Stabilized Rice Bran Research Articles

Gamma-oryzanol, Physicochemical and Antioxidant Properties of Stabilized Rice Bran Oil from Dough and Mature Grain Stages

Gamma-oryzanol, Physicochemical and Antioxidant Properties of Stabilized Rice Bran Oil from Dough and Mature Grain Stages

Kinetic analysis and back propagation neural network model for shelf-life estimation of stabilized rice bran

To establish a general model for predicting shelf-life of stabilized rice bran, different samples with varying residual enzyme activity, water activity (aw), and packaging materials were used, and hot air assisted-radio frequency (HA-RF) heating was applied as stabilization method. Free fatty acids (FFA) were recorded during storage at different temperatures and kinetic analysis was conducted to compare the effects of different conditions on rice bran shelf-life. FFA content increased rapidly during storage, and higher aw and lipase (LA) activity corresponded to a higher FFA generation rate. Only the increase in FFA of samples with low LA activity (≤30 mg/g) and aw (≤0.3) conformed to Zero-order model, while that of other samples conformed to Fractional Conversion model. For the inhibitory effect of packaging materials on the generation of FFA, BOPP/Kraft-paper/PE > PA/PE > PET/PE > LDPE. A back propagation neural network (BPNN) model was also constructed to predict rice bran shelf-life, which employing LA activity, aw, packaging materials, and storage temperature as input parameters. The BPNN model trained by Levenberg–Marquardt achieved the best prediction performance, with coefficient of determination (R2) of 0.996 and root mean square error (RMSE) of 2.077. Rice bran packaged by BOPP/Kraft-paper/PE with LA activity of 20 mg/g and aw of 0.2 had the longest shelf-life of 147 d at 25 °C. This model is of great help in predicting the shelf-life of stabilized rice bran and guiding the development of rice bran stabilization process.

Effects of rice bran stabilization procedures and proteases on rice bran protein hydrolysates

Rice bran stabilization is typically performed after rice milling to improve storage performance. In the present study, we investigated the effect of extrusion (EX) and superheated steam (SS) on the physicochemical and functional characteristics of rice bran protein hydrolysates (RBPHs) obtained with acid, alkaline, and neutral proteases (AP, ALP, and NP). The deactivation parameters were optimized as EX (140 °C, water content: 25%) and SS (130 °C, 5 min). After stabilization, the enzymatic hydrolysis of proteins was inhibited. The untreated RBPHs obtained with ALP exhibited the highest degree of hydrolysis (15.93%), while RBPH-EX-NP presented the lowest (10.75%). EX reduced the solubility of RBPHs, while SS improved the solubility at pH 2–4. Both stabilizations increased the β-sheet and β-turn contents of RBPHs while reducing the α-helix and random coil contents. The antioxidant activity of RBPHs decreased, while their emulsifying activity and ferrous chelating ability increased. This study could contribute to insight into the effects of industrial stabilization on RBPHs.

Improvement of gelation properties of indica rice flour with stabilized rice bran from different thermal treatment

AbstractBackground and ObjectivesRice bran is enriched with bioactive compounds, which makes it more competitive as a functional food raw material. The stabilization of rice bran can inhibit the activity of endogenous enzymes, reduce its oxidation sensitivity, and change its physical and chemical properties, providing more possibilities for its application in the food industry. In this study, rice bran from five stabilization treatments (atmospheric pressure cooking, high‐pressure cooking, atmospheric steam, microwave heating, and extrusion cooking) were investigated for their effect on the gel properties of indica rice flour.FindingsStabilized rice bran could enhance the hydration properties and increase the enthalpy value of rice flour. The gelatinization properties indicated that the viscosity and fluidity of the rice paste were increased, and the aggregation and rearrangement of rice starch were promoted. From the rheological properties, stabilized rice bran enhanced the viscoelasticity of the rice flour gel. In addition, the stabilized rice bran could also reduce the yield of freeze‐thawing water of the rice flour gel. Rice bran with thermal treatments can significantly improve the gel properties of indica rice flour.ConclusionsIndica rice flour mixed with stabilized rice bran showed significant improvements in hydration, gelatinization, rheological properties, and freeze‐thaw stability.Significance and NoveltyIt is potential for the application of the gel from rice flour with stabilized rice bran in the starch‐based food industry.

