Evaluation of Freeze-Dried Kefir Coculture as Starter in Feta-Type Cheese Production

ABSTRACT The use of freeze-dried kefir coculture as a starter in the production of feta-type cheese was investigated. Maturation of the produced cheese at 4ï¿½C was monitored for up to 70 days, and the effects of the starter culture, the salting method, and the ripening process on quality characteristics were studied. The use of kefir coculture as a starter led to increased lactic acid concentrations and decreased pH values in the final product associated with significantly higher conversion rates compared to salted rennet cheese. Determination of bacterial diversity at the end of the ripening process in salted kefir and rennet cheeses by denaturing gradient gel electrophoresis technology, based on both DNA and RNA analyses, suggested a potential species-specific inhibition of members of the genera Staphylococcus and Psychrobacter by kefir coculture. The main active microbial associations in salted kefir cheese appeared to be members of the genera Pseudomonas and Lactococcus, while in salted rennet cheese, Oxalobacteraceae, Janthinobacterium, Psychrobacter, and Pseudomonas species were noted. The effect of the starter culture on the production of aroma-related compounds responsible for cheese flavor was also studied by the solid-phase microextraction-gas chromatography-mass spectrometry technique. Kefir coculture also appeared to extend the shelf life of unsalted cheese. Spoilage of kefir cheese was observed on the 9th and 20th days of preservation at 10 and 5ï¿½C, respectively, while spoilage in the corresponding rennet cheese was detected on the 7th and 16th days. Microbial counts during preservation of both types of unsalted cheese increased steadily and reached similar levels, with the exception of staphylococci, which were significantly lower in unsalted kefir cheese. All types of cheese produced with kefir as a starter were approved and accepted by the panel during the preliminary sensory evaluation compared to commercial feta-type cheese.

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Evaluation of Pediococcus pentosaceus SP2 as Starter Culture on Sourdough Bread Making

Foods ◽

10.3390/foods9010077 ◽

2020 ◽

Vol 9 (1) ◽

pp. 77 ◽

Cited By ~ 3

Author(s):

Stavros Plessas ◽

Ioanna Mantzourani ◽

Argyro Bekatorou

Keyword(s):

Organic Acids ◽

Solid Phase ◽

Immobilized Cells ◽

Starter Culture ◽

Gas Chromatography Mass Spectrometry ◽

Bread Making ◽

Pediococcus Pentosaceus ◽

Sourdough Bread ◽

Fresh Freeze ◽

Freeze Dried

In the present study, a novel Pediococcus pentosaceus SP2 strain, recently isolated from kefir grains, was evaluated as a starter culture in sourdough bread making. The novel starter was applied in fresh, freeze-dried, and freeze-dried immobilized (on wheat bran) form. The type of culture (fresh, freeze-dried, immobilized cells) influenced the bread characteristics. Specifically, the application of freeze-dried immobilized cells led to higher total titratable acidity (TTA) values (9.81 mL NaOH N/10), and the produced bread presented higher resistance to mold and rope spoilage. Moreover, the produced sourdough breads were significantly better in terms of pH, TTA, organic acids content, and resistance to mold and rope spoilage, compared to breads made with a commercial, wild microbiota, sourdough. The organic acids content was also significantly higher than the commercial sourdough sample (2.93 g/kg lactic acid; 1.01 g/kg acetic acid). Determination of volatile compounds through solid-phase microextraction (SPME) gas chromatography/mass spectrometry (GC/MS) analysis and sensorial assessments indicated no significant differences between the tested sourdough breads.

