Partial extraction method for the rapid analysis of total lipids and γ-oryzanol contents in rice bran

Total lipids and γ-oryzanol in rice bran were determined by a partial extraction method. The results agreed well with the conventional total extraction methods. The proposed method uses fewer hazardous organic solvents, takes a shorter extraction time and requires no special extraction apparatus. Total lipids and γ-oryzanol in nine rice bran varieties were analysed by the developed technique. Daw Dum 5647 had the highest total lipids and γ-oryzanol while the lowest content was found in KD XBT 313-19-1-1 and SP XBT 43-7, respectively. The adsorption coefficient (K_d) of the lipids and γ-oryzanol, between hexane and bran, at 30 °C are between 1.16 and 2.00 and 2.02 and 2.65, respectively (depending on the moisture content of the bran). From the K_d values, it was estimated that about 92–95% of the lipids and 95–96% of the γ-oryzanol were extracted into hexane at a 10:1 (v/w) ratio of hexane to bran. The effect of solvents on the extraction of γ-oryzanol from rice bran was also studied. It was found that isopropanol was the most suitable solvent for extraction and determination of γ-oryzanol in rice bran. It showed better agreement with the total extraction method.     

Antioxidants in milling fractions of black rice cultivars

Coloured rice, particularly black rice, has been shown to possess bioactive properties, and rice bran contains high levels of several antioxidant compounds. The aim of this study was to quantify the major antioxidant compounds in the milling fractions of black rice. Whole black rice of two cultivars (Oryza sativa cv. Heugjinjubyeo and O. sativa L. Heugkwangbyeo) was milled into rice bran and endosperm using the gradual milling system (85% milling degree). Relatively high levels of free polyphenols and flavonoids from two cultivars were found in the bran fractions (98.5 and 81.0 mg of polyphenols and 19.8 and 15.1 mg of flavonoids) while low levels were found in endosperm fractions. Compared to free polyphenols and flavonoids, low levels of bound polyphenols and flavonoids were found in all fractions. The black rice bran contained most of the antioxidant compounds, including phytic acid, γ-oryzanol, anthocyanins, and vitamin E homologues.     

Gamma-oryzanol content,phenolic acid profiles and antioxidant activity of rice milling fractions

This study was aimed to determine γ-oryzanol content and total phenolics, individual phenolic acid profile and the antioxidant activity of the free and bound extracts of rice milling fractions namely, brown rice, unpolished rice, white rice, chalky rice, raw seed and rice bran. Gamma-oryzanol content of milling fractions which is designated with a simple chromatographic method was in the range of 12.19–3,296.5 mg/kg. The whitening and polishing steps reduced approximately 94% of γ-oryzanol of the brown rice when becoming the white rice. The contribution of bound phenolics to the total phenolic content was approximately 40%. Ferulic and p-coumaric acids were the most abundant phenolic acids in bound phenolic extracts and their amounts were 119.98 and 18.10 μg/g, respectively, in rice bran. The best source of γ-oryzanol, phenolics and antioxidants was clearly rice bran and followed by raw seed and brown rice.     

Evaluation of various Bacillus coagulans isolates for the production of high purity L-lactic acid using defatted rice bran hydrolysates

Defatted rice bran (DRB) constitutes an abundant by-product stream, generated during rice milling and subsequent bran oil extraction. Enzymatic hydrolysis of starch and protein content in DRB was optimised in terms of solid loading. Among the four solid loadings evaluated (10%, 15%, 20% and 25%), the hydrolysate derived from 20% solids resulted in the highest concentration of glucose (82.3 g L⁻¹) and free amino nitrogen (234.8 mg L⁻¹). The fermentability of the hydrolysate was evaluated via screening of sixteen isolates. All the strains were able to grow and produce high purity L-lactic acid, utilising the DRB as sole carbon and nutrient source. Among the studied strains, the Bacillus coagulans A107 isolate presented the most promising results in terms of final lactic acid concentration (75.9 g L⁻¹), yield (0.90 g g⁻¹) and productivity (2.7 g L⁻¹ h⁻¹). The results of this study indicate that DRB could be employed as an inexpensive, alternative substrate for L-lactic acid production.     

