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.     

γ-Oryzanol and tocopherol contents in residues of rice bran oil refining

Rice bran oil (RBO) contains significant amounts of the natural antioxidants γ-oryzanol and tocopherols, which are lost to a large degree during oil refining. This results in a number of industrial residues with high contents of these phytochemicals. With the aim of supporting the development of profitable industrial procedures for γ-oryzanol and tocopherol recovery, the contents of these phytochemicals in all the residues produced during RBO refining were evaluated. The samples included residues from the degumming, soap precipitation, bleaching earth filtering, dewaxing and deodorisation distillation steps. The highest phytochemical concentrations were found in the precipitated soap for γ-oryzanol (14.2 mg g⁻¹, representing 95.3% of total γ-oryzanol in crude RBO), and in the deodorisation distillate for tocopherols (576 mg 100 g⁻¹, representing 6.7% of total tocopherols in crude RBO). Therefore, among the residues of RBO processing, the deodorisation distillate was the best source of tocopherols. As the soap is further processed for the recovery of fatty acids, samples taken from every step of this secondary process, including hydrosoluble fraction, hydrolysed soap, distillation residue and purified fatty acid fraction, were also analyzed. The distillation residue left after fatty acid recovery from soap was found to be the best source of γ-oryzanol (43.1 mg g⁻¹, representing 11.5% of total γ-oryzanol in crude RBO).     

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. Copyright © 2011 Society of Chemical Industry     

A new rapid spectrophotometric quantitative determination method for γ-decalactone and application in high-throughput screening for γ-decalactone producing strains

A new, rapid spectrophotometric quantitative determination method for γ-decalactone (GDL) was developed based on the ferric hydroxamate reaction. Samples added to a mixture of NH₂OH·HCl and NaOH were heated to react. Then HCl was added. Ferric chloride was added for coloration, and 75% (v/v) ethanol was added. Absorbance values were measured after coloring for 10 min. The concentration range of a GDL calibration curve was 0.125–8.14 g/L. A 96-well plate high-throughput screening method was established to obtain desirable strains. A total of 215 GDL-producing strains were identified from 4,327 samples. The highest production was 179 mg/L.     

Development and application of a method for analysis of phthalates in ham sausages by solid-phase extraction and gas chromatography–mass spectrometry

A gas chromatography-mass spectrometry assay was developed and successfully applied for the determination of phthalates in ham sausage migrated from packaging film. The phthalates studied were dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), benzylbutyl phthalate (BBP), bis(2-ethylhexyl) phthalate (DEHP) and di-n-octyl phthalate (DNOP) , with dibutyl adipate (DBA) as internal standard. The sample pre-treatments included extraction with n-hexane, solvent evaporation and reconstitution with acetonitrile before and after solid-phase extraction (SPE). The extraction and cleaning up procedure was carried out with cartridges containing dimethyl butylamine groups, which showed extraction efficiencies over 87.3%. The calibration curves obtained were linear with correlation coefficients greater than 0.99. The method proved to be accurate and precise for the six phthalates used. It was successfully applied to a study on the migration of phthalates from packaging PVC film into ham sausage.     

Speciation of arsenite and arsenate in rice grain – Verification of nitric acid based extraction method and mass sample survey

Arsenite and arsenate speciation was performed in 121 commercially purchased samples of 12 rice types to understand their relative relevance in rice grain. General effectiveness of a recently developed extraction protocol based on 0.28 M nitric acid at 95 °C was verified by checking the recovery of total grain arsenic and by comparing arsenic speciation in NIST-CRM-1568a, NMIJ-CRM-7503a and IMEP-107 with certificated and literature values. The arsenic speciation highlights the predominance of arsenite in 115 and dimethylarsinic acid in six samples and common minor components including arsenate, monomethylarsonic acid and two unknown arsenical species. Our data also indicate potential influences of other trace elements on As speciation in rice grain. Averagely, arsenite accounts for 90% of inorganic grain arsenic regardless of geographic origin, rice type, grain size, cultural practice and polish treatment. The high arsenite predominance indicates an elevated toxic effect of arsenic in rice than is perceived to date.     

