大豆磷脂的应用

我国大豆磷脂资源丰富、原料价格低廉,但未被充分利用。本文叙述了三个问题,提高大豆浓缩磷脂质量的注意事项、大豆磷脂改性后HLB等的变化以及大豆磷脂在多种行业上的应用。     

胡芦巴不同溶剂粗提物对两种储粮害虫的驱避和触杀活性

为开发环境和谐的植物性杀虫剂,以乙醇、乙酸乙酯、丙酮、氯仿、石油醚为溶剂采用温浸回流法对胡芦巴Trigonella foenum-graecum L.种子中的生物活性物质进行提取;并以主要储粮害虫杂拟谷盗Tribolium confusum du Val、谷蠹 Rhyzopertha dominica Fbricius成虫为试验对象,采用滤纸药膜法对胡芦巴5种溶剂粗提物进行驱避、触杀活性测定.结果表明:5种溶剂粗提物对杂拟谷盗的驱避作用均优于对谷蠹的作用:在各粗提物剂量为1.6 μg/cm2时,对杂拟谷盗处理7 d后的平均驱避率均超过80%,驱避等级为Ⅴ级,其中丙酮粗提物效果最好.但5种溶剂粗提物对谷蠹的触杀作用却均优于对杂拟谷盗的作用:处理72 h后,乙醇、乙酸乙酯、丙酮、氯仿粗提物对谷蠹成虫的LD50依次为0.112、0.102、0.106、0.100 mg/cm2,石油醚粗提物的触杀活性相对较差;乙醇、乙酸乙酯、氯仿粗提物用0.91 mg/cm2剂量处理72 h后,杂拟谷盗成虫的平均死亡率分别为95.56%、72.22%、87.78%;丙酮、石油醚粗提物用1.04 mg/cm2剂量处理72 h后,杂拟谷盗成虫的平均死亡率分别为57.78%和53.33%.     

食用油产品追溯链编码研究

溯源制度已成为食品安全管理一项重要手段,全球食品产业和许多国家的政府越来越重视食品溯源系统的建立.食用油产品是我国人民广泛食用的农产品,因此,开展食用油产品追溯研究意义重大.要构建食用油产品的可追溯系统,基于追溯链的编码研究是基础也是关键,因此对食用油产品追溯链组成及其信息进行分析,设计出基于批次管理的食用油产品追溯链,提出产地、加工过程、终产品等核心环节的编码规则,使粮油产品追溯成为可能,同时也为其他农产品追溯提供参考.     

丙酸对费氏丙酸杆菌生长及脱氧腺苷钴胺素合成的影响

通过添加控制丙酸浓度考查了费氏丙酸杆菌发酵生产VB12的过程中丙酸抑制细胞生长的浓度范围,在此基础上利用树脂对发酵过程中丙酸进行了选择性吸附后细胞的生长和脱氧腺苷钴胺素合成的变化。研究结果表明,丙酸的浓度在10.0g/L时,对菌体细胞生长产生了明显的抑制。在丙酸浓度积累到10.0g/L之前,利用树脂对其吸附分离出2.5g/L的丙酸后,生物量提高了37.5%,脱氧腺苷钴胺素产量提高了50.0%。该实验为实现丙酸的在线分离和丙酸/VB12高效联产的新型耦合发酵工艺提供了基础。     

乳酸菌抑制ACE及病原菌代谢产物研究进展

主要对乳酸菌及其发酵乳产品产生降血压的血管紧张素转换酶(ACE)抑制肽及乳酸菌消除肠道微生物降解氨基酸产生致癌因子的作用进行了阐述,表明了乳酸菌在降血压及抗癌方面具有巨大的应用前景。      

Changes in the Composition of Raw Tea Leaves from the Korean Yabukida Plant during High-Temperature Processing to Pan-Fried Kamairi-Cha Green Tea