Free and bound total phenolic concentrations,antioxidant capacities,and profiles of proanthocyanidins and anthocyanins in whole grain rice (Oryza sativa L.) of different bran colours

To study the polyphenols in whole grain rice varying in bran colour, the total phenolics, flavonoids and antioxidant capacities of the solvent-extractable (Free) and cell-wall bound (Bound) fractions and the profiles of proanthocyanidins and anthocyanins were determined. Red and purple bran rices had significantly higher total (sum of Free- and Bound-) phenolic (PC) and flavonoid (FC) concentrations and antioxidant capacities than light-coloured bran rice or other cereals (P < 0.05), due to their higher concentrations of proanthocyanidins and anthocyanins, respectively. The concentrations of the Bound-PC and FC accounted for approximately half of the total PC and FC in the light-coloured bran rice, but were lower than those in purple and red bran rice (P < 0.05). High correlations were found between the concentrations of total phenolics and the three antioxidant capacity assays except for those in the bound fraction when related to iron chelating capacity. The concentrations of proanthocyanidins in red bran rice was 1.27 mg/g and its composition was 6.5%, 33.5%, 30.6% and 29.4% of 1–3, 4–6, 7–10 mers, and polymer (>10 mers), respectively. Cyanidin-3-glucoside was the predominant anthocyanin and peonidin-3-glucoside was the second highest; the profiles varied between purple bran cultivars. Whole grain rice differing in bran colour contained unique polyphenol subgroups, which have been proposed to positively impact human health.     

Short communication: Comparing real-time PCR and bacteriological cultures for Streptococcus agalactiae and Staphylococcus aureus in bulk-tank milk samples

For more than 30 yr, a control plan for Streptococcus agalactiae and Staphylococcus aureus has been carried out in more than 1,500 dairy herds of the province of Brescia (northern Italy). From 2010 to 2011, the apparent prevalence of Strep. agalactiae has been relatively stable around 10%, but the apparent prevalence of Staph. aureus has been greater than 40% with an increasing trend. The aim of this paper was to estimate and compare the diagnostic accuracy of 3 assays for the detection of Strep. agalactiae and Staph. aureus in bulk-tank milk samples (BTMS) in field conditions. The assays were a qualitative and a quantitative bacteriological culture (BC) for each pathogen and a homemade multiplex real-time PCR (rt-PCR). Because a gold standard was not available, the sensitivities (Se) and specificities (Sp) were evaluated using a Bayesian latent class approach. In 2012 we collected one BTMS from 165 dairy herds that were found positive for Strep. agalactiae in the previous 2-yr campaigns of eradication plan. In most cases, BTMS collected in these herds were positive for Staph. aureus as well, confirming the wide spread of this pathogen. At the same time we also collected composite milk samples from all the 8,624 lactating cows to evaluate the within-herd prevalence of Strep. agalactiae. Streptococcus agalactiae samples were cultured using a selective medium Tallium Kristalviolette Tossin, whereas for Staph. aureus, we used Baird Parker modified medium with added Rabbit Plasma Fibrinogen ISO-Formulation. In parallel, BTMS were tested using the rt-PCR. Regarding Strep. agalactiae, the posterior median of Se and Sp of the 2 BC was similar [qualitative BC: Se = 98%, posterior credible interval (95%PCI): 94–100%, and Sp = 99%, 95%PCI: 96–100%; quantitative BC: Se = 99%, 95%PCI: 96–100%, and Sp = 99%, 95%PCI: 95–100%] and higher than those of the rt-PCR (at 40 cycle threshold, Se = 92%, 95%PCI: 85–97%; Sp = 94%, 95%PCI: 88–98%). Also in case of Staph. aureus, the posterior medians of BC were generally higher than those of rt-PCR. In fact, although the Se of BC was slightly lower (rt-PCR at 40 cycle threshold, median Se = 99%, 95%PCI: 97–100%, and qualitative BC, median Se = 94%, 95%PCI: 87–99%), the Sp was much higher (rt-PCR at 40 cycle threshold, median Sp = 67%, 95%PCI: 38–97%; qualitative BC, median Sp = 95%; 95%PCI: 76–100%). Our study confirms that BC and rt-PCR are reliable diagnostic tools to detect Strep. agalactiae and Staph. aureus, and rt-PCR results should be confirmed by BC carried out on BTMS and possibly on composite milk samples.     