Evaluation of direct sampling method for trace elements analysis in Chinese rice wine by ICP–OES

A direct sampling method by inductively coupled plasma optical emission spectrometry was evaluated for determining trace elements (Co, Cr, Cu, Fe, Mg, Mn, Se and Zn) in Chinese rice wine. The parameters of ICP (plasma power, nebulizer pressure and sampling speed) were optimized considering the complicated matrix. Both the nebulizer pressure and the sampling speed were kept low, and plasma power was set at a high value of 1.35 kW. The good accuracy was confirmed by the recovery test (>95 %). The relative standard deviation was less than 5 %. Comparing with the dry ashing and wet ashing method, direct sampling showed to be fast, reliable and simple. The data of trace metals in Chinese rice wine were obtained: Co (0.088–0.106 mg/L), Cr (0.097–0.164 mg/L), Cu (0.085–0.126 mg/L), Fe (0.181–0.308 mg/L), Mg (0.179–0.311 mg/L), Mn (0.102–0.184 mg/L), Se (0.219–0.349) mg/L), and Zn (0.090–0.139 mg/L).     

A rapid PCR–RFLP method for the identification of Lophius species

The seven Anglerfish species, which belong to the genus Lophius, have a different value on the market, worldwide. If whole fishes can be identified by their morphological characteristics, they become indistinguishable when prepared or processed. In this study, a rapid method based on polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP) was developed for the authentication of the seven Lophius species, using a cytochrome b gene fragment of 566 bp. After a genus-specific PCR, a fast digestion with the restriction enzyme BfaI, followed by agarose gel electrophoresis, allowed a clear species identification by producing specific restriction patterns. The total time required was as low as 6 h, DNA extraction included. The method was then used to analyse 48 commercial samples, whose phylogenetic analysis confirmed the PCR–RFLP response at 100 %. Results showed that mislabelling occurs on the market regardless the kind of processing.     

A rapid LC/MS/MS method for the analysis of nonvolatile antiinflammatory agents from Mentha spp

Abstract: Mints (Mentha spp.), aromatic crops grown largely for their essential oils, also are rich sources of nonvolatile antiinflammatory agents. Identification and quantitation of the constituents responsible for their antiinflammatory activity is challenging owing to the lack of suitable chromatographic methodology. In the present research, the simultaneous quantitation of antiinflammatory constituents rosmarinic acid, oleanolic acid, and ursolic acid in mints was attained by using a unique tandem HPLC column system coupled with an electrospray ionization mass detection (MRM mode). The ion mode optimization for rosmarinic acid under negative and triterpenoid acids under positive was achieved by setting 2 time segments in a single run where the polarity mode was switched from negative (0 to 10 min) to positive (10 to 40 min). For the investigated concentration ranges of antiinflammatory agents in mints, good linearities (r²≥ 0.998) were obtained for each calibration curve. Validation of precision and accuracy for this method showed that intra‐ and inter‐day repeatabilities for all analytes were less than 5.51%, and the recoveries varied from 97.8% to 99.3%. The developed LC/MS/MS assay provides a suitable quality control method for the determination of antiinflammatory constituents in Mentha spp. There is a wide range of diversity in the natural product composition for these acids across the Mentha germplasm collection evaluated. The presence of these antiinflammatory acids in post‐distilled mints shows that value‐added nutraceutical enriched products can be developed with proper processing and recovery systems in addition to the distillation and capture of the valuable volatile essential oils. Practical Application: Results from this research would benefit both commercial farmers growing mint for essential oil and those in the food industry where value‐added phytopharmaceutical enriched products can be developed with proper processing, quality control, and recovery systems during mint essential oil distillation.     

Liquid chromatography–electrospray ionisation mass spectrometry method for the rapid identification of citrus limonoid glucosides in citrus juices and extracts

A rapid and selective liquid chromatography–electrospray ionisation mass spectrometry (LC–ESI-MS) method to screen citrus samples for limonoid glucosides and estimate their relative concentrations has been developed. This method utilises a phenyl stationary phase, whereas previous methods have relied on C-18. Samples may be analysed directly without treatment other than dilution. Peak areas from the extracted deprotonated molecular ion mass signals for individual limonoid glucosides were normalised against the sum of the areas to establish their relative concentrations. The method was successfully applied to the analysis of various juice, extracts, and liquid samples of partially purified limonoid glucosides.     

