薄层扫描法测定罗汉果糖苷(Ⅴ)含量的研究

建立了采用薄层扫描法测定罗汉果糖苷（V）含量的方法。点样于硅胶G板上，以正丁醇-乙醇-水（8；2：3）为展开剂,10％硫酸乙醇显色，单波长反射法锯齿扫描，λ=500nm。结果表明，罗汉果糖苷（V）在2．0～16．0μg范围内具有良好的线性关系，r=0.9921，平均回收率为97.62％，RSD为2．59％（n=4）。该法简便快速、准确灵敏，可用于罗汉果糖苷量产质量监控。     

薄层扫描法测定芦荟中芦荟甙含量的方法研究

用薄层扫描法测定芦荟中芦荟甙含量，线性范围0．4－2．0μg/点，纯品的相对标准编差为1．46(n=6），回收率为100．21％。方法快速、简便、重现性好。     

薄层扫描法测定保健饮料中牛磺酸的含量

目的 建立测定保健饮料中牛磺酸含量的方法.方法 采用薄层扫描法测定牛磺酸含量,以正丙醇-水-冰乙酸-乙醇(5.2:2:2:0.8)做展开剂,以1%茚三酮乙醇液为显色剂,双波长反射法锯齿扫描.结果 牛磺酸0.205～1.025 μg时与峰面积呈良好的线性关系(r=0.9994),加样回收率98.18%,RSD=2.21%.结论 此方法简便、快速、准确、灵敏度高.     

薄层扫描法测定保健饮料中牛磺酸的含量

目的建立测定保健饮料中牛磺酸含量的方法。方法采用薄层扫描法测定牛磺酸含量,以正丙醇-水-冰乙酸-乙醇(5.2∶2∶2∶0.8)做展开剂,以1%茚三酮乙醇液为显色剂,双波长反射法锯齿扫描。结果牛磺酸0.205～1.025μg时与峰面积呈良好的线性关系(r=0.999 4),加样回收率98.18%,RSD=2.21%。结论此方法简便、快速、准确、灵敏度高。     

罗汉果甜甙V在各部位的含量分布

以鲜罗汉果为原材料,将果皮、果囊和种子分离后,分别真空干燥得到罗汉果果皮、果囊和种子的质量百分数分别为25.42%～32.45%、30.00%～43.89%和29.29%～37.56%,再各取适量在微波辐射条件下,以水为溶剂提取罗汉果水溶物,经浓缩干燥,得到各部位水提物,将各提取物用无水乙醇回流后,利用分析型高效液相色谱法测定,得出干燥的罗汉果中果皮、果囊和种子中甜甙Ⅴ的含量在各部位的百分含量分别为0.26%、2.36%和0.06%。     

茶叶中咖啡因含量的薄层色谱扫描测定方法的建立

探讨了薄层色谱扫描法展开剂及配比的选择,并做了回收率及稳定性和精密度实验,与高效液相色谱法结果进行对比,通过F检验得出无显著性差异。从而确定实验室快速准确测定茶叶中咖啡因含量的方法为薄层色谱扫描法。     

薄层扫描测定果蔬中绿原酸含量

用薄层扫描测定绿原酸的含量，以３６％乙酸－乙酸乙酯－９５％乙醇为展开剂，用硅胶ＧＦ２５４薄层板分离，绿原酸Ｒｆ＝０．６６，展开效果很好，采用波长λ＝３３０ｎｍ反射扫描仪测定，最低检 为０．０１ｕｇ，回收率为１０５．１％，本试验设三次重复。     

薄层扫描法测定猪肝中克伦特罗残留量

采用薄层扫描法测定猪肝中克伦特罗残留量,用GF254板作载体,乙酸乙酯-甲醇-醋酸(8:l:0.8)为展开剂,克伦特罗的Rf值为0.8l。线性范围0.004～0.050μg,回收率为86.5%～94.9%,RSD为5.0%～5.8%(n=6)。     

高效液相色谱法测定罗汉果饮料中甜苷V的含量

建立了高效液相色谱法测定罗汉果饮料中甜苷V的方法。样品经70%甲醇溶液提取溶解,采用C18反相色谱柱分离,用乙腈-0.1%磷酸溶液(22∶78)为流动相进行洗脱,检测波长为203nm,流速为1m L/min,以色谱峰保留时间和紫外可见光谱进行定性,外标法进行定量,并应用该方法对多个样品中甜苷V含量进行检测。结果表明,甜苷V在0.0024~0.384mg/m L范围内线性关系良好(R2=0.9999),检出限为3mg/kg,加标回收率为98%~105%。该方法操作简单,精密度好,能满足罗汉果饮料中甜苷Ⅴ的检测要求。固体饮料甜苷V含量在0~65mg/100g之间,液体饮料在0~15mg/100g之间,甜苷在罗汉果饮料生产中对其含量控制较低,因其甜味性质,含量高会导致口感不佳,消费者难以接受。因此,该方法可作为罗汉果饮料产品的质量控制及真伪鉴别的检测方法。     

薄层扫描法测定微生物发酵转化液中熊果苷含量

目的：建立薄层扫描法测定微生物发酵转化液中熊果苷含量的方法。方法：微生物发酵转化液经过滤浓缩制备,以乙酸乙酯-乙酸-水（v乙酸乙酯：v乙酸：v水=3.1：1：1）为展开剂,检测波长570nm。结果：熊果苷在2～6μg范围内线性良好,相关系数r=0.9976。结论：本法快捷、简便、准确,可用于微生物发酵转化液中熊果苷含量的测定。     