Release of phenolic acids from defatted rice bran by subcritical water treatment

BACKGROUND: Oil production from rice bran, an undervalued by‐product of rice milling, produces defatted rice bran (DRB) as a waste material. Although it is considered a less valuable product, DRB still contains useful substances such as phenolic compounds with antioxidant, UV‐B‐protecting and anti‐tumour activities. In this study the phenolic acids in DRB were extracted with subcritical water at temperatures of 125, 150, 175 and 200 °C. RESULTS: Analysis of total phenolics using Folin–Ciocalteu reagent showed about 2–20 g gallic acid equivalent kg^?1 bran in the extracts. High‐performance liquid chromatography analysis showed low contents of phenolic acids (about 0.4–2 g kg^?1 bran). Ferulic, p‐coumaric, gallic and caffeic acids were the major phenolic acids identified in the extracts. Thermal analysis of the phenolic acids was also done. The thermogravimetric curves showed that p‐coumaric, caffeic and ferulic acids started to decompose at about 170 °C, while gallic acid did not start to decompose until about 200 °C. CONCLUSION: Subcritical water can be used to hydrolyse rice bran and release phenolic compounds, but the high temperatures used in the extraction can also cause the decomposition of phenolic acids. Copyright © 2010 Society of Chemical Industry     

Composition,industrial processing and applications of rice bran γ-oryzanol

Rice bran oil (RBO) (20–25 wt% in rice bran) is a unique rich source of commercially-important bioactive phytochemicals, most of them of interest in nutrition, pharmacy and cosmetics. The unsaponifiable constituents of RBO include mainly tocols (vitamin E, 0.10–0.14%) and γ-oryzanol (esters of trans-ferulic acid with sterols and triterpenic alcohols, 0.9–2.9%). The following topics concerning γ-oryzanol are reviewed: analytical methods for characterisation and determination; influence of genetic and environmental factors on the composition of rice bran; extraction approaches, including supercritical CO₂ and subcritical water; and biomedical and industrial applications, including food and pharmaceuticals. Concentration ranges of γ-oryzanol, tocopherols and tocotrienols found in rice bran and RBO from different varieties and geographical areas are summarised. This review focuses on the 2003–2008 period, where an average of 13–14 references per year were published; however, some relevant work reported during the 1998–2002 period is also briefly commented upon.     

Antioxidant efficacy of phytochemical extracts from defatted rice bran in the bulk oil system

The antioxidant compounds oryzanols, tocols and ferulic acid were identified in the methanolic extracts of defatted rice bran (DRB) by high pressure liquid chromatography (HPLC). The crude methanolic extract (CME) was partially purified by re-extraction with acetone to give an acetone extract (AE). For further purification of the acetone extract, sequential solvent extraction was employed yielding a lipophilic phase (AE-LP) with hexane and a polar phase (AE-PP) with acetone. The antioxidant potential of the DRB extracts and their phytochemical constituents in bulk oils were evaluated using the Schall oven test (SOT) and differential scanning calorimetry (DSC). The extracts were effective in inhibiting lipid oxidation as assessed by peroxide value, diene value and p-anisidine value. The activity of the extracts with respect to the inhibition of primary oxidation products followed the order AE-PP > AE-LP = AE > CME with the activity of AE-PP being equivalent to that of butylated hydroxytoluene (BHT) at a 200 ppm level. However, tertiarybutylhydroquinone (TBHQ) was most active as compared to extracts and pure compounds with AE-PP showing about 45% of the activity of TBHQ at 200 ppm level. Defatted rice bran extracts proved to be effective even at the high temperature employed in DSC. The antioxidant efficacy of AE-PP was close to that of TBHQ and far greater than that of BHT at a 200 ppm level as evident from DSC results. The increase in activity with purification might be due to the enhanced levels of antioxidants in purified extracts compared to CME.     

