Cooking rice in excess water reduces both arsenic and enriched vitamins in the cooked grain

This paper reports the effects of rinsing rice and cooking it in variable amounts of water on total arsenic, inorganic arsenic, iron, cadmium, manganese, folate, thiamin and niacin in the cooked grain. We prepared multiple rice varietals both rinsed and unrinsed and with varying amounts of cooking water. Rinsing rice before cooking has a minimal effect on the arsenic (As) content of the cooked grain, but washes enriched iron, folate, thiamin and niacin from polished and parboiled rice. Cooking rice in excess water efficiently reduces the amount of As in the cooked grain. Excess water cooking reduces average inorganic As by 40% from long grain polished, 60% from parboiled and 50% from brown rice. Iron, folate, niacin and thiamin are reduced by 50–70% for enriched polished and parboiled rice, but significantly less so for brown rice, which is not enriched.     

碱酶分步法从米粉中提取大米蛋白工艺的研究

用碱法和酶法两步加工米粉,制备大米蛋白.通过研究pH,温度,时间及料液比对大米蛋白提取率的影响,确定稀碱提取大米蛋白的较佳工艺条件为:pH11.0,温度50℃,时间2h,及料液比1:8,然后用碱性蛋白酶对碱提残渣进行二次提取,通过正交试验确定酶提大米蛋白最适条件为:加酶量1%,pH8.0,时间1h,料液比1:8,温度50℃.两步提取使大米蛋白提取率达到90.49%.     

Contribution of water and cooked rice to an estimation of the dietary intake of inorganic arsenic in a rural village of West Bengal, India

Arsenic contamination of rice plants by arsenic-polluted irrigation groundwater could result in high arsenic concentrations in cooked rice. The main objective of the study was to estimate the total and inorganic arsenic intakes in a rural population of West Bengal, India, through both drinking water and cooked rice. Simulated cooking of rice with different levels of arsenic species in the cooking water was carried out. The presence of arsenic in the cooking water was provided by four arsenic species (arsenite, arsenate, methylarsonate or dimethylarsinate) and at three total arsenic concentrations (50, 250 or 500 µg l^-1). The results show that the arsenic concentration in cooked rice is always higher than that in raw rice and range from 227 to 1642 µg kg^-1. The cooking process did not change the arsenic speciation in rice. Cooked rice contributed a mean of 41% to the daily intake of inorganic arsenic. The daily inorganic arsenic intakes for water plus rice were 229, 1024 and 2000 µg day^-1 for initial arsenic concentrations in the cooking water of 50, 250 and 500 µg arsenic l^-1, respectively, compared with the tolerable daily intake which is 150 µg day^-1.     

Contribution of water and cooked rice to an estimation of the dietary intake of inorganic arsenic in a rural village of West Bengal,India

Arsenic contamination of rice plants by arsenic-polluted irrigation groundwater could result in high arsenic concentrations in cooked rice. The main objective of the study was to estimate the total and inorganic arsenic intakes in a rural population of West Bengal, India, through both drinking water and cooked rice. Simulated cooking of rice with different levels of arsenic species in the cooking water was carried out. The presence of arsenic in the cooking water was provided by four arsenic species (arsenite, arsenate, methylarsonate or dimethylarsinate) and at three total arsenic concentrations (50,?250 or 500?µg?l^?1). The results show that the arsenic concentration in cooked rice is always higher than that in raw rice and range from 227 to 1642?µg?kg^?1. The cooking process did not change the arsenic speciation in rice. Cooked rice contributed a mean of 41% to the daily intake of inorganic arsenic. The daily inorganic arsenic intakes for water plus rice were 229, 1024 and 2000?µg?day^?1 for initial arsenic concentrations in the cooking water of 50, 250 and 500?µg?arsenic?l^?1, respectively, compared with the tolerable daily intake which is 150?µg?day^?1.     

