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1.
The aim of this study was to investigate the total mesophilic microorganisms, Pseudomonas genus, Enterobacteriaceae family, mold and yeast counts and the presence of Listeria monocytogenes and Salmonella spp on Tuber aestivum and Tuber melanosporum ascocarps. The results confirmed that the major percentage of the microorganisms, approximately 9.0 log ufc/g, were present in the peridium, the glebas of healthy truffles being practically free of microorganisms. The predominant microbial group was the Pseudomonas averaging 8.3 and 8.4 log cfu/g on T. aestivum and T. melanosporum whole ascocarps, respectively. The Enterobacteriaceae also achieved high populations, especially in T. aestivum truffles, with 6.3 log cfu/g. Molds and yeasts never exceeded 5.0 log cfu/g. The characterization of the isolates revealed that the fluorescens pseudomonads were the most prevalent. Raoultella terrigena and Enterobacter intermedius were the dominant Enterobacteriaceae. The identification of the yeast isolates revealed five species: Debaryomyces hansenii, Issatchenkia scutulata, Rhodotorula aurantiaca, Saccharomyces dairensis and Trichosporon beigelii subspecies A and B. The mold genera detected in both species of truffles were Aspergillus, Cladosporium, Penicillium and Fusarium, Trichoderma being present only in T. aestivum. L. monocytogenes was found in 10% of the samples of T. aestivum analysed but Salmonella spp. was not detected. Knowledge of the microbial population in terms of possible food borne and pathogen microorganisms is very useful for establishing successful disinfection and storage methods to prolong the shelf-life of ascocarps of T. aestivum and T. melanosporum.  相似文献   

2.
Streptococcus infantarius subsp. infantarius (Sii) and Streptococcus gallolyticus subsp. macedonicus are members of the Streptococcus bovis/Streptococcus equinus complex (SBSEC) associated with human infections. SBSEC-related endocarditis was furthermore associated with rural residency in Southern Europe. SBSEC members are increasingly isolated as predominant species from fermented dairy products in Europe, Asia and Africa. African variants of Sii displayed dairy adaptations to lactose metabolism paralleling those of Streptococcus thermophilus including genome decay. In this study, the aim was to assess the prevalence of Sii and possibly other SBSEC members in dairy products of East and West Africa in order to identify their habitat, estimate their importance in dairy fermentation processes and determine geographic areas affected by this potential health risk. Presumptive SBSEC members were isolated on semi-selective M17 and SM agar media. Subsequent genotypic identification of isolates was based on rep-PCR fingerprinting and SBSEC-specific16S rRNA gene PCR assay. Detailed identification was achieved through application of novel primers enhancing the binding stringency in partial groES/groEL gene amplification and subsequent DNA sequencing. The presence of S. thermophilus-like lacS and lacZ genes in the SBSEC isolates was determined to elucidate the prevalence of this dairy adaptation. Isolates (n = 754) were obtained from 72 raw and 95 fermented milk samples from Côte d'Ivoire and Kenya on semi-selective agar media. Colonies of Sii were not detected from raw milk despite high microbial titers of approximately 106 CFU/mL on M17 agar medium. However, after spontaneous milk fermentation Sii was genotypically identified in 94.1% of Kenyan samples and 60.8% of Kenyan isolates. Sii prevalence in Côte d'Ivoire displayed seasonal variations in samples from 32.3% (June) to 40.0% (Dec/Jan) and isolates from 20.5% (June) to 27.7% (Dec/Jan) present at titers of 106–108 CFU/mL. lacS and lacZ genes were detected in all Kenyan and 25.8% (June) to 65.4% (Dec/Jan) of Ivorian Sii isolates. Regional differences in prevalence of Sii and dairy adaptations were observed, but no clear effect of dairy animal, fermentation procedure and climate was revealed. Conclusively, the high prevalence of Sii in Kenya, Côte d'Ivoire in addition to Somalia, Sudan and Mali strongly indicates a pivotal role of Sii in traditional African dairy fermentations potentially paralleling that of typical western dairy species S. thermophilus. Putative health risks associated with the consumption of high amounts of live Sii and potential different degrees of evolutionary adaptation or ecological colonization require further epidemiologic and genomic investigations, particularly in Africa.  相似文献   

