Rice Bran Stabilisation and Oil Extraction Using the Microwave-Assisted Method and Its Effects on GABA and Gamma-Oryzanol Compounds

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 open label randomized controlled trial of the effects of rice bran oil on cardiometabolic risk factors, lipid peroxidation and antioxidant status in overweight/obese adults with metabolic syndrome

INTRODUCTION

We previously documented the beneficial effects of rice bran oil (RBO) on cardiac function and atherogenic cardiometabolic factors in men with coronary artery disease. Therefore, the existing evidence in this area aims to be expanded by investigating the impact of adding RBO to a daily standard diet on emerging insulin resistance surrogate markers, lipid peroxidation, antioxidant status, and metabolic disturbances in individuals with metabolic syndrome (MetSyn) through an open-label controlled trial.

METHODS

A total of 50 overweight/obese adults (mean body mass index (BMI) = 31.08 kg/m2) with at least 3 MetSyn components were randomly allocated to either the control group, which received a standard diet plan, or the intervention group, which was supplemented with 30 g/d RBO for 8 weeks. BMI, MetSyn components, metabolic score for insulin resistance (METS-IR), triglyceride‒glucose‒BMI (TyG‒BMI), malondialdehyde (MDA), total antioxidant capacity (TAC), and plasma polyphenol levels were measured before and after this open-label trial.

RESULTS

Analysis of covariance (ANCOVA) adjusted for baseline values revealed that, compared with patients who received only a standard diet, those who were supplemented with 30 g/d RBO presented significantly lower total cholesterol (P value = 0.005; effect size (ES):-0.92), LDL-cholesterol (P value = 0.048; ES:-0.62), fasting blood glucose (P value = 0.014; ES:-0.77), MDA (P value = 0.002; ES: -1.01), METS-IR (P value < 0.001; ES: -1.24), and TyG-BMI (P value = 0.007; ES:-0.85) after 8 weeks. Additionally, RBO consumption resulted in significantly higher levels of HDL-C (P value = 0.004; ES:0.94) and TAC (P value < 0.0001; ES:2.05). However, no significant changes were noted in BMI, waist circumference, serum triglycerides, plasma polyphenols, or blood pressure.

CONCLUSION

Although the current findings suggest that the hypocholesterolemic, antihyperglycemic, and antioxidative effects of 30 g/d RBO seem to be promising for MetSyn patients, they should be considered preliminary. Therefore, further well-designed clinical trials with larger sample sizes and longer durations are needed to confirm these findings.

Oxidised rice bran oil induced oxidative stress and apoptosis in IPEC-J2 cells via the Nrf2 signalling pathway

Rice bran oil is a type of rice oil made by leaching or pressing during rice processing and has a high absorption rate after consumption. When oxidative rancidity occurs, it may cause oxidative stress (OS) and affect intestinal function. Meanwhile, the toxic effects of oxidised rice bran oil have been less well studied in pigs. Therefore, the IPEC-J2 cells model was chosen to explore the regulatory mechanisms of oxidised rice bran oil on OS and apoptosis. Oxidised rice bran oil extract treatment (OR) significantly decreased the viability of IPEC-J2 cells. The results showed that OR significantly elevated apoptosis and reactive oxygen species levels and promoted the expression of pro-apoptotic gene Caspase-3 messenger RNA levels. The activation of Nrf2 signalling pathway by OR decreased the cellular antioxidant capacity. This was further evidenced by the expression of kelch-like ECH-associated protein 1, heme oxygenase 1, NADH: quinone oxidoreductase 1, superoxide dismutase 2 and heat shock 70 kDa protein genes and proteins were all downregulated. In conclusion, our results suggested that oxidised rice bran oil induced damage in IPEC-J2 cells through the Nrf2 signalling pathway.

Kinetic parameter for scale-up and γ-oryzanol content of rice bran oil as antioxidant: Comparison of maceration, ultrasonication, pneumatic press extraction

Rice bran oil is one of oryzanol source oils. Oryzanol is an antioxidant compound that is related to the absorption of cholesterol, and is used in hyperlipidemia treatment and menopause problems. RBO extraction, purification and its γ-oryzanol content have been carefully reviewed. The quality and concentration of γ-oryzanol depend on the extraction process and purification. In selecting the extraction method to obtain the highest oryzanol content, in addition to comparing the concentration of oryzanol obtained and it can also be done by comparing the extraction kinetics parameters. Modeling according to physical or empirical kinetics can contribute in increasing the result of extraction. This study aims to determine the highest oryzanol content in rice bran oil, comparing several extraction methods and studies of rice bran oil extraction kinetic is necessary for scale up purposes. In this study is conducted Rice Bran Oil Extraction with n-Hexane solvent using several different methods, such as maceration, ultrasonication, and pneumatic press extractions. Independent variable that is used is the extraction time and yield as dependent variable. The study shows that the best extraction method to get the highest yield is 10.34 % by ultrasonicator and oryzanol content is 5.09 mg/g by a pneumatic press machine. According to kinetic parameter k2 is 0.001546, Cs is 0.0589, and h is 0.4707, R2 = 0.9715 obtained from extraction using ultrasonicator.

