HPLC法测定雪莲果不同储藏条件下糖组成的变化

用热水抽提法提取雪莲果块根的总糖,采用高效液相色谱测定法以ZORBAX Carbohydrate柱(4.6×150mm,5μm)为固定相,75%乙腈为流动相,柱温35℃测定了雪莲果块根糖的组成。该方法简便快速、结果准确可靠,为雪莲果中糖组成分析提供了一种高效快速的测定方法。利用此方法研究了雪莲果在4℃和室温两种储藏条件下糖分组成的变化,为雪莲果果实的储藏提供指导和依据,为更好的利用雪莲果提供资料。     

高效液相色谱法测定蓝莓果浆中糖的组成和含量

目的：建立高效液相色谱法测定蓝莓果浆中糖的组成和含量的检测方法。方法：超声波水提样品中的糖类,色谱柱为Agilent Zorbax carbohydrate 柱(4.6 × 250mm,5μm),流动相为乙腈- 水(75:25,Ｖ:Ｖ),流速为1ml/min。结果：糖类浓度在0.5～10mg/ml 内呈现良好的线性关系,相关系数在0.9989(n=5)以上;精密度实验RSD为0.36%～2.18%(n=5);平均回收率为91.36%～101.34%。结论：该方法简便快速,结果准确可靠,为测定野生蓝莓果浆中糖组分提供了一种高效快速的测定方法。     

高效液相色谱法测定镇江香醋醋酸发酵过程中果糖和葡萄糖含量

建立了果糖和葡萄糖的高效液相色谱(HPLC)分析方法,并用于镇江香醋醋酸发酵过程中单糖含量的分析。分析条件:醋醅浸出液用C18固相萃取小柱进行预处理,以Cosmosil Sugar-D作为分离柱,乙腈∶水(78∶22,v/v)为流动相,柱温35℃,流速1.0 mL/min,示差折光检测器进行检测。结果表明,该方法具有良好重复性和准确度,平均加标回收率为96.28%～96.69%。该研究结果为食醋酿造过程中果糖和葡萄糖含量的定量分析提供了一种高效快速的测定方法。     

鲜玉米中可溶性糖含量的测定

采用高效液相色谱法对鲜玉米中可溶性糖含量进行检测。色谱柱为Agilent Zorbax carbohydrate柱(4.6mm×250mm,5μm),流动相为75%乙腈,柱温25℃,流速1mL/min。相关系数r在0.99839～0.99995(n=5)之间;精密度实验RSD为0.90%～3.80%(n=5);平均回收率在95.28%～101.02%之间。该方法准确、可靠,可以快速准确的对鲜玉米中可溶性糖进行定性定量分析。     

在线固相萃取—液相法测定食品中胡萝卜素

目的：采用两泵一阀的在线固相萃取-高效液相色谱技术建立一种能够快速检测食品中胡萝卜素的方法,避免了胡萝卜素在复杂前处理过程中的损失。方法：在线固相萃取柱PLRP-S(2.1 mm×12.5 mm)液相分离色谱柱PAH (2.1 mm×100 mm,1.8μm);固相萃取泵流动相,水+甲醇,液相分离流动相,甲醇+二氯甲烷;检测波长450 nm。结果：该方法在0.10～2.00μg/mL保持良好的线性,方法的检出限和定量限均能够满足检测需求。α-胡萝卜素回收率为92.0%～105.4%,β-胡萝卜素回收率91.1%～107.2%。结论：该方法利用两泵一阀的在线固相萃取技术,能高效、快速检测食品中胡萝卜素,检测效率高,前处理提取效率好,方法能够满足检测需要。     

基质固相分散-高效液相色谱法测定山楂中的有机酸

研究采用基质固相分散处理、高效液相色谱法测定山楂中的有机酸.以ZORBAX Stable Bound(4.6×50mm,1.8μm)快速分离柱为固定相,0.01mol/L NaH2PO4(pH2.98)和乙腈(体积比为98:2)为流动相,流速为2.0ml/min,柱温25℃,检测波长210nm.方法回收率为94%～98%;相对标准偏差为2.1%～3.0%;检出限为100～200μg/L.色谱分离时间不超过3.0min.并用于实际样品中有机酸分析,结果令人满意.     