3.
The application of Kluyveromyces marxianus (IFO 288), Lactobacillus delbrueckii ssp. bulgaricus (ATCC 11842) and Lactobacillus helveticus (ATCC 15009) as starter cultures for sourdough bread making was examined. Production of lactic and acetic acids, bread rising, volatile composition, shelf-life and organoleptic quality of the sourdough breads were evaluated. The amount of starter culture added to the flour, the dough fermentation temperature and the amount of sourdough used were examined in order to optimise the bread making process. The use of mixed cultures led to higher total titratable acidities and lactic acid concentrations compared to traditionally made breads. Highest acidity (3.41 g lactic acid/kg of bread) and highest resistance to mould spoilage were observed when bread was made using 50% sourdough containing 1% K. marxianus and 4% L. delbrueckii ssp. bulgaricus. The use of these cultures also improved the aroma of sourdough breads, as shown by sensory evaluations and as revealed by GC–MS analysis.  相似文献   

4.
The chitin contents of pileus and stipes of fruit bodies of Agaricus bisporus, Pleurotus ostreatus and Lentinula edodes (shii take) were determined and compared. The fruit bodies of different, common varieties of the cultivated mushroom species were taken from Hungarian and German large-scale farming. The analytical procedure was carried out on the powder of cleaned, dried and milled pileus and stipes. The pileus of A. bisporus variety ‘K-23’ showed a significant decrease (p < 0.05) during the cultivation’s flushes (breaks), 1–3, while the chitin level of stipes seemed to be constant. The other analysed A. bisporus varieties (var. ‘158’, ‘K-7’, ‘Sylvan A-15’, ‘Sylvan 608’, and Le Lion C-9) had practically the same chitin levels. This indicates that the chitin content is a stable characteristic of the species and there are no significant differences between the different varieties. The chitin levels of pileus and stipes were not significantly different (for A. bisporus, 6.68 and 7.25) but showed significant differences for P. ostreatus (p < 0.05) and L. edodes (p < 0.001). In the case of the latter two species, the pileus had the higher and the stipe the lower chitin content. The presented data confirm that a mushroom saprotrophic (A. bisporus) had higher chitin level than had the wood-rotting ones (P. ostreatus, L. edodes).  相似文献   

5.
Three species of dried mushrooms are commercially available in Taiwan, namely Agaricus blazei (Brazilian mushroom), Agrocybe cylindracea (black popular mushroom) and Boletus edulis (king bolete), and their non-volatile taste components were studied. All mushrooms were high in contents of carbohydrate, crude fiber and protein but low in contents of crude ash and fat. Arabitol, myo-inositol, mannitol and trehalose were detected in these three mushrooms, whereas glucose was not found in B. edulis. Contents of total soluble sugars and polyols ranged from 150.33 to 225.08 mg/g. Total free amino acid contents were low in these three mushrooms and ranged from 8.97 to 14.91 mg/g. The contents of MSG-like components ranged from 1.24 to 4.40 mg/g were in the descending order of the A. blazei, A. cylindracea and B. edulis. Total 5′-nucleotides contents of A. blazei and A. cylindracea were higher than that of B. edulis whereas flavor 5′-nucleotides content of A. blazei was higher than those of A. cylindracea and B. edulis. Equivalent umami concentrations values in three mushrooms ranged from 10.46 to 135.90 g per 100 g. Overall, these three mushrooms possessed highly umami taste.  相似文献   

