Isolation and structural elucidation of unique γ-oryzanol species in rice bran oil

Enhancement of Oryzanol application by constructing modified β-CD inclusion complex and polycaprolactone-chitosan electrospun fiber membranes: Perspectives on wound dressings and grape preservation

Oryzanol has a variety of physiological activities and is widely used in food and medicine. However, its utilization form and bioavailability are limited by poor solubility and photothermal stability. In this paper, an inclusion complex (IC) was prepared by modifying β-cyclodextrin as a molecular carrier to encapsulate Oryzanol. Polycaprolactone-chitosan (PCL-CS) and IC were prepared into a fiber membrane (PCL-CS-IC) using an electrostatic spinning technique and applied to wound healing and grape preservation. The results showed that the prepared ICs had a drug loading rate of 43.18 % with good antimicrobial, wettability, and air permeability properties. The PCL-CS-IC effectively reduced the inflammation of mouse wounds, with obvious re-epithelialization and inflammatory factors reduction in skin tissues. Meanwhile, the PCL-CS-IC delayed the decay process of grapes and extended shelf life. In conclusion, this study effectively improved the utilization of oryzanol and provided potential ideas for wound dressing preparation and food packaging materials development.

Effect of microemulsion system on water dispersibility and bioavailability of γ-oryzanol

This study developed water-dispersible γ-oryzanol (WD-OZ) using a microemulsion system and assessed their absorption in rats. While OZ itself is hardly soluble in water, WD-OZ exhibited high water dispersibility, and OZ, along with its metabolites, was detected in rat plasma. These findings provide a solid basis for future application of the microemulsion-based approach to enhance the bioavailability of OZ in food.

Disruption of aldehyde dehydrogenase decreases cell wall-bound p-hydroxycinnamates and improves cell wall digestibility in rice

In grass cell walls, ferulic acid (FA) serves as an important cross-linker between cell wall polymers, such as arabinoxylan (AX) and lignin, affecting the physicochemical properties of the cell walls as well as the utilization properties of grass lignocellulose for biorefinering. Here, we demonstrate that hydroxycinnamaldehyde dehydrogenase (HCALDH) plays a crucial role in the biosynthesis of the FA used for cell wall feruloylation in rice (Oryza sativa). Bioinformatic and gene expression analyses of aldehyde dehydrogenases (ALDHs) identified two rice ALDH subfamily 2C members, OsHCALDH2 (OsALDH2C2) and OsHCALDH3 (OsALDH2C3), potentially involved in cell wall feruloylation in major vegetative tissues of rice. CRISPR-Cas9 genome editing of OsHCALDH2 and OsHCALDH3 revealed that the contents of AX-bound ferulate were reduced by up to ~45% in the cell walls of the HCALDH-edited mutants, demonstrating their roles in cell wall feruloylation. The abundance of hemicellulosic sugars including arabinosyl units on AX was notably reduced in the cell walls of the HCALDH-edited mutants, whereas cellulose and lignin contents remained unaffected. In addition to reducing cell wall-bound ferulate, the loss of OsHCALDH2 and/or OsHCALDH3 also partially reduced cell wall-bound p-coumarate and sinapate in the vegetative tissues of rice, whereas it did not cause detectable changes in the amount of γ-oryzanol (feruloyl sterols) in rice seeds. Furthermore, the HCALDH-edited mutants exhibited improved cell wall saccharification efficiency, both with and without alkaline pretreatment, plausibly due to the reduction in cell wall cross-linking FA. Overall, HCALDH appears to present a potent bioengineering target for enhancing utilization properties of grass lignocellulose.

Research Progress on the Quality, Extraction Technology, Food Application, and Physiological Function of Rice Bran Oil

Rice bran oil is recommended by the World Health Organization as one of the three major healthy edible oils (along with corn and sesame oils), owing to its unique fatty acid composition and functional components. This study screened, organized, and analyzed a large number of studies retrieved through keyword searches, and investigated the nutritional value and safety of rice bran oil. It reviews the stability of raw rice bran materials and the extraction and refining process of rice bran oil and discusses food applications and sub-health regulations. Research has found that a delayed stabilization treatment of rice bran seriously affects the overall quality of rice bran oil. Compared with traditional solvent extraction, the new extraction technologies have improved the yield and nutritional value of rice bran oil, but most of them are still in the research stage. Owing to the lack of economical and applicable supporting production equipment, extraction is difficult to industrialize, which is a challenging research area for the future. Rice bran oil has stronger antioxidant stability than other edible oils and is more beneficial to human health; however, its application scope and consumption are limited owing to the product price and lack of understanding. Rice bran oil has significant antioxidant, anti-inflammatory, anti-cancer, hypoglycemic, lipid-lowering, and neuroprotective effects. Further exploratory research on other unknown functions is required to lay a scientific basis for the application and development of rice bran oil.

