液相色谱-质谱联用测定食品中19种激素

建立了食品中合成固醇类激素(群勃龙、勃地龙、诺龙、美雄酮、睾酮、司坦唑醇、甲基睾酮、黄体酮、丙酸诺龙、丙酸睾酮和苯丙酸诺龙)和糖皮质类激素(泼尼松龙、泼尼松、氢化可的松、地塞米松、倍他米松、甲基泼尼松、倍氯米松和氟氢可的松)多残留的液相色谱-串联质谱(LC-MS/MS)检测方法。样品经乙酸铵提取,甲醇再提取,加水混匀,ENVI-Carb固相柱和NH3固相柱净化,经C18柱分离后进行LC-MS/MS选择反应监测模式下定量分析。合成固醇类激素采用正离子模式检测,糖皮质激素采用负离子模式检测,一次前处理,2次进样。19种激素的定量检出限为0.1~1.0μg/kg;采用1,3和10倍定量进行分析,回收率在50%~110%之间,相对标准偏差为2.0%~12.0%。对134批次样品进行检测,统计得到内源性激素(黄体酮、氢化可的松和睾酮)的本底值。     

解吸附电晕束电离质谱法快速检测微量雌激素

目的 建立解吸附电晕束电离质谱(DCBI-MS)快速检测微量雌激素的分析方法。方法 通过DCBI-MS 直接分析, 对比标准物质一级和二级质谱图, 对检测样品中非法添加的炔诺酮、黄体酮、甲羟孕酮、左炔诺孕酮、醋酸甲地孕酮和枸橼酸氯米芬等 6 种雌激素进行快速定性和半定量检测。结果 各目标化合物均可在 1 min 内被检出。 基于一级分子离子的定量分析, 6 种雌激素的半定量检测结果可信, 线性关系最差的醋 酸甲地孕酮相关系数为 0.9471, 而黄体酮则为 0.9998。最低检出值分别是: 0.0875、0.045、0.1775、0.05、0.15、0.1 mg/L。结论 本方法无需复杂的前处理过程, 简便、快速、灵敏度高, 可用于保健食品和中成药中违禁添加微量雌激素的快速定性及半定量检测。     

UPLC-MS/MS法同时测定保健饮品中的3种雌激素

建立一种超高效液相色谱-串联质谱法测定保健饮品中3种雌激素(己烯雌酚、雌二醇和黄体酮)药物残留的方法。样品经乙腈提取,以水/乙腈为流动相,梯度洗脱,经ACQUITYTM BEH C18(2.1 mm×50 mm,1.7 m)色谱柱分离,采用正负离子同时扫描,多反应监测模式进行定性及定量分析。己烯雌酚和黄体酮在0.1~200 mg/L范围内,雌二醇在1~200 mg/L范围内,线性关系良好,相关系数r0.999,己烯雌酚、雌二醇和黄体酮的方法定量限分别为0.1,1和0.1 mg/L,加标回收率的平均值为73.8%~95.2%,RSD为1.05%~5.27%。该方法灵敏度高、操作简单高效,适用于保健饮品中雌激素的残留量分析。     

粮食中真菌毒素快速定量检测方法应用比较研究

采用便携式真菌毒素快速定量检测仪对玉米中黄曲霉毒素B1和呕吐毒素进行定量检测,同时与酶联免疫法对比检测结果。结果显示黄曲霉毒素B1快速定量检测卡检出限为1.75μg/kg;准确性与所采用酶联免疫法无显著差异;检测结果变异系数范围在7%~11.2%之间,平均变异系数为8.7%;定量检测仪台间无显著差异。呕吐毒素快速定量检测卡检测限为0.078 mg/kg;定量检测仪台间无显著差异;采用便携式定量检测仪具有简单、快速、成本低、能实现现场操作且实时上传数据并记录监测地点位置等优势,具有较好的推广使用价值,特别适用于卫生调查、研究、筛查等现场使用。     

高效液相色谱法同时测定保健品中15种激素

目的建立高效液相色谱法同时测定保健品中雌三醇、雌二醇、雌酮、己烯雌酚、泼尼松龙、氢化可的松、可的松、倍他米松、地塞米松、曲安奈德、醋酸泼尼松、睾丸酮、甲基睾丸酮、氯倍他索丙酸酯、黄体酮等15种激素的分析方法。方法用甲醇直接溶解提取,C_(18)固相萃取柱净化,以乙腈-水为流动相进行梯度洗脱,流量为1.0 mL/min,采用二极管阵列检测器双波长检测,波长分别为204、245 nm。结果 15种激素的线性范围为0.1～5mg/L,相关系数r0.99,添加回收率为85.0%～105%之间,相对标准偏差5%,定量限0.05 mg/kg。结论该方法简便、快捷、准确,适用于保健品中15种激素的测定。     

胶体金测试条快速定量测定呕吐毒素技术在粮食中的应用

采用胶体金测试条法对粮食中呕吐毒素进行快速定量检测,结果表明,呕吐毒素的检测限为118μg/kg,定量限为316μg/kg, 500～5000μg/kg质量浓度范围内,相关系数r为0.9987. 采用有证实物参考物质进行比较,正确度为90.3%～116.6%,变异系数为47%～19.6%. 采用配对t-检验,与高效液相色谱法的测定结果相比较,二者无显著差异.     

