香叶醇对柑橘酸腐病菌的抑菌机制

为研究香叶醇对柑橘酸腐病菌（Geotrichum citri-aurantii）的抑菌机制,用不同质量浓度的香叶醇处理柑橘酸腐病菌,通过生理生化分析及微观结构观察研究其对酸腐病菌孢子和菌丝体的影响。结果表明,香叶醇对柑橘酸腐病菌的最小抑菌质量浓度（minimal inhibitory concentration,MIC）和最小杀菌质量浓度（minimal fungicidal concentration,MFC）均为0.500 g/L;MIC香叶醇处理酸腐病菌12 h后其孢子萌发率仅为（3.28±1.28）%,显著低于对照组的（92.17±1.88）%(P<0.05)。透射电子显微镜观察发现,香叶醇处理破坏了酸腐病菌细胞的完整性,细胞壁与细胞膜发生质壁分离,细胞器无法分辨,呈现空泡化。细胞通透性发生改变,碱性磷酸酶和核酸发生外泄,相对电导率升高,膜脂质过氧化反应增强,活性氧积累。综上所述,香叶醇通过抑制柑橘酸腐病菌孢子萌发和菌丝生长、破坏细胞结构、促进脂质过氧化和活性氧积累从而影响其正常生理功能,本实验可为有效防治柑橘酸腐病提供新思路。     

柠檬醛对酸腐菌线粒体形态和功能的影响

本研究探讨了柠檬醛对酸腐菌线粒体形态、三磷酸腺苷（adenosine triphosphate,ATP）合成和三羧酸（tricarboxylic acid cycle,TCA）循环的影响。扫描电子显微镜结果显示,柠檬醛处理后,酸腐菌线粒体出现扭曲、坍塌甚至破裂的现象。酸腐菌线粒体结构的破坏导致其胞内ATP流失,胞外ATP含量增加。经最小抑菌浓度和最小杀菌浓度的柠檬醛处理后,酸腐菌TCA循环中柠檬酸合酶、α-酮戊二酸脱氢酶、异柠檬酸脱氢酶、琥珀酸脱氢酶和苹果酸脱氢酶活力以及柠檬酸含量都呈下降趋势。结论：柠檬醛处理影响了酸腐菌线粒体的形态和功能,从而抑制其生长。     

壳聚(寡)糖对柑橘酸腐、黑腐病菌的抑制作用及对采后病害的防治

通过体外实验测定不同浓度的壳聚糖和壳寡糖对酸腐和黑腐病菌孢子萌发、芽管长度和菌丝生长的抑制作用;采用刺伤接种方法评价壳聚糖和壳寡糖对柑橘果实两种病害的防治作用。离体实验结果表明,壳聚糖和壳寡糖浓度为10mg/mL时几乎完全抑制两种病原菌的菌丝生长;浓度为0.5mg/mL壳聚糖和壳寡糖能完全抑制柑橘酸腐病菌(Geotrichum candidum)孢子萌发和芽管伸长的效果,而2mg/mL的壳聚糖才能完全抑制柑橘黑腐病菌(Alternaria citri)孢子萌发和芽管伸长,但相同浓度的壳寡糖抑制A.citri的孢子萌发和芽管伸长效果较差。体内实验结果表明,其病害防治效果具有浓度依赖性,高浓度(1%)的壳聚糖和壳寡糖对果实病害的防治效果较低浓度的防治效果好。      

加拿大一枝黄花精油的提取及对灰霉菌抑制作用的研究

采用水蒸气蒸馏法从加拿大一枝黄花中提取挥发油,通过L9(34)正交实验研究料液比、浸泡时间、蒸馏时间对精油得率的影响。采用接触法评价该植物的花、叶精油对灰霉菌的抑菌活性,并由扫描和透射电镜观察对其灰霉菌丝体和内部超微结构的影响。结果表明:浸泡时间对精油得率的影响最大,最优提取方案为料液比1∶12(g/m L),浸泡时间3h,蒸馏时间3h。该植物的叶部和花部精油都对灰霉菌有抑制作用,抑制率与浓度呈正相关;2个部位精油处理都能导致菌丝变细、表面皱缩度提高;细胞壁受损且质地疏松,亚细胞结构及界限模糊,细胞质外渗。其中,该植物叶部精油的抑菌效果和对菌体的破坏能力高于花部精油。      

