Isolation of antibacterial components from infusion of Caesalpinia paraguariensis bark. A bio-guided phytochemical study

The antimicrobial activities and toxicity of infusion, decoction and tincture of Caesalpinia paraguariensis Burk. bark (CPBEs) were investigated to validate its traditional use as drink additive and to identify microbicidal component(s). The minimum inhibitory concentrations (MIC) of CPBEs against aerobic bacteria (Gram-negative and Gram-positive species) were determined using standardised dilution methods. The LC₅₀ were determined by Brine Shrimp Test. CPBEs showed bacteriostatic and bactericidal activity against tested strains. The highest activity was observed for infusion (MIC:200 μg/mL) against Morganella morganii, Erwinia carotovora, Bacillus spp., Staphylococcus spp. and Enterococcus spp. The bacterial species were susceptible to CPBEs (MIC:200–1993 μg/mL) at lower concentration than sodium benzoate, a known food preservative. Two bioactive components were isolated from liophylised infusion by bio-guided chromatographic procedures; these were identified by spectrometric techniques as ellagic and 3-O-methylellagic acids. This study demonstrated that C. paraguariensis bark infusion it is safe for human consumption and a possible source of food natural preservatives.     

Application of near infrared spectroscopy for the rapid determination of antioxidant activity of bamboo leaf extract

This study was carried out to evaluate the feasibility of using near infrared (NIR) spectroscopy for determining three antioxidant activity indices of the extract of bamboo leaves (EBL), specifically 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing/antioxidant power (FRAP), and 2,2′-azinobis-(3-ethylbenz-thiazoline-6-sulfonic acid) (ABTS). Four different linear and nonlinear regressions tools (i.e. partial least squares (PLS), multiple linear regression (MLR), back-propagation artificial neural network (BP-ANN), and least squares support vector machine (LS-SVM)) were systemically studied and compared in developing the model. Variable selection was first time considered in applying the NIR spectroscopic technique for the determination of antioxidant activity of food or agricultural products. On the basis of these selected optimum wavelengths, the established MLR calibration models provided the coefficients of correlation with a prediction (r_pre) of 0.863, 0.910, and 0.966 for DPPH, FARP, and ABTS determinations, respectively. The overall results of this study revealed the potential for use of NIR spectroscopy as an objective and non-destructive method to inspect the antioxidant activity of EBL.     

桅子黄色素的提取工艺及稳定性的研究

以栀子为原料,用蒸馏水浸泡提取天然桔黄色素,研究了食品中常用的几种添加剂对栀子黄色素稳定性的研究,并对色素的耐氧性、耐光性、耐酸性等性质进行了研究。     

杜仲叶和元宝枫叶提取物抗氧化性能的研究

用不同的提取方法分别从杜仲叶和元宝枫叶中提取抗氧化物质,比较了不同提取方法的提取率和不同提取物对食用油脂的抗氧化性能。得出杜仲叶用常温水提取、乙酸乙酯萃取,元宝枫叶用90℃热水提取、乙酸乙酯萃取的提取物产率高、抗氧化作用强。另外对猪肉、鱼肉的保鲜效果也进行了初步的研究。     

不同植物材料对烟草甲的引诱效果分析

为了减少烟草加工、贮存、流通等环节中烟草甲虫的为害,以10种具有不同特征气味的植物样品(辣椒、花椒、陈皮、香叶、白豆蔻、甘草、当归、白芷、罗汉果和绿茶)为材料,采用昆虫四臂嗅觉仪进行植物材料粉末及其提取物(甲醇、乙醇、正己烷单一溶剂提取物及甲醇正己烷、乙醇正己烷组合溶剂提取物)对烟草甲成虫引诱活性的试验。结果表明:辣椒、罗汉果、白芷、绿茶粉末对烟草甲成虫的引诱活性较高,引诱指数均达45%以上。在这4种植物材料单一溶剂提取物中,辣椒正己烷提取物、绿茶乙醇提取物的作用效果较好,引诱指数在40%以上。在植物组合溶剂提取物中,辣椒两种组合溶剂提取物均表现显著引诱效果,引诱指数分别为56.42%和67.46%,明显高于单一溶剂提取物;绿茶和罗汉果乙醇正己烷提取物的引诱活性优于甲醇正己烷提取物,也优于其单一溶剂提取物。     

洋葱皮乙醇提取物对玉米淀粉回生性质的影响

研究洋葱皮乙醇提取物(Ethanol Extract of Onion Skin, EEOS)对玉米淀粉热力学性质、结晶结构和微观结构的影响,综合评价EEOS对玉米淀粉回生的抑制作用以及对玉米淀粉体外消化性能的影响。结果表明,与对照组相比,添加2.5%、5%、10%的EEOS的玉米淀粉,在4℃回生5 d后,熔融焓值分别降低了29.77%、21.66%和15.26%,且随着EEOS添加量的增加,玉米淀粉的熔融焓值呈现先下降后上升的趋势;添加2.5%EEOS的淀粉,在4℃回生15 d后,其1 047/1 022的比值从下降了6.31%;与对照组相比,添加不同比例的EEOS的淀粉的相对结晶度有所下降;添加EEOS的玉米淀粉在4℃回生15 d后,表面光滑无破损现象;添加2.5%、5%、10%EEOS的玉米淀粉,在4℃回生5 d后,RDS的含量分别比对照组下降了21.36%、33.22%和29.87%,说明EEOS的添加对玉米淀粉中RDS的消耗有抑制作用。     

一种基于几何基元模型的人造目标提取方法

给出了从自然景物背景中提取人造目标的一种方法。基于图像灰度的差分方向算子将一幅图像分离成不同灰度差分方向的直线线段子图像,再对每幅子图像做直线段的后处理,最终将几幅子图像构建成一幅不同差分方向的直线线段集合。基于直线段集合图像给定区域内直线线段的结构文法及其所含几何基元数目和几何基元种类将人造目标从自然背景中提取出来。此算法可开发成实时硬件跟踪器应用于自动目标捕获。实验结果说明,对复杂的背景及低对比度情况下的红外目标图像,该方法提取人造目标的准确率达95％以上。     

高效液相色谱法测定海带浓缩制品中岩藻黄素的含量

目的：建立高效液相色谱法测定海带浓缩制品中岩藻黄素含量测定方法。方法：采用Thermo BDS HYPERSIL C18 色谱柱,以1%的乙酸胺水溶液、甲醇、乙腈为流动相,流速 1.0 mL/min,柱温 30℃,检测波长 450 nm,进样量20μL,外标法定量；结果：在该条件下,岩藻黄素浓度在 0.999 ~9.987 μg/mL 范围内,与峰面积呈良好的线性关系 (R_⁼0.9999) ,平均加样回收率为98.53%,相对标准偏差(RSD)为 1.1%(n=9)。结论：本研究建立的含量测定方法简便、准确,重复性好,可用于海带浓缩制品的质量控制。     

Encapsulation of Hibiscus sabdariffa Extract into Zein Nanoparticles

A combined approach for the extraction of antioxidants from Hibiscus sabdariffa and entrapment of the extract in zein nanoparticles is proposed. Different green extraction techniques were adopted: high-pressure and -temperature extraction, ultrasound-assisted extraction, and microwave-assisted extraction, using an ethanol/water mixture as extracting solvent. The extracts were used for the preparation of zein nanoparticles by liquid antisolvent precipitation. The impacts of process variables were investigated using response surface modeling, demonstrating that the proposed strategy allows high extract encapsulation efficiency, good particle size control, and high particle stability.