体外亚硝化模拟体系优选阻断NPYR生成的复合香辛料精油配比

为了有效抑制N-亚硝基吡咯烷(N-nitrosopyrrolidine,NPYR)的形成,在体外模拟亚硝化反应体系中,先通过单因素实验研究市售常见的8种超临界萃取香辛料精油(Spices essential oil,SEO),包括花椒精油、八角精油、青花椒精油、丁香精油、迷迭香精油、黑胡椒精油、当归风味姜油、砂仁精油,...     

Application of plant essential oils in prevention of fungal growth on Para rubber wood

Antifungal activities of essential oils (cinnamon, clove, eucalyptus, peppermint and lemongrass oils) against moulds (Penicillium sp., Aspergillus niger and Aspergillus versicolor) isolated from rubber wood surfaces were examined. Clove oil possessed consistent antifungal activity with the minimal inhibitory concentration (MIC) of 5 μl ml^?1 against all these fungi, while cinnamon oil had MICs from 2.5 to 10 μl ml^?1. However, only dip treatment with cinnamon oil inhibited the growth of A. niger on rubber wood for at least 25 weeks.     

迷迭香和甘草复配液对冷却肉李斯特菌抑制效果及品质的影响

对接种和不接种李斯特菌的冷却肉喷洒不同浓度的香辛料提取物复配液[V(迷迭香)∶V(甘草)=1∶1]后,采用气调包装(80%O2,20%CO2),测定其在贮存过程中微生物指标和理化指标的变化,以考察其保鲜效果。相对未经保鲜液处理的对照,喷洒不同浓度香辛料提取物复配液对冷却肉中李斯特菌和常见腐败菌都有很强的抑制作用,且提取物复配液的抑菌效果与浓度呈正比。贮存28d时喷洒2.5、5.0、10.0mg/mL提取物复配液的冷却肉中李斯特菌数与对照相比分别降低了2.9、3.1和3.6个对数循环;需氧菌数与对照相比分别降低了2.7、2.9和3.1个对数循环;假单胞菌数与对照相比分别降低1.6、2.1和2.6个对数循环;肠杆菌数与对照相比分别降低0.6、0.8和1.2个对数循环;均与对照组差异显著(P<0.05)。对不接种李斯特菌的冷却肉(气调包装)喷洒不同浓度复配液后进行理化指标测定,结果表明香辛料提取物对肉色无不良影响,对脂质氧化也起到了较好的抑制作用。     

Inhibitory effect of the essential oil of Curcuma longa L. and curcumin on aflatoxin production by Aspergillus flavus Link

Aflatoxins are highly toxic, mutagenic, teratogenic and carcinogenic mycotoxins. Consumption of aflatoxin-contaminated food and commodities poses serious hazards to the health of humans and animals. Turmeric, Curcuma longa L., is a native plant of Southeast Asia and has antimicrobial, antioxidant and antifungal properties. This paper reports the antiaflatoxigenic activities of the essential oil of C. longa and curcumin. The medium tests were prepared with the oil of C. longa, and the curcumin standard at concentrations varied from 0.01% to 5.0%. All doses of the essential oil of the plant and the curcumin standard interfered with mycotoxin production. Both the essential oil and curcumin significantly inhibited the production of aflatoxins; the 0.5% level had a greater than 96% inhibitory effect. The levels of aflatoxin B₁ (AFB₁) production were 1.0 and 42.7 μg/mL, respectively, for the samples treated with the essential oil of C. longa L. and curcumin at a concentration of 0.5%.     

