复合精油对黄曲霉联合抑菌作用研究

采用联合抑菌评价方法,通过测定植物精油抑菌圈直径、最低抑菌浓度(Minimum Inhibition Concentration,MIC)、最低生长下降浓度(Reduction Concentration,RC)、联合抑菌指数(Fractional Inhibitory Concentration,FIC),对植物精油单独及联合使用后的抑菌效果进行评价,筛选最佳抑制黄曲霉活性作用的复合精油种类及配比。结果表明:大蒜、肉桂、丁香、薄荷精油单独或复合使用均有较强抑制黄曲霉活性的作用。大蒜与肉桂精油联合抑菌评价为相加作用。当大蒜精油与肉桂精油复合体积比为1∶3时,复合精油具有最佳抑制黄曲霉活性的效果。因此,复合精油作为有效防霉保鲜成分具有良好的研发与应用前景。     

The effect of pH,sodium chloride,sucrose, sorbate and benzoate on the growth of food spoilage yeasts

The effects of pH, concentration of NaCl, concentration of sucrose and concentrations of sorbic and benzoic acids on growth were examined for 30 strains of food spoilage yeasts, representingDebaryomyces hansenii, Yarrowia lipolytica, Kloeckera apiculata, Zygosaccharomyces bailii, Zygosaccharomyces rouxii, Kluyveromyces marxianus, Pichia membranaefaciens, Pichia anomalaandSaccharomyces cerevisiae.Zygosaccharomyces bailiidid not grow at pH 7.0 andZ. rouxii, Kl. apiculataandP. membranaefaciensdid not grow at pH 8.0. OnlyKl. apiculatagrew at pH 1.5–2.0. The remaining species grew at pH 2.5–8.0. None of the species grew at 20% NaCl but strains ofD. hansenii, Z. rouxiiandP. anomalagrew at 15% NaCl.S. cerevisiaeandK. marxianuswere the least salt tolerant, showing no growth at 7.5% NaCl and 10% NaCl, respectively. Medium pH influenced growth in the presence of NaCl. ForY. lipolytica, D. hanseniiandS. cerevisiae, greatest tolerance of NaCl occurred at pH 5.0–7.0, but forKl.apiculata, D. membranaefaciensandZ. bailiibest tolerance occurred at pH 3.0.K. apiculatagrew in the presence of 12.5% NaCl at pH 2.0. All yeasts grew at 50% sucrose, withZ. rouxii, Z. bailiiandP. anomalaandD. hanseniigrowing at 60–70% sucrose. Medium pH in the range 2.0–7.0 had little effect on ability to grow in the presence of high sucrose concentrations.Z. bailiiandY. lipolyticawere the species most tolerant of sorbate and benzoate preservatives (750–1200 mg l⁻¹) at pH 5.0.     

Inhibitory effect of cinnamon, clove, lemongrass, oregano and palmarose essential oils on growth and fumonisin B1 production by Fusarium proliferatum in maize grain

The effect of cinnamon, clove, oregano, palmarose and lemongrass oils on growth and FB1 production by three different isolates of F. proliferatum in irradiated maize grain at 0.995 and 0.950 aw and at 20 and 30 degrees C was evaluated. The five essential oils inhibited growth of F. proliferatum isolates at 0.995 aw at both temperatures, while at 0.950 aw only cinnamon, clove and oregano oils were effective in inhibiting growth of F. proliferatum at 20 degrees C and none of them at 30 degrees C. Cinnamon, oregano and palmarose oils had significant inhibitory effect on FB1 production by the three strains of F. proliferatum at 0.995 aw and both temperatures, while clove and lemongrass oils had only significant inhibitory effect at 30 degrees C. No differences were found using 500 or 1000 microg essential oil g(-1). At 0.950 aw, none of the essential oils had any significant effect on FB1 production. The results suggest that mainly cinnamon and oregano oils could be effective in controlling growth and FB1 production by F. proliferatum in maize under preharvest conditions.     

