高效液相色谱法测定番石榴叶中的游离鞣花酸

研究高效液相色谱法测定番石榴叶中鞣花酸的方法。以甲醇(含0.01% HCl)作为提取液,70℃加热回流;色谱条件为：Intersil ODS-SP色谱柱(250mm×4.5mm,5μm),柱温35℃,进样体积10μL,紫外检测波长254nm;流动相为3%冰乙酸(A)-纯甲醇(B);梯度洗脱程序：0～4min B由20%至45%,保持6min,10～15min由45%至70%,15～20min由70%至100%,保持1min。结果表明：本方法的相对标准偏差为0.6%,鞣花酸在0.5～200mg/L范围内与峰面积呈良好的线性关系,相关系数为0.9998,加标回收率为95.86%～98.31%。本方法用于测定鞣花酸是切实可行的;番石榴叶片中鞣花酸含量高低与叶片的成熟度有关,其中幼嫩叶含量为0.814mg/g、成熟叶含量为0.023mg/g,而老叶中未检出。     

甜玉米粒烫漂护色技术研究

对甜玉米粒烫漂护色条件进行了研究。结果表明:以0.08%NaCl+0.03%VC+0.06%柠檬酸配制护色液,进行护色处理,护色效果佳。烫漂温度在90℃,时间为10min,料水比为1∶4.5时能最大限度地保证其品质。过氧化物酶活性与烫漂时间关系最大,其次是烫漂温度,与料水比的关系不显著。     

甜玉米馒头的加工工艺优化

本文将甜玉米粒进行热风干燥处理后打粉,将甜玉米粉与麦芯粉混合制作馒头,对其进行工艺优化。本文以质构、感官以及比容为评价指标,进行单因素试验。选取三因素三水平进行Box-Behnken响应面实验。结论表明:通过研究添加不同比例的甜玉米粉制作馒头,发现,当甜玉米粉添加量大于25%时,甜玉米馒头的比容明显降低,且感官评价指标已不足60分。依据此标准,选取甜玉米粉添加量为25%时进行进一步的优化实验。最终得出添加量为25%的甜玉米馒头最佳工艺条件为:发酵时间为78.19 min,醒发时间为19.51 min,搅拌时间为9.98 min,酵母添加量为1.02%。在此条件下,甜玉米馒头具有良好的感官品质为79.17分,比优化前增长9.64分;比容增加0.05 mL/g;质构指标有所改善,并且面筋网络结构更加紧致。     

甜玉米芯多糖纳米乳制备与评价

甜玉米芯多糖是一种水溶性多糖,但是其分子量较大,难以吸收及利用。采用自发乳化法制备甜玉米芯多糖纳米乳,通过伪三元相图筛选并比较不同质量分数的混合表面活性剂和甜玉米芯多糖溶液对甜玉米芯多糖纳米乳透明度及粒径的影响,得到最佳配方,并研究其体外释放效果和体外降血糖作用。结果表明,制备的甜玉米芯多糖纳米乳是一种W/O（油包水）型纳米乳液,其最佳配方为（Tween80:Span80=1:1）/无水乙醇/液体石蜡/1.5%甜玉米芯多糖水溶液=33.3%/11.1%/44.5%/11.1%,粒径为（43.22±4.84） nm;多分散系数（PDI）为（0.320±0.014）;pH为（7.6±0.2）;粘度为（209.9±4.1）cP;透明度为97.62%±0.39%;多糖含量为2.154±0.024 mg/mL,稳定性实验表明其具有良好的稳定性。体外模拟胃肠液消化实验表明,甜玉米芯多糖纳米乳具有缓释性能,能延长药效作用时间。体外降血糖实验表明,甜玉米芯多糖纳米乳对α-淀粉酶、α-葡萄糖苷酶都具有一定的抑制作用。     

Characterization of linoleic acid (C18:2) concentration in commercial corn silage and grain hybrids

