A rapid procedure for analysing rice bran tocopherol, tocotrienol and γ-oryzanol contents

Chemical composition and nutritional profile of cicada (Meimuna opalifera Walker) at different developmental stages: Implications for functional food applications

This investigation explored chemical changes in cicadas during their developmental stages (nymph, late nymph, and adult). Tocopherols (α, δ, γ) were found at a total content of 13.7 mg/g, while γ-oryzanol was observed at 2.6 mg/g, with nymphs having the highest levels, followed by late nymphs and adults. Essential amino acids increased progressively with maturation, with methionine being the predominant amino acid in all samples. The index of essential amino acids in each tissue was as follows: adult (0.36), late nymph (0.33), and nymph (0.12). Eicosapentaenoic acid concentrations varied from 230 mg/100 g in adults to 880 mg/100 g in nymphs. Protein analysis using the Protein Simple Jess system revealed a molecular weight distribution ranging from 10 to 75 kDa, accounting for approximately 70 % of the total protein content. These findings offer valuable insights for incorporating cicadas as functional food ingredients, diversifying food product formulations.

Discrimination of red and white rice bran from Indonesia using HPLC fingerprint analysis combined with chemometrics

HPLC fingerprint analysis combined with chemometrics was developed to discriminate between the red and the white rice bran grown in Indonesia. The major component in rice bran is γ-oryzanol which consisted of 4 main compounds, namely cycloartenol ferulate, cyclobranol ferulate, campesterol ferulate and β-sitosterol ferulate. Separation of these four compounds along with other compounds was performed using C18 and methanol-acetonitrile with gradient elution system. By using these intensity variations, principal component and discriminant analysis were performed to discriminate the two samples. Discriminant analysis was successfully discriminated the red from the white rice bran with predictive ability of the model showed a satisfactory classification for the test samples. The results of this study indicated that the developed method was suitable as quality control method for rice bran in terms of identification and discrimination of the red and the white rice bran.

Changes in the Bioactive Compounds Content of Soybean as a Function of Grain Moisture Content and Temperature during Long-Term Storage

Soybean is a rich source of bioactive compounds, such as phenolic acids, flavonoids, isoflavones, carotenoids, and tocopherols. The amount of bioactive compounds in freshly harvested soybeans and their derived products has been determined; however, when they are used in the food industry, soybeans are generally stored prior to being processed. This study aimed to evaluate the effects of soybean moisture content (12%, 15%, and 18%) and storage temperature (11, 18, 25, and 32 °C) on the free phenolic, total flavonoid, vanillic acid, total carotenoid, and δ- and γ-tocopherol content of soybeans stored for 12 mo. Moreover, the ABTS and DPPH radical scavenging activities of phenolic extracts were determined. There was an increase in free phenolics and total flavonoids in the stored grains compared with the grains on the 1st d of storage. Vanillic acid showed a decrease in soybeans stored at 15% and 18% moisture content and 25 or 32 °C, which indicated some degradation into other metabolites. Total carotenoid content decreased as a function of storage temperature and showed some temperature-dependent degradation. The δ- and γ-tocopherol content also tended to decrease in grains stored at 15% or 18% moisture content or 25 or 32 °C, regardless of the moisture content studied.

Conventional steaming retains tocols and γ-oryzanol better than boiling and frying in the jasmine rice variety Khao dok mali 105

The aim of this study was to determine the effect of various cooking methods on the white rice (WR), brown rice (BR) and parboiled geminated brown rice (PGBR) of the same variety, focusing on γ-oryzanol and tocols. The methods used for analysis of γ-oryzanol and tocols included solvent extraction and HPLC. The results indicated that PGBR had a higher content of γ-oryzanol and tocols compared to BR and WR, when different cooking methods (raw, steamed, boiled and fried) were used. Steaming method retained the higher γ-oryzanol content (53.6-62.2mg/100g) in both PGBR and BR, in comparison with boiling (53.0-60.6mg/100g) and frying (23.4-31.5mg/100g) methods. Frying reduced the γ-oryzanol content significantly regardless of the rice type. Regarding tocols, a similar trend was noticed in all the methods studied. Tocotrienol was the most abundant tocol found in PGBR and BR. Therefore, steaming is the best cooking method to preserved most of the bioactive compounds; however, a slight increase in total tocols was observed after frying.