植物复合精油对5种稻谷霉变优势菌株抑菌作用研究

为了研究天然植物精油(百里香、丁香、肉桂)对霉变稻谷的抑菌效果,以5种稻谷霉变优势菌株为受试菌,以霉菌抑菌圈直径大小和最低抑菌浓度（MIC）为指标,通过混料设计方法建立复合精油抑菌模型,结合方差分析得到抑菌效果最佳的植物精油配比。研究结果表明,单一精油抑菌活性对亮白曲霉（A. candidus）,杂色曲霉（A. versicolor）和聚多曲霉（A. sydowii）为肉桂精油>丁香精油>百里香精油;对稻黑孢霉（N. oryzae）为肉桂精油=丁香精油>百里精香油;对布罗克青霉菌（P. brocae）为丁香精油=百里香精油<肉桂精油。当肉桂精油:丁香精油:百里香精油的体积比为55.2%︰26.9%︰17.9%时,3种植物精油对5种菌株抑制效果最佳,复合抑制值大于90.9%。     

Effects of Essential Oils from Plants on Growth of Food Spoilage Yeasts

Thirty-two essential oils from plants were screened for inhibitory effects on 13 food-spoilage and industrial yeasts. Of these, essential oils of allspice, cinnamon, clove, garlic, onion, oregano, savory, and thyme were most inhibitory. Oils were subsequently tested for their effects on biomass production and pseudomycelium formation of eight genera of yeasts. Garlic oil was a potent inhibitor of yeast growth at concentrations as low as 25 ppm. The oils of onion, oregano and thyme were also strongly inhibitory. Essential oils (100 ppm) had no effect on pseudomycelium production by Candida lipolytica. However, all eight essential oils delayed pseudomycelium formation by Hansenula anomala, whereas six oils stimulated pseudomycelium production by Lodderomyces elongisporus. Cinnamon and clove oils were clearly stimulatory to pseudomycelium production by Saccharomyces cerevisiae.     

Some probiotic properties of yeast isolates from infant faeces and Feta cheese

The use of modified atmospheres to prevent fungal growth and mycotoxin production in cheese was evaluated. Eight fungal species: Mucor plumbeus, Fusarium oxysporum, Byssochlamys fulva, B. nivea, Penicillium commune, P. roqueforti, Aspergillus flatus and Eurotium chevalieri were inoculated onto cheese and incubated under conditions of decreasing concentrations of O2 (5% to < 0.5%) and increasing concentrations of CO2 (20-40%). Fungal growth was measured by colony diameter and ergosterol content. All fungi examined grew in atmospheres containing 20% and 40% CO2 with 1% or 5% O2, but growth was reduced by 20-80%, depending on species, compared with growth in air. The formation of aflatoxins B1 and B2, roquerfortine C and cyclopiazonic acid was greatly decreased but not totally inhibited in these atmospheres. At 20% or 40% CO2 with < 0.5% O2, only B. nivea exhibited growth, which was very slow. Growth of F. oxysporum, B. fulca, P. commune and A. flavus showed good correlations between colony diameter and ergosterol content. However, for the other species correlations were inconsistent.     

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.     

The growth, properties and interactions of yeasts and bacteria associated with the maturation of Camembert and blue-veined cheeses

The growth of yeasts and bacteria were monitored during the maturation of Camembert and blue-veined cheese produced in Australia. Yeasts were prominent throughout maturation, growing to 10(5)-10(9)/g, depending on the manufacturer. Debaryomyces hansenii predominated, but there were lesser, inconsistent contributions from Yarrowia lipolytica. Of the non-lactic acid bacteria, Acinetobacter species were significant during the maturation of Camembert but not blue-veined cheeses, and grew to 10(6)-10(8) cfu/g. Staphylococcus and Micrococcus species were consistently isolated from the cheeses with Staphylococcus xylosus growing to 10(5)-10(9) cfu/g, depending on the product. Lactic acid bacteria (10(7)-10(9) cfu/g) were present throughout maturation but were not identified. Interactions between the various yeasts and bacterial isolates were examined. Several strains of D. hansenii exhibited killer activity but not against Y. lipolytica. None of the yeasts were antagonistic towards the bacteria but some strains of D. hansenii enhanced the growth of Y. lipolytica and S. xylosus. The yeast and bacterial isolates exhibited various degrees of extracellular proteolytic and lipolytic activities.     

丁香和肉桂精油气相抑菌活性研究

采用超临界CO2萃取法提取丁香和肉桂精油,并通过滤纸片法、固相扩散法、气相扩散法等体外抗菌试验,比较了丁香、肉桂精油及混合精油和常用化学防腐剂山梨酸钾对11株食品中常见污染菌的抑菌作用。结果表明:丁香、肉桂精油及混合精油对供试细菌、霉菌和酵母菌均有较强的抑制作用,抑菌效果显著优于山梨酸钾;对霉菌的抑菌作用显著高于酵母菌和细菌,且气态抑制作用比固相抑菌作用强;混合精油对细菌的抑菌作用有拮抗作用,在气相中的拮抗作用更强;对酵母菌的抑菌作用没有影响;对黄曲霉和黑曲霉有相加作用;对桔青霉有协同作用。     

