魔芋甘露寡糖对ApoE-/-小鼠动脉粥样硬化的调节作用及机制

魔芋甘露寡糖(konjac mannan oligosaccharides,KMOS)具有多种有益人体健康的功能活性,但目前尚缺乏其对动脉粥样硬化(atherosclerosis,AS)的调节作用及机制方面的研究。采用高脂饮食(high fat diet,HFD)饲喂ApoE-/-小鼠14周,建立AS模型,探究KMOS干预后小鼠主动脉脂质堆积和血清脂质、炎症因子等的变化,并运用高通量测序技术,分析KMOS对于AS小鼠肠道菌群的调节作用。研究结果表明:KMOS干预显著抑制了HFD诱导引起的ApoE-/-小鼠体质量和肝脏质量的增加,主动脉窦的斑块病变面积比和总面积较HFD组分别降低57.4%和57.9%;血清中总胆固醇及低密度脂蛋白胆固醇含量分别降低21.1%和31.1%,高密度脂蛋白胆固醇含量增加了63.0%,AS小鼠肝脏脂质堆积情况明显改善;与AS模型组相比,KMOS组小鼠血清炎症因子(肿瘤坏死因子α、白介素-6、白介素-1β和单核细胞趋化蛋白-1)含量显著降低,肝脏胆固醇逆向转运相关基因的表达显著提高;此外,KMOS抑制了HFD诱导引起的ApoE-/-小鼠肠道菌群失调,增加了g_norank_f_Lachnospiraceae、g_Alistipes、g_norank_f_Ruminococcaceae的相对丰度;同时,KMOS可以增加小鼠盲肠短链脂肪酸含量,促进肠道紧密连接蛋白表达以抑制小鼠肠道屏障功能损伤。因此,KMOS可能通过调节胆固醇代谢和肠道菌群,抑制HFD诱导的ApoE-/-小鼠AS的发展,研究结果旨在为KMOS相关功能性食品的开发提供理论依据。     

脱乙酰基魔芋葡甘聚糖理化性质及其对凉皮质构和体外消化的影响

通过傅里叶变换红外光谱、X射线衍射图谱和扫描电子显微镜对不同脱乙酰度的脱乙酰基魔芋葡甘聚糖(deacetylatedkonjac glucomannan,DKGM)进行结构表征,并比较其黏度、持水性、热稳定性的变化;将高脱乙酰度的DKGM(脱乙酰度为72.70%)应用于凉皮制备,分析其对凉皮质构和体外消化特性的影响。结果表明,与KGM相比,DKGM在1 735 cm^-1处的乙酰基特征吸收峰减弱,表面变得粗糙,结晶度增加,热稳定性增加,黏度和持水性随脱乙酰度的增加而下降;添加高脱乙酰度的DKGM后,凉皮的硬度、咀嚼性和黏聚性整体均呈下降趋势,且其体外消化水解率降低,即添加高脱乙酰度的DKGM可提升凉皮口感及抗消化性,可为DKGM与淀粉复配体系在低血糖生成指数食品中的应用提供理论参考。     

Rapid detection of Vibrio parahaemolyticus strains and virulent factors by loop-mediated isothermal amplification assays

A loop-mediated isothermal amplification (LAMP) method for rapid detection of the foodborne Vibrio parahaemolyticus strains and related virulent factors had been developed and evaluated in this study. Six primers, including outer primers, inner primers, and loop primers, were specially designed for recognizing 8 distinct sequences on 3 target genes, which were tlh, tdh, and trh. The detection limits were found to be 100, 100 fg, and 1 pg DNA/tube for tlh, tdh, and trh, respectively. Application of LAMP assays were performed on 368 foodborne V. parahaemolyticus strains, the sensitivities of LAMP assays for the tlh, tdh, and trh were 100, 95.6, and 96.4%, and the negative predictive values (NPV) were 100, 84.7, and 93.1%, respectively; with a 100% specificity and positive predictive value (PPV) for all 3 target genes.     

Study on the degradation of chitosan by pulsed electric fields treatment

Chitosan solution was processed by applying pulsed electric fields (PEF) with different strengths up to 25 kV cm^− 1. Changes of the physicochemical properties of chitosan, such as molecular weight and crystallinity degree, were measured by analyses of scanning electron microscopy (SEM), viscosity molecular weight (M_v), X-ray diffractometry (XRD), FTIR and UV spectra. The results showed that after being treated at 25 kV cm^− 1, the chitosan granules were significantly deformed with many pits and cracks appeared on the surface. M_v was decreased with the increasing electric field strength, for example, the M_v was decreased from 2.81 × 10⁵ Da (initial chitosan) to 1.54 × 10⁵ Da after the PEF treatment at 25 kV cm^− 1. Meanwhile, the crystalline region of the treated sample was significantly damaged from XRD patterns. All results showed that the PEF technique is a possible method to obtain low molecular-weight chitosan.

