3种植物挥发油抑制食源性细菌生长活性成分及机理

采用无水乙醇浸法提取柠檬花、茶树叶、留兰香叶挥发油,用抑菌圈法及微量肉汤稀释法测定挥发油对大肠杆菌(Escherichia coli)、沙门氏菌(Salmonellas enteritidis)、金黄色葡萄球菌(Staphylococcus aureus)和李斯特菌(Listeria monocytogenes)的抑菌效果,并通过气相色谱-质谱联用分析其有效成分,抑菌机理通过实验菌菌液的电导率及扫描电子显微镜验证。结果表明:柠檬油、茶树油中有效抑菌成分分别为柠檬烯、1,8-桉叶素,其含量分别为65.50%、48.67%,留兰香油中有效抑菌成分为柠檬烯与左旋香芹酮,其含量分别为16.33%、35.67%。其中抑菌广谱性及抑菌效果最好的为留兰香油及其有效活性成分左旋香芹酮。实验中的有效活性物质可能是通过改变实验菌细胞膜的通透性,且可使细菌细胞发生皱缩破裂,以此起到抑菌及杀菌的作用。     

Star-anise (Illicium verum) and black caraway (Carum nigrum) as natural antioxidants

The various solvent fractions of star-anise (Illicium verum) and black caraway (Carum nigrum), along with their spice powders and volatile oils, were prepared and evaluated for antioxygenic activity, using different methods. Star-anise powder and its ethanol/water (80:20)-soluble fraction showed strong antioxygenic activity in refined sunflower oil while the petroleum ether fraction exhibited marginal antioxygenic activity and the water-soluble fraction was practically devoid of any activity in sunflower oil. The black caraway powder showed marginal antioxygenic activity while its ethanol/water fraction (80:20) showed strong antioxygenic activity and all other fractions showed slight pro-oxygenic activity in refined sunflower oil. Both the spice powders and their extracts were also evaluated for antioxidant activity by linoleic acid peroxidaton, β-carotene-linoleate and 1, 1-diphenyl-2-picryl hydrazyl (DPPH) methods. Both the star-anise and black caraway powders, as well as their ethanol/water extracts, exhibited strong antioxygenic activity. Volatile oils from both the spices exhibited antioxygenic activity and the activity did not seem to be concentration-dependent. Volatile oils from star-anise showed relatively higher antioxygenic activity than did those from black caraway. Gas chromatography–mass spectroscopy (GC–MS) studies on star-anise and black caraway volatile oils resulted in the identification of 25 and 22 compounds, respectively, representing 94–97% of the total content.     

Acaricidal activity of fennel seed oils and their main components against Tyrophagus putrescentiae, a stored-food mite

The acaricidal activities of components derived from Foeniculum vulgare (fennel) seed oils against Tyrophagus putrescentiae adults were examined using direct contact application and compared with those of the compounds benzyl benzoate, dibutyl phthalate and N,N-diethyl-m-toluamide. The biologically active constituent of the F. vulgare seeds was characterized as (+)-carvone by spectroscopic analyses. On the basis of LD₅₀ values, the compound most toxic to T. putrescentiae was naphthalene (4.28 μg/cm²) followed by dihydrocarvone (4.32 μg/cm²), (+)-carvone (4.62 μg/cm²), (−)-carvone (5.23 μg/cm²), eugenol (10.62 μg/cm²), benzyl benzoate (11.24 μg/cm²), thymol (11.42 μg/cm²), dibutyl phthalate (13.11 μg/cm²), N,N-diethyl-m-toluamide (13.53 μg/cm²), methyl eugenol (39.52 μg/cm²), myrcene (39.88 μg/cm²) and acetyleugenol (72.24 μg/cm²). These results indicate that acaricidal activity of the F. vulgare seed oil could be caused by carvone and naphthalene of which the former is likely to be more important because it is 74.7 times more abundant than naphthalene. Carvone and naphthalene merit further study as potential stored-food mite control agents or as lead compounds.     

