酶法水解脱脂米糠蛋白抗氧化性质研究

以脱脂米糠为原料,采用碱性蛋白酶、酸性蛋白酶和中性蛋白酶酶解制备米糠蛋白,并将制备酶解液与抗坏血酸在超氧阴离子自由基(O2-.)清除率、羟自由基(.OH)清除率、H2O2清除能力及还原能力等方面进行比较,研究米糠蛋白抗氧化活性。结果表明,米糠蛋白具有较强抗氧化活性,虽效果不如抗坏血酸;但对超氧阴离子自由基(O2-.)(最高为98.41%)、羟自由基(.OH)(最高达97.04%)及H2O2均有不同程度清除作用,并具有一定还原能力;且抗氧化能力与添加量存在一定量效关系,其中还出现有促氧化特殊现象。     

Production of functional substances from black rice bran by its treatment in subcritical water

Black rice bran was treated by water and subcritical water at temperatures ranging from 20 to 260 °C for 5 min and at 200 and 260 °C for 5-120 min. The bran extracts were analyzed for their radical scavenging activity, protein and carbohydrate contents, molecular-mass distribution, antioxidation activity, emulsifying activity, and emulsion-stabilizing activity. The radical scavenging activity and the protein content of the extract were higher at higher treatment temperature. The carbohydrate content also increased with increasing temperature up to 200 °C, then steeply decreased at the temperatures higher than 200 °C. The bran extracts treated at 260 °C for 5 min exhibited a suppressive activity toward autoxidation of linoleic acid with the increasing the weight ratio of the bran extract to linoleic acid. The bran extracts prepared at 40-200 °C for 5 min showed the emulsifying- and emulsion-stabilizing activities, while the extracts prepared at 220-260 °C were low in the activities.     

脱脂米抗氧化肽的分离纯化与研究

通过碱性蛋白酶酶解脱脂米糠蛋白制得脱脂米糠抗氧化肽（DRBAP）,用DEAE-52、SephadexG-15纯化DRBAP,薄层层析鉴定其纯度。通过亚油酸体系中抗氧化能力、自由基捕获能力、金属离子螯合力等不同的实验体系研究其纯化组分的体外抗氧化活性,同时分析了其氨基酸组分和分子量分布情况。结果表明,分离纯化得到抗氧化活性较高的组分G4,较纯化前的DRBAP其对铁离子的螯合率提高了近11%,对DPPH自由基、·OH、O2-·清除率依次提高了20%、9%、16%,在亚油酸体系中吸光值下降了0.7,其主要氨基酸成分为Asp、Glu、Leu、Phe、Arg、Pro,相对分子质量小于1000u的比例达到90.83%,分子量小于500u的达到14.38%。      

Cellulase-assisted extraction of oligosaccharides from defatted rice bran

ABSTRACT:  Defatted rice bran was subjected to cellulase treatment in order to increase its extractable oligosaccharides. Various combinations of enzyme concentration (0%, 0.5%, 1.0%, and 2.0%), temperature (room, 30, 40, and 50 °C), and time (1, 3, 5, and 16 h) were tested to identify the optimum extraction conditions. The saccharide content and composition of the extracts were analyzed by high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD). Digestibility was assayed in vitro with human salivary and porcine pancreatic α-amylases. Extraction yield ranged from 13.4% (without cellulase) to 39.9% (with 2% cellulase). Total carbohydrates, reducing sugars, and crude protein of the dried extracts ranged from 69.2% to 87.2%, 18.7% to 62.3%, and 7.1% to 22.3%, respectively. Mono- and disaccharides constituted more than 50% of the total carbohydrates in the extracts. Inherent oligosaccharides and those produced by cellulolysis made up less than 25%. The in vitro digestibility of the extracts by α-amylases was lower compared with that of the original rice bran sample and potato dextrin, which could be attributed to the increased concentrations of oligosaccharides and reducing sugars.     