负载二氢槲皮素的甘油解猪油微乳液体外抗氧化性及消化性

为解决含甘油解猪油的食品在贮藏过程中易被氧化的问题,向甘油解猪油中加入二氢槲皮素,制备负载二氢槲皮素的甘油解猪油微乳液,通过体外模型测定该微乳液的还原力以及对DPPH、ABTS和羟自由基的清除能力,探讨含二氢槲皮素甘油解猪油微乳液的体外抗氧化性,同时通过体外模拟胃肠消化测定其消化性。结果表明：该微乳液具有一定的还原力及DPPH、ABTS、羟自由基的清除能力,且还原力及自由基清除能力均随着二氢槲皮素负载量的增加而升高,相关性显著;该微乳液经胃消化2 h后二氢槲皮素的保留率为79.25%,说明该微乳液能有效保护二氢槲皮素实现靶向性肠道输送,在肠道消化2 h后,微乳液的游离脂肪酸释放率达到73.85%,二氢槲皮素生物利用率达33.3%。综上,负载二氢槲皮素的甘油解猪油微乳液在食品工业中有较大的应用潜力。     

Chemical,antioxidant and antifungal activities of volatile oil of black pepper and its acetone extract

GC and GC‐MS analysis of volatile oil obtained from Piper nigrum L resulted in the identification of 49 components accounting for 99.39% of the total amount, and the major components were β‐caryophyllene (24.24%), limonene (16.88%), sabinene (13.01%), β‐bisabolene (7.69%) and α‐copaene (6.3%). The acetone extract of pepper showed the presence of 18 components accounting for 75.59% of the total amount. Piperine (33.53%), piperolein B (13.73%), piperamide (3.43%) and guineensine (3.23%) were the major components. The oil was found to be 100% effective in controlling the mycelial growth of Fusarium graminearum in inverted petriplate technique. The acetone extract retarded 100% mycelial growth of Penicillium viridcatum and Aspergillus ochraceus in food‐poisoning technique. Volatile oil and acetone extract were identified as a better antioxidant for linseed oil, in comparison with butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). Copyright © 2004 Society of Chemical Industry     

大鲵油体外抗氧化活性研究

采用体外抗氧化实验研究大鲵油抗氧化活性,测定大鲵油对DPPH自由基、羟基自由基、超氧自由基清除能力和还原能力、Fe~(2+)螯合能力。以V_C为阳性对照,评价大鲵油的体外抗氧化活性。结果表明:大鲵油抗氧化能力强于鲐鱼油,添加复合抗氧化剂后抗氧化能力更强,对Fe~(2+)的螯合能力表现最好,相同质量浓度条件下强于V_C;对DPPH自由基、羟基自由基清除能力和还原能力与V_C相当。大鲵油对DPPH自由基、羟基自由基和Fe~(2+)螯合能力的半抑制质量浓度(IC_(50))分别为3.523、0.493、0.559 mg/m L,添加了复合抗氧化剂的大鲵油的相应IC_(50)分别为0.572、0.099、0.062 mg/m L。     

美藤果油体外抗氧化性能研究

以美藤果油为研究对象,TBHQ为阳性对照,采用典型的体外抗氧化试验体系测定了美藤果油对DPPH·、·OH、O-2·的清除能力,Fe2+的螯合能力以及还原能力,用于评价美藤果油的体外抗氧化性能。结果表明：美藤果油的体外抗氧化性能与其质量浓度之间存在良好的剂量效应关系;在试验质量浓度范围内,美藤果油5种体外抗氧化指标的最大值分别为DPPH·清除率75.24%、·OH清除率95.26%、O-2·清除率92.57%、Fe2+螯合率92.17%和还原能力1.22;在质量浓度相同的情况下,美藤果油对O-2·的清除能力和Fe2+的螯合能力优于TBHQ;美藤果油对DPPH·、·OH 和O-2·的清除能力以及Fe2+螯合能力的IC50分别为2.96、<0.01、0.20、2.77 mg/mL。研究结果表明美藤果油具有较强的体外抗氧化性能。     

