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Ultrasonics Sonochemistry Mar 2012The study determined the efficacy of Dynashock wave power ultrasound as an alternative processing technique for apple juice against a number of pathogenic and spoilage...
The study determined the efficacy of Dynashock wave power ultrasound as an alternative processing technique for apple juice against a number of pathogenic and spoilage microorganisms. The effects of several implicit, intrinsic and extrinsic properties on the Dynashock wave inactivation of the microorganisms were also investigated. Results showed that acid adaptation increased the resistance of Escherichia coli O157:H7 and Salmonella spp. but decreased that of Listeria monocytogenes. Spoilage yeast mixed inoculum composed of Debaryomyces hansenii, Torulaspora delbrueckii, Clavispora lusitaniae, Pichia fermentans and Saccharomyces cerevisiae was found to be more resistant than any of the adapted or non-adapted pathogens. Among the individual, acid-adapted E. coli O157:H7, the MN-28 isolate was found most resistant; while three other individual isolates had greater resistance than the composited E. coli inoculum. Increased in pulp content decreased the efficacy of Dynashock waves, but co-treatment with ultraviolet-C rays significantly enhanced inactivation in the cloudy apple juice. The results demonstrated the potential of Dynashock wave technology, together with other antimicrobial hurdles as alternative juice processing technique/s.
Topics: Bacteria; Beverages; Hydrogen-Ion Concentration; Malus; Microbial Viability; Temperature; Ultrasonics; Ultraviolet Rays; Yeasts
PubMed: 21802974
DOI: 10.1016/j.ultsonch.2011.06.003 -
Antonie Van Leeuwenhoek Apr 2019Enset (Ensete ventricosum) is the basis of the staple food consumed by about 20% of the Ethiopian population. Kocho is one of the food products generated from enset by...
Enset (Ensete ventricosum) is the basis of the staple food consumed by about 20% of the Ethiopian population. Kocho is one of the food products generated from enset by spontaneous fermentation of decorticated and pulverized pseudostem and corm sections. We isolated culturable microbes associated with kocho from different stages of fermentation. Twelve yeast species, six lactic acid bacteria (LABs) species and eleven species of aerobic bacteria were identified by sequencing ITS/D1D2 regions of 26S rDNA of yeasts and 16S rDNA of bacteria, respectively. More yeast species were identified in fresh (fermented for 2-5 days) kocho, compared to long-term (7-12 months) fermented kocho, while we observed an opposite trend for LABs. In fresh kocho, the most frequently isolated yeast species were Pichia exigua, Galactomyces geotrichum, and Pichia fermentans. From mid-term (3-4 months) kocho most frequently Candida cabralensis, G. geotrichum, and Candida ethanolica were isolated. In the long-term fermentations, the most frequently isolated yeast was Saturnispora silva. Lactobacillus plantarum was the most frequently isolated LAB in both fresh and mid-term kocho. In long-term fermented kocho, Acetobacter pasteurianus and L. plantarum were most frequently isolated. L. plantarum was consistently isolated from all the three stages of fermentation. Aerobic bacteria in fresh kocho were mostly gram-negative, with Raoultella planticola and Pantoea agglomerans being the most frequently isolated species. In long-term fermented kocho, mainly gram-positive, spore-forming bacteria of the genus Bacillus were found, among them also species of the Bacillus cereus group, Bacillus anthracis and Bacillus thurigiensis.
Topics: Bacteria; Ethiopia; Fermentation; Fermented Foods; Food Microbiology; Musaceae; Yeasts
PubMed: 30368690
DOI: 10.1007/s10482-018-1192-8 -
Indian Journal of Pharmaceutical... 2016Chiral alcohols are the key chiral building blocks to many enantiomerically pure pharmaceuticals. The biocatalytic approach in asymmetric reduction of corresponding...