Assessment and validation of methods for the determination of γ-glutamyltransferase activity in sheep milk

The determination of enzymatic activity in sheep milk is still today a practically unexplored field of research. This study proposes and fully validates two analytical procedures (i.e. by means of UV–vis spectrophotometry and RP-HPLC methods) for the determination of γ-glutamyltransferase activity in sheep milk. Both methods are characterised by low detection and quantification limits, excellent linearity over a wide enzymatic activity interval, very good repeatability and reproducibility, and are bias-free. The RP-HPLC method provides better sensitivity and automation capability levels than that of UV–vis, and its use is hence suggested for screening purposes. These methods have been preliminarily tested with a number of real samples of whole sheep milk, obtaining an average γ-glutamyltransferase activity value of 2.93 ± 0.50 U ml⁻¹ and a range from 2.72 ± 0.10 U ml⁻¹ to 3.46 ± 0.11 U ml⁻¹.     

Development of an HPLC–UV method for the simultaneous determination of tetracyclines in muscle and liver of porcine,chicken and bovine with accelerated solvent extraction

A simple and especially rapid method-using accelerated solvent extraction (ASE) and HPLC has been developed for the quantitative determination of oxytetracycline, tetracycline, chlortetracycline, minocycline, methacycline, demeclocycline and doxycycline in muscle and liver of porcine, chicken and bovine. Samples of muscle and liver were extracted with trichloracetic acid/acetonitrile using ASE instrument, parameters such as extraction temperature (40–80 °C) and pressure (45–85 bar) were investigated and the selected extraction (60 °C, 65 bar) was most effective. The limits of detection were lower than 10 μg/kg and limits of quantification no more than 15 μg/kg for all compounds in muscle and liver. The recoveries of tetracyclines spiked at levels of muscle 50–150 μg/kg, liver 150–450 μg/kg, averaged from 75.0% to 104.9% with the relative standard deviation values less than 10%. The method was applied to determine 30 real porcine livers. It is demonstrated that the new method is robust for detection and quantification of seven tetracycline residues in muscle and liver of porcine, chicken and bovine.     

Optimization of a solid phase extraction and hydrophilic interaction liquid chromatography–tandem mass spectrometry method for the determination of metformin in dietary supplements and herbal medicines

Metformin is one of the most common adulterants found in anti-diabetic dietary supplements and herbal medicines. An analytical method based on hydrophilic interaction chromatography (HILIC)/tandem mass spectrometry was developed and validated for the determination of metformin in dietary supplements and herbal medicines. Sample preparation involved solid phase extraction of the analyte using Plexa PCX cartridges, and cleanup by a primary–secondary amine (PSA) adsorbent for minimization of the matrix effect. Chromatographic separation was performed on a HILIC column using a mixture of 0.025 mol/L ammonium formate (pH 3) and acetonitrile (18:82, v/v) as the mobile phase at flow rate of 0.25 mL/min. The method was validated in four matrices (capsules, honeyed pills, tablets and oral solutions). The method had a good linear range (5–500 ng/mL), and the overall precision and accuracy ranged from 2.2% to 9.9% and 4.6% to 11.3%, respectively.     

Development of an accelerated solvent extraction,ultrasonic derivatisation LC‐MS/MS method for the determination of the marker residues of nitrofurans in freshwater fish

A rapid method using accelerated solvent extraction (ASE) and ultrasound enhanced derivatisation has been developed for the quantitative determination of metabolites of nitrofurans, namely 3‐amino‐2‐oxalidinone (AOZ), 5‐morpholinomethyl‐3‐amino‐2‐oxalidinone (AMOZ), 1‐amino‐hydantoin (AHD) and semicarbazide (SEM), in muscle and skin of carp and finless eel. The target analytes were extracted using ASE, ultrasonic derivatisation for 1?h and then purified by solid phase extraction. Averaged decision limits (CCα) and detection capability (CCβ) of the method were in the range of 0.07–0.13 and 0.31–0.49?µg?kg^?1 in carp and finless eel, respectively. The accuracy in terms of recovery was in the range 77.2–97.4%. The simplified and traditional methods were compared with incurred residue samples. The simplified method reduced the derivatisation time and has been applied to the determination of nitrofurans residues in fish.     