In vitro and in vivo antifungal activities of the essential oils of various plants against tomato grey mould disease agent Botrytis cinerea

The aim of this study was to find an alternative to synthetic fungicides currently used in the control of devastating fungal pathogen Botrytis cinerea, the causal agent of grey mould disease of tomato. Antifungal activities of essential oils obtained from aerial parts of aromatic plants, which belong to the Lamiacea family such as origanum (Origanum syriacum L. var. bevanii), lavender (Lavandula stoechas L. var. stoechas) and rosemary (Rosmarinus officinalis L.), were investigated against B. cinerea. Contact and volatile phase effects of different concentrations of the essential oils were found to inhibit the growth of B. cinerea in a dose-dependent manner. Volatile phase effects of essential oils were consistently found to be more effective on fungal growth than contact phase effect. A volatile vapour of origanum oil at 0.2 μg/ml air was found to completely inhibit the growth of B. cinerea. Complete growth inhibition of pathogen by essential oil of lavender and rosemary was, however, observed at 1.6 μg/ml air concentrations. For the determination of the contact phase effects of the tested essential oils, origanum oil at 12.8 μg/ml was found to inhibit the growth of B. cinerea completely. Essential oils of rosemary and lavender were inhibitory at relatively higher concentrations (25.6 μg/ml). Spore germination and germ tube elongation were also inhibited by the essential oils tested. Light and scanning electron microscopic (SEM) observations revealed that the essential oils cause considerable morphological degenerations of the fungal hyphae such as cytoplasmic coagulation, vacuolations, hyphal shrivelling and protoplast leakage and loss of conidiation. In vivo assays with the origanum essential oil, being the most efficient essential oil, under greenhouse conditions using susceptible tomato plants resulted in good protection against grey mould severity especially as a curative treatment. This study has demonstrated that the essential oils are potential and promising antifungal agents which could be used as biofungicide in the protection of tomato against B. cinerea.     

Silica Gel Chemically Modified with Ionic Liquid as Novel Sorbent for Solid-Phase Extraction and Preconcentration of Lead from Beer and Tea Drink Samples Followed by Flame Atomic Absorption Spectrometric Determination

Lead is a harmful metal element that has aroused considerable concern; therefore, it is of great importance to develop sensitive and reliable analytical techniques for the precise monitoring of lead in various foodstuffs. In the present study, an enrichment and separation procedure for lead via its solid-phase extraction as dithizone chelate on an ionic liquid 1,3-di(n-butyl) imidazolium hexafluorophosphate [DnBIM][PF₆]-chemically modified silica gel has been established prior to its flame atomic absorption spectrometric determination. The parameters that affect the extraction recovery of lead was investigated, including sample pH, dithizone concentration, eluent type and volume, and flow rate of sample and eluent. The analytical performance of the method was evaluated. Under the optimized conditions (sample pH, 8.0; dithizone concentration, 0.0005 % (w/v); eluent, 2 mL of 1.0 mol/L HNO₃; sample flow rate, 3 mL/min; eluent flow rate, 0.5 mL/min), the limit of detection was 0.36 μg/L (3σ, n?=?7), and the relative standard deviation was 3.5 % (c?=?5.0 μg/L, n?=?7). The proposed method was successfully applied to the determination of trace lead in beer and tea drink, and the recoveries for the spiked samples were in the range of 97.3–102.5 %.     

Effect of oregano and rosemary essential oils on lipid oxidation of stored frozen minced gilthead sea bream muscle

The study aimed to determine the effect of oregano and rosemary essential oils addition to minced gilthead sea bream muscle on lipid oxidation during frozen storage. Each essential oil was added to minced fish muscle at 500 mg/kg concentration which then was stored at ?22 °C for 12 months. Oregano essential oils inhibited the formation of conjugated diene and triene hydroperoxides and thiobarbituric reactive substances when compared with untreated samples after the first month and rosemary essential oils after the first and third month of frozen storage. Oregano and rosemary essential oils could be used as ingredients to prevent oxidation in stored frozen minced gilthead sea bream muscle, when long term preservation is not needed. The rate of lipid oxidation depends on antioxidant source. The rosemary essential oil proved to be more efficient in preventing lipid oxidation of minced gilthead sea bream muscle than oregano essential oil.     