The effect of stabilization heat treatment on rice bran quality parameters, including total phenolic content, gamma oryzanol content, antioxidant potential, oxidative stability and extraction yield during storage

The impact of rice bran stabilization thermal treatments on oxidative stability, extractability, and antioxidant potential was investigated. Freshly milled rice bran samples of the variety “Ld 368 –red” were subjected to four heat treatments: steaming, hot air drying, microwave treatment, and a combination of microwave and steaming. Solvent extraction was used to obtain rice bran oil (RBO). The Phenolic, γ-oryzanol contents and antioxidant potential of RBO were analyzed. Oil yield, free fatty acid content (FFA), and peroxide value (PV) were measured during 50-days storage at room temperature, with data collected at an interval of 10 days. The highest extraction yield was in coupled treatment (22.26 %). The coupled treatment and microwave were the most effective for the stabilization of rice bran in terms of oxidative stability, which provided the lowest FFA value (2.950 % & 2.993 %) and PV (0.518 & 0.620 mEqv/kg oil) (p ≤ 0.05). The lowest increment of FFA (2.945 %) and PV (4.23 mEqv/kg) was detected in RB stabilized by coupled treatment in 50 days of storage time. The microwaved sample exhibited the highest total phenolic content (4.147±0.190 mg GAE/g of extract), γ-oryzanol content (1.536±0.0173 %), and the highest antioxidant activity/ lowest IC50 value among the stabilized sample.

Rice bran stabilization using autoclave and optimization of crude rice bran oil recovery using ultrasound-assisted extraction

This research aimed to stabilize rice bran to reduce enzymatic reactions and optimize rice bran oil extraction using ultrasound-assisted extraction (UAE). The optimization was performed using response surface methodology (RSM). The results showed that rice bran oil has three primary fatty acids (oleic, linoleic, palmitic). Stabilization of rice bran using an autoclave (121 °C) for 10 min was recommended, with oil yield (14.2%), free fatty acid/FFA (0.41%), and gamma oryzanol (16.1 ppm). The storage significantly affected oil yield and gamma oryzanol but not FFA (p>0.05). The untreated and stabilized rice bran FFA during 18-day storage ranged from 1.33 to 5.73% and 0.41 to 1.12%. This confirmed that stabilization could inactivate lipase enzymes by reducing FFA. The optimization showed that the linear model best explained oil yield, total phenol content (TPC), and antioxidant activity (IC50), while the 2FI model was best fitted for gamma oryzanol. The optimal condition was found for UAE extraction at an amplitude of 90% and a time of 30 min. Verifying optimal conditions resulted in oil yield (13.6%), TPC (44.8 mg GAE/g), IC50 (207.2 ppm), and gamma oryzanol (15.8 ppm). Further in-depth studies are required to investigate using green solvents in the UAE and gamma oryzanol purification.

Rice lipases: a conundrum in rice bran stabilization: a review on their impact and biotechnological interventions.

The online version contains supplementary material available at 10.1007/s12298-023-01343-3.

Stabilization of Rice Bran by Infrared Radiation Heating for Increased Resilience and Quality of Rice Bran Oil Production.