Antioxidant activities and phenolic compounds of pigmented rice bran extracts

This study was carried out to investigate the antioxidant activities and phenolic compounds of pigmented rice (black, red, and green rice) and brown rice brans. Antioxidant activity was determined by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical assay, 2,2-azino-bis-(3-ethylenebenzothiozoline-6-sulfonic acid) (ABTS) radical cation assay, reducing power, and chelating ability. Phenolic compounds were measured by using HPLC. Pigmented rice brans were extracted by using aqueous mixtures of acetone, ethanol, and methanol to determine the most effective extraction solvent. Of all solvents examined, extract from 40:60 acetone-water mixtures (v/v) provided the highest DPPH radical assay as well as the highest total phenolic and flavonoid content. We finally selected 40% acetone as an extraction solvent for antioxidant study of pigmented rice bran. Antioxidant activities of 40% acetone extracts of pigmented rice bran, measured in the range of 0 to 1500 μg/mL. At 500 μg/mL concentration, red rice bran, which had the highest total phenolic (259.5 μg/mg) and total flavonoid (187.4 μg/mg) contents, showed the highest antioxidant activity: 83.6%, 71.5%, 1.2%, and 16.4% for DPPH radical assay, ABTS radical cation assay, reducing power, and chelating ability, respectively. Red rice bran showed a lower EC(50) value (112.6 μg/mL) than that of butylated hydroxytoluene (144.5 μg/mL) from the DPPH radical assay. The major phenolic acids of red rice bran were ferulic, vanillic and p-coumaric acids. The results indicated pigmented rice bran might be used as a natural antioxidant. PRACTICAL APPLICATION: The present study revealed black and red rice bran shows high antioxidant activities and they contain high amount of phenolic compounds. Indeed, black and red rice bran could be better raw materials for manufacturing the food with high antioxidant activity.     

脱脂米糠制备膳食纤维工艺条件的优化

采用化学试剂—酶结合分离法,以脱脂米糠制备膳食纤维.分别考察α-淀粉酶用量、酶解时间、碱解浓度、碱解时间对膳食纤维提取率的影响,并采用四元二次回归通用旋转组合试验优化工艺参数.结果表明:在α-淀粉酶用量0.40％,酶解40min,碱解浓度4.00％,碱解时间45min的条件下,从脱脂米糠中提取膳食纤维的得率为39.30％.     

超微脱脂米糠粉制备速溶冲剂的研究

本研究以熟化后的超微脱脂米糠粉为主要原料,研制一种营养丰富的米糠粉冲剂。该冲剂采用单因素和正交两种实验方法确定了实验最优配方及感官评价结果。实验结果:超微脱脂米糠冲剂的最优配方(以主要原料粉100g为单位)为:脱脂米糠粉20g、全脂奶粉55g、白糖粉25g、黄原胶0.220g、羧甲基纤维素钠0.08g、和微晶纤维素0.23g,最终感官风味得分为87分。      

米糠深加工技术的分析与评价(Ⅰ)--米糠制油及脱脂米糠的利用

米糠富含脂质、蛋白质、矿物质、维生素等多种营养物质,是一种具有很大潜力的食品资源、化工原料和药物原料.对米糠制油技术及脱脂米糠的利用技术进行了综合性评述,为米糠的综合开发利用提供参考.     

酶法提取脱脂米糠中蛋白质的研究

研究采用复合糖酶处理脱脂米糠后,降低了米糠中半纤维素和植酸盐含量,使蛋白质的提取率和纯度明显提高,米糠蛋白产品的蛋白含量达到80.2%,总糖含量仅为3.7%。聚丙烯酰胺电泳(SDS-PAGE)和高效凝胶过滤色谱(HPSEC)图谱表明,米糠蛋白分子量呈连续分布;HPSEC图谱表明,米糠蛋白的分子以聚集体形式存在。     

Suppression of the oxidation of methyl linoleate encapsulated with the extract from defatted rice bran by a compressed hot water treatment

Bran extracts prepared by a compressed hot water treatment at 120, 150, and 180 °C for 7.5 min were used in association with maltodextrin for encapsulation of methyl linoleate. Mixtures of the bran extracts at 120 and 150 °C showed a higher emulsion-stabilizing ability than that at 180 °C. The bran extracts prepared at the higher temperature provided a higher oxidative stability as shown by the longer induction period for the oxidation of the encapsulated methyl linoleate. The induction periods of the encapsulated methyl linoleate using the bran extract prepared at 250 °C for 5 min as the aqueous phase were 3–6 times longer than those of the encapsulated methyl linoleate using water.     