高效液相色谱法测定白酒中罗汉果V的含量

采用高效液相色谱法测定白酒中罗汉果甜苷V的含量,从而达到检测白酒中添加罗汉果浸泡液的目的。检测条件为:Welch Materials Column-XB-C18(4.6×250mm,5μm)色谱柱,以乙腈-水(77∶23)为流动相,流速为1mL/min,检测波长为203nm,柱温25℃。罗汉果甜苷V进样量在0.4～20μg之间线性关系良好(R2=0.9983),回收率范围在97.5%～105.5%,RSD为2.56%(n=6)。该方法操作简便、测定快速、结果准确,同时具有良好的精密度、重复性和稳定性,可作为白酒中添加罗汉果浸泡液的检测方法。     

An improved method for thin layer chromatographic analysis of saponins

Analysis of saponins by thin layer chromatography (TLC) is reported. The solvent system was n-butanol:water:acetic acid (84:14:7). Detection of saponins on the TLC plates after development and air-drying was done by immersion in a suspension of sheep erythrocytes, followed by washing off the excess blood on the plate surface. Saponins appeared as white spots against a pink background. The protocol provided specific detection of saponins in the saponins enriched extracts from Aesculusindica (Wall. ex Camb.) Hook.f., Lonicera japonica Thunb., Silene inflata Sm., Sapindusmukorossi Gaertn., Chlorophytum borivilianum Santapau & Fernandes, Asparagusadscendens Roxb., Asparagus racemosus Willd., Agave americana L., Camellia sinensis [L.] O. Kuntze. The protocol is convenient, inexpensive, does not require any corrosive chemicals and provides specific detection of saponins.     

Determination of docosahexaenoic acid in milk using affinity solid-phase purification with argentous ions and modified thin layer chromatography

This paper reports a simple method for docosahexaenoic acid determination in bovine milk. The method consists of three steps: (1) one-step DHA methylation in bovine milk without lipid extraction, (2) concentration of DHA methyl ester by AgNO₃-modified silica gel column chromatography, and (3) detection of DHA methyl ester using spot focused-high performance thin layer chromatography. DHA was directly methylated in bovine milk and selectively concentrated in accordance with its intrinsic affinity to argentous ions. Purified DHA methyl ester was developed on newly designed thin layer chromatographic plates with focusing slits and determined densitometrically using conventional software, following visualisation with iodine staining. In addition to the densitometrical analysis, it is also possible for practical, semiquantitative DHA determination to be visually performed on site in manufacturing industries. Unlike conventional methods, the method described needs neither lipid extraction procedures that use a large amount of organic solvent, nor a gas chromatograph system.     

Suitability of thin layer models for infrared-hot air-drying of onion slices

Onion slices were dried under different processing conditions applying infrared radiation assisted by hot air. Drying temperature, slice thickness, inlet air temperature and air velocity were varied to study the drying behavior. Thin layer models such as Page, modified Page, Fick's and Exponential models, which are used to describe the drying kinetics of food materials, were tested for the combination mode drying. The linear plots for Page and modified Page models gave a better fit (R²=0.980-0.995) over the other two models (R²=0.767-0.933). A combined regression equation developed to predict the drying parameters (k and n) for all the four models gave a fairly good fit (R²=0.852-0.989). The modified Page model gave better predictions for drying characteristics over the other models.     

罗汉果苷V提取条件优化研究

建立罗汉果苷V的最佳提取工艺。采用单因素试验和正交试验考察提取溶剂浓度、提取时间、提取温度、料液比对罗汉苷V的影响。结果表明,罗汉果苷V的最佳提取工艺条件:以浓度为50%的乙醇溶液作为提取剂,回流时间为120min,物料比为1∶15(m∶V),回流温度为60℃。该条件下罗汉果苷V的提取率可达到72%。     

高效液相色谱法测定槟榔中阿斯巴甜的含量

目的建立高效液相色谱法检测槟榔中阿斯巴甜的含量的分析方法。方法槟榔去除卤水及内层纤维后,以磷酸-水溶液(pH=2)为提取液、采用超声法提取槟榔中阿斯巴甜。提取液经Agilent ZORBAX SB-C_(18)(4.6 mm×250 mm,5μm)色谱柱分离,以乙腈-10 mmol/L KH2PO4水溶液(pH=3.5)(14:86,V:V)为流动相,流速为1 mL/min,采用紫外检测器在210 nm检测波长下对阿斯巴甜含量进行测定。结果阿斯巴甜在4.444~222.2μg/mL范围内呈现良好的线性关系,检出限为0.22μg/mL,精密度为0.17%,在3个加标水平下的平均回收率为99.80%。结论本提取方法易于操作、提取率高且稳定性良好,可用于槟榔中阿斯巴甜的提取;本检测方法具有线性范围广、灵敏度高、快速、准确等优点,适用于槟榔中阿斯巴甜的含量测定。     

Modeling of baking of thin layer of cake using the lumped reaction engineering approach (L-REA)

Baking is a simultaneous heat and mass transfer process commonly applied in the food industry. It is desirable to have a simple, accurate and robust model in order to assist efficient process design and evaluation of product quality. The reaction engineering approach which was proven to be accurate to model several challenging drying cases, was implemented in this study to model the baking of thin layer of cake. The equilibrium activation energy (ΔE_v,b) was evaluated according to the baking oven temperature and corresponding humidity. It was then combined with the relative activation energy (ΔE_v/ΔE_v,b) to produce a unique relationship. Results of the modeling indicate that the L-REA can describe the profiles of moisture content and temperature very well. While the results are accurate, the model itself remains simple. Another significant application of the REA for modeling the processing of food products has been made by this research.