米糠谷维素提取纯化方法研究进展

谷维素是米糠和米糠油加工过程中极有价值副产品,具有多种生理功能。该文从谷维素组成、生理功能、米糠油皂脚组成及谷维素提取和纯化方法等方面进行综述,重点阐述谷维素提取和纯化方法研究进展。     

Response surface methodology applied to the analysis of rice bran oil extraction process with ethanol

Vegetable oils can be extracted using ethanol as solvent. The main goal of this work was to evaluate the ethanol performance on the extraction process of rice bran oil. The influence of process variables, solvent hydration and temperature was evaluated using the response surface methodology, aiming to maximise the soluble substances and γ‐oryzanol transfer and minimise the free fatty acids extraction and the liquid content in the underflow solid. It can be noted that oil solubility in ethanol was highly affected by the water content. The free fatty acids extraction is improved by increasing the moisture content in the solvent. Regarding the γ‐oryzanol, it can be observed that its extraction is affected by temperature when low level of water is added to ethanol. On the other hand, the influence of temperature is minimised with high levels of water in the ethanol.     

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. Copyright © 2011 Society of Chemical Industry     

Phytosterols and γ‐oryzanol in rice bran oils and distillates from physical refining process

Commercially available refined rice bran oil (RBO) contained high contents of phytosterol and γ‐oryzanol, that is, 858–1034 and 248–887 mg per 100 g oil, respectively. Although the crude rice bran oil (CRBO) had high contents of both phytochemicals (1362–1376 mg phytosterol per 100 g and 1599–1666 mg γ‐oryzanol per 100 g), physical refining process resulted in their reduction to 820–895 mg phytosterol per 100 g and 933–960 mg γ‐oryzanol per 100 g in RBO (P < 0.05). Both phytochemicals evaporated and accumulated in the deodoriser distillate (DD) to some extent during the deodorising step. Further distillation of DD using molecular distillation (MD) evaporated the free fatty acids (FFAs), resulting in the unevaporated fraction (UMD) having the acid values of 5.6–9.3 mg KOH g^?1. The UMD also contained 1585–3391 mg phytosterol per 100 g and 781–848 mg γ‐oryzanol per 100 g. Results suggest potential use of DD as the source of phytochemicals for further concentration by MD.     

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     

UV法测定米糠油油脚和皂脚中谷维素的含量

通过测定不同产地和不同精炼工艺的米糠油所产生的油脚和皂脚中谷维素的含量,为工业生产天然阿魏酸提供原料参考。采用UV法,在(315±1)nm的波长处测定吸光度,计算含量。结果表明:米糠油不同精炼工艺的油脚和皂脚中谷维素含量区别显著,相同工艺油脚和皂脚而不同产地的谷维素含量无明显区别。化学碱炼工艺所得皂脚具有较高含量谷维素,可作为生产天然阿魏酸的原料;物理水化工艺所得油脚中谷维素含量低,不具备生产天然阿魏酸的实际意义。     

谷维素对3种食用植物油的抗氧化效果研究

从米糠油皂脚中提取纯化谷维素,按不同比例添加到大豆油、菜籽油和油茶籽油中,分别采用Schaal烘箱法和油脂氧化分析仪对3种植物油氧化稳定性进行测定,同时考察在植物油氧化过程中,谷维素对其脂肪酸组成的影响,并与常见的油脂抗氧化剂进行对比。结果表明:油脂中分别添加0.1%和0.5%谷维素均对大豆油、菜籽油和油茶籽油的氧化诱导期具有延长作用,其中对油茶籽油的作用最显著;在Schaal烘箱实验中,谷维素能够有效延缓大豆油和油茶籽油过氧化值的升高,并且对油中多不饱和脂肪酸的氧化有抑制作用,但对菜籽油的抗氧化作用不显著。     

Beneficial effect of the unsaponifiable matter from rice bran on oxidative stress in vitro compared with α‐tocopherol