Role of grapevine vegetative expression on Aspergillus spp. incidence and OTA accumulation in wines produced in a temperate humid climate

ABSTRACT

Aspergillus spp. and Penicillium spp. are the main producers of ochratoxin A (OTA), a mycotoxin responsible for fatal human diseases. Some authorities have established a maximum of 2 μg/L of OTA in wine. Although the incidence and occurrence of OTA in grapes and wine is highly related to climate conditions, as has been extensively documented, there is no conclusive information on the effects of cultivation systems on the presence of OTA. This study focuses on determining the effect of the trellis system, planting density and cordon height on plant microclimate and thus on Aspergillus spp. contamination and OTA production in Tannat wines in Southern Uruguay. Two experiments were conducted during the 2010–2011 growing season: (1) a strip split plot design with five replicates and two cordon heights (CH) (0.5 m and 1.0 m above the soil) were compared in two planting densities (PD) (0.8 and 1.5 m between plants); (2) a randomised complete block design, vertical shoot positioning (VSP) versus Lyra trellis systems were evaluated. The results suggest that, even the macro- and micro-climate growing conditions play an important part in Aspergillus developing on grapes. Agronomical practices also have an undoubted impact on the risk and control of OTA accumulation in wine.     

木霉LE02 β-1，3-葡聚糖酶酶学特性的研究

对木霉菌株LE02所产β-1,3-葡聚糖酶的酶学特性进行了研究。结果表明,该酶最适反应温度为55℃、最适反应pH值为5.0。Co~(2+)、K+、Zn~(2+)、Li~+、Ba~(2+)、Cu~(2+)以及1.0mmol/L的Fe~(2+)对该酶没有影响,Cd~(2+)和10.0mmol/L的Mg~(2+)对酶具有部分抑制作用,而低浓度的Hg~(2+)、5.0mmol/L以上的Mn~(2+)和10.0 mmol/L的Fe~(3+)能强烈抑制该酶的活性。该酶只能作用于β-1,3-糖苷键,以Larinami为底物时其米氏常数K_m值为128.34μg/mL,最大反应速度V_m为23.01μg/(min·mL)。经过SDS-PAGE测定的分子质量近似为80.137ku。     

Influence of different stabilizing operations and storage time on the composition of essential oil of thyme (Thymus officinalis L.) and rosemary (Rosmarinus officinalis L.)

The effect of different stabilizing techniques on the composition of essential oil of rosemary (Rosmarinus officinalis L.) and thyme (Thymus officinalis L.) during one year of storage is reported. The study was aimed to know what is the stabilizing technique to keep at the best the original essential oil composition. The fresh samples were collected and treated as follows: air-dried in a laboratory scale pilot dryer, frozen in a forced-air freezer and freeze-dried in a laboratory freeze-dryer. The fresh sample served as control. The treated samples were packaged with appropriate packaging material and stored at 20 °C or −20 °C for 12 months. All the samples were hydrodistilled every three months and the oils composition was obtained by means of gas chromatography/mass spectrometry (GC/MS). Quantification of known compounds was done with the use of an internal standard. Freezing best maintained the composition of rosemary and thyme essential oil. Appropriate packaging of air-dried and freeze-dried herbs resulted in negligible quality loss up to one year of storage. The frozen and stored thyme samples showed the best retention of thymol, the most important compound, as well as of γ-terpinene and carvacrol.     

