Rice bran stabilization and rice bran oil extraction using ohmic heating

Ohmic heating has been shown to increase the extraction yields of sucrose from sugar beets, apple juice from apples, beet dye from beet root, and soymilk from soybeans. Rice bran is a byproduct of the rice milling process that has economic potential by virtue of highly nutritious rice bran oil contained within the bran. In this study, ohmic heating was used to stabilize rice bran and to improve rice bran oil extraction yield as compared to microwave heating and a control (no heating). Results showed that ohmic heating is an effective method for rice bran stabilization with moisture addition. Free fatty acid concentration increased more slowly than the control for raw bran samples subjected to ohmic heating with no corresponding temperature rise, indicating that electricity has a non-thermal effect on lipase activity. Ohmic heating increased the total percent of lipids extracted from rice bran to a maximum of 92%, while 53% of total lipids were extracted from the control samples. Lowering the frequency of alternating current significantly increased the amount of oil extracted, probably due to electroporation. Ohmic heating was successfully applied to rice bran despite its high oil content. This could have important implications for the enhanced extraction of non-polar constituents.     

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.     

Fractionation of the rice bran layer and quantification of vitamin E, oryzanol, protein, and rice bran saccharide

Value-added processing with respect to rice milling has traditionally treated the rice bran layer as a homogenous material that contains significant concentrations of high-value components of interest for pharmaceutical and nutraceutical applications. Investigators have shown that high-value components in the rice bran layer vary from differences in kernel-thickness, bran fraction, rice variety, and environmental conditions during the growing season. The objectives of this study were to quantify the amount of rice bran removed at pre-selected milling times and to correlate the amount of rice bran removed at each milling time with the concentration of vitamin E, gamma-oryzanol, rice bran saccharide, and protein obtained. The ultimate goal of this research is to show that rice bran fractionation is a useful method to obtain targeted, nutrient-rich bran samples for value-added processing. Two long grain rice cultivars, Cheniere and Cypress, were milled at discrete times between 3 and 40 seconds using a McGill mill to obtain bran samples for analysis. Results showed that the highest oryzanol and protein concentrations were found in the outer portion of the rice bran layer, while the highest rice bran saccharide concentration was found in the inner portion of the bran layer. Vitamin E concentration showed no significant difference across the bran layer within a variety, though the highest magnitude of concentration occurs within the first 10 seconds of milling for both varieties. To extract the higher concentration of oryzanol and protein only the outer portion of the bran layer requires processing, while to extract the higher concentration of rice bran saccharide, only the inner portion of the bran layer requires processing. Rice bran fractionation allows for the selective use of portions of the bran layer and is advantageous for two reasons: (1) bran fractions contain higher concentrations of components of interest with respect to the overall bran layer average, and (2) less bran needs to be processed to obtain components of interest.     

Value-added subcritical water hydrolysate from rice bran and soybean meal

New value-added product was derived from agricultural by-products: rice bran and soybean meal by means of subcritical water (SW) hydrolysis. The effect of temperature (200-220 degrees C), reaction time (10-30 min), raw material-to-water weight ratio (1:5 and 2:5), was determined on the yields of protein, total amino acids, and reducing sugars in the soluble products. The suitable hydrolysis time was 30 min and the proper weight ratio of the raw material-to-water was 1:5. The reaction temperature suitable for the production of protein and amino acids was 220 degrees C for raw and deoiled rice bran, 210 degrees C for raw soybean meal, and 200 degrees C for deoiled soybean meal. The products were also found to have antioxidant activity as tested by ABTS(.)(+) scavenging assay. In addition, sensory evaluation of milk added with the hydrolysis product of deoiled rice bran indicated the potential use of the product as a nutritious drink.     

Optimization of enzyme-assisted improvement of polyphenols and free radical scavenging activity in red rice bran: A statistical and neural network-based approach

The current study is focused on optimizing the parameters involved in enzymatic processing of red rice bran for maximizing total polyphenol (TP) and free radical scavenging activity (FRSA). The sequential optimization strategies using central composite design (CCD) and artificial neural network (ANN) modeling linked with genetic algorithm (GA) was performed to study the effect of incubation time (60–90?min), xylanase concentration (5–10?mg/g), cellulase concentration (5–10?mg/g) on the response, i.e., total polyphenol and FRSA. The result showed that incubation time has a negative effect on the response, while the square effect of xylanase and cellulase showed positive effect on the response. A maximum TP of 2,761?mg ferulic acid Eq/100?g bran and FRSA of 778.4?mg Catechin Eq/100?g bran was achieved with incubation time (min)?=?60.491; xylanase (mg/g)?=?5.4633; cellulase (mg/g)?=?11.5825. Furthermore, ANN-GA-based optimization showed better predicting capabilities as compared to CCD.     