An Insight into the Thermal Degradation Pathway of γ-Oryzanol and the Effect on the Oxidative Stability of Oil

Thermal stability and antioxidant ability of γ-oryzanol in oil have been widely studied. However, further research is needed to explore its thermal degradation products and degradation pathways. The thermal degradation products of γ-oryzanol in stripped soybean oil were identified and quantified by employing high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS) during heating at 180 °C. The results revealed that γ-oryzanol undergoes ester bond cleavage to form trans-ferulic acid and free sterols, and trans-ferulic acid generated intermediate compound 4-vinylguaiacol, which ultimately generated vanillin. Analysis of kinetic and thermodynamic parameters revealed the thermal stability ranking of the four components of γ-oryzanol as follows: CampFA > CAFA > 24MCAFA > SitoFA. Furthermore, γ-oryzanol exhibited superior antioxidant activity at lower temperatures. The results of this study provide a theoretical basis for a better understanding of the thermal stability and antioxidant properties of γ-oryzanol in oil under thermal oxidation conditions.

Phytosterols in rice bran and their health benefits

With the continuous technological innovation in the high-value utilization of rice bran byproducts, rice bran oil retains a higher concentration of beneficial components such as a well-balanced composition of fatty acids and abundant phytosterols. This makes it a highly nutritious and healthy vegetable oil. This review provides an overview of the advancements made in separating, purifying, and processing phytosterols in rice bran oil. The review also introduces techniques for assessing the stability of rice bran oil. Moreover, the review emphasizes the nutritional value of phytosterols found in rice bran oil, highlighting their various health benefits, including their anticancer, anti-inflammatory, anti-allergic, antibacterial, cholesterol-lowering, skin-protective, anti-obesity, anti-diabetic, neuroprotective, gastroprotective, and immune-enhancing effects. Attaining a comprehensive understanding of the research progress made in phytosterols derived from rice bran oil can offer valuable guidance for the efficient utilization of rice bran.

Physicochemical Properties and Cookie-Making Performance as Fat Replacer of Wax-Based Rice Bran Oil Oleogels

Reducing the intake of trans and saturated fatty acids is a trend in healthy eating. In this study, the oleogels were prepared from rice bran oil (RBO), candle wax (CDW), beeswax (BW), rice bran wax (RBW), and carnauba wax (CRW), respectively, and the results based on their physicochemical properties and crystal structures at critical concentrations, 6 wt.%, 8 wt.%, and 10 wt.%, were determined to further investigate the oleogels as a shortening substitute in cookie recipes. Oleogel has a smooth, spreadable β' crystal shape which creates excellent sensory properties and improves the texture, but also has some economic benefits. A comparison between the oleogels formed at critical concentrations and those with improved mass fractions was performed in several analyses such as PLM and texture, and the oleogels with higher mass fractions had a greater hardness and stickiness and denser crystal structures. This study was used to optimize the cookie recipe by partially replacing shortening with oleogel and preparing the cookies according to the 0:1, 3:7, 1:1, 7:3, 1:0 oleogel shortening mixture, respectively. Based on the results of the textural analysis, a colorimetric and sensory evaluation of the optimized formulation of oleogels in cookies, it was evident that BW and RBW oleogels have more potential to replace shortening in cookies than CDW and CRW oleogels. In particular, oleogels with a concentration of 6 wt.% RBW (RBW-6) and at a 7:3 (oleogel:shortening) shortening replacement exhibited a hardness and crispness of 15.75 N and 97.73 g, respectively, with an L* value of 66.66 and a sensory score of 22.32 ± 0.09. The value for the color perception difference (dE) between the cookies and the control group was -3.73, which allowed us to obtain a good product with a quality and characteristics similar to shortening. This supports the feasibility of new solid fats to replace traditional plastic fats in baked goods.

Natural variation and underlying genetic loci of γ-oryzanol in Asian cultivated rice seeds

γ-oryzanol is the most studied component in rice (Oryza sativa L.) bran oil. It is not only associated with physiological processes of rice growth and development but also grain quality that is related to human health. Previous studies focused mainly on γ-oryzanol composition and content in various rice cultivars, while its biosynthetic and regulatory pathways remain unknown. Here we present the quantitative identification of γ-oryzanol in rice seeds across 179 Asian cultivated accessions using ultra-performance liquid chromatography-time-of-flight mass spectrometry (UPLC-TOF/MS), which revealed a significant natural variation in γ-oryzanol content among these tested rice accessions. In addition, we present, for the first time, the genome-wide association study (GWAS) on rice seed γ-oryzanol, which identified 187 GWAS signal hot spots and 13 candidate genes that are associated with variable γ-oryzanol content and provided the top 10 rice haplotypes with high γ-oryzanol content for breeding. Collectively, our study provides valuable germplasms for breeding rice cultivars rich in γ-oryzanol and genetic resources for elucidating genetic and biochemical bases of variable γ-oryzanol in rice.