Chiral alcohols are the key chiral building blocks to many enantiomerically pure pharmaceuticals. The biocatalytic approach in asymmetric reduction of corresponding prochiral ketones to the preparation of these optically pure substances is one of the most promising routes. The stereoselective reduction of different kinds of prochiral ketones catalyzed by various plants and microorganisms was studied in this work. Benzyl acetoacetate, methyl 3-oxopentanoate, ethyl 3-oxopentanoate, and ethyl butyryl acetate were chosen as the model substrates for β-ketoesters. Benzoyl acetonitrile, 3-chloro propiophenone, and 1-acetyl naphthalene were chosen as aromatic aliphatic ketones. Finally, 2-methyl benzophenone and 4-chloro benzophenone were selected as diaryl ketones. Plant catalysis was conducted by Daucus carota, Brassica rapa, Brassica oleracea, Pastinaca sativa, and Raphnus sativus. For microbial catalysis, Aspergillus foetidus, Penicillum citrinum, Saccharomyces carlbergensis, Pichia fermentans, and Rhodotrula glutinis were chosen. Chiral alcohols were obtained in high yields and with optical purity. A superiority in the microorganisms' performance in the bioreduction of prochiral ketones was detected. Among microorganisms, Rhodotrula glutinis showed remarkable results with nearly all substrates and is proposed for future studies.
PubMed: 27168684
DOI: 10.4103/0250-474x.180252 -
International Journal of Food Science 2019Identification of the yeast responsible for fermentation is important in order to be more consistent and for scale-up of production. In this study, yeast were isolated...
Identification of the yeast responsible for fermentation is important in order to be more consistent and for scale-up of production. In this study, yeast were isolated and identified from fermenting dough sample collected from household, hotels, and microenterprises, Addis Ababa. Initially, the yeast obtained from fermenting dough of different sources were selected on the basis of their CO production potentials. Its DNA sequencing of isolated yeast identified and The association of identified yeast to their sources indicated the presence of in fermenting dough samples collected from all sources whereas , and were shown to be present in samples collected from households, hotels, and microenterprises, respectively. The phenotypes and CO production potentials of this yeast were also documented. This study has confirmed the presence of different yeast species in the fermentation of dough and hinted the complex nature of dough fermentation.
PubMed: 31355246
DOI: 10.1155/2019/1291863 -
Applied and Environmental Microbiology Apr 2002Five different methods were used to identify yeast isolates from a variety of citrus juice sources. A total of 99 strains, including reference strains, were identified... (Comparative Study)
Comparative Study
Five different methods were used to identify yeast isolates from a variety of citrus juice sources. A total of 99 strains, including reference strains, were identified using a partial sequence of the 26S rRNA gene, restriction pattern analysis of the internal transcribed spacer region (5.8S-ITS), classical methodology, the RapID Yeast Plus system, and API 20C AUX. Twenty-three different species were identified representing 11 different genera. Distribution of the species was considerably different depending on the type of sample. Fourteen different species were identified from pasteurized single-strength orange juice that had been contaminated after pasteurization (PSOJ), while only six species were isolated from fresh-squeezed, unpasteurized orange juice (FSOJ). Among PSOJ isolates, Candida intermedia and Candida parapsilosis were the predominant species. Hanseniaspora occidentalis and Hanseniaspora uvarum represented up to 73% of total FSOJ isolates. Partial sequence of the 26S rRNA gene yielded the best results in terms of correct identification, followed by classical techniques and 5.8S-ITS analysis. The commercial identification kits RapID Yeast Plus system and API 20C AUX were able to correctly identify only 35 and 13% of the isolates, respectively. Six new 5.8S-ITS profiles were described, corresponding to Clavispora lusitaniae, Geotrichum citri-aurantii, H. occidentalis, H. vineae, Pichia fermentans, and Saccharomycopsis crataegensis. With the addition of these new profiles to the existing database, the use of 5.8S-ITS sequence became the best tool for rapid and accurate identification of yeast isolates from orange juice.
Topics: Beverages; Citrus; DNA, Ribosomal Spacer; Molecular Sequence Data; Mycological Typing Techniques; Phenotype; RNA, Ribosomal; RNA, Ribosomal, 5.8S; Reagent Kits, Diagnostic; Sequence Analysis, DNA; Yeasts
PubMed: 11916718
DOI: 10.1128/AEM.68.4.1955-1961.2002 -
Journal of Food Protection Oct 2006The potential use of the commercial biocontrol products Serenade (Bacillus subtilis QST-713) and Trichodex (Trichoderma harzianum Rifai strain T39) to inhibit the...