微波辅助水提法提取黑米花色苷的工艺研究

以黑米为原料,蒸馏水为提取剂,采用微波辅助水提法提取黑米中的花色苷,在单因素试验的基础上进行正交优化试验。结果表明:微波辅助水提法提取的最佳工艺参数为微波功率600 W、微波时间15 min、提取液pH 5、料液比1∶4(g/mL)。在该条件下,花色苷的得率最大为1.28%。     

响应面法优化水酶法提取米糠多酚

以脱脂米糠为原料,采用响应面法优化水酶法提取米糠多酚的工艺。在单因素试验的基础上,采用星点设计-效应面分析法,以米糠多酚提取量为响应值,对木聚糖酶添加量、料液比和酶解温度等工艺参数进行了优化。结果表明,米糠多酚的最佳提取工艺为木聚糖酶添加量2.3%、酶解温度55℃、料液比1∶29(g/mL)、酶解时间40min。在此条件下,米糠多酚的提取量为5.15mg/g,与预测值5.23mg/g的相对误差为1.62%。该法所得的优化提取工艺参数可靠,可为米糠资源的开发利用提供科学依据。     

碎籼米蛋白质中性蛋白酶酶法提取工艺优化

为提高碎籼米蛋白质提取率,在析因设计和爬陡坡实验基础上,利用中心组合响应面优化技术对碎籼米蛋白质中性蛋白酶酶法提取工艺进行了优化分析,建立了碎籼米蛋白质酶法提取工艺二阶多项式非线性回归方程和数值模型,验证了模型精准度并分析了加酶量(X_1)、酶解时间(X_2)和固液比(X_3)对蛋白质提取率的影响规律,以蛋白质提取率和蛋白质纯度为评价指标。优化方案为加酶量0.98%,固液比1∶10.20,酶解时间74.4 min,pH7.0和50℃。在优化条件下蛋白质提取率为89.82%±1.06%(n=3),与模型预测值91.23%基本吻合,偏差为-1.55%,所提取大米蛋白质纯度为81.02%。     

Digestion study of proteins from cooked meat using an enzymatic microreactor

A semi automatic flow procedure with photometric detection was developed for the study of meat protein digestion. This system comprised two independent flow pathways, gathered by two compartments. The gastric compartment was simulated by an ultrafiltration cell fitted with a 10 KDa cut off membrane and the intestinal compartment was simulated by a 1 KDa cut off dialysis membrane. The pathways were filled with solutions simulating digestive conditions. The proposed system was employed in digestion studies of whole protein extracts from raw and cooked (100°C) meat. A mathematical modelling for the determination of the digestive kinetic constants was established. The results show that meat cooking leads to an important decrease of protein digestibility by proteases of the digestive tract.     

An evaluation of extraction techniques for arsenic in staple diets (fish and rice) utilising both classical and enzymatic extraction methods

Enzymatic extraction methods were evaluated with classical extraction approaches for the determination of arsenic in food. The extraction efficiency for total arsenic was determined by analysing CRM materials DORM-3 fish protein, NIES 106 rice flour and GBW10015 spinach. These were compared with total arsenic concentration determined using microwave-assisted acid digestion and ICP-MS. The total arsenic concentrations in the CRM materials were in good agreement with the certified values. Enzymatic hydrolysis using trypsin has been successfully employed to extract arsenic species in DORM-3 and fish samples. Whilst this method of hydrolysing the proteins worked well for the fish samples, an alternative approach was required to facilitate the digestion of cellulose in plant materials. However, enzymatic extraction using cellulase was found to give unsatisfactory results for both the NIES and GBW10015 CRM materials. Dilute nitric acid (1% HNO₃) was found to give a more efficient extraction for arsenic species in the same CRM materials and rice samples. The study was extended to evaluate a range of real samples. Total arsenic concentrations in 13 different types of fish tissue were determined following microwave-assisted acid digestion using nitric acid/hydrogen peroxide, followed by measurement using HPLC-ICP-MS for speciation analysis. The results obtained for fish were in the range of 3.53–98.80 µg g^?1 As (dry weight). Similarly, the results of 17 rice samples were in the range of 0.054–0.823 µg g^?1. This study demonstrates the importance of selecting an appropriate extraction technique for the quantitative measurement of arsenic species in food.     