Economical viability of SFE from peach almond, spearmint and marigold

Supercritical fluid extraction (SFE) applies near critical carbon dioxide (CO₂) for the extraction of aromatic and bioactive products such as peach (Prunus persica) almond oil, spearmint (Mentha spicata L.) essential oil and marigold (Calendula officinalis L., Asteraceae) oleoresin. Due to the cost intensive nature of SFE, the estimation of process cost is necessary to appraise operation viability. Therefore, this work evaluated the economical viability of SFE from peach almond, spearmint leaves and marigold flowers, as a function of process parameters, using extraction data from the literature. The costs were determined by the software Tecanalysis, considering the specific costs to be equal to the market value of the oils. The results show that SFE from peach almond for 30 min in a 2 × 400 L extraction unit and from spearmint at 300 bar are lucrative processes. SFE from marigold was not economically viable, probably because of the imprecise operational parameters assumed.     

Aldehydes contained in edible oils of a very different nature after prolonged heating at frying temperature: Presence of toxic oxygenated α,β unsaturated aldehydes

The evolution of the abundance of the different types of aldehydes, including those that are genotoxic and cytotoxic, oxygenated α,β unsaturated, in the headspace of extra virgin olive, sunflower and virgin linseed oils, submitted to frying temperature for prolonged periods of time, in a discontinuous industrial fryer, was analysed. Very close relationships were found between the abundance of the aldehydes in the three oils at a certain heating time and the original oil composition in the main components. The equations that related these parameters, which can be used for predictive purposes, show not only which acyl group each aldehyde comes from, but also its quantitative influence. This is the first time that the presence of 4-oxo-(E)-2-decenal, and 4-oxo-(E)-2-undecenal have been detected, not only in frying oils, but also in foods. Furthermore, the concentration of aldehydes such as 4-hydroxy-(E)-2-nonenal, (E)-4,5-epoxy-(E)-2-decenal, 4-hydroxy-(E)-2-hexenal, and 4-oxo-(E)-2-nonenal have been determined simultaneously for the first time in these edible oils submitted to frying temperature. The fact that significant concentrations of these toxic compounds were found in some oils before the oil reached 25% of the polar compounds is a cause of concern for human health.     

Comparison of the most odour-active volatiles in different hop varieties by application of a comparative aroma extract dilution analysis

Application of a comparative aroma extract dilution analysis on the volatiles isolated from five different hops (Hallertau Perle, Hallertau Hersbrucker Spät, Slowenian Golding, Hallertau Smaragd, US Cascade) revealed linalool and myrcene with the highest Flavour Dilution (FD)-factors in all varieties, followed by 2-isopropyl-3-methoxypyrazine, 3-methylbutanoic acid and geraniol. Some odourants, however, showed high FD-factors only in certain varieties, for example, (5Z)-octa-1,5-dien-3-one and germacrene B in Hersbrucker Spät, (3E,5Z)-undeca-1,3,5-triene in Hersbrucker Spät and Cascade and nonanal in Cascade. The overall odour profile of the Cascade sample clearly differed from the other varietes, and was dominated by a black currant like odour note. The identification experiments revealed 4-methyl-4-sulfanylpentan-2-one, so far unknown as hop constituent, as key contributor to this odour. In addition, an odour-active undecatetraene was present, in particular, in Perle and Cascade. Synthesis and structural assignment of the four stereoisomers of (3E)-undeca-1,3,5,9-tetraene allowed the identification of the fresh, pineapple-like smelling compound as (3E,5Z,9E)-undeca-1,3,5,9-tetraene. Among the four isomers synthesised, this compound showed by far the lowest odour threshold of 0.01 ng/L in air.     