Corn silage and high-moisture corn grain are commonly recognized as risk factors for biohydrogenation-induced milk fat depression and may be due to the high concentration of linoleic acid (C18:2) in corn. Corn silage and corn grain have a low concentration of fatty acids (FA), but due to their high inclusion rate in diets they contribute substantially to unsaturated FA intake. The first objective of this study was to characterize the contribution of individual plant parts to total FA in whole-plant chopped corn. The second objective was to characterize the variation in FA profile in commercial silage and grain hybrids and evaluate the relationship between FA profile and other nutrients. To determine the location of FA in the corn plant, 4 stalks from 4 different commercial hybrids were separated into stalk, husk and shank, leaves, cob, and kernels. On a dry matter basis, 80.5% of total FA were in the kernels, 11.8% in the leaves, 5.1% in the stalk, 1.7% in the cob, and 1.0% in the husk and shank. More than 96% of the oleic acid (C18:1) and 92.5% of the C18:2 was in the kernels, whereas 71.0% of the linolenic acid (C18:3) was in the leaves. Next, the FA composition of fresh whole-plant chopped corn from 124 silage hybrids and grain from 72 grain hybrids was determined over 2 yr from test plots in Pennsylvania. Last, to extend the characterization, FA composition of whole-plant corn silage from 45 hybrids grown in test plots in South Dakota were characterized. In the fresh whole-plant chopped corn from PA test plots, C18:2 as a percentage of total FA averaged from 48.7% in 2013 (percentiles: 10th = 45.2, 90th = 52.2) and 48.0% in 2014 (percentiles: 10th = 44.1, 90th = 49.4). Concentration of C18:2 in corn grain averaged 57.5% in the 2013 (percentiles: 10th = 53.4, 90th = 60.8) and 56.1% in 2014 (percentiles: 10th = 53.5, 90th = 59.4). In the corn silage from South Dakota, the concentration of C18:2 as percentage of total FA averaged 45.4% (percentiles: 10th = 39.4, 90th = 50.2) and C18:2 concentration as a percent of dry matter averaged 1.1% (percentiles: 10th = 0.76, 90th = 1.41). An increase in the concentration of C18:2 was associated with a decrease in C18:3 in fresh whole-plant chopped corn and with a decrease in C18:1 in corn grain. Total FA and C18:2 (as a percentage of dry matter) were positively correlated with starch and negatively correlated with neutral detergent fiber in both fresh whole-plant chopped corn and corn silage samples, whereas no correlation with these traits was observed for C18:2 as a percentage of total FA. In conclusion, FA concentration and profile of corn silage reflects to a great extent the FA composition of kernels and the proportion of grain in the silage. The variation in C18:2 across hybrids provides the opportunity to develop selection programs to decrease C18:2 in corn silage and grain. Selection based on C18:2 concentration as a percent of total FA is preferred as this trait did not correlate with other nutritional properties.     

玉米芯的营养成分分析

本文主要分析了甜玉米、超甜玉米、两种糯玉米煮熟前后共8个样品的玉米芯的营养成分。实验结果表明,除水分外,纤维素、淀粉是玉米芯的主要成分,其中甜玉米芯的纤维素含量最高,可达0-3g佗;糯玉米芯淀粉含量比非糯型高50％,经蒸煮之后,糊化作用导致糯玉米芯的的淀粉损失率为50％;玉米芯的多酚含量≤1．34μg／g,而黄酮的含量最高可i态到0．05mg／g;8种玉米芯的氨基酸含量基本接近,其中以谷氨酸和脯氨酸含量最高,蛋氨酸和络氨酸含量最低,熟的甜玉米芯所含的氨基酸总量最高,为14．94mg／g,必需氨基酸含量占31．88％;玉米芯中矿质元素丰富,cu含量最高,为5．61-24．23mg／g,其次则是K和Mg。     

Effects of Blanching on Some Physical Properties and Processing Recovery of Sweet Corn Cobs

The effects of the blanching process of sweet corn on shearing stress, shearing energy, and processing recovery of kernels as well as weight and dry substance of kernels and cobs were studied. Sweet corn cobs were blanched in water, where blanching time ranged from 2 to 8 min and temperature ranged from 75 to 100 °C. Nonblanched cobs (fresh cobs) were used as control samples. It was found that all analyzed variables were significantly affected by blanching time and temperature. The average values of all analyzed variables, except moisture which decreased, increased with increasing of the blanching time and temperature. Changing the blanching time and temperature affected the dry substance of kernels and cobs, kernel and cob mass, recovery processing by increasing it, as well as the average values of shearing stress and shearing energy by decreasing them.     