在线净化/固相萃取-高效液相色谱法测定柑橘中 多菌灵痕量残留量

目的 通过在线净化/固相萃取-高效液相色谱技术建立测定柑橘中痕量多菌灵的方法。方法 样品在固相萃取小柱Cyclone-MCX中进行净化和富集后,通过阀将固相萃取小柱切换至分析流路,使待测物从富集柱冲洗至分析柱PA_ⅡC₁₈中,采用梯度洗脱方式完成多菌灵的分离和检测。结果 多菌灵在1～20μg/L范围内呈线性相关,线性方程为y=0.0921x-0.0016,相关系数r=0.9995;检出限为0.1μg/L(S/N=3);柑橘中3个水平添加回收率(n=6)在81.0%～96.7%;6次加标回收相对标准偏差在2.34%～3.11%。结论 建立的此套方法简便、快速、准确、重现性好,能够满足柑橘中多菌灵痕量残留量的测定。     

浓缩石榴汁中熊果苷的超高效液相-串联质谱检测方法研究

建立了浓缩石榴汁样品中熊果苷含量测定的固相萃取-超高效液相-串联质谱测定方法。样品用水稀释,HLB和氨基固相萃取柱净化,采用BEHAmide色谱柱(100mm×2.1mm,1.7μm)分离,以乙腈和水梯度洗脱,多反应监测模式测定,定量离子对为m/z271.2>108.0,定性离子对为m/z271.2>160.9,外标法定量。熊果苷的检测限为0.006mg/kg,在0.004～0.2mg/L浓度范围内,熊果苷的线性相关系数为0.9994,熊果苷的加标回收率均在80.6%～108.1%范围内,相对标准偏差均低于8.3%。该方法样品净化效果良好,检测简便、快速、准确,能够满足浓缩石榴汁中熊果苷含量测定和定性确证的要求。     

固相萃取-高效液相色谱法测定水产品中的甲基睾酮残留量

建立水产品中甲基睾酮残留量的固相萃取-高效液相色谱测定方法。样品经乙醚振荡提取、蒸发浓缩、正己烷除脂、LC-C18柱净化后吹干定容,以甲醇-0.1%甲酸溶液(75:25,V/V)为流动相经反相高效液相色谱检测定量。方法在7.0～200μg/kg添加范围内的平均回收率为82.0%～86.0%,相对标准偏差均小于7%,定量限为7.0μg/kg。     

食品中游离甲醛的高效液相色谱测定方法的研究

为优化食品中游离甲醛的测定方法,采用固相提取、高效液相色谱法测定食品中微量游离甲醛的含量.试样经水浸泡等方法处理后过滤,取过滤液与2,4-二硝基苯肼衍生反应后,经Oasis HLB富集净化,采用Luna 5 μ C18（2）色谱柱,水与乙腈为流动相,选用380 nm波长检测,与标准谱图比较进行定性,外标定量.本法的回收率分布于85.0%～97.4%,检出限为0.025 mg/kg.本方法具有简便、快速、准确的特点。     

浓缩蜜橘汁的工业化加工研究

以湘西蜜橘为原料加工成浓缩蜜橘桶汁,研究了浓缩蜜橘汁的加工工艺,结果表明:蜜橘果实榨汁时,用0.4%果胶酶在45℃下酶解处理果浆90min,可提高出汁率15%。通过正交试验,确定了真空浓缩最佳工艺参数为:真空浓缩温度50～55℃、真空度(9.33～10.0)×10~4Pa、果汁流量6000～6500L/h、蒸汽压力7.5～8.0×10~4 MPa;贮存温度≤-18℃下,产品pH值、总酸和Vc无影响,并制定了产品质量标准,为我国浓缩汁加工企业提供了有益的借鉴。     

