dried proteins exhibited higher porosity compared to the freeze-dried ones with smaller particle sizes (∼5.1 vs. 0.4 μm, respectively). The XRD patterns indicated that the SC-CO2-dried proteins had a lower crystallinity than the freeze-dried proteins. However, the surface hydrophobicities of the freeze-dried and SC-CO2-dried proteins were similar. The EAI results showed that the emulsifying activity of freeze-dried protein powder (40.6) was better than that of SC-CO2-dried protein powder (29.8). Nevertheless, the solubility of SC-CO2-dried proteins was higher than that of freeze-dried proteins in most of the pHs investigated. Overall, the proposed SC-CO2 drying method has the potential to generate porous protein powders with improved solubility that can be used in developing functional foods.

Rice Byproduct Compounds: From Green Extraction to Antioxidant Properties

Currently, rice (Oryza sativa L.) production and consumption is increasing worldwide, and many efforts to decrease the substantial impact of its byproducts are needed. In recent years, the interest in utilizing rice kernels, husk, bran, and germ for the recovery of different molecules, from catalysts (to produce biodiesel) to bioactive compounds, has grown. In fact, rice byproducts are rich in secondary metabolites (phenolic compounds, flavonoids, and tocopherols) with different types of bioactivity, mainly antioxidant, antimicrobial, antidiabetic, and anti-inflammatory, which make them useful as functional ingredients. In this review, we focus our attention on the recovery of antioxidant compounds from rice byproducts by using innovative green techniques that can overcome the limitations of traditional extraction processes, such as their environmental and economic impact. In addition, traditional assays and more innovative methodologies to evaluate the antioxidant activity are discussed. Finally, the possible molecular mechanisms of action of the rice byproduct antioxidant compounds (phenolic acids, flavonoids, γ-oryzanol, and vitamin E) are discussed as well. In the future, it is expected that rice byproduct antioxidants will be important food ingredients that reduce the risk of the development of several human disorders involving oxidative stress, such as metabolic diseases, inflammatory disorders, and cancer.

Total Phenols and Flavonoids in Germinated Barley Using Different Solvents

Sprouts are a source of secondary metabolites as phenolic compounds. Germination and the use of solvents can affect their content. The aim of this work was to identify the total content of phenols and flavonoids in ungerminated and germinated (3, 5, and 7 days) Esmeralda and Perla barley. Different solvents (water, 50 % acetone, 80 % methanol, 80 % ethanol) were used to recover total phenols and flavonoids. The 7-day germination proved to be ideal for total phenol and flavonoid obtention from Esmeralda barley and the highest total phenol and flavonoid content in Perla variety was observed at 5 and 7 days of germination, respectively. Methanol and ethanol (80 %) yielded the highest extraction percentage of total phenols; 50 % acetone recovered the highest flavonoid concentrations in Esmeralda barley and 80 % methanol in Perla barley. The highest total phenol concentration was obtained from Perla samples at 13.60 mg GAE/g, and the highest total flavonoids were observed in Esmeralda barley at 1.73 mg QE/g. A high correlation was found between the concentration of phenols (0.995) and total flavonoids (0.780) with the radicle size in the Esmeralda samples.