Unsaponifiable matter (UM) was prepared from rice bran using n‐hexane extraction followed by removal of its fatty acid methyl ester with supercritical CO₂ under heat‐stable conditions. The UM was made up of 1% of vitamin E isomers, 28% of γ‐oryzanol and 71% of uncharacterized compounds. The aim of this study was to determine the antioxidant activities of the UM, using α‐tocopherol (α‐T) as a positive control, by measuring the Fe³⁺‐reducing antioxidant power (FRAP), 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH^?) free‐radical‐scavenging property and lipid peroxidation in rat liver microsomes. In addition, the effects of the UM on the tert‐butyl hydroperoxide (t‐BOOH)‐induced cytotoxicity in cultured rat hepatocytes were also investigated. In FRAP assay and DPPH^? free‐radical‐scavenging assay, the results were expressed g^?1α‐T or g^?1 UM. The amount of UM used in lipid peroxidation assay and cytotoxicity assay was the amount required to have equal amounts of total vitamin E isomers in the sample and the control α‐T. The UM, as well as α‐T, exhibited significant antioxidant activities in FRAP, radical‐scavenging and membrane‐lipid oxidation. The FRAP value for total vitamin E isomers in the UM (TVEIUM) was 9.1 times higher than that for α‐T. In terms of their capacities to perform radical‐scavenging and lipid peroxidation, both TVEIUM and α‐T showed similar antioxidant activities. In experiments using cultured rat hepatocytes, the t‐BOOH‐induced lactate dehydrogenase release was significantly inhibited by the addition of 63.5 and 160 µg ml^?1 of TVEIUM treatments (84 and 89%, respectively), and that of 63.5 and 160 µg ml^?1 of α‐T treatment (88 and 93%, respectively). The antioxidant function against oxidative stress of the UM prepared from rice bran may extend its use to being a potential dietary supplement. Copyright © 2004 Society of Chemical Industry     

稻米油的营养成分、制取工艺及应用研究进展

稻米油不仅富含不饱和脂肪酸,还富含谷维素、植物甾醇等多种脂质伴随物,对人体健康十分有益。随着大健康产业的快速发展,稻米油的提质制取及高值化利用已成为大型油脂加工企业及科研者研究的热点。综述了稻米油中不饱和脂肪酸、谷维素、植物甾醇、角鲨烯、维生素E等营养成分的含量及功能,并对米糠稳定化处理、稻米油制取工艺及稻米油在煎炸食品、乳液递送、生物能源等方面的应用进行了梳理,旨在为稻米油的加工利用提供一定的理论基础及技术指导。     

米糠油谷维素提取方法研究进展

谷维素是从米糠油或胚芽油等谷物油脂中提取的一种天然混合物,是米糠油深加工过程中产生的极有价值的副产品。本文从谷维素的组成、提取和纯化方法进行综述,重点阐述不同提取工艺的特点和优缺点,分析实验中遇到的实际问题并且提出解决的办法。      

Determination of γ‐aminobutyric acid in Chinese rice wines and its evolution during fermentation

γ‐Aminobutyric acid (GABA) is a functional amino acid that is widely present in Chinese rice wine. In this study, high‐performance liquid chromatography coupled with ultraviolet detection (HPLC‐UV) was established for the determination of γ‐aminobutyric acid in 22 Chinese rice wines collected from the Shaoxing region of China. Furthermore, the evolution of GABA was studied in Chinese rice wine during primary and post‐fermentation process. Results showed that the HPLC method was reliable with good linearity, accuracy, precision and stability. Additionally, the GABA content varied significantly in the 22 Chinese rice wines, and the content was much higher in wine samples with long aging periods. Regarding the evolution of GABA in Chinese rice wine during the brewing process, the level slowly increased during primary fermentation. A decrease in GABA was observed in the wine at the early stage of the post‐fermentation process. However, a marked increase on the GABA content occurred in wine at the late stage of post‐fermentation. The findings from this study are that HPLC can be successfully applied to determine GABA in Shaoxing brewed rice wines, and further provide useful information on quality control of such wines. Copyright © 2017 The Institute of Brewing & Distilling     

Purification and physicochemical characterization of ovine β‐lactoglobulin and α‐lactalbumin