复合果蔬汁益生菌发酵乳的工艺研究

本研究以鲜乳为原料,添加番茄、草莓、橙三种果蔬汁进行乳酸菌发酵。采用正交试验选择最优配方。实验结果表明:①复合果蔬汁最优配方:番茄汁15%、草莓汁20%、橙汁10%、羧甲基纤维素钠0.25%、果胶0.1%;②复合果蔬汁发酵乳的最优配方:鲜牛乳70%、复合果蔬汁20%、酸果奶稳定剂0.25%、果胶0.1%、蔗糖9%、接种3%的乳酸菌菌种(Lb:St=1:1),在43℃恒温条件下发酵3.5h,置于0～4℃的冰箱中冷藏后熟10～12h。所得益生菌果蔬汁发酵乳组织均匀,口感细腻,酸甜适中,具有果蔬特有的滋味和芳香。     

Survival of human norovirus surrogates in milk, orange, and pomegranate juice, and juice blends at refrigeration (4 °C)

Fresh fruits, juices, and beverages have been implicated in human noroviral and hepatitis A virus outbreaks. The purpose of this study was to determine the survival of human norovirus surrogates (murine norovirus, MNV-1; feline calicivirus, FCV-F9; and bacteriophage MS2) in juices (orange and pomegranate juices), juice blends (pomegranate and orange juice) and milk over 0, 1, 2, 7, 14, and 21 days at refrigeration (4 °C). Juices, juice blends, and milk were inoculated with each virus over 21 days, serially diluted in cell culture media, and plaque assayed. MNV-1 showed no reduction in titer after 21 days in orange juice and milk, but moderate reduction (1.4 log) in pomegranate juice from a titer of 5 log(10) PFU/ml. However, MNV-1 was completely reduced after 7 days in the orange and pomegranate juice blend. FCV-F9 from a titer of 6 log(10) PFU/ml was completely reduced after 14 days in orange as well as pomegranate juice and by ～ 3 logs after 21 days in milk at 4 °C. Interestingly, FCV-F9 was completely reduced after 1 day in the orange and pomegranate juice blend at 4 °C. MS2 was reduced by ～ 1.28 log after 21 days in orange juice from a titer of 6 log(10) PFU/ml, and <1 log after 21 days in milk or pomegranate juice, with juice blends showing minimal reduction (<1 log) after 21 days at 4 °C. These results show the survival pattern of noroviruses that aid in the transmission of foodborne viral outbreaks. The data obtained can be used in quantitative viral risk assessment studies and to develop improved measures to prevent virus survival towards controlling outbreaks.     

基于色谱质谱联用技术分析纽荷尔脐橙果汁及其果酒的香气成分和苦味物质

为了研究纽荷尔脐橙果汁、果酒的香气成分及其苦味物质,本文通过顶空固相微萃取技术富集其中香味物质并采用气相-质谱联用技术测定所含物质及相对含量。其中果汁中鉴定化合物31种,主要成分为D-柠檬烯(33.74%)和巴伦西亚橘烯(25.12%);果酒中鉴定化合物27种,主要成分为4-萜烯醇(13.45%)、芳樟醇(8.54%)、苯乙醇(8.45%)以及高级脂肪酸乙酯。通过QuEChERS前处理方法,PSA填料净化,采用液相-质谱联用技术测定果汁、果酒中苦味物质含量,其中果汁中主要苦味物质为橙皮苷(13.4 μg/mL)、柠檬苦素(4.43 μg/mL)、橙皮素(0.02 μg/mL)、诺米林(0.07 μg/mL),果酒中主要苦味物质为橙皮苷(16.7 μg/mL)、柠檬苦素(0.05 μg/mL)、橙皮素(0.08 μg/mL)。酿造过程中,柠檬苦素通过酵母发酵、酶的作用等原因逐渐降解,转变为没有苦味的脱氢柠檬苦素及酸类,因此果酒中柠檬苦素的含量降低至0.05 μg/mL,橙皮苷和橙皮素的含量没有显著变化。     

利用氨基酸分析仪对橙汁中脯氨酸定量研究

利用氨基酸分析仪对橙汁饮料中的游离脯氨酸进行测定,结果表明,橙汁饮料中含有一定量的脯氨酸,其含量差异较大,含量范围在0～919mg/L之间。分析果汁含量和脯氨酸含量之间的关系,结果表明,其含量的大小不能作为橙汁饮料中天然果汁含量多少的判定依据,要综合考虑其他的检测因子才能判定是否掺假。     

