Effects of lactic acid bacteria fermentation on the bioactive composition,volatile compounds and antioxidant activity of Huyou(Citrus aurantium'Changshan-huyou')peel and pomace

Using lactic acid bacteria(LAB)to ferment Huyou peel and pomace could provide a reference for making full use of Huyou resources and provide valuable suggestions for the industrial production of functional foods.The effects of LAB fermentation on the bioactive composition,volatile compounds and antioxidant activity of Huyou peel and pomace were studied.Results showed that both Huyou peel and pomace were good substrates for LAB growth.LAB had remarkable influence on bioconversion of organic acids,among which ascorbic acid content was increased significantly.In addition,LAB could produce flavonoids with enhanced bioactivity and absorption.In particular,the contents of rhoifolin,quercitrin and quercetin were increased by over 100%.Besides,the volatile compounds contents and aroma complexity were improved.Furthermore,the antioxidant activity was enhanced.Thus,our study provides high-value applications of Huyou,and fermented products with improved nutritional value and flavor are potentially beneficial to human health.

钢铁行业产能过剩测度及影响因素分析——基于中国30个省份的经验验证

钢铁行业是经济发展的支柱型产业,在工业化进程中发挥着至关重要的作用。然而由于产能过剩等因素的影响,钢铁行业的发展正面临巨大的挑战。本文基于2008-2015年全国除西藏以外的30个省份钢铁行业的生产数据,利用随机前沿分析法测度不同省份钢铁产业的产能过剩指数,并借助协整回归等方法分析了该行业产能过剩的影响因素。研究结果显示:江苏、山东、广东、上海和北京等地区的产能过剩较为严重;政府财政补贴对该行业产能过剩具有显著的正向影响,而钢铁价格、市场需求和行业技术水平等与行业产能过剩之间呈现负相关关系。在分析影响钢铁行业产能过剩的主要因素基础上,提出了增强员工创新能力、提升企业科技水平以及合理控制钢铁行业补贴等政策建议。

耐高盐枯草芽孢杆菌XP合成球形纳米硒及其抑制草莓病原真菌生物活性

生物方法合成纳米材料具有低能耗、高安全性以及环境友好等优良特点,因而备受人们关注。利用细菌将硒酸盐或亚硒酸盐还原为单质硒,不仅可以降低硒毒性,而且还能获得价值更高的生物纳米材料。文中选用可耐受高盐环境胁迫的枯草芽孢杆菌亚种Bacillus subtilis subspecies stercoris strain XP构建生物模型,分别以LB液体培养基和亚硒酸钠为介质和底物(电子受体),解析菌株XP合成纳米硒的基本规律。通过扫描电镜(Scanning electron microscope,SEM)观察、X射线能谱分析(X-ray energy dispersive spectral analysis,EDAX)、X射线衍射(X-ray diffraction,XRD)分析、傅里叶红外变换光谱(Fourier transform infrared spectroscopy,FTIR)技术对合成的纳米硒进行物理化学表征分析,同时选用草莓枯萎、红叶、紫斑病病原真菌对其抗菌活性进行分析。结果表明,菌株XP介导合成的单质硒为球形纳米颗粒(Selenium nanoparticles,Se NPs),其生成量与反应时间呈正相关(0-48 h),且细胞形态未发生褶皱或破损等变化(耐受力强);Se NPs为非晶态,粒径范围在135-165 nm,表面元素组成以Se为主,同时存在C、O、N、S等有机元素;颗粒表面包裹生物大分子物质,-OH、C=O、N-H、C-H等官能团与Se NPs稳定性和生物活性密切相关;高浓度纳米硒对枯萎、红叶、紫斑病病原真菌均有显著抑制活性(P<0.05),其中对草莓红叶病与枯萎病病原真菌的抑制活性明显优于对紫斑病病原真菌的抑制活性。总而言之,菌株XP不仅耐受高盐胁迫能力强,同时还可介导合成生物Se NPs,其合成的纳米硒颗粒具有良好的稳定性和生物活性,在草莓病害防治以及绿色富硒草莓种植等领域具有潜在的应用价值。