Extraction of defatted rice bran with subcritical aqueous acetone

Defatted rice bran extracts were obtained by subcritical treatment using aqueous acetone as extractant. Treatment with 40% (v/v) acetone at 230 °C for 5 min yielded an extract with the highest 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity (0.274 mmol of ascorbic acid/g of bran), total carbohydrate (0.188 g/g of bran), protein (0.512 g/g of bran), and total phenolic contents (88.2 mg of gallic acid/g of bran). The effect of treatment temperature (70-230 °C) was investigated using 40% (v/v) acetone, and the extract under 230 °C treatment showed the highest levels of all the determinations described above. The extracts obtained with various concentrations of aqueous acetone were subjected to UV absorption spectra and HPLC analysis, and the results showed changes in composition and polarity. Antioxidative activity evaluated against oxidation of bulk linoleic acid of the extract obtained with 80% (v/v) acetone was higher than that not only of the extract from subcritical water treatment but also of that obtained 40% (v/v) acetone treatment.     

Hydrolysis of wheat bran,rice bran and jute powder by immobilized enzymes from Macrophomina phaseolina

The stability of cellulolytic and hemicellulolytic enzymes from Macrophomina phaseolina improved on immobilization and was 1.5 to 2-fold more active against pre-treated wheat bran, rice bran or jute powder. The hydrolysis efficiency of the catalyst increased with a decrease in its particle size. About 80% (w/v) of the sugar obtained from wheat bran was assimilated by Saccharomyces sp., whereas the corresponding values for rice bran and jute powder were about 70 and 50% (w/v), respectively.     

Preparation and characterization of activated carbon from rice bran

A study on the preparation of rice bran-based activated carbon was conducted, with and without an acid treatment step prior the activation process. The influence of the activation time on the structure of the activated carbons was evaluated. The acid treatment had a significant positive influence on sorption properties. The rice bran-activated carbon presented a BET surface area of 652m(2)g(-1) and a pore volume of 0.137cm(3)g(-1), with mesopores predominance (ca. 55%). These experimental results indicated the potential use of rice bran as a precursor in the activated carbon preparation process, thus representing an economically promising material.     

Kurosu, a traditional vinegar produced from unpolished rice, suppresses lipid peroxidation in vitro and in mouse skin

The in vitro antioxidative activities of various kinds of vinegar were investigated by using a linoleic acid autoxidation model detected by the thiobarbituric acid (TBA) method and the 1,1-diphenyl-2-picrylhydrazyl radical system. An ethyl acetate extract of Kurosu (EK), a vinegar made from unpolished rice, exhibited the highest antioxidative activity in both systems. EK (5 mg) inhibited 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced edema formation (14%) and myeloperoxidase activity (52%, P< 0.01) in female ICR mouse skin. Furthermore, EK significantly suppressed double TPA application-induced H2O2 generation (53%, P< 0.01) and lipid peroxidation determined by the TBA-reacting substance level (95 %, P< 0.01). In a two-stage carcinogenesis experiment with dimethylbenz[a]anthracene/TPA, EK significantly reduced the number of tumors per mouse by 36% (P<0.05) at 15 weeks after promotion. These results suggest that the antitumor-promoting effect may be partially due to the antioxidative properties of EK such as the decomposition of free radicals and interference with free radical-generating leukocytes.     

Anti-stress and anti-fatigue effects of fermented rice bran.

The anti-stress and anti-fatigue effects on rats and mice of a hot water extract of rice bran fermented with Saccharomyces cerevisae IFO 2346 were investigated. Oral administration (1 g/kg/day) of the hot water extract of fermented rice bran (FRB) inhibited major changes in the weight of the adrenal, thymus, spleen and thyroid, showing an anti-stress effect. The hot water extract of FRB also inhibited increases in the GPT and LDH activity, cholesterol and glucose in the serum. The administration (1 g/kg/day) for 2 weeks significantly prolonged the swimming time, resulting in an increase in the anti-fatigue effect. It is considered from these results that FRB had anti-stress and anti-fatigue effects.     