Rice bran, a by-product of rice milling, is a valuable source of rice bran oil (RBO). However, it is prone to rancidity and must be processed quickly after rice polishing. The researchers found that rice bran stabilization with infrared radiation (IR) at 125 V and 135 V for 5∼10 min. The most promising IR treatments were 125 V for 10 min and 135 V for 5 min, which resulted in the lowest lipase activity (93∼96% inhibition) and levels of γ-oryzanol and α-tocopherol comparable to those of the untreated control. However, the color of rice bran and RBO based on L*, a*, b*, and total color difference (ΔE) and Gardner-20 mm index darkened. Upon storage of rice bran at 38°C for 8 weeks, the use of these two IR treatments completely inhibited the rise in free fatty acid (FFA) content and peroxide values throughout the storage period. In contrast, the control had a pre-storage FFA more than double that of IR-stabilized rice bran, which further increased during storage and, in the 8th week, was more than 6-fold higher than the pre-storage level. γ-oryzanol and α-tocopherol slightly decreased with storage and their levels did not differ between stabilized and unstabilized rice bran. RBO color darkening was again observed, but the color lightened with storage, especially upon treatment at 135 V for 5 min. In contrast, the color of control RBO darkened with storage. Thus, IR at 135 V for 5 min was the most promising method for rice bran stabilization, based on which commercial IR treatment instruments can be developed.

Stabilization of Rice Bran: A Review.

One of the major problems in food science is meeting the demand of the world's growing population, despite environmental limitations such as climate change, water scarcity, land degradation, marine pollution, and desertification. Preventing food from going to waste and utilizing nutritive by-products as food rather than feed are easy and powerful strategies for overcoming this problem. Rice is an important staple food crop for more than half of the world's population and substantial quantities of rice bran emerge as the main by-product of rice grain milling. Usually, rice bran is used as animal feed or discarded as waste. Although it is highly nutritious and comprises many bioactive compounds with considerable health benefits, the rapid deterioration of bran limits the exploitation of the full potential of rice bran. Hydrolytic rancidity is the main obstacle to using rice bran as food, and the enzyme inactivation process, which is termed stabilization, is the only way to prevent it. This study reviews the methods of stabilizing rice bran and other rice-milling by-products comprising rice bran in the context of the efficiency of the process upon storage. The effect of the process on the components of rice bran is also discussed.

Nutritional composition and volatile compounds stability in dry‐heat and extruded stabilised rice bran during storage

SummaryFresh rice bran (RB) is susceptible to rancidity during storage and transportation and needs a stabilisation process to inactivate enzymes and retain maximum nutrients. Two stabilisation methods, i.e., dry‐heat and extrusion, were applied to study the changes in nutritional composition, volatile compounds, and storage stability of rice bran under varied conditions. Both methods stabilised phytic acid content at 0.55–0.60 μmol L−1; the overall oryzanol content was reduced and found to be less in untreated rice bran. The increase in dry‐heat treatment time and temperature accelerated the oryzanol loss and the loss rate was lower than untreated RB while the oryzanol content was higher at end of storage. Similarly, the reduction rate in oryzanol content by extrusion treatment was positively correlated with storage temperature. Both methods significantly increased the total dietary and soluble dietary fibre but reduced vitamin E content. The extrusion treatment was better at stabilising different volatile compounds (such as aldehydes and ketones) than the dry‐heat treatment in the rice bran. The most volatile substances were hydrocarbons. Dry heat and extrusion increase aldehydes and ketones, oxidising RB and reducing its quality while aldehydes and ketones decreased during storage.

Use of a rice industry by-product as a meat replacer in a hybrid chicken patty: Technological and sensory impact

The current demand for products with a reduced amount of animal meat encourages its replacement for plant-based ingredients. Rice bran (RB) is a by-product that derives from the milling of rice grain and can potentially serve as a viable source of protein, fat, and fiber that could have positive impacts on human health. The effects of adding rice bran on the physical, technological and sensory characteristics of hybrid chicken patties were studied.First, stabilized rice bran was physicochemical characterized and, subsequently, technological, and sensory characterization of five hybrid chicken patties with chicken meat (69, 67, 65, 63 and 61%), cooked pumpkin and carrot (30%), and different proportions of rice bran (0, 2, 4, 6, and 8%) was carried out. Rice bran shows that it is a good source of lipids, protein, fibers, and ash. The peroxide value (3.13 meqO2/kg) and aw (0.635) were within the range of the acceptable limit. Technological characteristics of hybrid patties decreased with increasing SRB level. Treatments with 0 and 2% rice bran were related to higher moisture content, color values, weight loss and positive sensory characteristics such as acceptability and juiciness. The results suggested that stabilized rice bran could be used in hybrid patties formulation to replace lean meat to supply cost production savings and serve today's consumer who demands food of high nutritional quality.