Impact of phytochemical-rich foods on bioaccessibility of mercury from fish

The effects of phytochemical-rich foods on bioaccessibility of mercury in fish tissue (the amount of mercury that is released from fish into gastrointestinal tract fluid following a simulated digestion) were investigated using an in vitro digestion. Total mercury in the aqueous phase following a simulated digestion of fish with added food treatments was used to measure mercury bioaccessibility. Green tea extract (31–2000 mg), black tea extract (31–2000 mg), and soy protein (50–100 mg) significantly reduced mercury bioaccessibility by 82–92%, 88–91%, and 44–87%, respectively. Grapefruit juice (0.5–10 ml) did not reduce mercury in the aqueous phase. Wheat bran (50–1000 mg) decreased mercury bioaccessibility (84%); oat bran and psyllium reduced bioaccessibility (by 59–75%, 15–31%, respectively) at amounts greater than 500 mg. We therefore suggest that co-consumption of foods containing phytochemicals at the same time as fish that contains mercury may potentially reduce mercury absorption compared to eating fish alone.     

Degradation of cereal bran polysaccharide-phenolic acid complexes by Aspergillus niger CFR 1105

Cereal brans such as wheat and rice are abundant sources for obtaining bioactive phenolic compounds such as ferulic and coumaric acids, in turn these can be bio-transformed into high value flavour compounds such as vanillin. Aspergillus niger CFR 1105, found to induce greater amounts of cell wall degrading enzymes, was inoculated into wheat and rice brans, and grown for 24, 48, 72 and 96 h to understand the degradation pattern of non-starch polysaccharides and phenolic acid complexes. Native wheat bran polysaccharides mainly consisted of arabinose, xylose, galactose, and glucose, in % of 27:39:2:30, with traces of mannose, whereas rice bran consisted of arabinose, xylose, galactose, and glucose in % of 9:27:31:32, respectively. Both the cereal bran arabinoxylans were degraded extensively by A. niger at 96 h, whereas the degradation of 1,3/1,4-β-d-glucans and cellulose was negligible. Bound phenolic acids of rice and wheat brans identified by HPLC were found to be mainly ferulic, coumaric, syringic acids in % of 93.6:6.3:0 (wheat), 34.7:55.8:9.5 (rice) and were drastically degraded/utilized at 96 h. The above results have indicated preferential degradation of arabinoxylans of wheat bran by A. niger, which can be exploited to obtain bioactive compounds such as ferulic acid.     

Preparation of Fiber and Mineral Enriched Pan Bread by Using Defatted Rice Bran

Wheat flour was gradually replaced with defatted rice bran (DRB) at different levels. Five treatments (T₀ = control i.e. without DRB; T₅ = 5% DRB; T₁₀ = 10% DRB; T₁₅ = 15% DRB; T₂₀ = 20% DRB) were used for bread preparation. Bread loaves were analyzed for chemical composition and sensory evaluation at different storage intervals i.e. S_0, S_24, S_48, S_72, S_96, and S₁₂₀ hours. Protein, ash, fiber, and mineral contents of breads were improved and moisture decreased significantly, whereas fat content showed non-significant effect for increasing levels of defatted rice bran. Maximum protein, ash, fiber, K, Ca, and Mg contents were found in T₂₀ while minimum values were observed in T_0. Moisture and Na contents were decreased by the subsequent addition of rice bran. Treatment T₅ got maximum scores for external characteristics (volume, color of crust, symmetry of form, evenness of bake, character of crust) and internal characteristics (grain, color of crumb, aroma, taste, and texture) of pan bread. From chemical assay and sensory evaluations, the authors concluded that the quality bread can be improved by the addition of 5% DRB having high fiber and mineral content for commercialization.     