超高压液相色谱-飞行时间质谱法分析国产油橄榄叶中酚类化合物

建立国产油橄榄(Olea europaea L.)叶中酚类化合物的超高压液相色谱-飞行时间质谱(ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry,UPLC/Q-TOF-MS)定性分析方法。液相色谱条件为Waters BEH-C18(10.0mm×2.1mm,1.7μm)色谱柱,乙腈和甲酸溶液梯度洗脱,流速0.25mL/min,紫外检测波长280nm;质谱条件为Waters ACQUITY Q-TOF-MS质谱仪,电喷雾电离接口,负离子模式检测。采用该方法得到了国产油橄榄叶提取物的紫外检测的色谱图、负离子监测的总离子流图以及一级质谱图,成功鉴定了国产油橄榄叶中的15种酚类化学成分。     

RP-HPLC测定金针菇中芦丁、槲皮素和丁香酸的含量

采用高效液相色谱法测定金针菇中的多酚类成分,使用Agilent ZORBAX SB-C18 分析柱(4.6mm × 250mm,5μm),流动相为乙腈(A)-0.4%乙酸(B),其中0～40min 为5% A-95% B,40～45min 为25% A-75% B,45～50min为35% A-65% B,之后运行5min,流速1.0ml/min,VWD 检测器,检测波长280nm,柱温30℃。本研究在鲜金针菇中检出芦丁和槲皮素、在干金针菇中检出槲皮素和丁香酸。     

玉米南瓜复合饮料的研制

试验以新鲜甜玉米、新鲜南瓜和菊花为主要材料,将玉米和南瓜打浆榨汁,菊花提取取汁后,研究玉米汁/南瓜汁/菊花汁的配比、柠檬酸、白砂糖和稳定剂对复合饮料感官的影响,以及均质条件对饮料均质效果的影响,得出复合饮料的最佳调配配方和工艺参数。复合饮料的最佳配方为:玉米汁/南瓜汁/菊花汁的配比为4∶4∶2,白砂糖添加量为4%,柠檬酸添加量为0.05%,复合稳定剂的添加量为黄原胶+羧甲基纤维素钠+海藻酸钠=0.1%+0.1%+0.05%,得到综合感官评分为70分;均质压力为40MPa,均质时间为5min。     

Pre-harvest accumulation of deoxynivalenol in sweet corn ears inoculated with Fusarium graminearum

Three types of commercial sweet corn hybrids [sugary (su1), shrunken or 'supersweet' (sh2) and sugary enhancer (se1)] were silk channel inoculated in 1996 and 1997 with a macroconidial suspension of Fusarium graminearum to determine how early the mycotoxin deoxynivalenol accumulates in kernels. Disease symptoms rapidly developed on all hybrids and were apparent 4 days after inoculation. Symptoms stabilized by 28 days after inoculation. Toxin levels were greater than 1 μg/g in kernels as early as 2 weeks after silk emergence and rapidly increased to extremely high levels. Susceptibility in all hybrids decreased as the silk dried out. Deoxynivalenol concentrations were correlated to disease severity. There was some indication that the sh2 genotype was more susceptible than the su1 or se1 genotypes. These results suggest that improvement needs to be made in sweet corn with respect to resistance to gibberella ear rot.     