Ovine whey proteins were fractionated and studied by using different analytical techniques. Anion‐exchange chromatography and reversed‐phase high‐performance liquid chromatography (HPLC) showed the presence of two fractions of β‐lactoglobulin but only one of α‐lactalbumin. Gel permeation and sodium dodecyl sulfate (SDS)‐polyacrylamide gel electrophoresis allowed the calculation of the apparent molecular mass of each component, while HPLC coupled to electrospray ionisation‐mass spectrometry (ESI‐MS) technique, giving the exact molecular masses, demonstrated the presence of two variants A and B of ovine β‐lactoglobulin. Amino acid compositions of the two variants of β‐lactoglobulin differed only in their His and Tyr contents. Circular dichroism spectroscopy profiles showed pH conformation changes of each component. The thermograms of the different whey protein components showed a higher heat resistance of β‐lactoglobulin A compared to β‐lactoglobulin B at pH 2, and indicated high instability of ovine α‐lactalbumin at this pH.     

Effect of pre‐germination time of brown rice on serum cholesterol levels of hypercholesterolaemic rats

BACKGROUND: Brown rice is unpolished rice with immeasurable benefits for human health. Brown rice (BR) and pre‐germinated brown rice (PGBR) are known to contain various functional compounds such as γ‐oryzanol, dietary fibre and γ‐aminobutyric acid (GABA). In the present study, the experimental diets containing BR and PGBR (24, 48 h pre‐germination) were used to investigate the influence of pre‐germination time of brown rice on blood cholesterol in Sprague–Dawley male rats. RESULTS: Hypercholesterolaemia and elevation of LDL‐cholesterol were successfully ameliorated by the experimental diets containing BR and PGBR (24 and 48 h pre‐germination). As compared to the control sample, the pre‐germination time had a significant (P < 0.05) effect on blood cholesterol of Sprague–Dawley male rats. It was also found that the significantly (P < 0.05) better effect on lipid profile of hypercholesterolaemic rats was observed by prolonging the pre‐germination time. As compared to non‐germinated brown rice, the germinated brown rice showed the higher cardio‐protective effect on hypercholesterolaemic Sprague–Dawley male rats. CONCLUSION: The present study suggests that the changes of blood cholesterol can be mainly modulated by using the PGBR rather than BR. The prolonging of pre‐germination time led to an increase in the bioactive components, thereby providing a more efficient functional diet affecting the high blood cholesterol. This study suggests that PGBR can be used instead of BR and polished rice in the human diet. Copyright © 2009 Society of Chemical Industry     

近红外光谱法快速测定米糠油中谷维素的含量北大核心CSCD

为了简便、快速、准确地测定米糠油中的谷维素含量,以LS/T 6121.2—2017的高效液相色谱法为测定米糠油中谷维素含量的参比方法,采用近红外光谱分析技术结合偏最小二乘法建立了米糠油中谷维素含量的定量分析模型。结果表明:所建定量分析模型的决定系数为99.81%,预测标准差为0.02849%,交叉验证标准差为0.03113%;利用99个验证集样品对定量分析模型进行外部独立验证,预测决定系数为99.81%,预测标准差为0.03090%,用该定量分析模型检测样品绝对误差在-0.081%~0.057%之间,相对误差在-11.86%~9.84%之间。所建立的定量分析模型预测效果较好,准确度较高,可用于米糠油中谷维素含量的测定。     

超临界流体萃取与二乙醇胺法综合制备米糠油

以市购米糠为原料,采用超临界流体萃取法提取米糠油,并对毛糠油的简化精炼工艺进行研究。原料经微波预处理降低解脂酶活性后,利用超临界CO2分段萃取,先后控制条件15MPa、32℃、1.0h和35MPa、40℃、4.0h获得毛糠油Ⅰ、Ⅱ。用二乙醇胺处理毛糠油Ⅱ,通过单因素实验和正交实验得出二乙醇胺法精炼毛糠油的最佳条件为:二乙醇胺加入量为油重的9%,精炼温度为50℃,振荡时间为15min。在此条件下精炼毛糠油,油脂酸价可降至0.85mgKOH/g,酸价降低率达到94.33%。超临界流体萃取与二乙醇胺法精炼综合处理所得米糠油清澈、透明,谷维素含量为1.73%,色度达到了国家标准。     