Direct enantiomeric analysis of Mentha essential oils

A rapid and fully automated screening of chiral compounds in essential oils, aimed to the selection of natural sources of pure enantiomers of limonene and carvone, is performed by using on-line coupled reversed phase liquid chromatography with gas chromatography and mass spectrometry (RPLC–GC–MS). Essential oils obtained from Mentha spicata and Mentha piperita were analysed by direct injection into RPLC. The reported procedure includes fractionation and clean-up in RPLC, selection of the fraction to be transferred from RPLC to GC, trapping and concentration of the target compounds in the interface, thermal desorption and, finally, enantiomeric resolution and identification of chiral compounds by GC–MS. The presence of (S)-limonene and (R)-carvone as the unique enantiomeric forms existing for both compounds could be unambiguously established by transferring different volume fractions from RPLC to GC. Data obtained demonstrate high separation efficiency and well tunable selectivity in the on-line coupled RPLC–GC–MS analysis of chiral compounds.     

Essential oils to control Botrytis cinerea in vitro and in vivo on plum fruits

BACKGROUND: The consequence of misusing chemical biocides in controlling pests and diseases has drawn the attention of policy makers to the development of methods potentially available in nature for this purpose. In the present study the inhibitory effects of black caraway, fennel and peppermint essential oils against Botrytis cinerea were tested at various concentrations in vitro and in vivo. RESULTS: The in vitro results showed that the growth of B. cinerea was completely inhibited by the application of black caraway and fennel oils at concentrations of 400 and 600 µL L^?1 respectively. The in vivo results indicated that black caraway, fennel and peppermint oils at all applied concentrations inhibited B. cinerea growth on plum fruits compared with the control. In addition, all three oils at higher concentrations showed positive effects on fruit quality characteristics such as titrable acidity, total soluble solids, carbohydrate content, pH and weight loss percentage. Thus the oils inhibited the infection of plum fruits by B. cinerea and increased their storage life. CONCLUSION: This research confirms the antifungal effects of black caraway, fennel and peppermint essential oils both in vitro and in vivo on plum fruits postharvest. Therefore these essential oils could be an alternative to chemicals to control postharvest phytopathogenic fungi on plum fruits. Copyright © 2012 Society of Chemical Industry     

Chemical and sensory characterisation of aroma of Viburnum opulus fruits by solid phase microextraction-gas chromatography-olfactometry

The aroma profile of four cultivars of Viburnum opulus and one cultivar of V. opulus var. sargentii fruits was studied by solid phase microextraction of headspace volatiles and subsequent analysis by gas chromatography, mass spectrometry and olfactometry (SPME-HS-GC-MS-O). In total, 41 compounds were identified, 3-methyl-butanoic acid (63.0-71.8% of identified volatile organic compounds) being the major constituent in the three V. opulus cultivars, while 2-octanone was dominant in one cultivar of V. opulus and in V. opulus var. sargentii, amounting to 28.1% and 25.6% of identified volatile compounds, respectively. Ten odour active compounds were detected and characterised by the trained panel of judges in the course of GC-O by using detection frequency analysis (DFA). 3-Methyl-butanoic and 2-methyl-butanoic acids as well as linalool and ethyl decanoate were found to be the main odour active components for V. opulus aroma.     

Changes in yogurt fermentation characteristics, and antioxidant potential and in vitro inhibition of angiotensin-1 converting enzyme upon the inclusion of peppermint, dill and basil

The present study investigated the effects of peppermint (Mentha piperita), dill (Anethum graveolens) and basil (Ocimum basilicum) on yogurt formation, proteolysis and inhibition of angiotensin-1 converting enzyme (ACE). Herbal-yogurts had faster rates of pH reduction than plain-yogurt. All herbal-yogurts had higher (p < 0.05) antioxidant activities than plain-yogurt, both at the end of fermentation and throughout the storage period. The o-phthalaldehyde (OPA) peptides in herbal-yogurts increased by 28-36% after 7 days of storage. All herbal-yogurts showed higher anti-ACE activity than plain-yogurt at corresponding storage periods. M. piperita yogurt had highest inhibitory effect on ACE activity throughout the storage period. Peppermint, dill and basil may be used to modify microbial fermentation of milk with the intention of producing dairy products with higher antioxidant and enhanced anti-ACE activities.     