ABSTRACT:  To develop a better understanding of compositional changes occurring during the production of commercial teas, we determined by high-performance liquid chromatography (HPLC) changes in ingredient levels during each of several manufacturing steps used to produce Kamairi-cha, a premium green tea. Kamairi-cha uses pan-frying instead of the usual blanching technique to inactivate the enzymes responsible for producing traditional black tea. The resulting tea lacks the characteristic bitterness of green tea, producing a green tea that is described as sweet tasting. The processing steps used to produce this pan-fried tea were as follows: 1st roasting, 1st rolling, 2nd roasting, 2nd rolling, 1st firing, and 2nd firing. The results show that during production at temperatures up to 300 °C, raw leaves lost (in percent) 97.3 water, 94 two chlorophylls, 14.3 seven catechins, and 2.75 caffeine. A separate analysis showed that the final product contained 21.67 mg/g dry wt of the biologically active amino acid theanine. The results of this 1st report on changes in individual catechins and other tea ingredients in tea leaves during pan-frying make it possible to select production conditions that maximize levels of beneficial tea ingredients. The possible significance of the results for the human diet is discussed.     

Steady and dynamic shear rheology of sweet potato starch–xanthan gum mixtures

The effect of xanthan gum at different concentrations (0.2–0.6% w/w) on the rheological properties of sweet potato starch (SPS) pastes was evaluated under steady and dynamic shear conditions. The presence of xanthan resulted in an increase in the consistency index and vane yield stress of SPS. The effect of temperature on the apparent viscosity of SPS–xanthan mixtures is well described by the Arrhenius equation. Dynamic moduli (G′, G″, and η^*) values of the mixtures increased with an increase in xanthan concentration while the tan δ values decreased. The addition of xanthan appeared to contribute to the elastic properties of the weak network of the SPS pastes. The structure development rate constant (k) of gelation during ageing was strongly influenced by the presence of xanthan. This suggests that the phase separation process caused by the incompatibility phenomena between the amylose component in starch and xanthan can increase the elastic characteristics of the SPS–xanthan mixtures.     

Identification of natural epimeric flavanone glycosides by NMR spectroscopy

Recently advanced analytical technology has provided evidence of the existence of stereoisomers of many natural products. Particularly, flavanones which might have two different configurations at C-2 exist in many food additives, e.g., citrus fruits. In this study, the possible stereoisomers of flavanone glycosides were identified by NMR spectroscopy. Based on NMR spectra of common flavanone glycosides such as naringin, hesperidin, and neohesperidin, the two existing diastereomeric forms of the molecules could clearly be distinguished. The ¹H NMR resonances of two diastereomers of each flavanone glycosides investigated in this study were fully assigned with the assistance of diverse 2D NMR spectroscopy methods.     

Antioxidant and antiproliferative properties of a tocotrienol-rich fraction from grape seeds

The antioxidant and antiproliferative activities of a tocotrienol-rich fraction (TRF) obtained from grape seeds were evaluated. TRF, a mixture of γ-tocopherol and α- and γ-tocotrienol, was prepared from a methanol-soluble fraction of grape seed oils by eluting with 10% ether (v/v) using silica gel chromatography. TRF had significantly higher antioxidant and antiproliferative activities compared to other fractions. TRF showed 3.5-, 40.0-, and 39.0-fold higher ABTS radical scavenging activity, inhibition of lipid peroxidation, and reducing power, respectively, compared to α-tocopherol fraction (5% diethyl ether fraction). TRF had higher antiproliferative activity against MCF7 (81%) and NCI-H460 (76%) cells at a concentration of 1.0 mg/ml. The results suggest that TRF from grape seeds has significant health-promoting effects, having excellent antioxidant and anticancer activities.     

Effects of Ultra High Pressure,Pressing Time and HCl Concentration on Non‐thermal Starch Hydrolysis Using Ultra High Pressure

Effects of ultra high pressure (UHP), pressing time and HCl concentration on non‐thermal starch hydrolysis using ultra high pressure were investigated. As regards ultra high pressure, starch granules maintained their structure up to 450 MPa and were partially disintegrated at 600 MPa. Degree of hydrolysis did not change up to 450 MPa and dramatically increased at 600 MPa indicating that starch hydrolysis increased with increasing destruction of starch granules. Pressing time did not affect the degree of hydrolysis. However, degree of hydrolysis and destruction of starch granules increased with increasing HCl concentration up to 4 M. Gel permeation chromatography showed that the soluble fraction of starch formed by hydrolysis mainly consisted of maltooligomers and maltose. X‐ray diffraction pattern changed from A type to C type upon hydrolysis, otherwise it remained as A type. This work provides fundamental information of UHP processing for starch and shows a potential of non‐thermal UHP processing for a new starch hydrolysis method.