牡丹籽油微乳液的制备及其性质研究

采取相转变法和拟三元相图法制备牡丹籽油微乳液,从不同表面活性剂、亲水亲油平衡值（HLB值）、助表面活性剂中筛选最佳组分以确定制备牡丹籽油微乳液的体系组成。同时,通过单因素试验和正交试验优化牡丹籽油微乳液的制备条件。结果表明：牡丹籽油微乳液的体系组成为牡丹籽油/Tween 80/Span 80/无水乙醇/水;最优的制备条件为制备温度25 ℃,以Tween 80与Span 80（质量比为6∶ 4）为混合表面活性剂（HLB值为11）,混合表面活性剂与助表面活性剂无水乙醇比例（Km）为1∶ 1,先将混合表面活性剂相与牡丹籽油混合均匀,再逐滴加水。在最优条件下,随着加水量的增加,得到的牡丹籽油微乳液结构以W/O型向双连续相再到O/W型转变,最终得到的牡丹籽油微乳液为微黄澄清透明状液体,粒径为（40.63±1.77）nm,多分散系数稳定在0.218±0003,电导率为（681.75±19.15）mS/cm。同时发现,低浓度盐离子（≤1.0 mol/L）的存在可以促进牡丹籽油微乳液的形成,但盐离子浓度过高（≥1.5 mol/L）时会抑制微乳液的形成。     

藻油DHA微乳在饮料中的应用研究

目的研究藻油DHA微乳在饮料中的应用稳定性。方法将藻油DHA微乳无菌添加至饮料中,分析饮料中添加不同量藻油DHA微乳后的感官品质及DHA保留率的变化情况,并考察不同储存条件及储存时间对其感官品质和DHA保留率的影响。结果在饮料中添加不同量的藻油DHA微乳(使其中DHA含量分别达到:2 mg/100 g和5 mg/100 g),初期对其感官品质的影响较小;而在储存过程中受高温的影响较大,在较低温度下储存时饮料的感官品质所受影响较小,且经过2个月的储存后DHA保留率普遍仍可达到70%以上;其中DHA添加量为2 mg/100 g时饮料的感官品质略优于5 mg/100 g,但不同添加量对饮料中DHA保留率的差异较小。结论藻油DHA微乳在饮料中的应用可行性较好,本研究为藻油DHA微乳在饮料中的应用,从而开发新型DHA功能性饮料提供了理论依据。     

油茶籽油微乳的制备及其性质研究

为制备油茶籽油微乳,采用伪三元相图法研究了不同乳化剂和助乳化剂、水与助乳化剂(W/A)质量比对油茶籽油微乳区面积的影响,并采用单因素实验建立油茶籽油微乳黏度与电导率随W/A添加量变化的模型,对油茶籽油微乳的水、油渗滤阈值进行预测。结果表明:油茶籽油微乳的最佳配方为乳化剂Tween80、助乳化剂丙三醇、W/A质量比1∶1;模型预测油茶籽油微乳的水、油渗滤阈值(W/A添加量)分别为40.75%、74%,对应的黏度、电导率分别为6 325.3 m Pa·s、86.166μS/cm。     

In vitro and in vivo antifungal properties of cysteine proteinase inhibitor from green kiwifruit

BACKGROUND: Higher plants possess several mechanisms of defense against plant pathogens. Proteins actively synthesized in response to those stresses are called defense‐related proteins which, among others, include certain protease inhibitors. It is of particular relevance to investigate plant natural defense mechanisms for pathogen control which include cystatins—specific inhibitors of cysteine proteases. RESULTS: In this study, a cysteine proteinase inhibitor (CPI), 11 kDa in size, was purified from green kiwifruit to homogeneity. Immuno‐tissue print results indicated that CPI is most abundant in the outer layer of pericarp, near the peel, and the inner most part of the pulp—sites where it could act as a natural barrier against pathogens entering the fruit. The purified protein (15 µmol L^?1) showed antifungal activity against two phytopathogenic fungi (Alternaria radicina and Botrytis cinerea) by inhibiting fungal spore germination. In vivo, CPI (10 µmol L^?1) was able to prevent artificial infection of apple and carrot with spore suspension of B. cinerea and A. radicina, respectively. It also exerted activity on both intracellular and fermentation fluid proteinases. CONCLUSION: Identification and characterization of plant defense molecules is the first step towards creation of improved methods for pathogen control based on naturally occurring molecules. Copyright © 2012 Society of Chemical Industry     