粮食中伏马毒素胶体金快速定量法研究

以小麦、玉米为原料,采用胶体金快速定量法检测其伏马毒素含量并探讨胶体金快速定量法的适用性,同时,采用高效液相色谱-串联质谱联用法(LC-MS/MS)验证该方法的准确性。结果表明,胶体金快速定量法检出限和定量限分别为208.5μg/kg和496.6μg/kg,重复性符合检测要求,方法回收率111.70%～114.32%,作为快速检测粮食中伏马毒素的技术具有较高的准确性、稳定性和良好的特异性。     

食源性致病菌快速检测方法的探索研究

目的探讨传统细菌培养法及荧光定量PCR检测两种检测方法在食源性致病菌上的检出效果。方法对2015年采集的7类食品共600例样品采用传统细菌培养法及增菌后的增菌液荧光定量PCR检测,对检测结果进行分析比较。结果被检食品存在食源性致病菌污染,600例样品共检测出35株致病菌,食品致病菌的总检出率为5.83%,其中副溶血性弧菌与金黄色葡萄球菌检出率最高,达到15%。蜡样芽胞杆菌检出率较高,达到10.00%。传统细菌培养法致病菌阳性检出率为2.67%,荧光定量PCR检测致病菌阳性检出率为3.17%,两种检测方法下的检出率差异没有明显差异(X~2=1.882,P0.05)。结论检测中将传统细菌培养法同荧光定量PCR检测这两种检测方法结合起来,不仅提高了食源性致病菌检出率,也可缩短检测时间,提高检出率。后续研究将继续加大样本量并覆盖更多食品种类。     

液相色谱串联质谱法测定玉米及其制品中的烟嘧磺隆残留

采用凝胶净化技术和液相色谱串联质谱联用相结合技术,建立了玉米及其制品中烟嘧磺隆的残留量检测方法。试验采用乙腈提取样品,提取液经凝胶色谱仪净化,用液相色谱串联质谱仪测定,外标法定量,并采用选择离子监测进行阳性确证。结果表明,该方法的定量限达0.010 mg/kg,线性范围为0.01～1.00 mg/kg,方法回收率为84.0%～101.6%。该方法检测结果准确可靠,线性范围宽,适用范围广,能够满足高质量检测的要求。     

饲料中7种霉菌毒素测定的研究

建立了《饲料卫生标准》规定的全部7种霉菌毒素的液质联用仪的检测方法,解决了霉菌毒素检测过程中常见的问题。采用乙腈和水提取,通过多功能柱净化,用内标定量。结果表明,7种霉菌毒素平均回收率为83.6%～123.6%;相对标准偏差为1.62%～5.32%;定量限为(1.0～50)μg/kg,是一种简便、经济、准确度和灵敏度高的检测方法。     

Effects of fat supplementation and immature alfalfa to concentrate ratio on plasma progesterone, energy balance and reproductive traits of dairy cattle

Forty-six multiparous Holstein cows were assigned at 5 d postpartum to a completely randomized design employing a 2 x 3 factorial arrangement of treatments. Factors were 0 and 5% added prilled long-chain fatty acids (DM basis) and three forage to concentrate ratios (45:55, 64:36, 84:16). Diets consisted of immature alfalfa silage and a concentrate of shelled corn and soybean meal with or without fat replacing a portion of the corn. Mean plasma concentration of cholesterol was higher for cows fed 5% vs. 0% fat and increased over the first 100 d in milk for all animals regardless of treatment. There were no differences in reproductive performance due to either of the main effects. Mean plasma progesterone was higher due to fat treatment in the mid to late luteal phase of the second postpartum cycle as well as the metestrous to early luteal phase and mid to late luteal phase of the third cycle. Even though progesterone concentrations were higher in cows fed 5% fat during the luteal phase after breeding, the conception rates at this service were not different from those fed 0% fat. The biological significance of increased plasma progesterone concentration was not identified with any postpartum reproductive trait measured in this trial.     