The potential use of the commercial biocontrol products Serenade (Bacillus subtilis QST-713) and Trichodex (Trichoderma harzianum Rifai strain T39) to inhibit the postharvest pathogenic molds Penicillium crustosum and Mucor circinelloides was investigated. Both products exhibited antagonistic activity in vitro against the pathogens, reducing their growth at different levels. In addition, epiphytic yeasts isolated from peaches were identified as Candida maltosa, Pichia fermentans, and Pichia kluyveri by PCR-restriction fragment length polymorphism of internal transcribed spacer regions and screened for antagonistic activity against the same molds. The efficacy of biocontrol in vitro was dependent on the concentration of the yeast cells. Optimal yeast concentrations were above 10(7) CFU ml(-1). However, C. maltosa and P. fermentans were more effective than P. kluyveri in inhibiting molds. The exclusion of antifungal metabolite production and direct competition for nutrients or space with the pathogens was proposed as the mechanism of biocontrol. Application of biocontrol agents directly on artificially wounded peach fruits significantly reduced the incidence of mold rot during storage at 20 degrees C.
Topics: Antibiosis; Bacillus subtilis; Colony Count, Microbial; DNA, Fungal; Food Preservation; Fungi; Humans; Mucor; Penicillium; Pest Control, Biological; Prunus; Species Specificity; Time Factors; Trichoderma; Yeasts
PubMed: 17066929
DOI: 10.4315/0362-028x-69.10.2465 -
Journal of Dairy Science Feb 2008Yeasts are commonly detected in cheese. Two yeast species, Kluyveromyces lactis and Pichia fermentans, were isolated at high populations from raw-milk Cantalet cheese, a...
Yeasts are commonly detected in cheese. Two yeast species, Kluyveromyces lactis and Pichia fermentans, were isolated at high populations from raw-milk Cantalet cheese, a French Protected Denomination of Origin hard cheese. To investigate the interest of these 2 species as adjunct cultures to promote flavor development of Cantalet cheese, they were added at 10(5) cfu/mL to microfiltered milk. The global microbiological, biochemical, and flavor changes induced by the presence of the yeasts in cheese were determined. Adjunct yeasts were present at 10(6) cfu/g in curd, declined to 10(4) to 10(5) cfu/g in cheese, and did not influence gross composition, content of free amino acids, or content of free fatty acids. By using 8-way gas chromatography-olfactometry in parallel with gas chromatography-mass spectrometry, 30 odorous compounds of Cantalet cheese were identified. The olfactory profiles of K. lactis cheeses contained significantly greater levels of 8 odorous compounds (ethanol, ethyl hexanoate, 4 aldehydes, and 2 branched-chain acids) compared with the control and P. fermentans cheeses. Sensory analysis of cheeses flavor discriminated K. lactis cheeses on only 2 attributes (acetaldehyde and alcohol odors). This study shows that yeast contribution is species-specific and that K. lactis, at a population of 10(6) viable cells/g, can influence Cantalet cheese flavor.
Topics: Amino Acids; Cheese; Colony Count, Microbial; Fatty Acids, Nonesterified; Food Microbiology; Gas Chromatography-Mass Spectrometry; Humans; Kluyveromyces; Odorants; Pichia
PubMed: 18218739
DOI: 10.3168/jds.2007-0136 -
Journal of Dairy Science Jul 2009In this study, various yeasts (Kluyveromyces marxianus, Saccharomyces turicensis, Pichia fermentans) and lactic acid bacteria (Lactobacillus kefiranofaciens,...