6.
One strategy that has been used to find germplasm for developing improved plant varieties is to test ancestral germplasm for the desired traits. Although the progenitors of commercial maize are not known, a hybrid (called Tripsacorn) developed from a perennial teosinte, Zea diploperennis, and eastern gamagrass, Tripsacum dactyloides, resembles the earliest known samples of primitive domesticated maize. We tested resistance of whole Tripsacorn to the primary storage pest (primary storage pests can infest intact kernels) the maize weevil, Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae), and resistance of ground Tripsacorn to the secondary storage pest (secondary pests usually cannot infest intact kernels) the sawtoothed grain beetle, Oryzaephilus surinamensis (L.) (Coleoptera: Silvanidae). Tripsacorn was immune to attack by S. zeamais. The weevils were unable to lay eggs in the Tripsacorn, and we hypothesized that the hardness of the fruitcase was responsible for lack of weevil oviposition. Oryzaephilus surinamensis were able to complete immature development on ground Tripsacorn, but duration of development was longer and weight of emerged adults was less than for beetles developing on wheat. Hardness of the fruitcase may have been a primitive mechanism of defense against insects and other pests, but probably would not be an acceptable trait in commercial varieties. It remains to be determined whether the possible antibiotic effect demonstrated in ground Tripsacorn would be a useful trait in commercial maize hybrids.  相似文献   

7.
Simultaneous analysis of purine alkaloids and catechins in tea from dry leaves of Camellia sinensis, Camellia ptilophylla and Camellia assamica var. kucha by a reversed-phase high-performance liquid chromatography (RP-HPLC) method. This HPLC method had been proved to be appropriate for the identification and quantification of purine alkaloids and catechins, and exhibited good correlation coefficients, detection levels and recovery rates. Caffeine, theobromine, theacrine, (+)-catechin, (−)-epicatechin, (−)-epigallocatechin, (−)-epigallocatechin gallate, (−)-epicatechin gallate, (−)-gallocatechin gallate and (−)-gallocatechin were identified and quantified in the three species of genus Camellia Sect. Thea. There was 2.72% caffeine and 0.26% theobromine in C. sinensis, 4.85% theobromine in C. ptilophylla, and 1.58% theacrine, 0.94% caffeine and 0.45% theobromine in C. assamica var. kucha. Theacrine in C. sinensis and C. ptilophylla, and caffeine in C. ptilophylla were not detected. These data highlight differences in the relative proportions of purine alkaloids in the three species of Camellia Sect. Thea. In addition, different catechins were identified and quantified. The highest content of catechin in dry leaves was (−)-epigallocatechin gallate (EGCG) 3.51%, (−)-gallocatechin gallate (GCG) 9.88% and (−)-epigallocatechin gallate (EGCG) 6.78% in C. sinensis, C. ptilophylla and C. assamica var. kucha, respectively.  相似文献   

8.
Staphylococcus aureus is an important cause of contagious intramammary infection in dairy cattle, and the ability to produce biofilm is considered to be an important virulence property in the pathogenesis of mastitis. The aim of this study was to characterize the biofilm formation capacity of methicillin-resistant Staph. aureus (MRSA), encoding mecA or mecC, isolated from bulk tank milk in Great Britain. For this purpose, 20 MRSA isolates were grown on microtiter plates to determine the biofilm production. Moreover, the spa-typing and the presence of the intercellular adhesion genes icaA and icaD were analyzed by PCR. All MRSA isolates tested belonged to 9 spa-types and were PCR-positive for the ica genes; 10 of them (50%) produced biofilm in the microtiter plate assay. This is also the first demonstration of biofilm production by mecC MRSA.  相似文献   

9.
Shu-Yao Tsai 《LWT》2007,40(8):1392-1402
Three mushrooms are currently available in Taiwan, including Agaricus blazei, Agrocybe cylindracea, and Boletus edulis. Their ethanolic and hot water extracts were prepared and antioxidant properties studied. Ethanolic extracts from three mushrooms were more effective than hot water extracts in antioxidant activity using the conjugated diene method and scavenging ability on 1,1-diphenyl-2-picrylhydrazyl radicals whereas hot water extracts were more effective in reducing power, scavenging ability on hydroxyl radials and chelating ability on ferrous ions as evidenced by their lower EC50 values. Overall, for both extracts, B. edulis was more effective among antioxidant properties assayed. Naturally occurring antioxidant components including total tocopherols (3.18-6.18 mg/g) and total phenols (5.67-5.81 mg/g) were found in the extracts and their contents were associated (r=0.636-0.907) with EC50 value of antioxidant properties. Based on the results obtained, both extracts from these three mushrooms were effective in antioxidant properties.  相似文献   