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High-Temperature Semi-Dry and Sweet Low Alcohol Wine-Making Using Immobilized Kefir Culture

Fermentation ◽

10.3390/fermentation7020045 ◽

2021 ◽

Vol 7 (2) ◽

pp. 45

Author(s):

Anastasios Nikolaou ◽

Yiannis Kourkoutas

Keyword(s):

High Temperature ◽

Solid Phase ◽

Principal Component ◽

Industrial Sector ◽

Gas Chromatography Mass Spectrometry ◽

Wine Production ◽

Wine Making ◽

Conversion Rates ◽

Freeze Dried ◽

Low Alcohol

Low alcohol wines (≤10.5% vol) represent novel wine products steadily gaining the commercial market interest. Considering the technological advancements of immobilized systems in association with the drastic reduction of industrial operational costs in high-temperature wine-making in regions with tropical climate or hot summer periods, the aim of the present study was to assess the fermentation efficiency of both wet and freeze-dried immobilized kefir culture on natural supports in low alcohol wine production at high temperatures (>30 °C). Immobilized kefir culture was evaluated and compared to free cells in repeated batch fermentations for 3 months, indicating high operational stability, and found suitable for simultaneous alcoholic and malolactic low alcohol wine fermentation at temperatures up to 45 °C. High ethanol productivity [up to 55.3 g/(Ld)] and malic acid conversion rates (up to 71.6%), which could be adopted by the industrial sector, were recorded. Principal Component Analysis (PCA) revealed that the state of the cells rather than the nature of kefir culture affected significantly the content of minor volatiles determined by Head Space Solid-Phase Microextraction (HS-SPME) Gas Chromatography–Mass Spectrometry (GC/MS) analysis. Notably, all new products were of high quality and approved by the sensory panel. The results suggested a high industrial potential of the proposed technology in semi-dry low alcohol wine-making at 37 °C and in developing novel wine products with a sweet (liquoreux) character at 45 °C.

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MICROBIAL COMMUNITY DURING BIOREMEDIATION EXPERIMENTAL ON OIL SPILL IN COASTAL OF PARI ISLAND

Jurnal Ilmu dan Teknologi Kelautan Tropis ◽

10.29244/jitkt.v3i1.7838 ◽

2011 ◽

Vol 3 (1) ◽

Author(s):

Lies Indah Sutiknowati

Keyword(s):

Oil Spill ◽

Deoxyribonucleic Acid ◽

Denaturing Gradient Gel Electrophoresis ◽

Gas Chromatography Mass Spectrometry ◽

Oil Degradation ◽

Sequence Determination ◽

Blast Search ◽

Degrading Bacteria ◽

Gradient Gel Electrophoresis

There is an information how to identify hydrocarbon degrading bacteria for bioremediation of marine oil spill. We have Bioremediation treatment for degradation of oil spill on Pari island and need two kind of experiment there are tanks experiment (sampling 0 to 90 days) and semi enclosed system (sampling 0 to 150 days). Biostimulation with nutrients (N and P) was done to analyze biodegradation of hydrocarbon compounds. Experiment design using fertilizer Super IB and Linstar will stimulate bacteria can degrade oil, n-alkane, and alkane as poly aromatic hydrocarbon. The bacteria communities were monitored and analyzed by Denaturing Gradient Gel Electrophoresis (DGGE) and Clone Library; oil chemistry was analyzed by Gas Chromatography Mass Spectrometry (GCMS). DNA (deoxyribonucleic acid) was extracted from colonies of bacteria and sequence determination of the 16S rDNA was amplified by primers U515f and U1492r. Strains had been sequence and had similarity about 90-99% to their closest taxa by homology Blast search and few of them suspected as new species. The results showed that fertilizers gave a significant effect on alkane, PAH and oil degradation in tanks experiment but not in the field test. Dominant of the specific bacteria on this experiment were Alcanivorax, Marinobacter and Prosthecochloris. Keywords: Bioremediation, Biostimulation, DGGE, PAH, Pari Island

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Development and Validation of a Nested-PCR-Denaturing Gradient Gel Electrophoresis Method for Taxonomic Characterization of Bifidobacterial Communities

Applied and Environmental Microbiology ◽

10.1128/aem.69.11.6380-6385.2003 ◽

2003 ◽

Vol 69 (11) ◽

pp. 6380-6385 ◽

Cited By ~ 52

Author(s):

R. Temmerman ◽

L. Masco ◽

T. Vanhoutte ◽

G. Huys ◽

J. Swings

Keyword(s):