玉米芯不溶性膳食纤维制备工艺的研究

以玉米芯为原料,采用酸碱结合法提取不溶性膳食纤维,对提取过程中酸、碱用量和反应时间进行优化。结果表明：玉米芯在料液比1∶10（g∶mL）,反应温度95 ℃,硫酸体积分数2.0%条件下提取40 min,漂洗后,再于料液比1∶10（g∶mL）,反应温度95 ℃,NaOH质量浓度2.0 g/100 mL条件下提取60 min,可制得膨胀力为4.1 mL/g,持水力为5.1 g/g的终产品。产物的蛋白质、淀粉含量显著降低,分别为0.7 g/100 g、7.4 g/100 g,吸油性能有显著提升,为2.3 g/100 g,还原能力略有下降,A700 nm为0.327。     

超声波辅助提取玉米花丝多酚工艺优化及其抑菌活性研究

本文以玉米花丝多酚为研究对象,在单因素实验的基础上,利用响应面优化超声波辅助提取玉米花丝多酚工艺,考察超声波频率、超声波功率、超声波温度和超声波时间对玉米花丝多酚提取量的影响,同时探究玉米花丝多酚对大肠杆菌和金黄色葡萄球菌的抑菌活性。结果表明:在液料比30: 1、乙醇浓度60%、超声波频率40 kHz、超声波功率350 W、超声波温度56 ℃、超声波时间45 min时,玉米花丝多酚提取量为（13.31±0.12）mg/g;抑菌活性试验表明:不同浓度玉米花丝多酚对大肠杆菌和金黄色葡萄球菌均有一定的抑制效果,其最小抑菌浓度分别为2.5 mg/mL和2 mg/mL。     

Accumulation of phenolics,antioxidant and antiproliferative activity of sweet corn (Zea mays L.) during kernel maturation

Phenolic profiles and gene expression pattern in their synthetic pathway, total antioxidant activities and antiproliferative activities in two genotypes of sweet corn (YT16 and YT28) during kernel maturation were analysed. Results showed that increasing trends of phenolics and flavonoids in the two genotypes of kernels from 10 to 30 days after pollination (DAP). Gallic acid, chlorogenic acid, p-coumaric acid and ferulic acid were identified and quantified as the main phenolic compounds in both genotypes of kernels. High expressing levels of C4O and PAL resulted in the increasing phenolic contents. Higher expressing levels of CHS in YT28 led to higher flavonoid contents than that in YT16. The phenolic contents, antioxidant capacities and antiproliferative abilities of the two genotypes of sweet corn were competitive comparing to many fruits and vegetables. In addition, the maturation process of sweet corn could raise the kernel’s bioactive ability as well as nutritional values.     

高效液相色谱法测定玉米须中刺芒柄花素的含量

目的：建立玉米须中刺芒柄花素含量测定的方法。方法：运用高效液相色谱法测定,色谱柱为HypersilC18 (4.6mm × 250mm,5μm),流动相为甲醇-0.1% 磷酸(55:45,V/V),流速0.8ml/min;检测波长254nm。结果：刺芒柄花素在2.3～23μg/ml 范围内线性关系良好,r=0.9991。平均回收率为96.93%,RSD 为1.30%。结论：本法方便、准确,可以用于玉米须的质量控制。     

番茄及其制品中全反式番茄红素及bate-胡萝卜素含量的C30-HPLC内标法定量分析

目的：建立C30-HPLC 内标法对番茄及其制品中全反式番茄红素和β- 胡萝卜素进行同步定量检测方法。方法：色谱条件：固定相：YMC Carotenoid column C30 色谱柱 (4.6mm × 250mm,5μm);流动相A：乙腈:甲醇(3:1,V/V);流动相B：甲基叔丁基醚(MTBE);流动相A 与B 中分别添加体积分数0.05% 的三乙胺;洗脱条件：B 在0～10min 内保持30%,在10～20min 内,B 由30% 线性增至90%,20～30min 内B 维持在90%;流速：1mL/min;色谱图检测波长470nm 和450nm;进样量：20μL;柱温：室温。内标物为全反式-8'- 阿朴-8'-β- 胡萝卜素醛。结果：此方法的最小定量限为0.01μg/mL。在0.3～0.6μg 范围内,内标物对全反式番茄红素和β-胡萝卜素的相对校正因子分别为1.36 和1.22,重复性RSD 分别为小于0.50%和0.70%,加样回收率均在99.00% 以上。结论：应用本方法可对番茄及其制品中的全反式番茄红素和β- 胡萝卜素进行定量分析。     