Comparison of steroid hormone patterns in different fat tissues of Synovex-S implanted and control steers

Four different adipose tissues (kidney fat, heart fat, fat over rib, tailhead fat) of six control and seven Synovex-S (containing progesterone and 17#-estradiol benzoate)-implanted steers were investigated for their profiles of progesterone, androgens, and their precursors and metabolites. The steers were implanted with Synovex-S and slaughtered after 84 days. The tissues represent different bovine depot fats. Kidney and heart fat deposit at an earlier stage of development than the other subcutaneous fat tissues was investigated. Androgens, their precursors and progesterone were analysed by GC-MS. Estrogens could not be detected by GC-MS. Resulting hormone patterns were compared between treatments and between fat depots. The statistical Kruskal-Wallis-H-test was used for comparison. The adipose tissues showed similar hormone patterns. Only progesterone showed an increased concentration in adipose tissues of implanted steers. The steroid patterns did not show the influence of exogenous steroid administration.     

Stimulation of luteal cell progesterone production by lipoproteins from cows fed control or fat-supplemented diets.

Plasma lipoproteins from lactating dairy cows fed 0 or 7% supplemental fat were examined for their composition and ability to stimulate luteal cell progesterone production in vitro. Ultracentrifugation was utilized to isolate blood lipoproteins, and heparin affinity chromatography allowed separation of lipoprotein fractions based on the presence (low density lipoproteins) or absence of apolipoprotein B (high density lipoproteins). A portion of high density lipoproteins was fractionated by size, utilizing gel filtration chromatography. Slaughterhouse corpora lutea were dissociated, and plasma lipoproteins were added to the luteal cells on d 3 of culture and incubated for 48 h. In Experiment 1, blood was collected from heifers fed a diet that was not supplemented with fat. The addition of cholesterol from large, high density lipoproteins with a high cholesterol to protein ratio to luteal cultures increased progesterone production by an average of 17% compared with the addition of cholesterol from small, high density lipoproteins with a low cholesterol to protein ratio. In Experiment 2, electrophoretic mobility, apolipoprotein composition, and size of lipoproteins from control and fat-supplemented cows were similar. Lipoproteins from cows assigned to either a control or fat-supplemented diet showed no difference in their ability to stimulate progesterone production. Increased plasma progesterone concentration in lactating dairy cows fed supplemental fat does not appear to be mediated by alterations in lipoprotein composition.     

氯仿-甲醇法和酸水解法测定禽蛋中脂肪的方法比较

目的 对比富含磷脂等结合态脂肪的蛋制品中脂肪含量测定的方法,弥补目前国标中规定的酸水解检测方法无法准确地测定富含磷脂等结合态脂肪样品的不足。方法 采用氯仿－甲醇提取法对比国标中规定的蛋制品脂肪测定方法-酸水解法,测定蛋制品中的脂肪含量, 考察了两种方法测定不同蛋制品的提取结果、提取时间、精密度和重复性。结果 采用氯仿－甲醇法对比酸水解法提取蛋制品中的脂肪含量,结果表明,氯仿-甲醇提取法可以有效的提取蛋制品的磷脂等结合态脂肪,对蛋制品脂肪的测定具有较高的精密度和较好的重复性,相对标准偏差在0.91%-1.62%之间,且测定周期短,测定次数少。结论 氯仿－甲醇法弥补了酸水解法水解磷脂的不足且测定快速、准确,适合测定蛋制品中的脂肪含量。     

Supercritical CO2 Extraction for Total Fat Analysis of Food Products

Supercritical CO₂ extraction (SFE) is a promising alternative to solvent extraction for the measurement of total fat in food products. Total fat was extracted by SFE from samples of food products of different compositions and fat contents. Results using SFE were statistically compared with those using standard methods. This feasibility study showed very promising results. A suitable method was developed for analysis of full milk powder and dietetic milk powder and recoveries were 97.4 and 98.4% respectively. The content of the major fatty acids of fat extracted with SFE was similar to that of Röse-Gottlieb solvent extraction.     

Transplantation of bovine mammary tissue to athymic nude mice: growth subcutaneously and in mammary gland-free fat pads