Yeasts as adjunct starters in matured Cheddar cheese

Debaryomyces hansenii and Yarrowia lipolytica are typical foodborne yeast species frequently associated with dairy products and capable of predominating the yeast composition in such systems. The two species fulfil a number of criteria to be regarded as co-starters for cheesemaking. They are known for their proteolytic and lipolytic activity as well as their compatibility and stimulating action with the lactic acid starter cultures when co-inoculated. Recent studies indicated that yeasts could be included as part of starter cultures for the manufacturing of cheese, enhancing flavour development during the maturation. The potential of D. hansenii and Y. lipolytica as agents for accelerated ripening of matured Cheddar cheese has been evaluated during four cheese treatments. The interaction between the two yeast species and the lactic acid bacteria was surveyed incorporating (i) D. hansenii, (ii) Y. lipolytica, (iii) both species as adjuncts to the starter culture and (iv) a control cheese without any additions for the production of matured Cheddar cheese. The physical and chemical properties of the cheeses were monitored in order to evaluate the contribution of the yeasts to cheese maturation. The yeasts grew in association with the lactic acid bacteria without any inhibition. The yeasts species when individually added contributed to the development of bitter flavours despite accelerated development of strong Cheddar flavours. When both species were incorporated as part of the starter culture, the cheese, however, had a good strong flavour after a reduced ripening period. The cheese retained this good flavour and aroma after 9 months of production. The simultaneous application of D. hansenii and Y. lipolytica as part of the starter culture for the production of matured Cheddar cheese is proposed.     

ANTIFUNGAL ACTIVITIES OF THYME, CLOVE AND OREGANO ESSENTIAL OILS

The antifungal potential of essential oils of oregano (Origanum vulgare), thyme (Thymus vulgaris) and clove (Syzygium aromaticum) was determined. To establish this antifungal potential, two molds related to food spoilage, Aspergillus niger and Aspergillus flavus, were selected. The agar dilution method was employed for the determination of antifungal activities. The three essential oils analyzed presented inhibitory effects on both molds tested. Oregano essential oil showed the highest inhibition of mold growth, followed by clove and thyme. Aspergillus flavus was more sensitive to thyme essential oil than A. niger. Clove essential oil was a stronger inhibitor against A. niger than against A. flavus.     

Effects of Allspice, Cinnamon, and Clove Bud Essential Oils in Edible Apple Films on Physical Properties and Antimicrobial Activities

ABSTRACT:  Essential oils (EOs) derived from plants are rich sources of volatile terpenoids and phenolic compounds. Such compounds have the potential to inactivate pathogenic bacteria on contact and in the vapor phase. Edible films made from fruits or vegetables containing EOs can be used commercially to protect food against contamination by pathogenic bacteria. EOs from cinnamon, allspice, and clove bud plants are compatible with the sensory characteristics of apple-based edible films. These films could extend product shelf life and reduce risk of pathogen growth on food surfaces. This study evaluated physical properties (water vapor permeability, color, tensile properties) and antimicrobial activities against  Escherichia coli  O157:H7,  Salmonella enterica,  and  Listeria monocytogenes  of allspice, cinnamon, and clove bud oils in apple puree film-forming solutions formulated into edible films at 0.5% to 3% (w/w) concentrations. Antimicrobial activities were determined by 2 independent methods: overlay of the film on top of the bacteria and vapor phase diffusion of the antimicrobial from the film to the bacteria. The antimicrobial activities against the 3 pathogens were in the following order: cinnamon oil > clove bud oil > allspice oil. The antimicrobial films were more effective against  L. monocytogenes  than against the  S. enterica . The oils reduced the viscosity of the apple solutions and increased elongation and darkened the colors of the films. They did not affect water vapor permeability. The results show that apple-based films with allspice, cinnamon, or clove bud oils were active against 3 foodborne pathogens by both direct contact with the bacteria and indirectly by vapors emanating from the films.     

Effects of essential oils and oleoresins of plants on ethanol production,respiration and sporulation of yeasts

Ethanol production, respiration, and sporulation of yeasts as effected by essential oils and oleoresins of allspice, cinnamon, clove, garlic, onion, oregano, savory, and thyme were investigated. Essential oils of allspice, cinnamon, and clove had little or no effect on ethanol production by Sacchraromyces cerevisiae. Oils of onion, oregano, savory, and thyme delayed and/or reduced the production of ethanol. Overall, essential oils effectively suppressed ethanol production by Hansenula anomala. At the highest concentrations tested (500 μg/ml), only cinnamon, clove, garlic and thyme oleoresins substantially delayed and/or reduced ethanol production by S. cerevisiae. Most of the essential oils (100 μm/ml) impaired the respiratory activity of S. cerevisiae as evidenced by a reduction in CO₂ production. Thyme oleoresin was the strongest inhibitor. Allspice and garlic oils impaired sporulation by H. anomala. All oils delayed sporulation of Lodderomyces elongisporus).     