Nested Pcr ◽

Gel Electrophoresis ◽

Denaturing Gradient Gel Electrophoresis ◽

Temporal Changes ◽

Rrna Gene ◽

Specific Pcr ◽

Gradient Gel Electrophoresis ◽

Species Specific ◽

Taxonomic Characterization

ABSTRACT The taxonomic characterization of a bacterial community is difficult to combine with the monitoring of its temporal changes. None of the currently available identification techniques are able to visualize a “complete” community, whereas techniques designed for analyzing bacterial ecosystems generally display limited or labor-intensive identification potential. This paper describes the optimization and validation of a nested-PCR-denaturing gradient gel electrophoresis (DGGE) approach for the species-specific analysis of bifidobacterial communities from any ecosystem. The method comprises a Bifidobacterium-specific PCR step, followed by purification of the amplicons that serve as template DNA in a second PCR step that amplifies the V3 and V6-V8 regions of the 16S rRNA gene. A mix of both amplicons is analyzed on a DGGE gel, after which the band positions are compared with a previously constructed database of reference strains. The method was validated through the analysis of four artificial mixtures, mimicking the possible bifidobacterial microbiota of the human and chicken intestine, a rumen, and the environment, and of two fecal samples. Except for the species Bifidobacterium coryneforme and B. indicum, all currently known bifidobacteria originating from various ecosystems can be identified in a highly reproducible manner. Because no further cloning and sequencing of the DGGE bands is necessary, this nested-PCR-DGGE technique can be completed within a 24-h span, allowing the species-specific monitoring of temporal changes in the bifidobacterial community.

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A high-throughput and sensitive methodology for the quantification of urinary 8-hydroxy-2′-deoxyguanosine: measurement with gas chromatography-mass spectrometry after single solid-phase extraction

Biochemical Journal ◽

10.1042/bj20040004 ◽

2004 ◽

Vol 380 (2) ◽

pp. 541-548 ◽

Cited By ~ 78

Author(s):

Hai-Shu LIN ◽

Andrew M. JENNER ◽

Choon Nam ONG ◽

Shan Hong HUANG ◽

Matthew WHITEMAN ◽

...

Keyword(s):

Gas Chromatography ◽

Solid Phase Extraction ◽

Healthy Subjects ◽

Solid Phase ◽

Large Population ◽

Urine Samples ◽

Gas Chromatography Mass Spectrometry ◽

Phase Extraction ◽

Freeze Dried ◽

Wide Range

8-Hydroxy-2´-deoxyguanosine (8OHdG) is a widely used biomarker for the measurement of endogenous oxidative DNA damage. A sensitive method for the quantification of 8OHdG in urine by single solid-phase extraction and GC-MS (gas chromatography with MS detection) using selective ion monitoring is described in the present study. After solid-phase extraction, samples are freeze-dried, derivatized by trimethylsilylation and analysed by GC-MS. The urinary 8OHdG was quantified using heavy isotope dilution with [18O]8OHdG. The recovery of 8OHdG after the solid-phase extraction ranged from 70 to 80% for a wide range of urinary 8OHdG levels. Using 1 ml of urine, the limit of quantification was >2.5 nM (2.5 pmol/ml) and the calibration curve was linear in the range 2.5–200 nM. This method was applied to measure 8OHdG in urine samples from 12 healthy subjects. The intra- and inter-day variations were <9%. Urinary 8OHdG levels in spot urine samples from four healthy subjects were also measured for 1 week and, again, the variation was small. The presence of H2O2 in urine did not cause artifactual formation of 8OHdG. Since this assay is simple, rapid, sensitive and reproducible, it seems suitable to be used as a routine methodology for the measurement of urinary excretion of 8OHdG in large population studies.