脱脂米糠全组分膜的制备及表征

为开发低成本、高产能的可降解膜材料加工原料和制备工艺,探索了利用米糠加工副产物制备膜材料的技术途径。以米糠饼粕为原料制备多种米糠基制膜原料,再采用碱处理-湿法成膜工艺制备多种米糠基膜材料,比较不同米糠基膜材料的机械性能,优选出最佳的制膜原料,在此基础上对制膜助剂(交联剂与增塑剂)进行选择,采用正交试验优化膜制备工艺条件,并对其结构进行表征。结果表明：米糠压榨饼经醇洗得到的醇洗米糠(AWRB)全组分为最佳的制膜原料;以戊二醛(GA)为交联剂,甘油(Gly)为增塑剂制膜,AWRB全组分膜制备最优工艺条件为固液比1∶5、碱处理温度50℃、碱处理时间60 min、Gly用量10%(以AWRB质量计)、GA用量1.6%(以AWRB质量计),在此条件下所得AWRB全组分膜的拉伸强度为16.9 MPa,断裂伸长率为1.6%。结构表征结果显示,AWRB全组分膜的热稳定性较高,结构致密,无皲裂。AWRB中的多糖和蛋白质在GA交联作用下形成了热稳定性更高的网络结构;而不溶性的粗纤维及蛋白质起到协同增效作用,有效提升了米糠基膜材料的机械强度。AWRB全组分膜的原料制备无需复杂分离操作,且有望实现米糠制油、植...     

米糠贮藏时间对米糠可溶性膳食纤维抗氧化性质的影响

以新鲜米糠为原料贮藏0、1、3、5、10 d得到不同酸败程度的米糠,稳定化和脱脂后制备米糠可溶性膳食纤维,研究米糠贮藏时间对米糠可溶性膳食纤维抗氧化性质的影响。结果表明:随着新鲜米糠贮藏时间的延长,米糠可溶性膳食纤维的还原能力、金属离子螯合能力和清除ABTS~+·、DPPH·、·OH、O_2~-·能力均先上升后下降;米糠可溶性膳食纤维还原能力、金属离子螯合能力和清除ABTS~+·、DPPH·、·OH在新鲜米糠贮藏5 d时达到最大值,分别为0.943(OD_(700))、35.16%、32.28%、73.51%和13.83%,米糠可溶性膳食纤维清除O_2~-·能力在新鲜米糠贮藏1 d达到最大值,为60.58%。     

响应面法优化脱脂米糠植酸提取工艺

利用响应面分析法优化了脱脂米糠中植酸的提取工艺条件,建立了植酸提取的二次多项式数学模型。在单因素试验基础上,选择pH、液料比、提取时间和提取温度为自变量,植酸得率和残渣蛋白质量为响应值,响应面优化得出最佳工艺条件为:pH3.9,液料比9∶1,提取时间4.4h,提取温度50℃。在最佳工艺条件下,植酸得率为5.27%,残渣蛋白质量为1.4034g(10g原料脱脂米糠)。在响应面优化工艺的基础上,选择了一浸一洗的浸提方式,并利用阴、阳离子交换树脂纯化了植酸粗溶液,浓缩得到了50%植酸溶液,植酸纯度为94.72%。     

超声波辅助提取小麦麸皮酚基木聚糖的研究

以小麦麸皮为原料,研究了超声波超声功率、超声时间、碱液质量分数、碱提时间、碱提温度对小麦麸皮中水溶性酚基木聚糖和总酚基木聚糖得率的影响,同时分析了小麦麸皮水溶性酚基木聚糖的抗氧化特性和总酚含量.结果表明,小麦麸皮中酚基木聚糖提取的最佳工艺条件是超声功率300 W,超声时间30 min,碱液质量分数2％,碱提时间2h,碱提温度55℃,在此条件下,酚基木聚糖得率为38.73％,水溶性酚基木聚糖得率为29.05％.对提取的麸皮水溶性酚基木聚糖的抗氧化性的研究表明,水溶性酚基木聚糖对羟自由基有明显的清除作用,并呈现明显的量效关系.水溶性酚基木聚糖的总酚含量为12.27mg/g.     