The Effects of Thermal Treatment on Lipid Oxidation, Protein Changes, and Storage Stabilization of Rice Bran.

Rice bran is a nutrient-rich and resource-dense byproduct of rice milling. The primary cause of rice bran utilization limitation is oxidative deterioration and inadequate storage facilities. Improving stability to extend the shelf-life of rice bran has thus become an utmost necessity. This study aimed to stabilize raw fresh rice bran (RB) by using dry heat methods at 120 °C (233, 143, and 88 min) and 130 °C (86, 66, and 50 min). The results indicated that after dry heat pretreatment, peroxidase levels were at 90%, and the storage stability of dry-heat-stabilized RB was better. However, with an increase in treatment temperature and time, the peroxidase activity improved while the lipase activity decreased to a certain extent without significant changes. The total saturated and unsaturated fatty acids were significantly unchanged during storage, while oleic/linoleic acid increased substantially by 1% at 120 °C for 88 min. The increase in treatment time and temperature was beneficial in controlling the fatty acid values. However, extended treatment time caused an increase in the peroxide value and MDA. The essential and non-essential amino acid ratios, which evaluate a protein's nutritional value, remained relatively stable. The essential subunit of rice bran protein was not affected by the temperature and time of dry heat treatment and storage time.

Analysis of the aroma volatile compounds in different stabilized rice bran during storage

Rice bran is rich in nutrients and bioactive components, which plays an important role in reducing dyslipidemia and regulating intestinal flora. However, due to the rice bran’s instability resulting from rancidity during storage, the development is limited. E-nose, GC–MS and E-tongue were used to monitor the flavor and bitterness of different stabilized rice bran during accelerated storage, and the change of physicochemical properties in rice bran was determined. The rice bran flavor significantly changed after five stabilization treatments. The bitterness increased during storage, but the growth was small (from 7.39 to 7.62). Besides, after stabilization treatments, lipase (LA) activities gradually decreased from 10.11 to 2.03 mg/g, and lipoxygenase (Lox) activities decreased from 3.71 to 1.38 U/g. These results comprehensively elucidate changes in volatile composition, bitterness and physicochemical properties of stabilized rice bran samples during storage and lay the foundation for improving its acceptability and edibility in the future.

The Effect of Stabilized Rice Bran Addition on Physicochemical, Sensory, and Techno-Functional Properties of Bread.

Rice bran (RB) is a valuable byproduct derived from rice milling that represents an excellent opportunity for dietary inclusion. Bioactive components with antioxidant potential have been reported in RB, gaining the considerable attention of researchers. However, RB requires a stabilization process after milling to prevent it from becoming rancid and promote its commercial consumption. The aim of this study was to evaluate the effects of substituting stabilized rice bran (SRB) for wheat flour at levels of 10, 15, 20 and 25% on the proximate composition, dietary fiber, dough rheology, antioxidant properties, content of bioactive compounds, and sensory attributes of white wheat-based bread. Results indicated that the incorporation of SRB increased the bread's insoluble dietary fiber, phytic acid, total polyphenol content, γ-oryzanol, γ-aminobutyric acid, and antioxidant properties, while decreased its water absorption capacity, elasticity, volume, β-glucans, and soluble dietary fiber content. Moreover, substituting wheat flour for SRB at levels higher than 15% affected sensory attributes, such as color, odor, flavor, and softness. This study highlights the potential application of SRB flour in bread-making to increase nutritional, and functional properties of white wheat bread.