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Hydrogen sulphide inhibits PSII of lichen photobionts

The Lichenologist ◽

10.1017/s0024282912000667 ◽

2013 ◽

Vol 45 (1) ◽

pp. 101-113 ◽

Cited By ~ 10

Author(s):

Stefano BERTUZZI ◽

Mauro TRETIACH

Keyword(s):

Hydrogen Sulphide ◽

Vascular Plants ◽

Solid Phase ◽

Photosynthetic Apparatus ◽

Sample Surface ◽

Gas Chromatography Mass Spectrometry ◽

Solid Phase Micro Extraction ◽

Action Mechanisms ◽

Species Specific ◽

Closed Chambers

AbstractThe effects of hydrogen sulphide (H2S) on five lichens with different photobionts, ecology, and tolerance to the pollutant were studied by means of samples exposed in closed chambers containing two known H2S solutions. The H2S concentration in the void volume at equilibrium with the liquid phase was measured by gas chromatography-mass spectrometry, combined with the use of solid phase micro extraction (GC/MS SPME). It was determined as 8 and 28 ppm H2S in the absence of lichen material, andc. 2 and 10 ppm H2S respectively with living lichen material inserted for 8 hours in the exposure chambers. Significant differences in the species-specific emission of chlorophyllafluorescence (ChlaF) were observed, with a pronounced depression ofFv/Fmalready detectable after 2 h exposure at 28 ppm H2S in all the species. The decreased intensity was positively correlated to sample surface and, to a lesser extent, to the species-specific pre-exposureFv/Fmvalue. Dark-exposed samples were less affected than light-exposed ones. All four chlorolichens could recover the pre-exposure ChlaF emission after two days in the absence of H2S, both in the light and in the dark, whereas the cyanolichen did not recover when kept in the dark. The results are thoroughly discussed on the basis of the known action mechanisms of H2S on the photosynthetic apparatus of vascular plants and cyanobacteria.

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MICROBIAL COMMUNITY DURING BIOREMEDIATION EXPERIMENTAL ON OIL SPILL IN COASTAL OF PARI ISLAND

Jurnal Ilmu dan Teknologi Kelautan Tropis ◽

10.28930/jitkt.v3i1.7838 ◽

2011 ◽

Vol 3 (1) ◽

Author(s):

Lies Indah Sutiknowati

Keyword(s):

Oil Spill ◽

Deoxyribonucleic Acid ◽

Denaturing Gradient Gel Electrophoresis ◽

Gas Chromatography Mass Spectrometry ◽

Oil Degradation ◽

Sequence Determination ◽

Blast Search ◽

Degrading Bacteria ◽

Gradient Gel Electrophoresis

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Denaturing Gradient Gel Electrophoresis Analysis of the 16S rRNA Gene V1 Region To Monitor Dynamic Changes in the Bacterial Population during Fermentation of Italian Sausages

Applied and Environmental Microbiology ◽

10.1128/aem.67.11.5113-5121.2001 ◽

2001 ◽

Vol 67 (11) ◽

pp. 5113-5121 ◽

Cited By ~ 240

Author(s):

Luca Cocolin ◽

Marisa Manzano ◽

Carlo Cantoni ◽

Giuseppe Comi

Keyword(s):

Gel Electrophoresis ◽

Denaturing Gradient Gel Electrophoresis ◽

Rrna Gene ◽

Dynamic Changes ◽

Good Tool ◽

Reverse Transcription Pcr ◽

Dna And Rna ◽

Fermented Sausages ◽

Brochothrix Thermosphacta ◽

Gradient Gel Electrophoresis

ABSTRACT In this study, a PCR-denaturing gradient gel electrophoresis (DGGE) protocol was used to monitor the dynamic changes in the microbial population during ripening of natural fermented sausages. The method was first optimized by using control strains from international collections, and a natural sausage fermentation was studied by PCR-DGGE and traditional methods. Total microbial DNA and RNA were extracted directly from the sausages and subjected to PCR and reverse transcription-PCR, and the amplicons obtained were analyzed by DGGE. Lactic acid bacteria (LAB) were present together with other organisms, mainly members of the family Micrococcaceae and meat contaminants, such as Brochothrix thermosphacta andEnterococcus sp., during the first 3 days of fermentation. After 3 days, LAB represented the main population, which was responsible for the acidification and proteolysis that determined the characteristic organoleptic profile of the Friuli Venezia Giulia fermented sausages. The PCR-DGGE protocol for studying sausage fermentation proved to be a good tool for monitoring the process in real time, and it makes technological adjustments possible when they are required.