Kinetic study of the quenching reaction of singlet oxygen by seven rice bran extracts in ethanol solution. Development of a singlet oxygen absorption capacity (SOAC) assay method

Measurements of singlet oxygen (1O2) quenching rates (kQ (S)) and the relative singlet oxygen absorption capacity (SOAC) values were performed for seven rice bran extracts 1–7, which contained different concentrations of antioxidants (AOs) (such as α-, β-, γ-, and δ-tocopherols and -tocotrienols, three carotenoids (lutein, β-carotene, and zeaxanthin), and γ-oryzanol), in ethanol at 35 °C using UV–vis spectrophotometry. The concentrations of four tocopherols and four tocotrienols, three carotenoids, and γ-oryzanol contained in the extracts were determined using HPLC-MS/MS, UV-HPLC, and UV–vis absorption spectroscopy, respectively. Furthermore, comparisons of kQ (S) (Obsd.) values observed for the above extracts 1–7 with the sum of the product { [AO-i]} of the values obtained for each AO-i and the concentration ([AO-i]) of AO-i contained in extracts 1–7 were performed. From the results, it has been ascertained that the SOAC method is applicable to general food extracts to evaluate their 1O2-quenching activity.

Nanoencapsulation of rice bran oil increases its protective effects against UVB radiation-induced skin injury in mice

Excessive UV-B radiation by sunlight produces inflammatory and oxidative damage of skin, which can lead to sunburn, photoaging, and cancer. This study evaluated whether nanoencapsulation improves the protective effects of rice bran oil against UVB radiation-induced skin damage in mice. Lipid-core nanocapsules containing rice bran oil were prepared, and had mean size around 200 nm, negative zeta potential (∼-9 mV), and low polydispersity index (<0.20). In order to allow application on the skin, a hydrogel containing the nanoencapsulated rice bran oil was prepared. This formulation was able to prevent ear edema induced by UVB irradiation by 60 ± 9%, when compared with a hydrogel containing LNC prepared with a mixture of medium chain triglycerides instead of rice bran oil. Protein carbonylation levels (biomarker of oxidative stress) and NF-κB nuclear translocation (biomarker of pro-inflammatory and carcinogenesis response) were reduced (81% and 87%, respectively) in animals treated with the hydrogel containing the nanoencapsulated rice bran oil. These in vivo results demonstrate the beneficial effects of nanoencapsulation to improve the protective properties of rice bran oil on skin damage caused by UVB exposure.

Kinetic study of the scavenging reaction of the aroxyl radical by seven kinds of rice bran extracts in ethanol solution. Development of an aroxyl radical absorption capacity (ARAC) assay method

Recently, a new assay method that can quantify the aroxyl radical (ArO•) absorption capacity (ARAC) of antioxidants (AOHs) was proposed. In the present work, the second-order rate constants (ks(Extract)) and ARAC values for the reaction of ArO• with seven kinds of rice bran extracts 1-7, which contain different concentrations of α-, β-, γ-, and δ-tocopherols and -tocotrienols (α-, β-, γ-, and δ-Tocs and -Toc-3s) and γ-oryzanol, were measured in ethanol at 25 °C using stopped-flow spectrophotometry. The ks(Extract) value (1.26 × 10(-2) M(-1) s(-1)) of Nipponbare (extract 1) with the highest activity was 1.5 times larger than that (8.29 × 10(-3)) of Milyang-23 (extract 7) with the lowest activity. The concentrations (in mg/100 g) of α-, β-, γ-, and δ-Tocs and -Toc-3s and γ-oryzanol found in the seven extracts 1-7 were determined using HPLC-MS/MS and UV-vis absorption spectroscopy, respectively. From the results, it has been clarified that the ArO•-scavenging rates (ks(Extract)) (that is, the relative ARAC value) obtained for the seven extracts 1-7 may be approximately explained as the sum of the product {Σ ks(AOH-i) [AOH-i]/10(5)} of the rate constant (ks(AOH-i)) and the concentration ([AOH-i]/10(5)) of AOH-i (Tocs, Toc-3s, and γ-oryzanol) included in rice bran extracts. The contribution of γ-oryzanol to the ks(Extract) value was estimated to be between 3.0-4.7% for each extract. Taken together, these results suggest that the ARAC assay method is applicable to general food extracts.