Nitric oxide counteracts the senescence of rice leaves induced by abscisic acid

In the present study, we evaluate the protective effect of nitric oxide (NO) against senescence of rice leaves promoted by ABA. Senescence of rice leaves was determined by the decrease of protein content. ABA treatment resulted in (1) induction of leaf senescence, (2) increase in H2O2 and malondialdehyde (MDA) contents, (3) decrease in reduced form glutathione (GSH) and ascorbic acid (AsA) contents, and (4) increase in antioxidative enzyme activities (superoxide dismutase, ascorbate peroxidase, glutathione reductase, and catalase). All these ABA effects were reduced by free radical scavengers such as sodium benzoate and GSH. NO donors [N-tert-butyl-alpha-phenylnitrone (PBN), sodium nitroprusside, 3-morpholinosydonimine, and AsA + NaNO2] were effective in reducing ABA-induced leaf senescence. PBN prevented ABA-induced increase in the contents of H2O2 and MDA, decrease in the contents of GSH and AsA, and increase in the activities of antioxidative enzymes. The protective effect of PBN on ABA-promoted senescence, ABA-increased H2O2 content and lipid peroxidation, ABA-decreased GSH and AsA, and ABA-increased antioxidative enzyme activities was reversed by 2-(4-carboxy-2-phenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, a NO-specific scavenger, suggesting that the protective effect of PBN is attributable to NO released. Reduction of ABA-induced senescence by NO in rice leaves is most likely mediated through its ability to scavenge active oxygen species including H2O2.     

Changes in moisture content,mycoflora and aflatoxin content of rice bran during storage

The changes in moisture content, storage mycoflora and aflatoxin B₁ (AFB₁) in bran from untreated or raw rice (Rr) and parboiled rice (Pbr) stored in small lots in polyethylene bags were studied at 15-day intervals up to 60 days, using five lots of each type of bran. Deterioration was more rapid with reference to all the three parameters, in Rr bran compared to Pbr bran, the former becoming completely overgrown and caked with fungi by the end of 60 days.Aspergillus flavus was the dominant fungus in Pbr bran, whereasA. candidus andTrichoderma viride were abundant in Rr bran. The frequency of incidence as well as concentration of AFB₁ increased with storage time in both types of bran, but the rate of increase as well as overall concentration were much higher in Rr bran. Thus raw rice bran is unsuitable for prolonged storage.Abbreviations AFB₁ aflatoxin B₁ - MC moisture content - Pbr parboiled rice - Rr raw rice     

Biodiesel production from rice bran by a two-step in-situ process

The production of fatty acid methyl esters (FAMEs) by a two-step in-situ transesterification from two kinds of rice bran was investigated in this study. The method included an in-situ acid-catalyzed esterification followed by an in-situ base-catalyzed transesterification. Free fatty acids (FFAs) level was reduced to less than 1% for both rice bran A (initial FFAs content = 3%) and rice bran B (initial FFAs content = 30%) in the first step under the following conditions: 10 g rice bran, methanol to rice bran ratio 15 mL/g, H₂SO₄ to rice bran mass ratio 0.18, 60 °C reaction temperature, 600 rpm stirring rate, 15 min reaction time. The organic phase of the first step product was collected and subjected to a second step reaction by adding 8 mL of 5 N NaOH solution and allowing to react for 60 and 30 min for rice bran A and rice bran B, respectively. FAMEs yields of 96.8% and 97.4% were obtained for rice bran A and rice bran B, respectively, after this two-step in-situ reaction.     