Industrial Relevance

Chitosan solution was treated by using pulsed electric fields (PEF) with different strengths up to 25 kV·cm^-1. Changes of the physicochemical properties of chitosan were measured by analyses of scanning electron microscopy (SEM), viscosity molecular weight (M_v), X-ray diffractometry (XRD), FTIR and UV spectra. The results showed that the PEF technique is a promising method for scale-up industrial manufacture of low-molecular-weight chitosan.     

清净方法对甘蔗糖蜜组分及抗氧化活性的影响

通过分析检测清净处理后糖蜜的组分、抗氧化能力(采用DPPH法)和金属还原能力(采用普鲁士蓝法)的变化,考察了不同清净方法对甘蔗糖蜜组分及抗氧化活性的影响,结果表明,糖蜜经6倍质量水稀释后,采用聚丙烯酰胺(添加磷酸作为辅助澄清剂)进行絮凝,然后离心并进行酸解,其所得的甘蔗糖蜜的还原糖含量最高,糖蜜的抗氧化能力和金属还原能力的损失很小。     

糖浆气浮工艺条件的研究

研究了糖浆气浮工艺中磷酸加入量、预灰pH值、硫熏强度、硫熏中和pH值等因素对糖浆脱色率和气浮效果的影响,并对几种因素进行正交试验研究,确定了最佳气浮工艺条件的组合方案,结果表明最佳工艺条件是磷酸加入量为800mg/kg,预灰pH7.5,硫熏强度12ml,硫熏中和pH8.5。     

B-藻红蛋白多层复合薄膜的静电组装及其光谱特性

B-藻红蛋白是一种理想的生物光电材料.利用静电组装技术制备了聚二甲基二烯丙基氯化铵(PDDA)与B-藻红蛋白组装的多层复合薄膜.对薄膜的可见吸收光谱和荧光光谱进行了分析,结果表明:与B-藻红蛋白在溶液中的光谱特征相比,B-藻红蛋白在薄膜上的最大吸收峰由545 nm红移至553 nm,并在573 nm处产生了延迟荧光现象,且薄膜的最大吸光度和光致发射强度均与组装层数呈线性递增关系.随着薄膜组装层数的增加,倒置荧光显微镜能很好地观察到B-藻红蛋白在薄膜上出现明显的聚集体.     

Comparison of the phytohaemagglutinin from red kidney bean (Phaseolus vulgaris) purified by different affinity chromatography

Affinity chromatography (AC) on Affi-Gel blue gel column and thyroglobulin (Tg)-Sepharose 4B column, respectively, were compared for their efficiency in purifying phytohaemagglutinin (PHA) from red kidney beans (Phaseolus vulgaris). Considering the purity and haemagglutinating activity of the obtained samples, Affi-Gel blue gel exhibited less affinity for PHA than Tg-Sepharose matrix. Affi-Gel blue purified sample showed multiple bands in SDS-PAGE gel, which further confirmed that Affi-Gel blue bound non-PHA proteins as well as PHA. PHA purified by one-step Tg-Sepharose column gave significantly (p < 0.05) higher purity (0.75 ± 0.13 mg PHA/mg lyophilized powder) than the sample purified by two-step (Affi-Gel blue first and then Tg-Sepharose) purification (0.62 ± 0.20 mg PHA/mg lyophilized powder). Circular dichroism (CD) spectra showed that the sample purified by one-step Tg-Sepharose column had similar secondary structures with the sample purified by two-step purification. Thus, one-step Tg-Sepharose purification was effective and time-saving for the preparation of PHA and a promising substitute for the two-step purification method.     

沙海参多糖的分离和特性研究

通过木瓜蛋白酶酶解方法从沙海参中提取粗多糖,再经H2O2脱色、乙酸钾除蛋白、柱层析等程序后得到精制的酸性粘多糖.琼脂糖凝胶电泳试验表明:该多糖为单一成分,经GPC法测定重均分子量为98748.沙海参粘多糖中硫酸基、葡萄糖醛酸、氨基半乳糖、岩藻糖含量分别为27.73%、19.04%、14.38%、10.12%.