Infrared stabilization of rice bran and its effects on γ-oryzanol content, tocopherols and fatty acid composition

BACKGROUND

Rice bran is a nutritionally valuable by-product of paddy milling. In this study an experimental infrared (IR) stabilization system was developed to prevent rice bran rancidity. The free fatty acid content of raw and IR-stabilized rice bran samples was monitored every 15 days during 6 months of storage. In addition, energy consumption was determined.

RESULTS

The free fatty acid content of rice bran stabilized at 600 W IR power for 5 min remained below 5% for 165 days. No significant change in γ-oryzanol content or fatty acid composition but a significant decrease in tocopherol content was observed in stabilized rice bran compared with raw bran. IR stabilization was found to be comparable to extrusion with regard to energy consumption.

CONCLUSION

IR stabilization was effective in preventing hydrolytic rancidity of rice bran. By optimizing the operational parameters of IR stabilization, this by-product has the potential for use in the food industry in various ways as a value-added commodity.

Assessment of the quality of bran and bran oil produced from some Egyptian rice varieties

BACKGROUND

Rice (Oryza sativa L.) is one of the leading food crops of the world, the staple food of over half the world's population. The bran, which is an important byproduct obtained during rice milling, constitutes about 1/10 of the weight of the rice grain. Rice bran is the outer brown layer including the rice germ that is removed during the milling process of brown grain. This milling byproduct is reported to be high in natural vitamins and minerals, particularly vitamin E.

OBJECTIVES

The present study was conducted to determine the chemical composition of bran and bran oil of 13 different rice varieties commonly produced in Egypt, to study the utilization of rice bran in bread production, and to assess the quality and acceptance of the rice bran edible oil produced.

METHODS

Rice bran was produced from 13 Egyptian varieties of recently harvested rice as well as from paddy rice stored for 1 year. The extracted bran was immediately stabilized then subjected to chemical analysis (such as moisture content, protein, fat, carbohydrates, fiber, and ash) as well as trace and heavy metals determination (P, K, Na, Ca, Fe, Zn, Cu, and Mg). Bread was produced by adding Giza172 rice bran at three different concentrations to wheat flour then subjected to chemical analysis, caloric content, and organoleptic examination. Bran oil was extracted from the different varieties of rice bran (recently harvested and stored) then subjected to chemical and organoleptic examinations as well as vitamin E and oryzanol determination.

RESULTS

The percentage of rice bran of newly harvested Egyptian rice was 11.68% and was 10.97% in stored rice. The analysis showed mean values of 5.91 and 5.53% for moisture, 14.60 and 14.40% for crude protein, 14.83 and 15.20% for fat, 44.77 and 45.40% for carbohydrates, 6.55 and 7.06% for crude fiber, and 8.87 and 8.50% for ash for newly harvested and stored rice bran, respectively. Bread containing 15% rice bran showed the highest score percentages for organoleptic quality compared with the control (100% wheat flour). Rice bran oil showed higher scores of taste, smell, appearance, and texture than corn oil and sunflower oil.

CONCLUSION

Rice bran contains high nutritional components as well as phytochemicals such as vitamin E (i.e. tocopherols and tocotrienols) and the γ-oryzanol fraction that have positive effects on human health. Storage of paddy rice before milling resulted in significant effect on all studied rice bran characters and rice bran oil characters under the present investigation except crude protein and carbohydrates characters.