米水比对米饭食用品质的影响

研究米水比对米饭食用品质的影响,揭示米饭品质变化趋势,利用低场核磁共振(LF-NMR)、色差仪、质构仪等对米饭进行品质分析,通过体外消化实验,对米饭的淀粉组成及体外血糖生成指数(eGI)进行测定。结果表明,不同米水比制作的米饭品质指标之间均存在差异性(P<0.05);当米水比达到1∶1.3前,快消化淀粉(RDS)、亮度、白度、eGI等指标缓慢增长,硬度、咀嚼性等指标缓慢下降,随着进一步增加水分,变化幅度增大。综合食用品质及淀粉消化各方面指标,推荐米水比在1∶1.3～1∶1.5之间,食用品质较好。     

Effect of cooking method and rice type on arsenic concentration in cooked rice and the estimation of arsenic dietary intake in a rural village in West Bengal,India

Arsenic (As) contamination of rice plants can result in high total As concentrations (t-As) in cooked rice, especially if As-contaminated water is used for cooking. This study examines two variables: (1) the cooking method (water volume and inclusion of a washing step); and (2) the rice type (atab and boiled). Cooking water and raw atab and boiled rice contained 40 μg As l^?1 and 185 and 315 μg As kg^?1, respectively. In general, all cooking methods increased t-As from the levels in raw rice; however, raw boiled rice decreased its t-As by 12.7% when cooked by the traditional method, but increased by 15.9% or 23.5% when cooked by the intermediate or contemporary methods, respectively. Based on the best possible scenario (the traditional cooking method leading to the lowest level of contamination, and the atab rice type with the lowest As content), t-As daily intake was estimated to be 328 μg, which was twice the tolerable daily intake of 150 μg.     

响应面法优化米糠多酚水酶法提取工艺

以辽宁产大米糠为原料,采用响应面法优化米糠多酚的水酶法提取工艺。在单因素试验的基础上,采用响应面分析法,以米糠多酚得率为响应值,对酶加入量、料液比和酶解温度等工艺参数进行了优化。结果表明,以pH 4.8的柠檬酸缓冲溶液为提取溶剂,纤维素酶酶解提取米糠多酚的最佳工艺为:酶加入量4.80%,酶解温度63℃,料液比1∶28 g/mL,酶解时间1 h。此条件下,米糠多酚的得率为4.45 mg/g,与预测值4.52 mg/g的相对误差为1.57%。该法所得的优化工艺参数准确可靠,具有一定的实际应用价值;该研究结果为米糠的基础研究提供了理论依据。     

Antiproliferative and immunoactivatory ability of an enzymatic extract from rice bran

The validation of natural products as source of functional foods or nutraceuticals has become an important issue in current health research. Thus, the present work has tested on MOLT-4 cells (human T cell acute lymphoblastic leukemic) the antiproliferative effect of a water-soluble enzymatic extract from rice bran (EERB). Present work shows that EERB induces cellular death in MOLT-4 cells in a dose-dependent way (0–10 mg/mL) but not in non-tumoral lymphocytes. Flow cytometric analysis of MOLT-4 cells treated with EERB showed the presence of death cells by apoptosis rather than necrosis. Additionally, EERB also exerts an immunoactivatory effect on N13 microglia cells, by inducing TNF-alpha (tumour necrosis factor-α) expression, which plays a key role in the innate immune response to infection. Accordingly, we can propose EERB as a useful natural standardized extract with antiproliferative and immunoactivatory ability that would be beneficial to apply in the functional food field.     

酶法提取枸杞多糖的研究

研究了纤维素酶提取枸杞多糖的最佳工艺条件。以提取率为指标,分别考虑了加水量、酶解pH、酶解温度、酶解时间、加酶量对纤维素酶酶解反应的影响。试验确定了纤维素酶酶解工艺的最佳条件为加水量50mL、pH5.0、酶解温度50℃、酶解时间60min、加酶量0.5%。在这种条件下,枸杞多糖的得率为11.2%。     

酶水解米渣蛋白制备大米肽研究

该研究利用米渣蛋白制备大米肽的适宜酶水解条件,结果表明:在pH 8．5、温度55℃、酶用量2．0％条件下水解3h,水解液中5％TCA可溶性肽含量可达37％以上。     

Removal of arsenic from contaminated soils by microbial reduction of arsenate and quinone

We investigated bioremediation of As-contaminated soils by reductive dissolution of As using a dissimilatory As(V)-reducing bacterium (DARB), Bacillus selenatarsenatis SF-1. We also examined the effect of anthraquinone-2,6-disulfonate (AQDS), an extracellular electron-shuttling quinone, on the As extraction. When B. selenatarsenatis was incubated with As(V)-laden Al precipitates, no acceleration of As dissolution was observed in the presence of AQDS, even though the microbial reduction of AQDS occurred actively. In contrast, AQDS addition significantly enhanced the reductive dissolution of As and Fe in analogous experiments with As(V)-laden Fe(III) precipitates, whereas As dissolution did not occur in the absence of the As(V) reducer. These results indicate the dissolution of As was accelerated by indirect reduction of solid-phase Fe(III) following microbial AQDS reduction, although As(V) reduction is vital for As extraction. B. selenatarsenatis was able to extract As from two types of industrially contaminated soils through reduction of solid-phase As(V) and Fe(III). The copresence of AQDS with B. selenatarsenatis improved the removal efficiency of As from the contaminated soils, concomitantly releasing Fe(II), suggesting that simultaneous use of DARB and electron-shuttling compounds can be an effective strategy for remediation of As-contaminated soils.     