Dephytinisation of rice bran and manufacturing a new food ingredient

Rice bran was extruded at 130 °C and a screw speed of 140 rpm for 20 s to inactivate lipase and prevent lipid oxidation. Although the extrusion process induced further complex formation between phytic acid and protein as well as between phytic acid and starch, nearly 94% of phytic acid in the extruded rice bran could still be removed by solid/liquid extraction conducted at 25 °C for 30 min using hydrochloric acid at pH 2 as solvent and a solvent/rice bran ratio of 15. After the extract had been neutralised and phytic acid removed, it was added back to the rice bran solid to replenish the nutritional and functional components of the solid. The mixture was then dried in a drum dryer to yield a powdered product. The dephytinised rice bran product contained most of the protein, fat, dietary fibre and B vitamins and more than 50% of the oryzanol originally present in the raw rice bran. © 2001 Society of Chemical Industry     

Rice varietal differences in bioactive bran components for inhibition of colorectal cancer cell growth

Rice bran chemical profiles differ across rice varieties and have not yet been analysed for differential chemopreventive bioactivity. A diverse panel of seven rice bran varieties was analysed for growth inhibition of human colorectal cancer (CRC) cells. Inhibition varied from 0% to 99%, depending on the variety of bran used. Across varieties, total lipid content ranged 5–16%, individual fatty acids had 1.4- to 1.9-fold differences, vitamin E isoforms (α-, γ-, δ-tocotrienols, and tocopherols) showed 1.3- to 15.2-fold differences, and differences in γ-oryzanol and total phenolics ranged between 100–275 ng/mg and 57–146 ng GAE/mg, respectively. Spearman correlation analysis was used to identify bioactive compounds implicated in CRC cell growth inhibitory activity. Total phenolics and γ-tocotrienol were positively correlated with reduced CRC cell growth (p < 0.05). Stoichiometric variation in rice bran components and differential effects on CRC viability merit further evaluation elucidate their role in dietary CRC chemoprevention.     

Effect of soaking and phytase treatment on phytic acid,calcium, iron and zinc in rice fractions

With the aim to maximise phytic acid removal and minimise losses of dry matter and minerals (Ca, Fe, Zn) in rice, three products (whole kernels and flour milled from white and brown rice; and bran, all from the same batch of variety Kenjian 90-31) were soaked in demineralized water at 10 °C (SDW), NaAc buffer of pH 3.5 at 10 °C (SAB), and 500 U L⁻¹ phytase of pH 5.5 at 50 °C (SPS). In whole kernels and flour of white rice, phytic acid removal was 100% by all treatments; losses of dry matter, Ca, Fe, and Zn were 2–5%, 12–63%, 9–10%, and apparent gain of 63–72%, respectively. In whole brown rice, SAB removed 75% phytic acid, and SPS 100% from flour; dry matter, Ca, Fe, and Zn losses were 1–16%, 26–56%, 39–45%, and 23–24%. In rice bran, SPS removed 92% phytic acid, and SAB 50%; dry matter, Ca, Zn, and Fe losses were 20%, 48%, 63%, and apparent gain of 5%, respectively.     

Purification of soluble rice bran fiber using ultrafiltration technology

Defatted rice bran (DRB), an excellent source of soluble rice bran fiber (SRBF), is a byproduct of rice bran oil extraction from whole rice bran. The common process for purifying SRBF extracted from DRB, dialysis and alcohol precipitation, is a complex process. Ultrafiltration technology was evaluated as an alternative process. Membranes of molecular weight cut-off (MWCO) 1, 5, and 10 kDa were used to purify the SRBF at 100 kPa. The apparent viscosity and °Brix of the SRBF solution increased after ultrafiltration, which demonstrated that the SRBF solution was concentrated during the ultrafiltration process. The apparent viscosity of the retentate collected in the ultrafiltration unit with the 1 kDa MWCO membrane had a higher (P < 0.05) viscosity than those collected in the 5 and 10 kDa MWCO membrane. The SRBF solution purified with 1, 5, and 10 kDa MWCO had similar concentrations of arabinose, galactose, and glucose, while the retentate of SRBF obtained from 10 kDa MWCO membrane had slightly lower xylose concentration than that resulting from 1 kDa MWCO. The 10 kDa MWCO membrane at a pressure of 100 kPa more effectively purified the SRBF solution than did 1 and 5 kDa MWCO membranes at the same pressure.     