Use of Stabilized rice bran for preparing Beef Burger

This study was performed to investigate the effect of thermal processing (microwave oven, roasting by dry heat at 130°, for 10 and 20 min. and steaming by using an autoclave under atmospheric pressure for 10 and 20 min.) on the stability of rice bran and the utilization of microwave stabilized rice bran as fat replacers in preparing a low-fat beef burger. The obtained results revealed that: rice bran contained high levels of carbohydrates and moderate amounts of ether extract and crude protein. No differences were detected in the refractive index of rice bran oil among the stabilization procedures, whereas slight differences were found in the case of specific gravity. When rice bran oil was subjected to stabilized procedures, the acid value, iodine value, peroxide value, saponification value, and unsaponifiable matter were reduced. Moreover, the total saturated fatty acids content of rice bran oil increased as a result of subjecting to stabilization procedures whereas the total unsaturated fatty acid content decreased. The results show that stabilized rice bran is effective in improving the chemical and functional characteristics of a beef burger.

Changes in content of antioxidants and hydrolytic stability of black rice bran after heat‐ and enzymatic stabilizations and degradation kinetics during storage

This research aimed to compare heat and enzymatic stabilization methods in terms of hydrolytic stability and changes in antioxidant compounds of rice brans during ambient storage. Raw non-pigmented and black rice bran (RNB and RBB) showed high lipase activity (269.0 and 241.9 U/kg, respectively). Heat-stabilized non-pigmented and black rice brans (HNB and HBB) and enzymatically stabilized non-pigmented and black rice brans (ENB and EBB) had much lower lipase activity (25.8 to 32.8 U/kg). Lipase activity was not increased in the stabilized samples during 8-week storage and had high hydrolytic stability. Compared with raw rice brans, tocols, and anthocyanin contents in HNB and HBB decreased significantly, but γ-oryzanol increased significantly, while all antioxidant compounds in ENB and EBB increased significantly. Antioxidant contents of rice bran decreased during storage following zero- and first-order reaction kinetics. EBB showed the lowest k and the highest t1/2 values, indicating more stability of these antioxidants.

Microwave treatment of rice bran and its effect on phytochemical content and antioxidant activity

An alternative approach for rice bran stabilization is microwave treatment. However, the effects of the microwave treatment on the contents of bioactive compounds and antioxidant activities of the rice bran have rarely been reported in detail. In this study, microwave pretreatment (130–880 W for 0.5–5.0 min) of rice bran was proposed where the antioxidant activity, total flavonoids, and total phenolic contents were determined using UV–Vis spectrometry. Tocols, γ-oryzanols, squalene, phytosterols and phenolic compounds were quantified using high-performance liquid chromatography. The results showed an increase in the antioxidant activity (0.5 folds), total phenolic contents (1.3 folds), total flavonoid contents (0.9 folds), total tocols (2.6 folds), total γ-oryzanols (1.6 folds), and total phytosterols (1.4 folds). Phytochemicals were enhanced, especially trans-p-coumaric acid (10.3 folds) and kaempferol (8.6 folds). The microwave treatment at 440 W for 2.5 min provided the best contents of the bioactive compounds and antioxidant activity. This work revealed the microwave treatment as a potential tool for stabilizing rice bran and increasing the usability of its phytochemicals, which applies to several industries concerning the use of rice bran as an ingredient.