Utilization of Barley or Wheat Bran to Bioconvert Glutamate to γ‐Aminobutyric Acid (GABA)

This study deals with the utilization of agro‐industrial wastes created by barley and wheat bran in the production of a value‐added product, γ‐aminobutyric acid (GABA). The simple and eco‐friendly reaction requires no pretreatment or microbial fermentation steps but uses barley or wheat bran as an enzyme source, glutamate as a substrate, and pyridoxal 5’‐phosphate (PLP) as a cofactor. The optimal reaction conditions were determined on the basis of the temperatures and times used for the decarboxylation reactions and the initial concentrations of barley or wheat bran, glutamate, and PLP. The optimal reactions produced 9.2 mM of GABA from 10 mM glutamate, yielding a 92% GABA conversion rate, when barley bran was used and 6.0 mM of GABA from 10 mM glutamate, yielding a 60% GABA conversion rate, when wheat bran was used. The results imply that barley bran is more efficient than wheat bran in the production of GABA.     

稻米胚及米胚油的品质分析

从原料米糠中分离出纯稻米胚和纯米糠,利用溶剂浸出法分别提取其中油脂并进行品质分析对比,以研究稻米胚及米胚油的营养品质。结果表明:稻米胚粗脂肪含量27.06%,粗蛋白含量19.50%,粗纤维含量4.88%,比米糠粗脂肪、粗蛋白含量明显提高,粗纤维含量降低;米胚油的酸值(KOH)、过氧化值、维生素E含量、谷维素含量、植物甾醇含量分别为21.7 mg/g、6.1 mmol/kg、43.18 mg/100 g、0.47%、3.07%,与米糠油相比,米胚油的酸值(KOH)降低了23.8 mg/g,过氧化值降低了1.7 mmol/kg,维生素E含量提高了17.18 mg/100 g,植物甾醇含量相差不大,谷维素含量降低0.93个百分点。米胚油在酸值和维生素E含量方面较米糠油具有明显优势,新鲜稻米胚既可以直接作为营养丰富的产品,也是优质食用油的原料。     

物理精炼法生产富含谷维素米糠油

概述了谷维素的营养价值,并通过生产实践对比,详细叙述了物理精炼法生产富含谷维素米糠油工艺中各工序的操作过程、参数、设备等,给出了检测方法及详细的检测结果.生产的成品油符合国家四级米糠油标准,并保留了米糠油中谷维素等主要营养成分,其氧化稳定性显著提高.     

ULTRASONICALLY ASSISTED EXTRACTION OF PHENOLIC COMPOUNDS FROM AROMATIC PLANTS: COMPARISON WITH CONVENTIONAL EXTRACTION TECHNICS

Extracts of aromatic plants contain bioactive substances such as phenolic compounds, which could be used as natural antioxidants. Conventional, as well as ultrasonically assisted extractions (UAEs ) of phenolic compounds from aromatic plants using different solvents, have been studied. Reversed phase high performance liquid chromatography (RP‐HPLC ) with ultraviolet detection was employed for the analysis of phenolic compounds. Total phenolic compounds were determined by the Folin–Ciocalteu assay. The amount of extractable phenolic substances for this method decreased with decreasing polarity of the solvent in the order water, 60% methanol, 60% acetone, and ethyl acetate/water (60:30, v/v). The HPLC results indicate that UAE is a more effective technic compared to the conventional method but was dependent on the solvent and the temperature employed. Increasing the temperature of sonication, the efficiency of extraction of phenolic compounds for all solvents is enhanced. However, water extraction was found to give reduced amounts of phenolic compounds when compared with the conventional method.     

米糠的功能组分及其在化妆品中的应用

为促进我国米糠资源的多样化利用和开发,介绍了米糠中的功能组分及其在化妆品领域的应用。米糠的功能组分主要有米糠油、米糠蛋白、植物甾醇、米糠多糖、维生素等。米糠在化妆品中的应用主要有两种途径,一是直接使用,二是提取的功效成分的应用。米糠中提取的功效成分如米糠油、谷维素、植物甾醇、二十八烷醇、维生素、植酸等,可赋与化妆品保湿、防晒、抗衰老、抗氧化、抗皱等功效。