糙米状态下水酶法提取米糠油的方法研究

为避免因碾磨糙米时被激活的脂肪酶与米糠油接触后发生水解反应,得到品质稳定的高级食用米糠油,本试验创新性地在糙米状态下采用水酶法提取米糠油,以米糠出油效率为指标,通过单因素试验和响应面分析对酶解条件进行优化,得到糙米状态下最优水酶法提取米糠油工艺条件。结果表明,在优化培养条件:加酶量1.6%,酶解温度45℃,酶解时间50 min,初始pH 6.0,料液比1:4(m:V),出油效率为69.85%,在此条件下获得的米糠油的酸价为1.26 mg/g。扫描电子显微镜观察表明,水酶法提油处理后的糙米的表面结构明显发生变化和处理后的糙米经过加工制成的精米品质完好。     

超声波辅助水酶法提取米糠油的工艺研究

为了提高米糠的出油率,本文采用超声波辅助水酶法,对混合液进行破乳,得到最佳工艺条件。通过研究复合酶的种类、比例、添加量以及酶解条件对米糠出油率的影响,在单因素的基础上,进行Box-Benhnken响应面实验。结果表明超声波辅助水酶法提取米糠油的最佳条件为:料液比1∶6,酶解温度设定为51℃,酶解时间5 h,超声波功率230 W,超声时间20 min,酶添加量为1.38%（碱性蛋白酶∶纤维素酶∶果胶酶=1∶2∶1）。此条件下得到米糠的出油率为90.53%。      

糙米和发芽糙米吸水动力学研究

采用Peleg方程,探讨了糙米和发芽糙米在不同温度(25～65℃)和不同时间间隔下(20～140min)的吸水动力学性质。实验结果表明:Peleg方程能较好地描述糙米和发芽糙米在实验条件下的吸水性质,且相对误差(E)小于10%。在糙米和发芽糙米的吸水模型中,Peleg方程参数K1均随温度升高而减小,K2无明显变化趋势。     

生食蔬菜模拟污染米饭样本中蜡样芽胞杆菌和呕吐毒素基因分布状况研究

目的 分析被生食蔬菜模拟污染的米饭样本中蜡样芽胞杆菌（Bc）和呕吐毒素基因（ces）的分布状况,为Bc食物中毒科学防控提供基础数据。方法 采集生食蔬菜样本50件,每件样本用0.85%生理盐水盥洗后污染“新煮熟米饭”,置于30 ℃、70% RH培养箱中放置24 h。对生食蔬菜和“污染米饭”进行Bc的定量计数、荧光PCR检测和数字PCR检测。对基于不同采集地点、不同蔬菜类型分组的生食蔬菜样本和及被其污染的“污染米饭”的各项检出率指标进行统计学分析。结果 生食蔬菜样本中Bc检出率为80.00%（40/50）,ces基因和Bac16s RNA基因检出率分别为0（0/50）和10.00%（5/50）;“污染米饭”样本Bc检出率为94.00%（47/50）,ces基因和Bac16s RNA基因检出率分别为14.00%（7/50）和90.00%（45/50）。采集自农贸市场和农户土地的2组生食蔬菜中Bc检出率差异有统计学意义（χ²=11.063,P=0.000 88校正）,被上述2组生食蔬菜类污染的“污染米饭”Bac16s RNA基因检出率和ces基因检出率差异均有统计学意义（χ²=3.926,P=0.047 5校正;χ²=5.444,P=0.019 6校正）。7件“污染米饭”基于荧光PCR检测ces基因阳性,Ct值介于24.12~37.73,数字PCR结果介于6.8 copes/μL~6.2×10⁶ copes/μL。结论 被生食蔬菜模拟污染的米饭样本可具有导致Bc食物中毒风险的病原学特征。