Chemical response of Picea glehnii seed-epiphytic Penicillium species to Pythium vexans under in vitro competitive conditions for mycelial growth

The potential protection of Picea glehnii seedlings from damping-off by seed-epiphytic Penicillium species was investigated. We studied the chemical response of seed-epiphytic Penicillium species (Pen. cyaneum, Pen. damascenum, and Pen. implicatum) to Pythium vexans, a damping-off fungus, in vitro. Penicillium species were cultured singly or cocultured with Pyt. vexans for 14 or 18 d, and mycelial growth, pH of culture filtrate, antifungal activity of the culture filtrate against Pyt. vexans, and the amount of antifungal compound produced by each Penicillium species, were examined. The filtrate of both the single culture of Penicillium and the coculture of Penicillium and Pyt. vexans showed antifungal activity against Pyt. vexans. In a coculture with Pyt. vexans, Pen. cyaneum produced an antifungal compound (patulin) as in the single culture. Pen. damascenum cocultured with Pyt. vexans produced an antifungal compound (citrinin), as it did in the single culture and in larger amounts on day 10. Pen. implicatum produced two antifungal compounds, frequentin and palitantin, and the ratio of frequentin (with higher antifungal activity than palitantin) to palitantin was higher in the coculture with Pyt. vexans than in the single culture. Our results indicate that these Penicillium species have the ability to produce antifungal compounds and to keep antifungal activity under competitive condition with Pyt. vexans. The chemical response of these Penicillium species to Pyt. vexans may contribute to protect P. glehnii seedlings from damage by Pyt. vexans.     

固相萃取-高效液相色谱法测定苹果汁及其饮料中展青霉素的含量

建立固相萃取-高效液相色谱法测定苹果汁及其饮料中展青霉素含量的检测方法。样品经预处理后,采用固相萃取柱净化处理,以乙腈-水作为流动相,C18色谱柱分离,二极管阵列检测器进行检测。结果表明：方法检出限为8 μg/kg,方法定量限为25 μg/kg;展青霉素标准溶液在50.0～500.0 μg/L质量浓度范围内,决定系数R2为0.999 6;样品中展青霉素含量为25～100 μg/kg时,回收率在90.2%～102.8%之间,精密度（变异系数）为0.57%～1.44%。此方法准确度较高,成本适中,操作较简便,适合苹果浓缩汁生产企业用于产品安全自控。     

液相色谱串联质谱法测定混合果酱中展青霉素含量

目的建立混合果酱中展青霉素含量测定的液相色谱串联质谱方法。方法样品用乙腈提取,MAX固相萃取柱净化,用液相色谱串联质谱进行检测。结果展青霉素在0.5～100.0ng/mL范围内线性关系良好,相关系数大于0.999,回收率为95.2%～105.8%,相对标准偏差为3.14%～4.98%,检出限为0.1μg/kg,定量限为0.3μg/kg。结论该方法准确、可靠,快速、灵敏度高,可为混合果酱的质量控制提供检测依据,同时满足我国GB 2761-2011对水果制品中展青霉素残留量的检测要求。     

辉光放电等离子体对水溶液中棒曲霉素的降解作用

研究辉光放电等离子体在不同酸度条件下和不同催化剂存在时对水溶液中棒曲霉素的降解作用。结果表明：当直流电压为600 V,电流范围为145～155 mA时,辉光放电等离子体可在40 min内有效降解水溶液中的棒曲霉素。在pH 4.0时降解棒曲霉素效率更高,Fe2＋、H2O2对降解反应具有催化作用,可提高棒曲霉素的降解速率,而纳米ZnO却减小了棒曲霉素的降解速率。     

拮抗酵母菌控制水果及其制品中展青霉素研究进展

展青霉素是由部分曲霉、青霉产生的有毒的代谢产物,主要污染水果及其制品,对人、畜危害较大。水果及其制品中展青霉素的常用控制方法是物理方法和化学方法,但物理方法和化学方法都存在一些弊端,限制了其在实际生产上的应用。近年来,采用拮抗酵母菌控制水果及其制品中展青霉素已成为学术研究的热点。本文对拮抗酵母菌控制水果及水果制品中展青霉素的研究进展进行了综述。     