Quality Changes in Mango Juice Treated by High-Intensity Pulsed Electric Fields Throughout the Storage

The effect of high-intensity pulsed electric fields (HIPEF) processes on Listeria innocua inhibition, physicochemical parameters and activity of oxidative enzymes of mango juice was evaluated to set the optimal HIPEF treatment time. Quality parameters, microbial population and bioactive compounds of HIPEF-treated (35 kV/cm, 1800 μs) and thermally treated (TT) (90 °C, 60 s) mango juices were studied and compared with those non-treated during 75 days of storage at 4 °C. HIPEF treatment for 800 μs ensured 5 log reductions of L. innocua. Polyphenoloxidase (PPO), lipoxygenase (LOX) and peroxidase (POD) residual activities were significantly reduced to 70, 53 and 44%, respectively, at treatment times of 1800 μs. Similar sensory properties compared with fresh mango juice were attained from product treated at 1800 μs. Moreover, fresh mango juice colour (L* = 38.79, h° = 106.57) was preserved after HIPEF treatment throughout storage. Moulds and yeasts and psychrophilic bacteria counts in HIPEF-treated (1800 μs) mango juice remained below 6 log cycles CFU/mL up to 2 months of refrigerated storage. The content of total phenolic compounds in those HIPEF-treated increased from 333 to 683 μg of GAE/mL from day 0 to the end of storage. Hence, the application of HIPEF may be a feasible treatment in order to ensure microbiological stability, high bioactive compound content and fresh-like characteristics of mango juice.     

超临界CO2萃取辣根精油及其在酱油中的应用

采用超临界CO2萃取辣根精油,研究萃取压力、萃取温度和萃取时间对得率的影响,并利用正交试验优化最适的萃取条件,将萃取的辣根精油进行最小抑菌浓度(minimal inhibitory concentration,MIC)和酱油中应用的实验。结果表明:当萃取压力25MPa、萃取温度40℃、萃取时间90min时,辣根精油得率为0.91%;辣根精油对大肠杆菌和枯草芽孢杆菌的MIC均为0.04μL/mL;与添加1.0g/kg苯甲酸钠相比,单独添加0.04μL/mL辣根精油或同时添加0.02μL/mL辣根精油和0.5g/kg苯甲酸钠,均使酱油在37℃条件下保藏30d品质良好,其中同时添加两种物质的应用性更好。     

Physical and chemical properties of encapsulated rosemary essential oil by spray drying using whey protein–inulin blends as carriers

The objective of this study was to evaluate the influence of whey protein isolate (WPI) and inulin blends on the properties of rosemary essential oil microencapsulated by spray drying. The following ratios (w/w) of WPI to inulin were evaluated: 1:1, 1:3 and 3:1. Increasing the WPI concentration increased the particle instantanisation times and decreased the moisture content. The samples did not differ significantly (P > 0.05) in hygroscopicity and porosity. The microcapsules produced at higher inulin concentration showed the highest bulk density and tapped density and were significantly different from other treatments. WPI/inulin blends of 1:1 and 3:1 proved to be effective carriers to entrap rosemary essential oil. The encapsulated oil composition in particles proved to be quite similar to pure oil, and no interaction between wall matrix and encapsulated oil was demonstrated. The analysis of particle size distribution revealed that the particle size varied from 11.5 to 11.9 μm and that all samples had an amorphous structure.     

Inhibitory effect of Turkish Rosmarinus officinalis L. on acetylcholinesterase and butyrylcholinesterase enzymes

In the current study, we have tested acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activity of the petroleum ether, ethyl acetate, chloroform, and methanol extracts, rosmarinic acid as well as the essential oil obtained from Rosmarinus officinalis L. growing in Turkey by a spectrophotometric method of Ellman using ELISA microplate-reader at 0.2, 0.5, and 1.0 mg/mL concentrations. In addition, quantification of rosmarinic acid, a common phenolic acid found in rosemary, was carried out by reversed-phase HPLC in the methanolic extract of the plant, which was found to have 12.21 ± 0.95% (122.1 ± 9.5 mg/g extract) of rosmarinic acid. Rosmarinic acid was also tested for its AChE and BChE inhibitory effect and found to cause 85.8% of inhibition against AChE at only 1.0 mg/mL. Besides, the essential oil was analyzed by GC–MS technique, which was shown to be dominated by 1,8-cineol (44.42%) and followed by α-pinene (12.57%).     