10.
Three species of mushroom mycelia are commercially available in Taiwan, namely Grifola frondosa (maitake), Morchella esculenta (morel), and Termitomyces albuminosus (termite mushroom), and their nonvolatile taste components were studied. All mycelia were high in contents of carbohydrate, crude fat and protein but low in contents of crude ash and fiber. Arabitol, glucose, mannitol and trehalose were detected in these three mycelia and total amounts of sugars and polyols were 63.69-83.89 mg/g. Total free amino acid contents in three mycelia ranged from 35.67 to 50.37 mg/g. The monosodium glutamate-like components of G. frondosa mycelia (6.51 mg/g) was approximately twofold higher than M. esculenta and T. albuminosus mycelia (3.58 and 3.11 mg/g, respectively). As compared with other components, sweet and bitter components were much higher in these three mycelia. Contents of total 5′-nucleotides in these three mycelia ranged from 13.32 to 26.19 mg/g and were in the descending order of T. albuminosus>M. esculenta>G. frondosa. Equivalent umami concentration of T. albuminosus mycelia was higher than those of G. frondosa and M. esculenta mycelia. Overall, three mycelia possessed highly intense umami taste.  相似文献   

11.
Coriandrum sativum L. is a source of a variety of polyphenols and other phytochemicals, related to its high antioxidant activity and to its use for indigestion, rheumatism, and prevention of lipid peroxidation damage. Plant cell cultures are a means to study or to produce some active metabolites, such as polyphenols. This technique was applied to the investigation of coriander, and a detailed analysis of individual polyphenols in vivo and in vitro grown samples was performed. The in vivo vegetative parts showed quercetin derivatives as the main flavonoids and quercetin-3-O-rutinoside (3296 mg/kg dw) was the main polyphenol found in this part of coriander. The fruits revealed only phenolic acids and derivatives, caffeoyl N-tryptophan hexoside (45.33 mg/kg dw) being the most abundant phenolic derivative. In vitro samples also gave a high diversity of polyphenols, being C-glycosylated apigenin (2983 mg/kg dw) the main compound. Anthocyanins were only found in clone A, which was certainly related to its purple pigmentation, and peonidin-3-O-feruloylglucoside-5-O-glucoside was the major anthocyanin found (1.70 μg/kg dw). In vitro culture can be used to explore new industrial, pharmaceutical, and medicinal potentialities, such as the production of secondary metabolites like flavonoids.  相似文献   

12.
Essential oils extracted by hydrodistillation from Cuminum cyminum and Rosmarinus officinalis were characterized by means of GC and GC–MS. C. cyminum and R. officinalis contained α-pinene (29.1%, 14.9%), 1,8-cineole (17.9%, 7.43%) and linalool (10.4%, 14.9%), respectively, as the major compounds. C. cyminum oil exhibited stronger antimicrobial activity than did R. officinalis oil against E. coli, S. aureus and L. monocytogenes. Complete death time on exposure to Cuminum cyminum L. and Rosmarinus officinalis L. oils were 20 and 25 min 180 and 240 min and 90 and 120 min for E. coli, S. aureus and L. monocytogenes, respectively. Radical-scavenging and antioxidant properties were tested by means of 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay and the β-carotene bleaching test. These properties were compared to those of Thymus x-porlock essential oil, used as a reference ingredient. The radical scavenging performance of the rosemary oil was better than that of C. cyminum. Results from the antioxidant test were better than those provided by the radical-scavenging activity. C. cyminum and R. officinalis essential oils may be considered as potent agents in food preservation.  相似文献   