Self-assembly embedding of curcumin by alkylated rice bran protein

Lysine-rich rice bran protein (RBP) can be used as raw material for alkylation modification to improve the self-assembly performance of protein. The results of 1H NMR, degree of alkylation, and DSC analysis showed that the alkyl chain was successfully attached to the RBP. The surface hydrophobicity and absolute ζ-potential increased. The three-dimensional structure of the alkylated RBP (ARBP) become more porous and ARBP-2 was selected as the material for embedding curcumin. The XRD results revealed that curcumin induced self-aggregation of ARBP-2 and the inclusion of curcumin was attained. The maximum encapsulation efficiency of curcumin was 82.67 % and the maximum loading amount was 171.37 g/100 g RBP. The results of atomic force microscopy (AFM), particle size, and polydispersity index (PDI) analyses revealed that the particles in the system were aggregated after curcumin was added. Curcumin was well protected by encapsulation in the self-assembled particles. Thus, this study provides a new strategy for the embedding and delivery of curcumin.

Gamma-aminobutyric acid (GABA): a comprehensive review of dietary sources, enrichment technologies, processing effects, health benefits, and its applications

Gamma-aminobutyric acid (GABA) is a naturally occurring potential bioactive compound present in plants, microorganisms, animals, and humans. Especially, as a main inhibitory neurotransmitter in the central nervous system, GABA possesses a broad spectrum of promising bioactivities. Thus, functional foods enriched with GABA have been widely sought after by consumers. However, the GABA levels in natural foods are usually low, which cannot meet people's demand for health effects. With the increasing public awareness on the food securities and naturally occurring processes, using enrichment technologies to elevate the GABA contents in foods instead of exogenous addition can enhance the acceptability of health-conscious consumers. Herein, this review provides a comprehensive insight on the dietary sources, enrichment technologies, processing effects of GABA, and its applications in food industry. Furthermore, the various health benefits of GABA-enriched foods, mainly including neuroprotection, anti-insomnia, anti-depression, anti-hypertensive, anti-diabetes, and anti-inflammatory are also summarized. The main challenges for future research on GABA are related to exploring high GABA producing strains, enhancing the stability of GABA during storage, and developing emerging enrichment technologies without affecting food quality and other active ingredients. A better understanding of GABA may introduce new windows for its application in developing functional foods.

Composition, Microbiota, Mechanisms, and Anti-Obesity Properties of Rice Bran

Rice is a major cereal crop and a staple food for nearly 50% of people worldwide. Rice bran (RB) is a nutrient-rich by-product of rice processing. RB is rich in carbohydrates, fibers, proteins, lipids, minerals, and several trace elements (phosphorus, calcium, magnesium, potassium, and manganese). The extraction process and storage have influenced RB extracts and RB oil's quality. The RB composition has also varied on the rice cultivars. The color of RB indicates the richness of the bioactive compounds, especially anthocyanins. γ-oryzanol, tocopherols, tocotrienols, and unsaturated fatty acids are major components of RB oil. It has been established that RB supplementation could improve the host's health status. Several preclinical and clinical studies have reported that RB has antioxidant, anticancer, anti-inflammatory, anticolitis, and antidiabetic properties. The beneficial biological properties of RB are partially attributed to its ability to alter the host microbiome and help to maintain and restore eubiosis. Non-communicable diseases (NCDs), including heart disease, diabetes, cancer, and lung disease, account for 74% of deaths worldwide. Obesity is a global health problem and is a major reason for the development of NCDs. The medical procedures for managing obesity are expensive and long-term health supplements are required to maintain a healthy weight. Thus, cost-effective natural adjuvant therapeutic strategy is crucial to treat and manage obesity. Several studies have revealed that RB could be a complementary pharmacological candidate to treat obesity. A comprehensive document with basic information and recent scientific results on the anti-obesity activity of RB and RB compounds is obligatory. Thus, the current manuscript was prepared to summarize the composition of RB and the influence of RB on the host microbiome, possible mechanisms, and preclinical and clinical studies on the anti-obesity properties of RB. This study suggested that the consumption of RB oil and dietary RB extracts might assist in managing obesity-associated health consequences. Further, extended clinical studies in several ethnic groups are required to develop dietary RB-based functional and nutritional supplements, which could serve as an adjuvant therapeutic strategy to treat obesity.

Optimization of Oil Recovery from Japonica Luna Rice Bran by Supercritical Carbon Dioxide Applying Design of Experiments: Characterization of the Oil and Mass Transfer Modeling

This study presents an optimization strategy for recovery of oil from Japonica Luna rice bran using supercritical carbon dioxide (scCO2), based on design of experiments (DoE). Initially, a 24−1 two level fractional factorial design (FFD) was used, and pressure, temperature, and scCO2 flow rate were determined as the significant variables; while the yield, total flavonoids content (TFC), and total polyphenols content (TPC) were the response functions used to analyze the quality of the extracts recovered. Subsequently, central composite design (CCD) was applied to examine the effects of the significant variables on the responses and create quadratic surfaces that optimize the latter. The following values of pressure = 34.35 MPa, temperature = 339.5 K, and scCO2 flow rate = 1.8 × 10−3 kg/min were found to simultaneously optimize the yield (6.83%), TPC (61.28 μmol GAE/g ext), and TFC (1696.8 μmol EC/g ext). The fatty acid profile of the oils was characterized by GC-FID. It was demonstrated that the acids in largest quantities are C16:0 (15–16%), C18:1 (41%), and C18:2 (38–39%). Finally, three mass transfer models were applied to determine the mass transfer coefficients and assess the cumulative extraction curves, with an AAD% of 4.16, for the best model.