Protective effect of rutin against ultraviolet b-induced cyclooxygenase-2 expression in mouse epidermal cells

Rice bran was heated at 120°C for 0 to 30 min to extend the oxidative stability. Also, effects of visible light irradiation on the crude rice bran oil (RBO) from rice bran heated at 120°C for 20 min were studied. As heat treatment time increased from 0 to 30 min, rice bran had significantly high oxidative stability at 40°C for 12 days (p<0.05). Headspace oxygen content in rice bran without heat treatment decreased significantly (p<0.05) whereas those in heat treated rice bran did not change significantly (p>0.05). Results of acid value and conjugated dienoic acid (CDA) confirmed the higher oxidative stability of heat treated rice bran. γ-Oryzanol content was not significantly different among crude RBO during heat treatment and storage (p>0.05). Visible light irradiation caused similar degree of lipid oxidation in crude RBOs from rice bran irrespective of heat stabilization for 48 h, which may be due to the presence of photosensitizers in crude RBO like chlorophylls. This study showed that heat treatment was not effective to enhance the oxidative stability of RBO under visible light irradiation and products containing rice bran should be stored in the dark conditions.     

The analysis of phenolic constituents in glabrous canaryseed groats

Nineteen glabrous canaryseed samples, comprising brown- and yellow-coloured seeds, were investigated to determine the nature of phenolic constituents present. Total phenolic content (TPC) was determined, using the Folin–Ciocalteau assay. Flavonoid and phenolic acid compositions were determined, using high performance liquid chromatographic and mass spectrometric (LC–MS/MS) techniques. TPC ranged from 174 to 209 mg/100 g for canaryseed wholemeal samples. The canaryseed bran contained twice as much TPC as the wholemeal. The brown- and yellow-coloured whole canaryseeds exhibited the same flavonoid profiles. LC–MS/MS analysis showed that the canaryseed acetone extract was rich in flavonoid glycosides, with the bran being mainly composed of O-pentosyl isovitexin and the flour having a compound at m/z 468. No proanthocyanidins were detected in the 19 samples. Ferulic acid was the dominant phenolic acid, followed by caffeic and p-coumaric acids. The wholemeal obtained from the brown-coloured group had significantly higher contents of ferulic (>196 mg/kg) and caffeic (>96 mg/kg) acids in comparison to the yellow-coloured canaryseed group. The latter had ferulic and caffeic acids at levels less than 165 and 78 mg/kg, respectively, with one exception which had relatively higher levels (190 and 94 mg/kg). Whilst canaryseed flour contained significantly very low levels of ferulic acid (22–34 mg/kg), the bran was enriched in ferulic (593–766 mg/kg), caffeic (304–452 mg/kg) and p-coumaric (119–142 mg/kg) acids.     

Phytochemicals and antioxidant properties of solvent extracts from Japonica rice bran

The yield, major phytochemicals (oryzanols, tocopherols (T), and tocotrienols (T3)) and antioxidant properties of Japonica rice bran extracts were investigated, for illustrating the major effects from solvent property. Generally, the extract yield varied with the solvent used in the order of methanol (MeOH) > ethyl acetate (EtOAc) > hexane. In contrast to hexane extracts, both MeOH and EtOAc extracts exhibited a higher total content in phenolic compounds (∼2.5 g gallic acid equivalent/kg bran), oryzanols (1.6–1.8 g/kg bran), or tocols (126–130 mg/kg bran), and a higher T3% in tocols (24–26%). The MeOH extract (at 1 mg/ml) showed the greatest capability in inhibiting linoleic acid peroxidation (57%), scavenging DPPH radicals (93%), reducing power (78%), and Fe²⁺ chelating activity (∼1300 μg EDTA equivalent/g) than the other two extracts, partly attributed to its high antioxidant contents. It is newly found that the yield, total content in phenolic compounds, oryzanols, and tocols, and T3% in tocols of the extracts increased with increasing Synder’s polarity value in a quite good linear manner (R² = 0.923–1.000), associated with an increased solvent viscosity. This clearly suggests the potential of using Synder’s polarity value as an index in isolation of desired rice bran phytochemical extracts.