13.
Searching for effects of candidate gene polymorphisms on fatness traits is an important goal for pig industry. In this study we evaluated polymorphism of four porcine genes involved in energy metabolism (RETN, UCP1, UCP3 and ADRB3). Moreover, their association with fat deposition traits was analyzed in two breeds (Polish Landrace, Polish Large White) and a Polish synthetic line (L990). Altogether, five SNPs were identified, including two novel ones in the 5′-flanking region of the RETN gene and a novel missense substitution in the UCP3. Distribution of these polymorphisms in the studied five breeds and the synthetic line was not uniform. Two of the analyzed SNPs: g.−178G > A in the RETN and g.946C > T in the UCP3 gene revealed a significant association with abdominal fat weight or backfat thickness. Such associations were not observed for the UCP1 or ADRB3 gene polymorphisms. Our study showed that polymorphisms of the UCP3 and RETN genes are potentially associated with porcine fatness traits.  相似文献   

14.
The effect of the fungal entomopathogen Beauveria bassiana (Balsamo) Vuillemin (Hyphomycete) on the losses caused to durum wheat and beans by storage insects was investigated. Grains were infested with Tribolium castaneum (Herbst), Sitophilus oryzae (L.) and Acanthoscelides obtectus (Say). Beauveria bassiana was produced in inoculated autoclaved rice. The spore formulation (ground rice and B. bassiana) was applied to grain (wheat or bean) and shaken to evenly cover the grain. Adults of T. castaneum or S. oryzae were added to wheat and adults of A. obtectus to bean. Five replicates were set up for each treatment and controls (milled rice but no conidia). The insecticidal effect of B. bassiana was tested by measuring the fresh weight and weight loss of grains after four months of storage. Wheat grains infested with S. oryzae without the conidia was significantly more damaged by weevils than grains treated with B. bassiana. The mean fresh weight of grains with the conidia was significantly greater (18.4%) than the corresponding mean without the fungus when S. oryzae were present. Percentage weight loss decreased by 81.5% and was significantly smaller than the loss from the untreated grain. Significant differences were not found in the fresh weight of seed infested with T. castaneum or A. obtectus in treated or untreated grain nor in the percentage weight loss of grains infested with these insects, with and without B. bassiana.  相似文献   

15.
The purpose of this study was to evaluate the toxicological effects of feeding the oils of Calophyllum inophyllum, Pentaclethra macrophylla and Terminalia catappa to rats. The effects on physical appearance, feed intake, weight gain, plasma and tissue cholesterol and triacyglycerol levels in rats with 5% of the oils in normal rat feed were determined. Weekly monitoring of the rats showed good physical appearance and steady weight gain, with no mortality recorded for the period of the study. Haematological analysis of the rats indicated that they were not anaemic. Histopathotogical examination of the sections of the heart, liver, kidney and spleen revealed moderate (T. catappa oil) to severe fatty change and necrosis in the liver. Glomerulonephrotic changes in the kidneys of rats fed with T. catappa oil were moderate, while it was severe in the group fed with P. macrophylla oil. Severe myocardiac necrosis as well as atherosclerotic clefts in vasa vasori was observed in the vasa vasori of the hearts of rats fed with P. macrophylla oil. This change was moderate in the heart of rats fed with C. inophyllum, while no such observation was made in the group fed with T. catappa oil. There was a significant difference in the plasma cholesterol levels of the rats fed with C. inophyllum and T. catappa oils when compared with the control rats, while those fed with P. macrophylla oil had no significant difference. The oil of T. catappa appears more suitable for consumption than the oils from C. inophyllum and P. macrophylla. Fatty acid analysis of the oils showed that they have high amounts of unsaturated fatty acids with linoleic and oleic acids as the major ones.  相似文献   

16.
This study compared lactic acid resistance of individual strains of wild-type and rifampicin-resistant non-O157 Shiga toxin-producing Escherichia coli (STEC) and of susceptible and multidrug-resistant (MDR) and/or MDR with acquired ampC gene (MDR-AmpC) Salmonella against E. coli O157:H7. After inoculation of sterile 10% beef homogenate, lactic acid was added to a target concentration of 5%. Before acid addition (control), after acid addition (within 2 s, i.e. time-0), and 2, 4, 6 and 8 min after addition of acid, aliquots were removed, neutralized, and analyzed for survivors. Of wild-type and of rifampicin-resistant non-O157 STEC strains, irrespective of serogroup, 85.7% (30 out of 35 strains) and 82.9% (29 out of 35 strains), respectively, reached the detection limit within 0–6 min. Of Salmonella strains, 87.9% (29 out of 33 isolates) reached the detection limit within 0–4 min, irrespective of antibiotic resistance phenotype. Analysis of non-log-linear microbial survivor curves indicated that non-O157 STEC serogroups and MDR and susceptible Salmonella strains required less time for 4D-reduction compared to E. coli O157:H7. Overall, for nearly all strains and time intervals, individual strains of wild-type and rifampicin-resistant non-O157 STEC and Salmonella were less (P < 0.05) acid tolerant than E. coli O157:H7.  相似文献   