Mechanism of rice bran lipase inhibition through fermentation activity of probiotic bacteria

Rice bran oil is known as wonder oil and it is the most important vegetable oil in Asia. Rice bran oil is extracted from bran that is the outer hard layer of rice. It is an emerging category in edible oil with a lot of nutritional properties and health benefits. Rice bran oil is heart-friendly, boosts up immunity, and prevents from other diseases occurring commonly in Pakistan. The current study aimed to stabilize rice bran oil through different probiotic isolates and to assess the nutritional content of rice bran oil after stabilization. The study was aimed to inactivate naturally occurring lipases that can hydrolyze oil into glycerol and free fatty acid which is a serious problem that gives it a rancid taste and smell. Antilipase activity was used to inactivate naturally occurring lipases that are a huge threat to the stabilization process. The fermentation process utilizes antilipase activity without affecting the nutritional value of oil. Lactobacillus strains were used for the stabilization of rice bran oil. Rice bran oil was extracted in the Soxhlet apparatus. The probiotic lab isolates Lactobacillus delbrueckii S2, Lactobacillus casei S5 and Lactobacillus plantarum S13 were applied to it to increase its shelf life and prevent oxidative rancidity. The extraction temperature of rice bran oil was maintained above 40 °C to inhibit lipase activity. Rice bran oil samples were stored at refrigeration temperature to arrest lipase activity. Probiotics maintained acidic pH to keep oil stabilization. Qualitative analysis was done to confirm rice bran oil stabilization. Determination of Free Fatty Acid (FFA) and saponification value confirmed that oxidative rancidity of rice bran oil was controlled by probiotics. FFA count was less than 10% and Saponification Value (SV) was 180. GC analysis was performed to analyze the FFA profile. Gas Chromatography results have shown 3 fatty acids. Statistical analysis has shown non-significant effect on different incubation temperatures of Lactobacillus isolates. Among the biological methods of stabilization, the use of probiotics is a novel concept and recommended for commercial application.

Protective Mechanism of Rice-Derived Lipids and Glucosylceramide in an In Vitro Intestinal Tract Model

We previously reported that the ethanol extract from polished rice suppresses inflammation and the formation of aberrant crypt foci in the mouse colon and particularly focused on the plant sphingolipid glucosylceramide (GlcCer). Here, we investigated the effects of rice lipid fractions and GlcCer on differentiated Caco-2 cells treated with lipopolysaccharide (LPS), in particular, we evaluated the mechanism of action of GlcCer using related substances and metabolic enzyme inhibitors. Rice-derived polar lipids suppressed the LPS-induced reduction in the number of cells. The polar lipids with higher GlcCer content exerted a better effect than the other fractions. GlcCer-related substances reversed the LPS-induced reduction in the number of cells, and GlcCer-metabolic inhibitors, including a sphingosine kinase inhibitor, suppressed the beneficial effects of GlcCer-related substances. These results suggest that GlcCer is a rice component with intestinal protection. Secondly, GlcCer is metabolized during inflammation and protects intestinal cells by maintaining the sphingolipid levels in cells and producing sphingoid base-1-phosphate.

Spice fixed oils as a new source of γ-oryzanol: nutraceutical characterization of fixed oils from selected spices

γ-Oryzanol is an important group of nutraceuticals that play a key role in addressing metabolic disorders. This study, for the first time, examined volatile-free spice fixed oils (FOs) as an alternate plant source for γ-oryzanol and other nutraceuticals (phenolics, flavonoids, phytosterols, and tocopherols) using HPLC, HR-MS and NMR. The in vitro antioxidant activities of FOs were also analysed. The selected spices were Alpinia galanga, Cinnamomum zeylanicum, Trigonella foenum-graecum, Foeniculum vulgare and Myristica fragrans. The major polyphenols and flavonoids quantified were gallic, protocatechuic, vanillic, syringic, para-coumaric, ferulic, rutin, trans-cinnamic, and quercetin. T. foenum-graecum FOs recorded high levels of ergosterol (48.56 mg/100 g) and stigmasterol (247.36 mg/100 g). The fucosterol levels were high in A. galanga (268.31 mg/100 g) FOs, whereas C. zeylanicum FOs showed high content of β-sitosterols (7037.77 mg/100 g). C. zeylanicum and T. foenum-graecum FOs recorded high α-tocopherol content (47.55 and 15.96 mg/100 g respectively). C. zeylanicum FOs showed high levels of three ferulates, namely, cycloartenyl ferulate, 24-methylene cycloartenyl ferulate and β-sitosteryl ferulate, whose contents were 89.42, 170.23 and 50.23 mg/100 g respectively which was confirmed by HRMS with a molecular mass (m/z) of 601.45, 615.47, and 589.45 respectively. Further, γ-oryzanol ferulates in C. zeylanicum FOs were confirmed by 1H-NMR analysis. The acidified methanolic extractives of FOs showed high free radical scavenging activity and antioxidant potential. These spice FOs have excellent antioxidant activities, and are novel potential functional ingredients against lifestyle disorders.