Improvement effects of micronization on morphology, functional and nutritional attributes of stabilized rice bran

Micronization affects physicochemical and functional properties of materials and hence might improve the quality of rice bran, following stabilization treatments. The micronization effects of stabilized rice bran via extrusion or radio frequency treatments on their morphology and functional properties, and releasable capability were investigated. Micronization reduced particle size, water binding capacity and swelling capacity of rice bran, and increased their whiteness, water solubility index, and nutrient releasability. However, no significant changes in oil binding capacity and thermal index after micronization were observed. Moreover, micronization could decrease the bulk density of rice bran stabilized by extrusion. The releasability of phenolics, flavonoids, γ-oryzanol, and minerals (K, Mg, Zn and Fe) from rice bran after micronization was improved based on in vitro digestion models. These findings suggested that micronization of rice bran following stabilization, especially extrusion treatment, could improve its functional and nutritional properties. The types of stabilization processing of rice bran, followed by micronization, should be considered practically for functional and nutritional properties.

Influence of Carboxymethyl Cellulose on the Stability, Rheological Property, and in-vitro Digestion of Soy Protein Isolate (SPI)-Stabilized Rice Bran Oil Emulsion.

In this study, carboxymethyl cellulose (CMC) was added to soybean protein isolate (SPI)-stabilized rice bran oil (RBO) emulsion to improve its physicochemical stability and free fatty acid (FFA) release characteristics. RBO emulsions stabilized by SPI and various contents of CMC were prepared and assessed by measuring zeta potential, particle size, transmission, and microstructure, the rheological properties were analyzed by dynamic shear rheometer. In addition, its chemical stability was characterized by a storage experiment, and the FFA release was explored by a simulated gastrointestinal tract (GIT) model. It showed that the negative charge of the droplets of RBO emulsion was increased with increasing CMC content. The decrease in transmission of SPI-stabilized RBO emulsion with increasing CMC content was due to the droplets not being free to move by the special network interaction and an increase in the viscosity. According to the determination of the reactive substances of lipid hydroperoxide and thiobarbituric acid during 30 days storage at 37°C, the chemical stability of the emulsion added with CMC was enhanced compared with the SPI-stabilized RBO emulsion. In-vitro digestion studies not only evaluated the structural changes of RBO emulsions at different stages, but also found that RBO emulsion with CMC showed a higher level of free fatty acids release in comparison with that without CMC. It indicated that the utilization of CMC can improve the bioavailability of RBO emulsions.

Assessment of Genetic Variability and Bran Oil Characters of New Developed Restorer Lines of Rice (Oryza sativa L.).

Rice is one of the most important crops in Egypt. Due to the gap between the demand and the availability of the local edible oils, there is need to raise the nutritional value of rice and, therefore, to improve the nutritional value of the consumer. This research was carried out at the Experimental Farm of Sakha Agricultural Research Station, Sakha, Kafr El-Sheikh, Egypt, during the 2019 and 2020 seasons. Five newly developed genotypes of rice, namely NRL 63, NRL 64, NRL 65, NRL 66, and Giza 178 as check variety (control), were used to evaluate the analytical characterization of raw rice bran and rice bran oil from rice bran, study the genetic variability and genetic advance for various quantitative and qualitative traits in rice as well as, rice bran oil. The genotypes were evaluated in a randomized complete block design (RCBD) with three replications. Analysis of variance revealed highly significant variations among the genotypes for all the studied characters. Data revealed that high estimates of the phenotypic coefficient of variance (PCV%) and genotypic coefficient of variance (GCV%) were observed for amylose content percentage, peroxide value (meq/kg oil), myristic C14:0, and arachidic C20:0, indicating that they all interacted with the environment to some extent. The line NRL66 and NRL64 showed the highest and high values of mean performance for grain yield (t/h), grain type (shape), amylose content percentage, crude protein, ether extract and ash of milled rice, crude protein, ether extract, ash, phosphorus, magnesium, manganese, zinc, and iron of stabilized rice bran oil. Genetic advance as a percentage of mean was high for most of the studied traits. It indicates that most likely, the heritability is due to additive gene effects, and selection may be effective. The percentage of advantage over the Giza 178 as the commercial variety was significant and highly significant among the genotypes for all the characters studied in the two years, indicating that the selection is effective in the genetic improvements for these traits.