山茶油微乳液的制备及稳定性分析

以山茶油为原料,采用拟三元相图法优化微乳液配方并研究其稳定性。探讨助表面活性剂种类、表面活性剂与助表面活性剂质量比(Km值)和制备温度对形成微乳液的影响,通过计算并比较拟三元相图微乳区面积确定各因素的最佳值,然后采用电导率法区分山茶油微乳液类型,最后对其稳定性进行分析。结果表明,制备具有最大加水量的山茶油微乳液的最佳条件为:固定山茶油与肉豆蔻酸异丙酯(IPM)(质量比1∶2)作油相占比34%,加水量15%,Tween80与Span80质量比4∶1作表面活性剂,正丁醇为助表面活性剂,Km值4∶1,混合表面活性剂与油相质量比6∶4,制备温度25℃。在最佳条件下,微乳液的类型为W/O型,并具有良好的热稳定性、离心稳定性、储藏稳定性、耐盐性和耐碱性。     

In vitro antifungal activity and chemical composition of Warionia saharae essential oil against 3 apple phytopathogenic fungi

Essential oil of aerial parts of Warionia saharae was obtained by hydrodistillation and analyzed by GC and GC-MS. Thirty-nine compounds were identified, accounting for 93.2% of the total oil. β-Eudesmol (34.9%), nerolidol-E (23%), and linalool (15.2%) were the most abundant components. The antifungal activity of the W. saharae oil was tested by poisoned food (PF) technique and the volatile activity (VA) assay against 3 phytopathogenic causing the deterioration for apple. The results indicated that the W. saharae oil inhibited significantly the mycelial growth of all strains tested (p<0.05). The minimum inhibitory concentration against Alternaria sp. was 2 μL/mL air in VA assay, whereas >2 μL/mL in PF technique for all strains. Fungal spore production was completely inhibited at 1 μL/mL air for Alternaria sp. and at 2 μL/mL air for Penicillium expansum and Rhizopus stolonifer.     

Technical note: High-throughput method for antifungal activity screening in a cheese-mimicking model

In this study, we developed a high-throughput antifungal activity screening method using a cheese-mimicking matrix distributed in 24-well plates. This method allowed rapid screening of a large variety of antifungal agent candidates: bacterial fermented ingredients, bacterial isolates, and preservatives. Using the proposed method, we characterized the antifungal activity of 44 lactic acid bacteria (LAB) fermented milk-based ingredients and 23 LAB isolates used as protective cultures against 4 fungal targets (Mucor racemosus, Penicillium commune, Galactomyces geotrichum, and Yarrowia lipolytica). We also used this method to determine the minimum inhibitory concentration of a preservative, natamycin, against 9 fungal targets. The results underlined the strain-dependency of LAB antifungal activity, the strong effect of fermentation substrate on this activity, and the effect of the screening medium on natamycin minimum inhibitory concentration. Our method could achieved a screening rate of 1,600 assays per week and can be implemented to evaluate antifungal activity of microorganisms, fermentation products, or purified compounds compatible with dairy technology.     

Phenolic extracts of cachaça aged in different woods and quantifying antioxidant activity and antifungal properties

The antioxidant and antifungal activities of the phenolic compounds in different alcoholic extracts of aged cachaça were evaluated. The physico‐chemical analyses were performed in the Laboratório de Qualidade de Aguardente of the Universidade Federal de Lavras according to the methods of the Ministério Agricultura Pecuária e abastecimento. Total phenol content was determined by the Folin–Ciocalteu method, quantification of these compounds was performed by HPLC and antioxidant activities were determined by methods involving inhibition of the DPPH (1,1‐diphenyl‐2 picrylhydrazyl) radical, the β‐carotene/linoleic acid system, ABTS (2,2 azinobis‐[3‐ethyl‐6‐benzothiazolinesulfonic acid]) radical, reducing power and thiobarbituric acid. Determination of antifungal activity was accomplished through the technique of dissemination in discs using Aspergillus carbonarius, Aspergillus niger, Aspergillus flavus, Penicillium commune and Penicillium cladosporoides fungi at the Laboratório de Micologia de Alimentos. The values obtained for the phenolic compounds ranged from 0.41 to 9.69 mg L^?1; syringaldehyde, vanillic acid and gallic acid were predominant. A satisfactory antioxidant activity was observed in all of the tests with the alcoholic extracts. A moderate activity against P. commune and P. cladosporoides, but no inhibition of the growth of A. carbonarius, A. niger or A. flavus was observed. Copyright © 2016 The Institute of Brewing & Distilling