微波消解-分光光度法测定乳清蛋白营养强化粉中磷的含量

目的 建立微波消解、紫外分光光度度法测定乳清蛋白营养强化配方粉中磷的含量。方法 称取适量的乳清蛋白营养强化配方粉,加入硝酸与石墨消解仪中预消解,待冷却后加入30%过氧化氢使用微波消解仪消解,样品经过赶酸,转移至容量瓶中并定容至刻度,在稀释液中加入钒钼酸铵试剂后使用紫外可见分光光度计进行检测。结果 磷在浓度2-15μg/mL之间呈现良好的线性关系, r_²=0.9997, 平均回收率为98.8%, 相对标准偏差为2.0%。结论 该方法操作简便、准确、安全、重现性好, 能准确测定磷含量, 可在实验室推广。     

原料蛋黄粉中锌含量的检测

目的 建立原料蛋白粉中锌含量的简便检测方法。方法 蛋黄粉待测样品经微波消解, 加入5 mL浓硝酸后缓慢振摇几次, 再加入2 mL过氧化氢放置5 min, 拧紧盖子在微波消解设备中进行充分消解, 冷却后在带孔式电热板上赶酸至1 mL, 用2%的盐酸溶液转移至50 mL容量瓶中, 摇匀。结果 该检测方法仪器检出限为0.092 mg/kg, 在元素线性范围内相关系数R为0.999以上, 回收率为97.2%~101.5%。结论 本检测方法操作步骤简便, 检测结果准确可靠。     

厌氧接触+射流曝气+Fenton流化床技术处理制浆造纸废水运行实例

介绍厌氧接触+射流曝气+Fenton流化床技术处理制浆造纸生产废水的工程参数、运行效果和工程效益。六个月的运行数据显示,厌氧单元出水COD平均浓度为1321 mg·L^-1,平均去除率为61%;好氧单元出水COD浓度为185 mg·L^-1左右,平均去除率为78%;深度处理部分COD出水浓度为44 mg·L^-1,平均去除率为73%,可实现废水达标排放。     

Protein quality and antioxidant properties of soymilk derived from black soybean after in vitro simulated gastrointestinal digestion

Protein quality and antioxidant properties of soymilk derived from black soybean (eight varieties) in China were analysed following in vitro simulated gastrointestinal digestion (including dialysis). Soymilk from black soybean possessed high okara weight but low yield, protein content and sensory scores. The in vitro digestibility of protein in all black soymilk samples was higher than 60%, and the Shenmu black soybean exhibited the highest digestibility. Non-digested milk from the black soybean exhibited significantly high total phenolic content (TPC) (127.15–173.04 mg/100 mL), ferric-reducing antioxidant power (FRAP) (272.18–366.27 μmol L⁻¹) and DPPH free radical-scavenging activity (61.20–83.81%). These parameters were significantly lower in the non-digested soymilk than those in soymilk after gastric digestion but higher than those of soymilk in the dialysed fraction. Gastric digestion significantly increased bioactive compound levels released from black soymilk, and the bioaccessibility of phenolic compounds was 24.37–36.05%. Hence, black soymilk was sufficiently available for human absorption.     

Effects of water-soluble soybean polysaccharide on rheological properties,stability and lipid digestibility of oil-in-water emulsion during in vitro gastrointestinal digestion

Water-soluble soybean polysaccharide (SSPS) is a naturally occurring emulsifier. SSPS was used as the sole emulsifier to stabilize an oil-in-water (O/W) emulsion. The effects were investigated of different SSPS concentrations (3–20% (w/w)) on the lipid digestibility, rheological properties and stability of O/W emulsions during in vitro digestion model. The droplet size of the emulsions tended to increase during the oral phase because the emulsions were unstable and droplets coalesced, except with a SSPS concentration of 20% (w/w). The presence of SSPS markedly reduced the free fatty acid (FFA) content after its stabilized O/W emulsion passed through in vitro gastrointestinal digestion. The amount of FFA significantly decreased as the concentration of SSPS increased due to SSPS stabilization film on oil droplet surface and high viscous system. SSPS may be an attractive alternative ingredient to control the lipid digestibility of emulsions for various food products.     

天然复合调味品中微量元素和重金属含量的测定

建立了微波消解电感耦合等离子体发射光谱法测定天然复合调味品中微量元素和重金属含量的方法,并用该法测定了10种天然复合调味品中Fe,Mn,Cu,Zn,Cr,Cd和Pb等元素的含量.该方法的加标回收率在96.0％～103.0％之间,相对标准偏差RSD≤4.50％,结果表明:天然复合调味品中Fe和Mn含量低于单一天然香料调味品,与味精、鸡精等其他化学合成调味品相比,天然复合香料调味品中Fe,Mn,Cu,Zn,Cr含量较高,而其Cu/Zn比值较低,重金属含量普遍较低,此测定结果可为探讨天然复合香料调味品的保健作用与微量元素含量的相关性提供科学数据.     

火焰原子吸收/发射光谱法对小麦粉中钠的检测

本文对钠元素在食品中的检测方法进行了简要比较,同时采用火焰原子吸收和火焰原子发射光谱法对国家标准物质小麦粉中的钠元素进行了检测,对前处理干法消化、湿法消化两种不同过程进行了比较,在两种前处理方法的称样量、消化时间、所用试剂、损失等方面进行了对比,找到两种方法各自的优缺点;同时本实验也对检测方法进行了比较,在前处理过程对结果无较大的影响,发射光谱法较吸收光谱法测得结果略微偏低。本文对于试验研究中,尤其是营养标签必测项Na元素的检测,选择何种前处理方法和检测方法具有一定参考价值。     

一种用于测定纸浆中过渡金属含量的样品预处理方法

研究了一种用于测定纸浆中过渡金属含量的样品预处理方法(酸处理法).选择了最具代表性的铁为研究对象,通过对酸的种类和浓度、处理温度和时间等条件的选择及优化,得出最佳处理条件为:采用3 mol/L的硫酸溶液来分散纸浆(浆料浓度可视过渡金属离子含量的多少适当调整),然后将其装入密封的容器内在120℃下处理5h.通过与灰分法和消化法预处理后的测定结果比较可知,采用酸处理法对样品进行预处理,可使测定过渡金属离子含量的误差在7％以内,且克服了灰分法中硅化合物的干扰.