Schiff bases of (+)/(–)-carvone: influence of chirality on flavour

The structure-flavour relationships of some Schiff bases are discussed. The carbonyl part – (S)-(+)-/(R)-(–)-carvone – showed a greater impact on the aroma of the imine than the amine part. The different aromas of the two enantiomeric Schiff bases could clearly be distinguished. No flavours similar to Maillard products were detected in aromatic or heteroaromatic compounds with a structurally related imine unit. Some new and interesting aroma notes were discerned.     

Antioxidant properties of cold-pressed black caraway,carrot, cranberry,and hemp seed oils

Cold-pressed black caraway, carrot, cranberry, and hemp seed oils were extracted with methanol and evaluated for radical-scavenging activities against ABTS⁺ and DPPH, chelating activity, oxygen radical absorbing capacity (ORAC), and total phenolic contents (TPC). All the oil extracts had significant antioxidant activities. The ORAC value ranged from 28 to 220 μmol TE/g oil for the cold-pressed hemp, carrot, and black caraway seed oils, whereas the ABTS⁺ – scavenging capacity ranged 8.9–30.8 μmol TE/g oil for the four cold-pressed edible seed oils. The greatest TPC, 3.53 mg gallic acid equivalent (GE) per gramme of oil, was detected in the cold-pressed black caraway seed oil extract, while the lowest TPC, 0.44 mg GE/g, was observed in the cold-pressed hemp seed oil extract. In addition, methanol extracts of the cold-pressed black caraway and cranberry seed oils were evaluated for their inhibitory capacities on human LDL oxidation by measuring the reduction of the thiobarbituric acid-reactive substance production (TBARS). Both oil extracts significantly suppressed the lipid peroxidation in human LDL, with TBARS reductions of 2.84 and 3.77 mg/g for cranberry and black caraway seed oil extracts, respectively. These results suggest that cold-pressed black caraway, cranberry, carrot and hemp seed oils may serve as dietary sources of natural antioxidants for health promotion and disease prevention, and the cold-pressed black caraway seed oil may be used as a natural antioxidative food additive for improving food quality and stability.     

The influence of frying technique,cooking oil and fish species on the changes occurring in fish lipids and oil during shallow-frying,studied by 1H NMR

Fillets of farmed gilthead sea bream (Sparus aurata) and European sea bass (Dicentrarchus labrax) were pan- and microwave-fried using extra-virgin olive and sunflower oils. Moreover, both oils were heated under the same conditions in the absence of food. Proton Nuclear Magnetic Resonance spectroscopy (¹H NMR) was employed to study the changes occurring both in the frying oils and in the fish lipids, in terms of main and of some minor components. These results confirm that there is a migration of main and some minor lipidic compounds between oil and fish, this exchange being linked to the proportion of each component in the original lipidic medium. The occurrence of trans-2-alkenals, alkanals, cis,trans- and trans,trans-2,4-alkadienals, trans-9,10-epoxystearate and 1,2-diglycerides in all these systems was quantified. No signals related to primary oxidation compounds were detected. Pan-frying provoked a greater oil thermo-oxidation degree than microwave-frying did. Regarding aldehyde formation, extra-virgin olive oil is safer and more suitable than sunflower oil for shallow-frying.     

Evaluating the effects of herbal essences from spearmint and wild thyme on the quality of camel's milk

The aim of this study was to improve the sensory and physicochemical properties of camel's milk using two essential oils (EOs), spearmint (Mentha spicata) and wild thyme (Zataria multiflora). Total bacterial counts in the flavoured milks were lower than those of the plain milk, and microbial population was the lowest in the milk containing spearmint EO during 5 days of storage. Considering the sensory evaluations, milks treated with the above EOs received higher scores compared with those of untreated milk. The highest scores were given to the milk containing spearmint EO at 0.09 mL L^?1. No significant differences were observed in the mean particle sizes of the samples after 5 days of storage. The addition of EOs from camel's milk resulted in higher organoleptic properties and shelf life, and, in turn, it can improve the consumption rate of camel's milk.     