Reaction of beta-alkannin (shikonin) with reactive oxygen species: detection of beta-alkannin free radicals

beta-Alkannin (shikonin), a compound isolated from the root of Lithospermum erythrorhizon Siebold Zucc., has been used as a purple dye in ancient Japan and is known to exert an anti-inflammatory activity. This study aimed to understand the biological activity in terms of physico-chemical characteristics of beta-alkannin. Several physico-chemical properties including proton dissociation constants, half-wave potentials and molecular orbital energy of beta-alkannin were elucidated. This compound shows highly efficient antioxidative activities against several types of reactive oxygen species (ROS), such as singlet oxygen ((1)O2). superoxide anion radical (.O2), hydroxyl radical (.OH) and tert-butyl peroxyl radical (BuOO.) as well as iron-dependent microsomal lipid peroxidation. During the reactions of beta-alkannin with 1O2, .O2- and BuOO., intermediate organic radicals due to beta-alkannin were detectable by ESR spectrometry. Compared with the radicals due to naphthazarin, the structural skeleton of beta-alkannin, the beta-alkannin radical observed as an intermediate in the reactions with (1)O2, and .O2- was concluded to be a semiquinone radical. On the other hand, during the reactions of beta-alkannin and naphthazarin with BuOO., ESR spectra different from the semiquinone radical were observed, and proposed to result from the abstraction of hydrogen atoms from phenolic hydroxyl groups of beta-alkannin by BuOO.. Based on the ROS-scavenging abilities of beta-alkannin, the compound was concluded to react directly with ROS and exhibits antioxidative activity, which in turn exerts anti-inflammatory activity.     

Antitumor effect of RBS (rice bran saccharide) on ENNG-induced carcinogenesis

We examined whether orally administered RBS (rice bran saccharide), prepared from rice bran by hot water extraction, increases immunocompetence, inhibits gastrointestinal carcinogenesis with N-ethyl-N-nitro-N-nitrosoguanidine (ENNG) or shows an antitumor effect. After the administration of RBS, phytohemagglutinin (PHA)- and pokeweed mitogen (PWM)-stimulated blastogenesis of lymphocytes derived from the mesenteric lymph nodes and peripheral blood was enhanced, and the helper/ suppressor T-cell ratio was elevated, and migration activity of peritoneal macrophages was also increased in rats treated continuously with ENNG. ENNG-induced gastrointestinal carcinomas were observed in 43% of those administered RBS (ENNG-RBS) as compared with 88% in the control (ENNG) and 94% in the prednisolone (PRD) group (ENNG-PRD). The 12-month survival rate of rats bearing gastrointestinal cancer was 58% in the ENNG-RBS group as compared with 25% in the ENNG group and 15% in the ENNG-PRD group. RBS prevented the reduction in immunocompetence in the course of carcinogenesis, suppressed carcinogenesis, and prolonged the survival of rats with gastrointestinal cancer. Antitumor activities of RBS are thought to be a kind of host mediated action. The growth inhibition ratio of transplantable ENNG-induced cancer in Wistar rats was 42.1% in the RBS and 51.8% in the 5-FU group. Since little is known about the potent antitumor activity of -glucan, it would be interesting to consider the relationship between the structure and the biological activities of polysaccharides.     

Changes in the radical-scavenging activity of sliced red and green cabbages during storage

Vegetables are rich source of antioxidative components such as ascorbic acid and polyphenols, which scavenge free radicals and reactive oxygen species and prevent life-style related diseases. In this work, the changes of radical-scavenging activity in shredded red and green cabbage leaves during storage were determined as well as ascorbic acid and polyphenol contents. Shredded cabbage leaves were stored at 10 degrees C for 7 days in the presence or absence of oxygen. Radical-scavenging activity, ascorbic acid content, and polyphenol content of shredded cabbage leaves remained for 7 days in the presence and absence of oxygen. These results demonstrate that the radical-scavenging activity, ascorbic acid, and polyphenols are stable in shredded cabbage leaves and that oxygen does not affect the activity and active components.     

A two-step acid-catalyzed process for the production of biodiesel from rice bran oil

A study was undertaken to examine the effect of temperature, moisture and storage time on the accumulation of free fatty acid in the rice bran. Rice bran stored at room temperature showed that most triacylglyceride was hydrolyzed and free fatty acid (FFA) content was raised up to 76% in six months. A two-step acid-catalyzed methanolysis process was employed for the efficient conversion of rice bran oil into fatty acid methyl ester (FAME). The first step was carried out at 60 degrees C. Depending on the initial FFA content of oil, 55-90% FAME content in the reaction product was obtained. More than 98% FFA and less than 35% of TG were reacted in 2 h. The organic phase of the first step reaction product was used as the substrate for a second acid-catalyzed methanolysis at 100 degrees C. By this two-step methanolysis reaction, more than 98% FAME in the product can be obtained in less than 8 h. Distillation of reaction product gave 99.8% FAME (biodiesel) with recovery of more than 96%. The residue contains enriched nutraceuticals such as gamma-oryzanol (16-18%), mixture of phytosterol, tocol and steryl ester (19-21%).     