Effects of Essential Oil Vapour Treatment on the Postharvest Disease Control and Different Defence Responses in Two Mango (<Emphasis Type="Italic">Mangifera indica</Emphasis> L.) Cultivars

The purpose of this study was to investigate the inhibitory effect of essential oils (thyme, clove and cinnamon) in vapour phase against the major fungal diseases of mango in vitro and in vivo. Thyme oil vapour (5 μL/Petri plate) completely inhibited the mycelial growth of Colletotrichum gloeosporioides and Lasiodiplodia theobromae under in vitro condition. Thyme oil vapour at 66.7 μL L^?1 significantly reduced artificially inoculated C. gloeosporioides and L. theobromae in mangoes for 4 days. GC/MS analysis revealed thymol, eugenol and benzofuran, 3-methyl as the dominant compounds in thyme, clove and cinnamon oils, respectively. The activities of defence and antioxidant enzymes including peroxidase, chitinase, phenylalanine ammonia-lyase, β-1,3-glucanase, catalase and superoxide dismutase were enhanced by thyme oil (66.7 μL L^?1) treatment and also help to maintain the phenolic content. Hence, postharvest thyme oil vapour treatment may prove to be an alternative means of controlling disease in mangoes.     

Effect of Rosemary Oil and HPMC Concentrations on Film Structure and Properties

The objective of this work was to study the effect of rosemary oil and hydroxylpropyl methyl cellulose (HPMC) concentrations on film structure and functional properties. Films with different concentrations of HPMC (2, 4 and 6 %) and with different rosemary oil concentrations (0.0, 0.4, 0.7, 1.0 and 2.0 %) were prepared. Film microstructure, mechanical properties and water vapour permeability (WVP) were evaluated. Results showed that the microstructure of the films was not affected by different HPMC concentrations, whereas the distribution of oil droplets into HPMC film was different as function of HPMC concentration. The different amount of rosemary oil did not have a significant effect on mechanical behaviour with the exception of the elongation to break of film at 6 % of HPMC which is reduced at high oil concentration. WVP of HPMC films increased as increased HPMC concentration for increased hydrophilic groups. Only for film at 6 % of HPMC, a reduction of water vapour permeability was achieved for oil concentration up to 1 %.     

Purification, characterization, and production of β-mannanase from Bacillus subtilis TJ-102 and its application in gluco-mannooligosaccharides preparation

A novel β-mannanase-producing strain, Bacillus subtilis TJ-102, was identified and characterized. Response surface method was applied to improving and enhancing the enzyme production. The optimized media components were obtained: 45.25 g/L konjac, 9.29 g/L Na₂HPO₄·12H₂O, 2.60 g/L CaCO₃, 1.0 g/L (NH₄)₂SO₄, 0.3 g/L KH₂PO₄, 1.0 g/L NaCl, 1.0 g/L MgCl₂·6H₂O, and 0.01 g/L FeSO₄. Under these conditions, the β-mannanase activity could achieve 205.3 U/mL in a 7-L fermentor. Then, β-mannanase was 7.39-fold purified by salting out, ultrafiltration, anion-exchange, and size-exclusion preparative chromatography with a recovery of 21.41 % and a specificity of 125.36 U/mg proteins. β-Mannanase was stable below 65 °C and pH 5.0–8.0, which exhibited excellently enzymatic efficiency in the preparation of gluco-mannooligosaccharides (GMOS) by hydrolyzing konjac flour. The GMOS yield of 57.76 % has been achieved with 8.71 % of mannose and 14.49 % of glucose, demonstrating the potential use of β-mannanase in food industry.     