RECOMMENDATIONS

Substitution of wheat flour with rice bran by 15% in bread production to fortify the bread with vitamin E and to reduce the amount of imported flour is recommended.

Comparison of the activities of hydrophilic anthocyanins and lipophilic tocols in black rice bran against lipid oxidation

The antioxidant capabilities of anthocyanin and tocol extracts from black rice bran were evaluated using an emulsion system containing either cholesterol (1.0mg/ml) or fish oil (10mg/ml). The cholesterol oxidation product, 7-ketocholesterol, increased to 180.1 μg/ml in the control emulsion after 168 h of oxidation, while it was only 15.4 and 39.0 μg/ml in the emulsions containing 1 μg/ml of the anthocyanin and tocol extracts, respectively; but below 1.2 μg/ml in the emulsion having 5 μg/ml of anthocyanins or tocols. In the fish oil emulsion, over 80% of C20:5 and C22:6 were oxidised after a 48 h incubation at 37°C, while they were retained above 38% and 65% in the emulsions containing 10 μg/ml of anthocyanins and tocols, respectively, and above 85% in the emulsion containing 20 μg/ml of anthocyanins or tocols. Compared with the tocols extract, the capability of the anthocyanin extract was relatively greater in stabilising cholesterol but lower in inhibiting fatty acids oxidation.

γ-Oryzanol, tocol and mineral compositions in different grain fractions of giant embryo rice mutants

BACKGROUND

Rice embryo is concentrated with lipid, protein and some bioactive chemicals. Two rice mutants IR64-GE and TNG71-GE (M7 generation) were characterised by an enlarged embryo compared with their wild types. In the present study, distributions of protein, lipid, total phenolics, γ-oryzanol, tocols and some essential minerals in these two giant embryo mutants and their respective normal embryo wild types IR64 and TNG71 were compared.

RESULTS

The embryo dry weights of giant embryo mutants IR64-GE and TNG71-GE were 0.92 and 1.32 mg per seed respectively. These values were higher than those of their respective normal embryo genotypes (0.50 and 0.62 mg per seed). Large variations in protein, lipid, phenolic, γ-oryzanol, tocol and minerals levels were found between mutant and wild-type pairs. The brown rice of TNG71-GE had higher total γ-oryzanol (average of 24% increase) and total tocol (average of 75% increase) levels than TNG71, IR64 and IR64-GE.

CONCLUSION

The embryo and bran parts of giant embryo mutant TNG71-GE were found to be good sources of vitamin E and γ-oryzanol. Therefore it could be used to produce high-value by-products from milled embryo and bran parts and as a genetic resource for rice improvement programmes. TNG71-GE can also be used as a nutrient-fortified rice cultivar.

Optimization of ultrasonic-assisted extraction of natural antioxidants from rice bran using response surface methodology

Ultrasonic technology was applied for extraction of polyphenols and antioxidants from the rice bran using ethanol as a food grade solvent. Response surface methodology (RSM) was used to optimize experimental conditions for extraction of polyphenols and antioxidants. Three independent variables such as solvent percentage (%), temperature (°C) and time (min) were studied. Effect of ethanol concentration was found to be significant on all responses. Total phenolic content (TPC) varied from 2.37 to 6.35mg gallic acid equivalent/g of dry sample. Antioxidant activity of the extracts was determined by the ferric reducing antioxidant power (FRAP) assay and scavenging activity of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. FRAP and DPPH values varied from 31.74 to 57.23μmol Fe(2+)/g of dry sample and 16.88% to 55.61% inhibition, respectively. Extraction yields ranged from 11 to 20.2%. Optimal ultrasonic-assisted extraction (UAE) conditions were identified as 65-67% ethanol, 51-54°C, 40-45min. The experimental values agreed with those predicted by SRM models, thus indicating suitability of the model employed and the success of RSM in optimizing the extraction conditions.