Economic analysis of consumer choices based on rice attributes in the food markets of West Africa—the case of Benin

The focus of this study was to investigate consumer preferences for various attributes of rice marketed in Benin. Consumer choice theory postulates that products are consumed not for themselves, but for the characteristics they possess that satisfy consumers’ greater liking of one attribute over another. In the case of rice, quality attributes, as incentives for both producers and consumers, have important price implications. In this study, we empirically analyzed the relationship between the price paid by consumers for their choice of rice and its attributes in the markets of Benin using hedonic pricing and discrete choice models of demand. We used data collected from rice-consuming households in four major provinces of Benin, in both rural and urban areas, during 2006. The results of this econometric estimation indicated that there was considerable variability in consumer preferences for different rice attributes across the regions studied. Nevertheless, consumers paid a premium price for observable attributes, such as grain size and breakage. In addition, both urban and rural consumers preferred imported and parboiled rice to domestic and raw rice. The study results showed that implicit prices paid by consumers for both domestic and imported rice were based on quality attributes. These findings have important implications for future breeding programs aimed at making domestic rice more competitive with imported rice.     

High performance liquid chromatography method for the simultaneous determination of α-, γ- and δ-tocopherol in vegetable oils in presence of hexadecyltrimethylammonium bromide/n-propanol in mobile phase

A rapid methodology by RP-HPLC, 10 min of total analysis time, for the analysis of α-, γ- and δ-tocopherol in vegetable oils, in presence of retinol, retinyl acetate and α-tocopherol acetate was developed. Hexadecyltrimethylammonium bromide 0.1 M/n-propanol 65% (v/v) are used as mobile phase. Tocopherols were detected using UV and fluorescence detection. The quantification limits for α-, γ- and δ-tocopherols were 0.28, 0.12 and 0.23 mg L⁻¹, respectively. The method yielded satisfactory results when it was applied to vegetable oils and thus, it is suitable for their quality control.     

Applications and opportunities for ultrasound assisted extraction in the food industry — A review

Ultrasound assisted extraction (UAE) process enhancement for food and allied industries are reported in this review. This includes herbal, oil, protein and bioactives from plant and animal materials (e.g. polyphenolics, anthocyanins, aromatic compounds, polysaccharides and functional compounds) with increased yield of extracted components, increased rate of extraction, achieving reduction in extraction time and higher processing throughput. Ultrasound can enhance existing extraction processes and enable new commercial extraction opportunities and processes. New UAE processing approaches have been proposed, including, (a) the potential for modification of plant cell material to provide improved bioavailability of micro-nutrients while retaining the natural-like quality, (b) simultaneous extraction and encapsulation, (c) quenching of the radical sonochemistry especially in aqueous systems to avoid degradation of bioactives and (d) potential use of the radical sonochemistry to achieve targeted hydroxylation of polyphenolics and carotenoids to increase bioactivity.Industrial relevanceThe application of ultrasonic assisted extraction (UAE) in food processing technology is of interest for enhancing extraction of components from plant and animal materials. This review shows that UAE technology can potentially enhance extraction of components such as polyphenolics, anthocyanins, aromatic compounds, polysaccharides, oils and functional compounds when used as a pre-treatment step in a unit process. The higher yield obtained in these UAE processes are of major interest from an industrial point of view, since the technology is an “add on” step to the existing process with minimum alteration, application in aqueous extraction where organic solvents can be replaced with generally recognised as safe (GRAS) solvents, reduction in solvent usage, and shortening the extraction time. The use of ultrasonic for extraction purposes in high-cost raw materials is an economical alternative to traditional extraction processes, which is an industry demand for a sustainable development.