臭氧对苹果汁中棒曲霉素的降解效果研究

主要研究臭氧对苹果汁中棒曲霉素(Pat)的降解效果及对果汁品质的影响。研究采用臭氧对水和苹果汁中500、250、200、100、50μg/LPat浓度进行5、10、15、20、30min的降解处理。结果表明,臭氧处理对各浓度的Pat都有降解作用,浓度越低,降解效果越好。随着处理时间延长降解效果越好,15min以后降解率不再增加。臭氧处理15min,50μg/L的Pat降解效率最佳,在该条件下,臭氧对苹果汁的pH、VC含量、可溶性固形物和色值均没有明显的影响,因此,臭氧处理是高效、安全、低廉的Pat降解方法。     

Reduction of patulin in aqueous solution by lactic acid bacteria

This study aims to investigate the ability of lactic acid bacteria (LAB) to remove patulin (PAT) from aqueous solution with respect to the bacterial viability, initial PAT concentration, incubation time, temperature, and pH. The removal of PAT determined by high-performance liquid chromatography (HPLC) coupled with UV detector. The maximum PAT uptake was achieved by Bifidobacterium bifidum 6071 and Lactobacillus rhamnosus 6149 strains (52.9% and 51.1%) for viable and (54.1% and 52.0%) for nonviable cells after 24 h incubation. The highest removal of PAT was at pH 4.0 and 37 °C and increased with decreasing of toxin levels. The removal ability of selected strains could represent new strategies for a possible application in contaminated food products and animal feed.     

Activity of Electrolyzed Oxidizing Water Against Penicilium expansum in Suspension and on Wounded Apples

ABSTRACT: Spores of Penicillium expansum , the primary organism responsible for the occurrence of patulin in apple juice, were exposed to electrolyzed oxidizing (EO) water in an aqueous suspension and on wounded apples. Full-strength and 50% EO water decreased viable spore populations by greater than 4 and 2 log units, respectively. Although EO water did not prevent lesion formation on fruit previously inoculated with P. expansum , cross-contamination of wounded apples from decayed fruit or by direct addition of spores to a simulated dump tank was substantially reduced. EO water, therefore, has potential as an alternative to chlorine disinfectants for controlling infection of apples by P. expansum during handling and processing operations.     

Quantification of patulin in fruit leathers by ultra-high-performance liquid chromatography-photodiode array (UPLC-PDA)

Patulin is a mycotoxin commonly found in certain fruit and fruit products. For this reason many countries have established regulatory limits pertaining to, in particular, apple juice and apple products. Fruit leathers are produced by dehydrating fruit puree, leaving a sweet product that has a leathery texture. A recent report in the literature described the detection of patulin at substantial levels in fruit leathers. To investigate this further, an ultra-high-performance liquid chromatography-photodiode array (UPLC-PDA) method was developed for the sensitive detection of patulin in fruit leathers. Investigations were also made of the suitability of direct analysis in real time-mass spectrometry (DART-MS) for detection of patulin from the surface of fruit leathers. Results indicated DART-MS was insufficiently sensitive for quantification from the surface of home-style apple leathers, although patulin spiked onto the surface of leather or peel could be detected. The UPLC-PDA method was used to determine the fate of patulin during the preparation of home-made fruit leathers. Interestingly, when a home-style process was used, the patulin was not destroyed, but rather increased in concentration as the puree was dehydrated. The UPLC-PDA method was also used to screen for patulin in commercial fruit leathers. Of the 36 products tested, 14 were above the limit of detection (3.5 μg kg^–1) and nine were above the limit of quantification (12 μg kg^–1). Positive samples were confirmed by UPLC-MS/MS. Only one sample was found above the US regulatory limit for single-strength apple juice products (50 μg kg^–1). These results suggest patulin can be concentrated during preparation and can be found in fruit leathers. The limited survey suggests that patulin is fairly prevalent in such commercial products, but that the levels are usually low.