Mammary epithelium from five Holstein cows was transplanted as subcutaneous slices and as collagenase dissociated epithelial cells into mammary gland free-fat pads of athymic nude mice. Two weeks posttransplantation, mice were injected daily for 20 d with saline, 17 beta-estradiol plus progesterone, or 17 beta-estradiol plus progesterone plus growth hormone plus prolactin. In a second experiment, mice were treated with saline, cholera toxin, 17 beta-estradiol (subcutaneous pellet of 2 mg 17 beta-estradiol and 38 mg cholesterol), or 17 beta-estradiol plus cholera toxin. In each experiment mammary slices maintained normal morphology. Growth of epithelium within slices ([3H]thymidine autoradiography) was increased 167% by estradiol plus progesterone, 264% by estradiol plus progesterone plus growth hormone plus prolactin, 90% by estradiol, 60% by cholera toxin, and 137% by estradiol plus cholera toxin. Cells injected into mammary gland free fat pads formed hollow, multilayered, spherical "organoids." Organoid area was increased 47% by estradiol plus progesterone, 189% by estradiol plus progesterone plus growth hormone plus prolactin, 72% by estradiol, 86% by cholera toxin and 74% by estradiol plus cholera toxin. Thus, athymic nude mice appear suitable for the ex vivo in vivo study of bovine mammary epithelial growth and differentiation.     

Dynamic supercritical CO2 extraction for removal of cholesterol from anhydrous milk fat

The feasibility of different extraction techniques for the selective removal of cholesterol from anhydrous milk fat (AMF) by supercritical carbon dioxide has been studied. A dynamic extraction system was used to determine both the experimental solubility of anhydrous milk fat in the supercritical solvent and the selectivity of cholesterol over anhydrous milk fat at 40–70°C and 8–40MPa at various stages during extraction. In addition, adsorbents were used for the selective removal of cholesterol from anhydrous milk fat. The results indicate that a direct extraction alone or with several separators in series are not practical, but a selective removal of 97% of the cholesterol from the extracted anhydrous milk fat is possible by using an adsorbent with recovery of solvent and cholesterol. A schematic industrial countercurrent process for the removal of cholesterol and the fractionation of milk fat is proposed.     

The comparison of physico-chemical and textural properties, as well as volatile compounds, from low-fat and regular-fat sausages

In order to determine the optimum method for extraction of the entire flavour profile of sausages, three extraction techniques, solvent extraction (SE), purge and trap (PT), and simultaneous distillation extraction (SDE), were compared. Similarly, to effectively analyse the volatile compounds of low‐fat (<3%) and regular‐fat (approximately 15%) sausages, three isolation techniques were investigated and gas chromatography (GC) and gas chromatography–mass spectrometry (GC/MS) were used for final identification of compounds. A total of thirty‐three volatile compounds were identified in the sausages by SDE, twelve by SE, and nine by PT. In the SE method, fats interfered in the extraction of some volatile components, resulting in lower recovery and longer isolation time when compared with the other two methods. The PT method might not be a good extraction method because of the loss of heterocyclic compounds. However, the SDE method showed greater yields and recognized more volatiles when compared with SE. Furfural, trans‐caryophyllene, and myristicine were the predominant volatile compounds extracted by SDE. These results suggest that the SDE method is the most efficient method in isolating volatile compounds in both regular‐ and low‐fat sausages. The amounts of volatile compounds, such as, 4‐acethyl‐3‐methyl pyrazole, 1,4‐dimethyl benzene, p‐ethylguaiacol and β‐caryophyllene were higher in regular‐fat sausages; however, the amounts of myristicine and hexadecanoic acid were higher in low‐fat sausages.     

Supercritical Carbon Dioxide Extraction of Androstenone and Skatole from Pork Fat

Boar taint, an unpleasant odor observed in pork from some mature intact male pigs, is attributed primarily to the presence of two compounds in boar fat, androstenone (Sα-androst-16-ene-3-one) and skatole (3-methyl indole). A rapid extraction method for the preparation of fat samples for androstenone/skatole screening assays would lead to more efficient use of boar carcasses for pork production. Supercritical carbon dioxide removed 97 ± 2% of the androstenone (extraction at 40°C; 5 min) and 65 ± 3% of the skatole (extraction at 40°C; 20 min) from 0.5 g of boar backfat. Supercritical CO₂ provides the basis for a fairly rapid extraction method to remove compounds associated with boar taint.     

辣椒籽脂肪的快速提取与脂肪酸分析

采用超声波辅助索氏提取法对辣椒籽脂肪的快速提取进行探索,研究辣椒籽粒度、超声功率、时间及温度对辣椒籽脂肪提取率的影响。结果表明：通过单因素和正交试验优化后获得最佳提取方法为辣椒籽粒度80目、功率70W、时间30min、室温(25℃左右);在此条件下对19个辣椒品种的辣椒籽脂肪进行提取,脂肪提取率为13.37%～28.81%,平均值为18.92%;利用气相色谱法对上述材料的脂肪酸组成及含量进行分析,结果供试辣椒材料辣椒籽脂肪酸组成主要为亚油酸、棕榈酸、油酸、硬脂酸、亚麻酸、山嵛酸、花生酸、肉豆蔻酸,且19个辣椒品种间脂肪酸组成及含量存在一定差异。