Quantification of tocopherols, tocotrienols, and γ-oryzanol contents and their distribution in some commercial rice varieties in Taiwan

The eight vitamin E isomers [α-, β-, γ-, and δ-tocopherols (T) and α-, β-, γ-, and δ-tocotrienols (T3)] and γ-oryzanol are known to possess diverse biological activities. This study examined the contents of these compounds and their distribution in 16 commercial rice varieties in Taiwan. Results showed that the order of vitamin E, total T, total T3, and γ-oryzanol contents was rice bran > brown rice > rice husk > polished rice. γ-T3 was the highest vitamin E isomer present in all rice samples, while β-T, β-T3, δ-T, and δ-T3 were present in trace amounts. The Japonica varieties contained a higher total T, total T3, and γ-oryzanol than the Indica varieties. They also have a higher level of α-T and α-T3 but a lower level of γ-T and γ-T3 than the Indica varieties. However, no obvious difference in total T, total T3, and γ-oryzanol content was noted between black- and red-colored rice varieties.

Comparisons of protein, lipid, phenolics, γ-oryzanol, vitamin E, and mineral contents in bran layer of sodium azide-induced red rice mutants

BACKGROUND

The bran part of red rice grain is concentrated with many phytochemicals, including proanthocyanidins, oryzanol and vitamin E, that exert beneficial effects on human health, but it contains low levels of essential minerals such as Fe and Zn. In the present study, the protein, lipid, phytochemicals and mineral contents in bran samples were compared among red rice SA-586 and its NaN₃-induced mutants.

RESULTS

The plant heights of NaN₃-induced mutants were decreased. The contents of protein, lipid, total phenolics, total flavonoids, total anthocyanins, total proanthocyanidins, total γ-oryzanol, total tocopherols and total tocotrienols also varied among the tested mutants. The brans of mutants M-18, M-56 and M-50 contained more proanthocyanidins, γ-oryzanol, vitamin E than that of SA-586, respectively. M-54 accumulated more Fe content (588.7 mg kg⁻¹ bran dry weight) than SA-586 (100.1 mg kg⁻¹ bran dry weight).

CONCLUSIONS

The brans of M-18, M-50 and M-56 are good sources of proanthocyanidins, vitamin E and γ-oryzanol, respectively, while the bran of M-54 is rich in Fe. Thus these mutants could be used to produce high-value phytochemicals or Fe byproducts from bran during rice grain milling or as genetic resources for rice improvement programs.

Phytochemicals and antioxidant capacities in rice brans of different color

Rice bran, a byproduct of the rice milling process, contains most of the phytochemicals. This study aimed at determining the concentrations of lipophilic, solvent-extractable (free), and cell wall-bound (bound) phytochemicals and their antioxidant capacities from brans of white, light brown, brown, purple, and red colors, and broccoli and blueberry for comparison. The concentrations of lipophilic antioxidants of vitamin E (tocopherol and tocotrienols) and γ-oryzanols were 319.67 to 443.73 and 3861.93 to 5911.12 μg/g bran dry weight (DW), respectively, and were not associated with bran color. The total phenolic, total flavonoid, and antioxidant capacities of ORAC (oxygen radical absorbance capacity), DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging, and iron-chelating in the free fraction were correlated with the intensity of bran color, while variations of these in the bound fraction were less than those in the free fraction among brans. Compounds in the bound fraction had higher antioxidant capacity of ORAC than DPPH, relative to those in the free fraction. The bound fraction of light-color brans contributed as much to its total ORAC as the free fraction. Total proanthocyanidin concentration was the highest in red rice bran, while total anthocyanin was highest in purple brans. The predominant anthocyanin was cyanidin-3-glucoside. Red and purple brans had several fold higher total phenolics and flavonoids as well as ORAC and DPPH, from both free and bound fractions, than freeze-dried blueberry and broccoli. These results indicate that rice brans are natural sources of hydrophilic and lipophilic phytochemicals for use in quality control of various food systems as well as for nutraceutical and functional food application.