In this study, various yeasts (Kluyveromyces marxianus, Saccharomyces turicensis, Pichia fermentans) and lactic acid bacteria (Lactobacillus kefiranofaciens, Lactobacillus kefiri, Leuconostoc mesenteroides) were entrapped in 2 different microspheres using an entrapment ratio for the strains that was based on the distribution ratio of these organisms in kefir grains. The purpose of this study was to develop a new technique to produce kefir using immobilized starter cultures isolated from kefir grains. An increase in cell counts with fermentation cycles was observed for both the lactic acid bacteria (LAB) and yeasts, whereas the cell counts of kefir grains were very stable during cultivation. Scanning electron microscopy showed that the short-chain lactobacilli and lactococci occupied the surface of the LAB microspheres, whereas the long-chain lactobacilli were inside the microspheres. When the yeasts were analyzed, cells at a high density were entrapped in cracks on the surface and within the microspheres, where they were surrounded by the short-chain lactobacilli. The distribution of the LAB and yeast species in kefir produced from grains and microspheres showed that there was no significant difference between the kefirs produced by the 2 methods; moreover, Leu. mesenteroides and K. marxianus were the predominating microflora in both types of kefir. There was no significant difference in the ethanol and exopolysaccharide contents between the 2 kefirs, although the acidity was different.
Topics: Alginates; Cultured Milk Products; Fermentation; Food Handling; Food Technology; Glucuronic Acid; Gram-Positive Bacteria; Hexuronic Acids; Lactobacillus; Leuconostoc; Microscopy, Electron, Scanning; Microspheres; Yeasts
PubMed: 19528577
DOI: 10.3168/jds.2008-1669 -
Applied Microbiology Sep 1961Cacao beans must be subjected to fermentation before they are used in making chocolate, and their commercial value is related to a proper procedure. Saccharomyces rosei,...
Cacao beans must be subjected to fermentation before they are used in making chocolate, and their commercial value is related to a proper procedure. Saccharomyces rosei, Hansenula anomala, Pichia fermentans, Pichia membranaefaciens, and Trichosporon cutaneum were found in fermenting cacao beans. All species isolated during the investigation grew on cacao pulp, but only S. rosei, H. anomala, and P. fermentans exhibited fermenting capacity on the sugars of cacao pulp. Species of the genus Saccharomyces were identified as the agents responsible for the alcoholic phase of the cacao fermentation.
Topics: Cacao; Fabaceae; Fermentation; Yeasts
PubMed: 13767275
DOI: 10.1128/am.9.5.370-371.1961 -
Journal of Applied Microbiology Jan 2010Investigating the influence of an added starter culture on the properties of fermented liquid pig feed.
Effect of starter culture inoculation on feed hygiene and microbial population development in fermented pig feed composed of a cereal grain mix with wet wheat distillers' grain.
AIMS
Investigating the influence of an added starter culture on the properties of fermented liquid pig feed.
METHODS AND RESULTS
Diets of cereal grain blended with wet wheat distillers' grain that were either not inoculated (WWDG), inoculated with a silage starter culture at start (WWDGsc1) or at start and at each backslopping (replacement of 80% the content with fresh mixture, simulating feed outtake, WWDGsc5) were fermented for 5 days, followed by 5 days of daily backslopping. Numbers of undesirable micro-organisms (enterobacteria, moulds) were reduced in all fermentations; particularly enterobacteria in the starter culture inoculated diets. Lactobacillus plantarum present in the starter culture became dominant in diets WWDGsc1 and WWDGsc5. However, Lactobacillus panis that was dominating WWDG was also abundant in WWDGsc1 and WWDGsc5. Yeast populations were not influenced by the starter culture, with Pichia fermentans dominating all fermentations. All diets had similar chemical characteristics with the exception of a significant increase of all tested organic acids in WWDGsc5.
CONCLUSIONS
The addition of a starter culture influences the bacterial population in fermented liquid feed, but there is also a strong impact of the flora already present in the feed ingredients. The yeast population is not influenced by adding a lactic acid bacteria (LAB) starter culture. A consortium of LAB and yeast strains adapted to the fermentation should be used as starter culture.
SIGNIFICANCE AND IMPACT OF THE STUDY
The results suggest that it is possible to influence the current unpredictable and spontaneous process of feed fermentation when appropriate starter cultures are used. For this purpose, LAB and yeasts with desirable characteristics should be isolated.
Topics: Animal Feed; Animals; Fermentation; Food Microbiology; Industrial Microbiology; Lactobacillus plantarum; Pichia; Swine; Triticum
PubMed: 19583798
DOI: 10.1111/j.1365-2672.2009.04399.x