Antimicrobial efficacies of essential oils/nanoparticles incorporated polylactide films against L. monocytogenes and S. typhimurium on contaminated cheese

Polylactide based films were formulated by incorporating polyethylene glycol, selected nanopowders (zinc oxide, silver-copper), and essential oils (cinnamon, garlic, and clove) by solvent casting method. Films were tested against three foodborne pathogens (one gram-positive and two gram-negative) for their antibacterial activity. The effectiveness of selected cinnamon oil-based film was ascertained by performing a challenge test with cheese as a food model. In vitro antibacterial efficacies of nanopowders and essential oils were also determined by the decimal reduction concentrations and the minimum bactericidal concentrations for those foodborne pathogens. It was observed that nanopowders exhibited considerably poorer decimal reduction concentrations and minimum bactericidal concentration values in comparison to the essential oils. Silver-copper alloy nanopowders exhibited lower decimal reduction concentrations and minimum bactericidal concentrations values than ZnO against tested pathogens whereas essential oils showed distinct antimicrobial effectiveness against all those pathogens with in vitro decimal reduction concentration values of 87–157 and 77–220 µg/mL for cinnamon and clove oils, respectively. Among the various formulations, it was observed that only essential oils (especially cinnamon and clove) incorporated films exhibited a significant antimicrobial activity against the selected microorganisms. These results indicate that the poor antibacterial activity of the nanopowders and the hydrophobicity of polylactide could be responsible for the ineffectiveness of nanopowders in polylactide based films. Furthermore, the challenge test indicated the polylactide/polyethylene glycol/cinnamon oil film was appropriate to inhibit the growth of L. monocytogenes and S. typhimurium on cheese up to 11 days at refrigerated storage.     

丁香和肉桂挥发油的提取、主要成分测定及其抗菌活性研究

本文采用水蒸汽蒸馏法提取丁香和肉桂的挥发油,并对所得挥发油主要成分进行气相测定,通过体外抗菌试验,比较了这两种挥发油及其主要成分和目前常用化学防腐剂苯甲酸钠和山梨酸钾对金黄色葡萄球菌、大肠杆菌、枯草芽孢杆菌、沙门氏菌和志贺氏菌等5株食品中常见污染菌的抗菌作用。结果表明丁香油中丁香酚含量为78.1%,肉桂油中肉桂醛含量为86.8%;这两种挥发油及其主要成分丁香酚和肉桂醛的抗菌作用均强于两种化学防腐剂,其中肉桂油与其主要成分肉桂醛表现出的抗菌活性最强,最小抑菌浓度(MIC)为200～1600mg/L;仅为苯甲酸钠和山梨酸钾MIC(6400～25600mg/L)的1/64～1/16;丁香油及其主要成分丁香酚的抗菌活性次之,MIC为800～1600mg/L,相当于苯甲酸钠和山梨酸钾MIC的1/16～1/8。     

Molecular monitoring of spoilage yeasts during the production of candied fruit nougats to determine food contamination sources

In the present work, we have analysed the yeast microbiota present in a manufacturing plant of candied fruits and nougats. Four yeasts species (Zygosaccharomyces bailii, Zygosaccharomyces rouxii, Sporobolomyces roseus, and Debaryomyces hansenii) and a filamentous fungi (Nectria mauriiticola) were identified according to restriction analysis of 5.8S-ITS rDNA. These identifications were subsequently confirmed by sequencing the D1/D2 domain of the 26S rRNA gene. Z. rouxii and Z. bailii were isolated at high frequency along the whole manufacturing process. Since food alteration by Z. bailii and Z. rouxii is the cause of important economic losses for the food industry, there is a need for differentiating yeasts at the strain level as an essential part of quality control programs in this industry. For this purpose, we have tested the performance of three molecular techniques (RFLP mtDNA, RAPD-PCR, and microsatellite with (GAC)5 and (GTG)5 primers) to differentiate strains belonging to these two Zygosaccharomyces species. Those techniques with the best discriminatory power were applied to differentiate Zygosaccharomyces species isolates. The results of this analysis indicate that one strain of Z. bailii and two strains of Z. rouxii were involved in the spoilage of candied fruits. Moreover, the Z. bailii strain was also present in the spoiled nougat, hence being responsible of this alteration.     