Study on total phenolic contents and their antioxidant activities of Thai white, red and black rice bran extracts

In this study, different brans of Thai rice cultivars which were divided into 3 groups: white color (Hom mali 105, Supan, Saohai, Hom chaiya and Hom jun), red color (3256, GS 18003, 21606, 21699 and 5718) and black color (96041-20, 96051-37, 96004-49, 96023-35 and 96065-42) were investigated their Total Phenolic Content (TPC) and antioxidant activities. The rice brans were firstly extracted using methanol. The extracts were analyzed using Folin-Ciocalteau method for total phenolic content while thiocyanate method and 1,1-diphenyl-2-picrylhydrasyl (DPPH) free radical-scavenging assay were used for antioxidant activities determination. The results indicated that the total phenolic content of white, red and black rice bran extract were in the range of 0.8931-0.9884, 1.0103-1.0494 and 1.0810-1.2239 mg gallic acid equivalent (GAE mg(-1)), respectively. With thiocyanate method, percentage inhibition were in the range of 10.15-20.68, 30.64-38.80 and 25.52-26.28 for white, red and black rice bran extract, respectively. With DPPH radical-scavenging assay, methanolic extract of 5718 showed the highest (IC50=0.0057 mg mL(-1)) while Homchaiya showed the lowest (IC50=0.2582 mg mL(-1)) activities. All of extracts showed lower activity than BHA (IC50=0.0012 mg mL(-1)). However, the antioxidant activity of all rice bran extracts indicated high antioxidant efficiency in the following order: red>black>white color rice brans. It is a promising that Thai rice bran are potential antioxidant sources.

Tocotrienol distribution in foods: estimation of daily tocotrienol intake of Japanese population

Tocotrienol (T3) is an unsaturated form of natural vitamin E that has been focused on because of its potential health benefits (i.e., antioxidative, antihypercholesterolemic, and antiangiogenic effects). The presence of T3 in some plant sources (e.g., rice bran and palm oil) is known, but its distribution in other edible sources and its daily intake remain unclear. In this study, we aimed at clarifying the distribution of T3 in various food sources and estimating the daily T3 intake of Japanese population. T3 contents of 242 food items and 64 meal items were measured by using normal-phase HPLC with fluorescence detection. As for the results, T3 contents were nondetectable to 12 mg T3/kg wet wt of food items, and nondetectable to 1.3 mg T3/item of processed (cooked) meal. Accordingly, the daily intake of T3 was estimated as 1.9-2.1 mg T3/day/person. The estimated daily intake of T3 appears rather low compared with the intake of tocopherol (8-10 mg/day/person as reported in the Japanese National Nutrition Survey), and additional T3 is important for its therapeutic aspects.

Lipophilic and hydrophilic antioxidants and their antioxidant activities in purple rice bran

Purple rice bran was separated and collected at two different milling periods, resulting in two bran (outer and inner layer) fractions. The distribution of lipophilic and hydrophilic antioxidants and their antioxidant activities in the two fractions were studied. The bran fractions were extracted with hexane followed by methanol to obtain lipophilic and hydrophilic extracts, respectively. The total phenolic content and free radical scavenging activity of the extracts were determined and compared. The lipophilic extract from the outer bran fraction (OBF) exhibited a lower level of total tocols and gamma-tocols, compared with the inner bran fraction (IBF), while the levels of gamma-oryzanol in both fractions were not different. However, the lipophilic phenolic content and free radial scavenging activity of the OBF were 6.0 microg catechin equivalent (CE)/g and 5.6 micromol trolox equivalent (TE)/g and higher than those of the IBF, respectively. For the hydrophilic extracts, the level of anthocyanins in the IBF (29.0 mg/g) was 8 times higher than that in the OBF. Also, the hydrophilic phenolic content and free radical scavenging activity of the IBF were 489.1 microg CE/g and 433.6 micromol TE/g, respectively, while they were 113.9 microg CE/g and 78.2 micromol TE/g in the OBF. Both hydrophilic extracts showed significantly higher phenolic content and free radical scavenging activity than any lipophilic extract. The results of this study indicated that the activity of purple rice bran hydrophilic antioxidants was much greater than that of its lipophilic antioxidants and anthocyanins and gamma-tocols largely located in the inner portion of purple rice bran.