反相高效液相色谱法同时测定马铃薯块茎中酚酸类物质

目的：运用反相高效液相色谱法同时测定马铃薯中的绿原酸、咖啡酸、对香豆酸和阿魏酸。方法：色谱柱为YMC-C18(250mm×4.6mm,5μm),流动相为甲醇-水-冰醋酸(30:70:1,V/V)等度洗脱,柱温25℃,检测波长327nm。结果：绿原酸、咖啡酸、对香豆酸和阿魏酸在进样质量浓度分别为7.80～1000、0.78～100、0.312～40、0.078～10μg/mL范围内线性关系良好(r值范围0.9968～0.9999),平均回收率为92.38%～101.73%。结论：本法分析快速准确、灵敏度高、重现性好,江西、北京和新疆3个地域的环境条件对马铃薯的酚酸含量有一定的影响。     

促进玉米直链淀粉回生的甘薯淀粉晶种的筛选及表征

通过向四次回生的玉米直链淀粉中添加草酸侵蚀的四次回生的甘薯淀粉、甘薯直链和甘薯支链淀粉晶种(质量分数:1%),研究甘薯淀粉晶种对玉米直链淀粉回生的影响。结果表明,甘薯淀粉晶种明显促进了玉米直链淀粉回生长晶,其中甘薯直链淀粉晶种使得玉米直链淀粉回生率达到59.5%,比不添加晶种提高了19.3%。可见吸收光谱研究表明,甘薯淀粉晶种及长晶后的玉米直链淀粉均保持了双螺旋结构。X-射线研究表明草酸侵蚀后甘薯淀粉、甘薯直链淀粉、甘薯支链淀粉均为A+B型。将其分别添加到玉米直链淀粉中并长晶后的样品,结构均为B型。DSC研究表明,甘薯支链淀粉晶种具有最高的吸热焓,说明其晶体含量最高。三种晶种分别促进玉米直链淀粉长晶后的结构较为相似,晶体含量也较相近。该研究为提高淀粉的回生率、研究回生淀粉结晶结构提供良好的技术支持。     

粟米油中脂肪酸及其主成分亚油酸的分析

高效液相色谱法对粟米油脂肪酸的组成和主成分亚油酸进行定量分析。采用索氏提取法从玉米胚芽中提取粟米油,并对粟米油中脂肪酸进行甲酯化处理,利用气相色谱- 质谱法对其脂肪酸组成进行鉴定。色谱柱：KromasilC18;流动相为异丙醇:乙腈=35:65;柱温：25℃;205nm 检测波长条件下对亚油酸进行测定。结果表明：由粟米油中分离鉴定出8 种脂肪酸,脂肪酸的主要组成是不饱和脂肪酸,不饱和脂肪酸占74.94%,主要成分为亚油酸和油酸,其中亚油酸为46.33%,油酸为28.01%。亚油酸变异系数小于1.35%,回收率为98.8%～109.1%。本方法简便、准确,适合粟米油中亚油酸含量的分析。     

Purification,antioxidant activity and protein-precipitating capacity of punicalin from pomegranate husk

Punicalin is a kind of ellagitannin, existing in pomegranate husk, and has shown remarkable biological activities. A rapid and large-scale separation method of punicalin from pomegranate husk was established, using medium pressure liquid chromatography (MPLC). The optimal mobile phase consisted of 5% methanol and 0.1% (v/v) TFA in water, and the optimal loading amount and flow rate were 1.0 g and 80 ml/min, respectively. Under this condition, 339 mg of 95.9% punicalin could be obtained in 40 min. 59.7 mg of 78.0% gallic acid could be separated simultaneously. This method was practical for industrial utilisation of pomegranate husk. Afterwards, the antioxidant and protein-precipitating capacities of the purified punicalin, together with punicalagin, were evaluated. Results showed that punicalin had strong antioxidant activity, and it exhibited a low affinity for protein. This suggested that the antioxidant of punicalin would not be greatly masked by tannin–protein precipitation in application, and hence confirmed punicalin to be a promising antioxidant.