Yeasts associated with Sardinian ewe's dairy products

In the present work, the occurrence of yeasts in different types of typical Sardinian ewe's cheeses (32 samples of pecorino, 32 of caciotta, 40 of feta, 56 of ricotta) was determined. For the strains isolated the following properties were studied: proteolytic and lipolytic activities, the ability to grow at different temperatures, different concentrations of salt, and to assimilate and/or ferment compounds like lactate, citrate, lactose, glucose, galactose, lactic acid. Of 160 samples analysed, 76.2% yielded growth of yeasts. Yeast counts showed a certain variability among the samples. The highest levels were observed in caciotta and feta cheeses. A total of 281 strains belonging to 16 genera and 25 species were identified. In general, Debaryomyces hansenii was the dominant species, representing 28.8% of the total isolates. Other frequently appearing species were Geotrichum candidum, Kluyveromyces lactis and K. marxianus. Other genera encountered were Pichia, Candida, Dekkera, Yarrowia and Rhodotorula. With regard to the biochemical and technological properties of the yeasts, only K. lactis, K. marxianus and Dek. anomala assimilated and fermented lactose, whereas the majority of the species assimilated lactic acid. The assimilation of citrate was a characteristic of D. hansenii, R. rubra and Y. lipolytica. On the whole, the yeasts were weakly proteolytic while lipolytic activity was present in several species. A high percentage of strains showed a certain tolerance to low temperatures while only some strains of D. hansenii and K. lactis were able to grow at a 10% NaCl concentration.     

Antibacterial properties of plant essential oils

Fifty plant essential oils were examined for their antibacterial properties against 25 genera of bacteria. Four concentrations of each oil were tested using an agar diffusion technique. The ten most inhibitory oils were thyme, cinnamon, bay, clove, almond (bitter), lovage, pimento, marjoram, angelica and nutmeg. The most comprehensively inhibitory extracts were angelica (against 25 genera), bay (24), cinnamon (23), clove (23), thyme (23), almond (bitter) (22), marjoram (22), pimento (22), geranium (21) and lovage (20).     

Safety assessment of dairy microorganisms: the hemiascomycetous yeasts

Hemiascomycetous yeasts constitute a class of unicellular fungi often associated with the food and drink processing industries. A number of species including Kluveromyces lactis, Debaryomyces hansenii, Yarrowia lipolytica, play a key role in the cheese-making process by providing aroma, affecting texture and/or permitting the growth of other microorgansisms. The large majority of yeast infections are due to a few opportunistic species presently classified within the genus Candida, and occur in immunocompromised patients. Recent advances in taxonomy have provided evidence for the incorrect classification of a number of yeasts and suggest that their association with the genus Candida should be reconsidered. Indeed, none of the most common pathogenic Candida species are found in cheese. Improved techniques, combined with more advanced analytical methods have brought to light several emerging pathogens, some of which are involved in cheese-making, for example D. hansenii and Y. lipolytica. Other emerging pathogens may also be found as rare occurrences in cheese. Problems in designation of these isolates are due in part to the still limited range of specific methods of identification and are exacerbated by lack of consensus concerning yeast taxonomy. These organisms cause rare infections in immunocompromised and hospitalized patients, which are generally mild and either self-limiting or easily treated. From studies with Saccharomyces cerevisiae, it seems that it is more the exposure to high doses of yeast than the identity of the species or strain that is associated with infection. As such yeasts in cheese cannot be considered to constitute a risk for healthy individuals.     

Inhibition of Growth and Germination of C. botulinum 33A, 40B, and 1623E by Essential Oil of Spices

Effects of clove, thyme, black pepper, pimenta, origanum, garlic, onion, and cinnamon oils on growth and germination of Clostridium botulinum types 33A, 40B, and 1623E were studied. At 200 ppm, ail oils highly inhibited growth of C. botulinum 33A, 40B, and 1623E. At 10 ppm, inhibitory activity of most oils diminished. By activity on C. botulinum growth, oils could be divided into three categories: (1) very active: cinnamon, origanum, and clove; (2) active: pimenta, and thyme; (3) least active: garlic, onion, and black pepper. Effectiveness on germination was quite different. At 150 and 200 ppm all oils totally prevented germination. At 10 ppm garlic and onion showed higher activity than the others. Spores of 33A were more sensitive than 40B and 1623E.