Evaluation of a chemotype of spearmint (Mentha spicata L.) grown in Siwa Oasis,Egypt

A distinguishable chemotype of spearmint (Mentha spicata) was found in Siwa Oasis, Egypt. The locals in very limited areas grow this type. Stolones of this type were transplanted to some other locations in Egypt namely; Owainate, Kharga, Samallot, and Arish. The oil content in the air-dried herb grown in Siwa reached 2.93 and 2.99% in the seasons of 2001 and 2002, respectively. The oil content of that type increased to 3.85 and 3.90%, in the two seasons when it was cultivated in Owainat territory, while it decreased to 1.59 and 1.61% when cultivated in Arish territory. These two geographical locations greatly differed in the average, maximum and minimum temperatures, relative humidity, sunshine duration, and solar radiation. Samples of spearmint distributed in the local market and cultivated around Cairo contained only 1.28% oil. In oils of Siwa mint cultivated in the different locations, carvone was the main constituent; its content ranged between 42.23 and 57.61%, while limonene came in the second rank ranging between 26.15 and 34.83%. In contrast, oil of spearmint collected from the local market (grown in Cairo) was characterized by higher carvone (73.18%) and lower limonene (5.00%) contents. Siwa mint is a distinguishable type of spearmint regarding its oil content and composition.     

Chemical and aroma profiles of yuzu (Citrus junos) peel oils of different cultivars

The essential oils of six different yuzu cultivars, Kumon (KUM), Nagano (NAG), Yasu (YAS), Jimoto (JIM), Komatsu Sadao (KOS) and Komatsu Koichi (KOK), were extracted by cold-pressing method. A total of 69 compounds of the six samples were identified. Application of GC-olfactometry and aroma extraction dilution analysis technique in three-fold stepwise dilution of the neat oil for all samples indicated eight odourants with the highest flavour dilution (FD) values. Those were limonene, α-pinene, α- and β-phellandrene, myrcene, γ-terpinene, (E)-β-farnesene and linalool. ‘KOS’ was differentiated from the other oil samples by showing the highest number of components having yuzu-like odour notes and also from the PCA analysis of the FD-factor values. This is the first time the aroma characteristics of yuzu essential oils of specified cultivars were investigated.     

Identification and olfactometry of French fries flavour extracted at mouth conditions

The aim of this study was to isolate and identify odour active compounds from French fries at mouth conditions. Volatile compounds were released from French fries by purge-and-trap, trapped on Tenax TA, and identified with GC–MS. GC–olfactometry was used to determine odour active compounds with a trained panel using the detection frequency method. A total of 122 compounds were identified of which 85% originated from either sugar degradation and/or Maillard reaction and 15% from lipid degradation, based on relative areas. About 50 odour active compounds were, due to coelution, responsible for 41 odours perceived by the panel. 3-Methylbutanal and 2-methylbutanal, hexanal, 2,3-dimethylpyrazine, 2-methylpropanal, 2,3-butanedione, pyridine, heptanal, 2,5-dimethylpyrazine and/or 2,6-diemethylpyrazine and/or ethylpyrazine, dimethyl trisulfide, octanal, phenylacetaldehyde, 2,5-diethylpyrazine, (E)-2-nonenal, 3-methylbutanoic acid and/or 2-methylbutanoic acid, (E,Z)-2,4-heptadienal, (E)-2-octenal, 5-ethyl-2,3-dimethylpyrazine and/or 2-ethyl- 3,5-dimethylpyrazine, nonanal, and tentatively 2-methylpyrrole had the highest detection frequencies. This resulted in a strong malty and fried potato note, combined with caramel/buttery, green, spicy, and deep-fried notes. Also chemical and sweaty odours were observed.     