Antimicrobial activity of whey protein based edible films incorporated with oregano,rosemary and garlic essential oils

The use of edible films to release antimicrobial constituents in food packaging is a form of active packaging. Antimicrobial properties of spice extracts are well known, however their application to edible films is limited. In this study, antimicrobial properties of whey protein isolate (WPI) films containing 1.0–4.0% (wt/vol) ratios of oregano, rosemary and garlic essential oils were tested against Escherichia coli O157:H7 (ATCC 35218), Staphylococcus aureus (ATCC 43300), Salmonella enteritidis (ATCC 13076), Listeria monocytogenes (NCTC 2167) and Lactobacillus plantarum (DSM 20174). Ten millilitres of molten hard agar was inoculated by 200 μl of bacterial cultures (colony count of 1 × 10⁸ CFU/ml) grown overnight in appropriate medium. Circular discs of WPI films containing spice extracts, prepared by casting method, were placed on a bacterial lawn. Zones of inhibition were measured after an incubation period. The film containing oregano essential oil was the most effective against these bacteria at 2% level than those containing garlic and rosemary extracts (P < 0.05). The use of rosemary essential oil incorporated into WPI films did not exhibit any antimicrobial activity whereas inhibitory effect of WPI film containing garlic essential oil was observed only at 3% and 4% level (P < 0.05). The results of this study suggested that the antimicrobial activity of some spice extracts were expressed in a WPI based edible film.     

Synergistic antifungal effects of thyme essential oil and Lactobacillus plantarum cell‐free supernatant against Penicillium spp. and in situ effects

This study evaluates the synergistic antifungal effects between thyme essential oils and Lactobacillus plantarum cell‐free supernatant (LCFS) against Penicillium spp. and in situ antifungal activity in rice grains. Thyme essential oil and LCFS showed remarkable antifungal activities against Penicillium spp. with the minimum inhibitory concentration (MIC) of 40 and 80 µL/mL, respectively. The analysis of fractional inhibitory concentration (FIC) index showed the antifungal synergism between thyme essential oil and LCFS against Penicillium spp. with FIC index of 0.5. This synergism also resulted in fourfold reduction in their MICs when applied in combination. The antifungal modes of action were characterized by observing the changes in cell membrane permeability and degradation of fungal cell wall. The combination of thyme essential oil and LCFS (2 × MIC of each) showed remarkable in situ antifungal effect and completely inhibit the growth of Penicillium in rice seeds. The results suggested the possible applications of the observed synergism on actual crops.

Practical applications

Essential oils are used as preservative in food industry and high concentration of essential oil is associated with negative organoleptic characteristics. This study presented a novel approach for synergistic antifungal effects by using the combination of thyme essential oil and Lactobacillus plantarum cell‐free supernatant (LCFS) against Penicillium spp. and systematic evaluation of the antifungal effect by using fractional inhibitory concentration (FIC) index method. This approach will be a role model for future research on synergism and overcome the major drawbacks of using live bacteria and the negative effects arising from antimicrobial activities of essential oils.     

Enhancement of Functional Properties of Wami Tilapia (Oreochromis urolepis hornorum) Skin Gelatin at Different pH Values

The effects of several agents in two different concentrations and pH values (5.0 and 8.0) on the functional properties of tilapia (Oreochromis urolepis hornorum) skin gelatin were evaluated and compared using a control tilapia skin gelatin and a commercial mammalian gelatin. The addition of the agents (sucrose 4 % and 8 % (w/v), glycerol 5 % and 10 % (v/v), NaCl 0.3 and 0.8 mol/L, MgCl₂ 0.3 and 0.8 mol/L, MgSO₄ 0.3 and 0.8 mol/L, KCl 0.3 and 0.8 mol/L, and transglutaminase 10 and 15 mg/mL) slightly increased the turbidity. There were different ratios of rheological properties depending on the agent, concentration, and pH. The addition of all agents increased the viscosity of the gelatin solution, mainly at pH 5.0. The addition of glycerol (10 % (v/v)) raised viscosity up to 7.45 cP. The setting time was prolonged by incorporating the agents. The gelatin samples with the addition of MgSO4 0.8 mol/L showed higher gel strength than the mammalian gelatin, exhibiting values of 298 and 295g_f at pH 5.0 and 8.0, respectively.