Pulsed electric field processing effects on flavor compounds and microorganisms of orange juice

The headspace flavor compounds of fresh squeezed orange juice processed by pulsed electric field (PEF) at 30 kV/cm for 240 or 480 μs, or heat at 90°C for 1 min were isolated by a solid phase microextraction (SPME) coating and separated by gas chromatography. The average losses of flavor compounds in orange juice processed by 240, 480 μs PEF and heat process were 3.0%, 9.0% and 22.0%, respectively (P < 0.05). The flavor loss was mainly due to vacuum degassing in the PEF process. The total plate counts of control, 240, 480 μs PEF, and heat processed orange juice were 5400, 21, 19, and 4, respectively. The yeast and mold counts of control, PEF for 240, 480 μs and heat processed orange juice were 2800, 15, 9, and 4, respectively. ©     

Changes in orange juice color by addition of mandarin juice

The most natural way of improving the color of orange juices is by adding other juices, which provide a more intense coloration. The US legislation allows the addition of up to 10% of mandarin juice to the orange juice to improve its color. The first objective of this study was to compare the color characteristics of juices from 11 mandarin cultivars, currently being grown in Spain. Experimental results proved that only the green-red coordinate, a*, of the orange juices can be improved by adding mandarin juice. The mandarin cultivar that provided a juice with the highest values of a* was Clemenules. Once this selection was made, the effects of adding mandarin juice at different ratios, up to 10%, on the color characteristics of the orange juice were studied. Values of the a* coordinate went from 5.50 for the pure orange juice up to 6.29 for the mixture of 90% orange juice plus 10% of mandarin juice. Finally, hedonic tests proved that regular juice consumers preferred the color of mandarin juice to that of orange juice and that they liked better the color of the juice mixture containing 10% mandarin juice than that containing 3% mandarin juice.     

Comparative study on shelf life of orange juice processed by high intensity pulsed electric fields or heat treatment

The effects of high intensity pulsed electric fields (HIPEF) processing (35 kV/cm for 1,000 μs; bipolar 4-μs pulses at 200 Hz) on the microbial shelf life and quality-related parameters of orange juice were investigated during storage at 4 and 22 °C and compared to traditional heat pasteurization (90 °C for 1 min) and an unprocessed juice. HIPEF treatment ensured the microbiological stability of orange juice stored for 56 days under refrigeration but spoilage by naturally occurring microorganisms was detected within 30 days of storage at 22 °C. Pectin methyl esterase (PME) of HIPEF-treated orange juice was inactivated by 81.6% whereas heat pasteurization achieved a 100% inactivation. Peroxidase (POD) was destroyed more efficiently with HIPEF processing (100%) than with the thermal treatment (96%). HIPEF-treated orange juice retained better color than heat-pasteurized juice throughout storage but no differences (p<0.05) were found between treatments in pH, acidity and °Brix. Vitamin C retention was outstandingly higher in orange juice processed by HIPEF fitting recommended daily intake standards throughout 56 days storage at 4 °C, whereas heat-processed juice exhibited a poor vitamin C retention beyond 14 days storage (25.2–42.8%). The antioxidant capacity of both treated and untreated orange juice decreased slightly during storage. Heat treatments resulted in lower free-radical scavenging values but no differences (p<0.05) were found between HIPEF-processed and unprocessed orange juice.     

高效液相色谱法测定菠萝果实中的糖分

研究了用高效液相色谱法测定菠萝果实中糖分的方法。色谱柱为Luna5μmNH2100A,250mm×4.6mm,流动相为70%乙腈水溶液,柱温35℃,用示差折光检测器检测菠萝果实中的糖类。本方法的相对标准偏差为0.52%～2.24%,相关系数在0.9992以上,加标回收率为98.8%～100.3%。该方法简便、灵敏、结果可靠,三种糖都得到了较好的分离,适用于菠萝果实中糖类的分析。