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Odor fingerprinting of Listeria monocytogenes recognized by SPME–GC–MS and E-nose

Canadian Journal of Microbiology ◽

10.1139/cjm-2014-0652 ◽

2015 ◽

Vol 61 (5) ◽

pp. 367-372 ◽

Cited By ~ 16

Author(s):

Yong-xin Yu ◽

Xiao-hong Sun ◽

Yuan Liu ◽

Ying-jie Pan ◽

Yong Zhao

Keyword(s):

Listeria Monocytogenes ◽

Solid Phase ◽

Gas Chromatography Mass Spectrometry ◽

Growth Stages ◽

Relative Peak Area ◽

Volatile Organic ◽

Microbial Volatile Organic Compounds ◽

Odor Compounds ◽

Species Specific ◽

Different Growth Stages

Microorganisms can produce species-specific microbial volatile organic compounds (MVOCs), or odor compounds, which can be characterized by odor fingerprinting. The objective of this study was to characterize the odor fingerprint of Listeria monocytogenes. Solid-phase microextraction – gas chromatography – mass spectrometry (SPME–GC–MS) and electronic nose (E-nose) were used to recognize the MVOCs of L. monocytogenes in pure culture medium. The main MVOCs of L. monocytogenes were identified by SPME–GC–MS analysis as alcohols, aldehydes, ketones, alkanes, and heterocyclics, among which the relative peak area of one compound, 3-hydroxy-2-butanone, increased along with the growth of L. monocytogenes. The odor fingerprint of L. monocytogenes at different growth stages could be clearly discriminated by E-nose. In addition, E-nose signals had a very good linear relationship with the concentration of this bacterium (R2 = 0.9937). Our study may help to establish the analysis of the odor fingerprint of microorganisms as a potential routine method in microbiology.

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Molecular Analysis of Spoilage-Related Bacteria in Pasteurized Milk during Refrigeration by PCR and Denaturing Gradient Gel Electrophoresis

Journal of Food Protection ◽

10.4315/0362-028x-72.3.572 ◽

2009 ◽

Vol 72 (3) ◽

pp. 572-577 ◽

Cited By ~ 20

Author(s):

HONGFEI HE ◽

JIN DONG ◽

CHIN NYEAN LEE ◽

YONG LI

Keyword(s):

Shelf Life ◽

Gel Electrophoresis ◽

Denaturing Gradient Gel Electrophoresis ◽

Plate Count ◽

Pasteurized Milk ◽

Milk Samples ◽

Gradient Gel Electrophoresis ◽

Aerobic Plate Count ◽

Species Specific

Bacterial diversity in fluid milk products has been extensively studied in order to improve milk quality. Here, we illustrate the utility of viable counts and PCR–denaturing gradient gel electrophoresis (DGGE) for monitoring the microbial spoilage of pasteurized milk during shelf life. Five pasteurized milk samples stored at 4°C were examined at 10 and 5 days before expiration and on the expiration day. With bacterial DNA extracted directly from the samples, PCR-DGGE analysis indicated that Pseudomonas became dominant in four samples. Meanwhile, the aerobic plate count of these four samples exceeded the regulatory limit of 20,000 CFU/ml at 5 days before expiration, and the rapid psychrotrophic count markedly surpassed the aerobic plate count on the expiration day. Streptococcus and Buttiauxella spp. were detected in several samples. Sequence analysis of DGGE fragments revealed high diversity among Pseudomonas spp. in the milk samples. P. putida and P. migulae grew to high numbers during refrigerated storage. Further identification of Pseudomonas at the species level was facilitated by PCR and multiplex PCR using species-specific primers; consequently, P. fluorescens and P. fragi were observed. These results highlight an important role of Pseudomonas in the shelf life of pasteurized milk.

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