17.
The dominant compounds in Satureja horvatii oil were p-cymene (33.14%), thymol (26.11%) and thymol methyl ether (15.08%). The minimum inhibitory concentration (MIC) varied from 0.03 to 0.57 mg/mL for bacteria, and from 0.56 to 2.23 mg/mL for yeast strains, while minimum bactericidal/yeast-cidal concentration (MBC/MYC) varied from 0.07 to 1.15 mg/mL and 1.11 to 5.57 mg/mL for bacteria and yeasts, respectively. The antiradical potential of the essential oil was evaluated using hydroxyl radical (•OH) generated in Fenton reaction. The meat preserving potential of essential oil from Satureja horvatii was investigated against L. monocytogenes. Essential oil successfully inhibited development of L. monocytogenes in pork meat. Sensorial evaluation on flavor and color of meat was performed. The color and flavor of meat treated with essential oil improved after 4 days of storage. S. horvatii essential oil can act as a potent inhibitor of food spoiling microorganisms, in meat products and also can be a useful source of natural antioxidants.  相似文献   

18.
Lactuca sativa L var. anagustata is widely used as both a delicious vegetable and a traditional medicine in China. Chemical investigation of the methanolic extract of L. sativa L var. anagustata has now led to the isolation of three new sesquiterpenes, together with eight known ones. All the compounds were isolated by chromatography on a silica gel column and preparative thin-layer chromatography (PTLC). Their structures were elucidated by means of spectroscopic methods, including 2D-NMR experiments. Cytotoxicity of the new compounds was assayed against selected cancer cell lines, including the human epithelial carcinoma (HeLa) and human colon carcinoma (HCT-116) cell lines. Radical-scavenging activities of the seven compounds were determined by DPPH radical-scavenging assay.  相似文献   

19.
The antimicrobial effect of bovine lactoferrin (LF) and its amidated and pepsin-digested derivatives, at concentrations varying from 0.25 to 20 mg/mL, against 3 Salmonella Enteritidis strains and 3 Pseudomonas fluorescens strains was investigated. Lactoferrin showed its maximum antimicrobial effect at 10 mg/mL against the 3 Salmonella strains, with reductions ranging from 1.3 to 2.0 log units, and the 3 Pseudomonas strains, with reductions ranging from 1.8 to 5.4 log units. In the case of amidated LF, the maximum effect on the 3 Salmonella strains was recorded at 0.25 mg/mL, with reductions in the range of 0.8 to 1.2 log units, whereas it was recorded at 1 mg/mL for the 3 Pseudomonas strains, with reductions in the range of 4.4 to 6.0 log units. Pepsin-digested LF showed its maximum antimicrobial effect at 1 mg/mL against the 3 Salmonella strains, with reductions ranging from 2.6 to 3.4 log units, and at 20 mg/mL against the 3 Pseudomonas strains, with reductions ranging from 4.5 to 5.4 log units. It is worth noting the pronounced effect (reductions exceeding 2.5 log units) of a low (1 mg/mL) concentration of pepsin-digested LF, which is naturally formed in the gastrointestinal tract, on Salmonella and Pseudomonas strains. A highly significant inverse correlation was found between capsule polysaccharide levels of bacterial strains and their lethality in the presence of different concentrations of amidated lactoferrin.  相似文献   

20.
The compositions of the essential oils of three Jordanian Salvia species, S. lanigera and S. spinosa from a desert climate, and S. syriaca from a Mediterranean habitat, were studied. All three oils are rich in monoterpene derivatives (68–73%).  相似文献   

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