Phytochemicals characterization of solvent extracts from taro-scented japonica rice bran

The major phytochemicals and antioxidant properties of taro-scented rice bran (TaiNung 71; TN71) extracts using 3 different solvents are characterized. Some progress is realized in creating an economic value for rice bran that has long been considered an agricultural waste. Various solvent extracts reveal the presence of phenolic compounds, oryzanols, tocopherols, and tocotrienols. Ethyl acetate (EtOAc) can extract more oryzanols (1.55 ± 0.20 g/kg rice bran). Meanwhile, the methanol (MeOH) extract possesses a higher yield in total contents (15.42 ± 1.41 g/kg bran), which includes phenolic compounds (2.69 ± 0.29 g gallic acid equivalent/kg bran), tocopherols (251 ± 26 mg/kg bran) and tocotrienols (111 ± 4 mg/kg bran). The MeOH extract exhibits more effective antioxidant activity against various oxidative systems in vitro, including the inhibition of linoleic acid peroxidation (33.89%), scavenging of DPPH radicals (83.88%), and reducing power. It is found that the yield, total content in phenolic compounds and tocols of the extracts increase with increasing Synder's polarity value and viscosity, which can then be used as the indices in isolation of the desired rice bran phytochemicals extracts.     

Comparison of releasing bound phenolic acids from wheat bran by fermentation of three Aspergillus species

Wheat bran was fermented at 28 °C for 7 days under 70% humidity by Aspergillus niger, Aspergillus oryzae and Aspergillus awamori. Total phenolic content (TPC) of the unfermented sample was 1531.5 μg g^?1 wheat bran. After the fermentation of Aspergillus awamori, Aspergillus oryzae and Aspergillus niger, TPC reached 5362.1, 7462.6 and 10 707.5 μg g^?1, respectively. The antioxidant activity in the extractions of fermented wheat bran also increased significantly compared with the unfermented sample (P < 0.05). Aspergillus niger showed the greatest capacity to release bound ferulic acid (416.6 μg g^?1). Aspergillus oryzae and Aspergillus awamori had the advantages of releasing more chlorogenic acid (84.0 μg g^?1) and syringic acid (142.3 μg g^?1), respectively. The destructive effect of Aspergillus niger on wheat bran structure was the strongest, followed by that of Aspergillus oryzae. This effect of Aspergillus niger may be due to its higher cellulase, xylanase, arabinofuranosidase and β‐xylosidase activities. Besides, Aspergillus oryzae possessed higher β‐glucosidase activity, and Aspergillus awamori had higher α‐amylase and feruloyl esterase activities. Aspergillus niger may be the best to release bound phenolic acids in the three Aspergillus species. These will provide the helpful information for understanding mechanism of the fermentation by Aspergillus species releasing bound phenolic in wheat bran.     

静态亚临界水提取脱脂咖啡渣中抗氧化活性成分的研究

研究了静态亚临界水不同提取温度(110、130、150、170、190℃)、时间(15、30、45、60、75min)、料液比(1:10、1:20、1:30、1:40、1:50、1:60、1:70)对脱脂咖啡渣中多酚类物质提取效果的影响,并对不同提取液的抗氧化活性进行研究。结果表明,提取液中总酚、总黄酮含量及其清除自由基(ABTS·+、DPPH·)能力均随着提取温度、时间、液料比升高先增加后减少,当提取温度达到170℃、时间达到45min、料液比达到1:50时,提取液中总酚和总黄酮含量均达到最高,其抗氧化活性也达到最高值。170℃、45min、1:50是亚临界水提取脱脂咖啡渣中的多酚类物质的最佳提取条件,脱脂咖啡渣提取液可以作为一种天然的抗氧化剂来源。     

利用弱碱性阴离子交换树脂从脱脂米糠中制取植酸的研究

以脱脂米糠为原料,通过酸浸、离子交换吸附、洗脱、精制、浓缩过程利用D318型弱碱性阴离子交换树脂制得植酸。试验结果表明,D318型阴离子交换树脂从脱脂米糠植酸粗溶液中吸脱植酸的最佳工艺条件为:吸附液浓度为10 mg/ml,吸附液流速为1.0 ml/min,NaOH洗脱液的流速为2.0 ml/min,NaOH洗脱液浓度为1.5 mol/L,操作温度为45℃,pH值为2.5左右。