Inactivation of rice bran thiamine-binding protein by N,N'-dicyclohexylcarbodiimide

The addition of a carboxyl-modifying reagent N,N'-dicyclohexylcarbodiimide (DCCD) to thiamine-binding protein isolated from rice bran resulted in a remarkable loss of its binding activity with [14C]thiamine. Thiamine and chloroethylthiamine substantially protected the protein against inactivation by DCCD, whereas thiamine phosphates did not. Another carboxyl reagent N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ) also inactivated rice bran thiamine-binding protein. Inactivation of the thiamine-binding protein was accompanied by covalent binding of DCCD to the protein as shown by the use of [14C]DCCD. The binding of [14C]DCCD to the thiamine-binding protein was specific, and significantly inhibited by the addition of thiamine. The loss of thiamine-binding activity was proportional to the specific binding of [14C]DCCD. For complete inactivation of the thiamine-binding activity, the binding of 2.46 mol of [14C]DCCD per mol of thiamine-binding protein was required. Furthermore, limited proteolysis of the binding protein by trypsin yielded two polypeptides with molecular weights of 35,000 (large polypeptide) and 12,500 (small polypeptide) which were separated by SDS-polyacrylamide gel electrophoresis. The binding sites of [14C]DCCD were found to be located on the large polypeptide. These results suggest that a specific carboxyl residue in the large polypeptide releasable from rice bran thiamine-binding protein by trypsin digestion when modified by DCCD is involved in the binding of thiamine.     

Transdermal absorption enhancement of rice bran bioactive compounds entrapped in niosomes

Niosomes composed of Tween 61 and cholesterol at 1:1 molar ratio were entrapped with the mixture of the three semi-purified rice (Oryza sativa L., Family Gramineae) bran bioactive compounds [ferulic acid (F), γ-oryzanol (O), and phytic acid (P)] at 0.5%, 1.5%, and 1.5%, respectively, by the supercritical CO₂ technique. The transdermal absorption by vertical Franz diffusion cells of the compounds entrapped in niosomes (Nio FOP), the unentrapped compounds (Mixed FOP), the compounds incorporated in gel and cream (Gel FOP and Cream FOP), and the compounds entrapped in niosomes and incorporated in gel and cream (Gel nio and Cream nio) was investigated. At 6 h, F and P from Nio FOP gave lower cumulative amount in viable epidermis and dermis (VED) than from Mixed FOP of 1.1 and 1.6 times, respectively, while O from Nio FOP exhibited higher cumulative amount in VED than from Mixed FOP of 2.4 times. The highest cumulative amount in VED of F, O, and P were from Gel nio, Cream nio, and Mixed FOP at 1.564 ± 0.052, 15.972 ± 0.273, and 25.857 ± 0.025 ng/cm², respectively. Niosomes enhanced the transdermal absorption of the hydrophobic compound O, while retarded the hydrophilic compounds F and P indicating the less systemic risk of F and P than O when entrapped in niosomes. Thus, transdermal absorption of F, O, and P appeared to depend on niosomal size, lipophilicity of the bioactive compounds, and types of formulations. These preclinical results can be applied for the design of the clinical study of the developed rice bran niosomal topical products.     

Sulfated modification of the polysaccharides obtained from defatted rice bran and their antitumor activities

Nine sulfated defatted rice bran polysaccharides (sRBPS), with various degrees of sulfation (DS) and carbohydrate content, were prepared by chlorosulfonic acid–pyridine (CSA–Pyr) method according to orthogonal test. Nine sulfated derivatives sRBPS were obtained and their antitumor activities were compared by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The results showed that when DS within the scope of 0.81–1.29, carbohydrate content in the range of 41.41–78.56%, sulfated derivatives exhibit relatively strong antitumor activity in vitro. The optimum modification conditions were reaction temperature of 70 °C, the ratio of chlorosulfonic acid to pyridine of 1:4 and the reaction time of 2 h.