A forgotten vegetable (Smyrnium olusatrum L., Apiaceae) as a rich source of isofuranodiene

Smyrnium olusatrum, well known as wild celery or Alexanders, is a biennial herb belonging to the Apiaceae and used for many centuries as an edible vegetable because of the aromatic flavour of its parts. Its use on the table has decreased since the Middle Ages when it was replaced by common celery (Apium graveolens). In the present work the composition of the essential oils obtained by hydrodistillation of various plant parts was investigated by gas chromatography (GC–FID and GC–MS), while quantitation of a heat-sensitive compound, isofuranodiene, known for its anticancer activity, and of its Cope rearrangement product curzerene, was achieved by HPLC-DAD. All essential oils were composed mainly of furanosesquiterpenoids (54.1–76.2%) with isofuranodiene (19.5–45.8%) as the main constituent. Results showed that GC analysis provides underestimation (up to five times) of isofuranodiene levels in essential oils and that curzerene could be considered an artifact since it is produced during heating of plant material, occurring during hydrodistillation.     

超声波辅助-盐析-水蒸气蒸馏法提取葛缕子精油的研究

对超声波辅助-盐析-水蒸气蒸馏法提取葛缕子精油的工艺进行研究。以葛缕子精油得率为考察指标,考察料液比、氯化钠浓度、浸泡时间、超声频率、超声功率和超声时间6个因素对超声辅助水蒸气蒸馏法提取葛缕子精油得率的影响以及最佳工艺条件。实验结果表明,超声辅助-盐析-水蒸气蒸馏法提取葛缕子精油的最佳工艺条件为:料液比1:15,氯化钠浓度为15%,浸泡时间60min,超声频率25kHz,超声功率250W,超声时间30min,在此条件下,葛缕子精油的平均得率可达到5.42%±0.01%,比盐析-水蒸汽蒸馏法得率提高了1.24%。利用气相色谱-质谱联用技术对葛缕子精油的化学成分进行鉴定,共分离鉴定出27种化学成分,其主要成分是柠檬烯（31.08%）和右旋香芹酮（66.42%）,与盐析-水蒸汽蒸馏法提取精油在组成成分（15种化合物）和主要成分含量上（柠檬烯21.84%和右旋香芹酮76.29%）都存在比较大的差异。结果表明超声辅助-盐析-水蒸汽蒸馏法提取葛缕子精油不仅可以缩短提取时间,提高精油产率,还可以改善精油的质量。      

Identification of the odour-active aldehyde trans-4,5-epoxy-(E,Z)-2,7-decadienal in yuzu (Citrus junos Sieb. ex Tanaka)

Yuzu (Citrus junos Sieb. ex Tanaka) is a variety of sour citrus fruit that is popular in Japan. In this study, we investigated its aroma, which many people, especially in Japan, find appealing. Aroma extract dilution analysis was used to screen the odour-active compounds in the yuzu volatile oil. An unknown odorant with an albedo-like odour and a high flavour-dilution factor was detected. To identify this odorant, it was separated via flash column chromatography on silica gel and then fractionated by preparative high-performance liquid chromatography on a reverse-phase column. The volatile fraction, which contained a significant amount of the target unknown compound, was analysed by gas chromatography–mass spectrometry and gas chromatography–olfactometry to determine its mass spectrum, retention index, and odour quality. By comparing the resultant data with that of a synthesised authentic reference compound, it was evident that the unknown odorant was trans-4,5-epoxy-(E,Z)-2,7-decadienal (3); this is the first time that it has been identified as an odour-active unsaturated aldehyde in yuzu volatile oil. From the results of a model formation experiment, we propose that trans-4,5-epoxy-(E,Z)-2,7-decadienal originates from α-linolenic acid via 13(S)-hydroperoxy-(Z,E,Z)-9,11,15-octadecatrienoic acid (13(S)-HPOT), which is a lipoxygenase-induced oxidation product of α-linolenic acid.