Changes in pH and plate count were assessed for hygiene evaluation of the drink before fermentation (0 time), after fermentation (48 h) and at the seventh and fourteenth days of storage in 4 °C. The pH was measured using a Methohm 744 pHmeter (Metholhm, Ltd., Herisau, Switzerland) previous calibrated according to the manufacturer’s recommendations. For viable count, a conventional dilution procedure was conducted, and samples from the selected dilutions were spread plated on Violet Red Bile Dextrose agar (VRBD, Merck, Germany) incubated aerobically at 37 °C during 24 h for enumeration of Enterobacteriaceae and on Rogosa agar (Oxoid) incubated anaerobically (Gas Pak Anaerobic system, BBl, Becton Dickinson and company, Franklin Lakes, NJ, USA) at 37 °C for 72 h for lactobacilli count.
Violet red bile dextrose agar
Manufactured by Merck Group
Sourced in Germany
Violet Red Bile Dextrose agar is a microbiological culture medium used for the selective isolation and enumeration of coliform bacteria and Enterobacteriaceae. It contains crystal violet and bile salts to inhibit the growth of Gram-positive bacteria, while the dextrose serves as a carbon source. This agar is commonly used in food, water, and environmental testing to detect the presence of these target microorganisms.
Automatically generated - may contain errors
Lab products found in correlation
Anaerocult a, by Merck Group (2 mentions)
Mannitol salt phenol red agar, by Thermo Fisher Scientific (2 mentions)
Rogosa agar, by Thermo Fisher Scientific (1 mentions)
De man rogosa sharpe agar, by Merck Group (1 mentions)
Mannitol salt phenol red agar, by Merck Group (1 mentions)
Buffered peptone water (bpw), by Thermo Fisher Scientific (1 mentions)
Potato dextrose agar (pda), by Merck Group (1 mentions)
Potato dextrose agar (pda), by Thermo Fisher Scientific (1 mentions)
Plate count agar, by Thermo Fisher Scientific (1 mentions)
De man rogosa sharpe agar, by Thermo Fisher Scientific (1 mentions)
Ringer solution, by Merck Group (1 mentions)
Bagmixer, by Interscience (1 mentions)
Rose bengal chloramphenicol agar, by Merck Group (1 mentions)
Man rogosa sharpe agar, by Thermo Fisher Scientific (1 mentions)
6 protocols using violet red bile dextrose agar
1
Hygiene Evaluation of Fermented Drink
2
Enumeration of Microbial Populations in Food
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Samples of 25 g were added to 225 mL physiological saline (0.85 NaCl%) and homogenized in a stomacher (Lab Stomacher, London, UK) for 1 min. In determining the number of lactic acid bacteria, de Man Rogosa Sharpe Agar (Merck, Darmstadt, Germany) was used and incubation was carried out at 30 °C for 48 h under anaerobic conditions (Anaerocult A, Merck, Darmstadt, Germany). Mannitol Salt Phenol Red Agar (Merck) was used for the enumeration of Micrococcus/Staphylococcus, and the plates were incubated aerobically at 30 °C for 48 h. Enterobacteriaceae were determined on Violet Red Bile Dextrose Agar (Merck), and the plates were incubated at 30 °C for 48 h under anaerobic conditions (Anaerocult A, Merck) [23 ].
3
Microbial Analysis of Meatballs
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The researcher aseptically took 10-g samples from the meatballs, and homogenized
them for 3 min with buffered peptone water (BPW, Oxoid Ltd., UK) at dilution 1:9
(w/v) in a Stomacher Lab-Blender 400 (UK). The researcher also made serial
decimal dilutions in BPW, and plated them in duplicate for bacterial counts.
Total viable counts (mesophilic aerobic bacteria) were determined using plate
count agar (PCA Oxoid CM463, Oxoid) after incubation for 24–48 h at
37°C. Psychrotrophic bacteria were determined using plate-count agar
after incubation for 10 d at 7°C. The study incubated total coliform
counts using Violet Red Bile Dextrose Agar (Merck, 1.10275) at 30°C for 2
d. Yeast and molds were aerobically incubated on Potato Dextrose Agar (Merck,
1.10130) at 30°C for 2 d.
them for 3 min with buffered peptone water (BPW, Oxoid Ltd., UK) at dilution 1:9
(w/v) in a Stomacher Lab-Blender 400 (UK). The researcher also made serial
decimal dilutions in BPW, and plated them in duplicate for bacterial counts.
Total viable counts (mesophilic aerobic bacteria) were determined using plate
count agar (PCA Oxoid CM463, Oxoid) after incubation for 24–48 h at
37°C. Psychrotrophic bacteria were determined using plate-count agar
after incubation for 10 d at 7°C. The study incubated total coliform
counts using Violet Red Bile Dextrose Agar (Merck, 1.10275) at 30°C for 2
d. Yeast and molds were aerobically incubated on Potato Dextrose Agar (Merck,
1.10130) at 30°C for 2 d.
4
Microbiological Analysis of Food Samples
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Sample solutions for microbiological analysis were prepared by the homogenization of 25 g sample with 225 mL physiological saline (0.85% NaCl) in a Stomacher (Laboratory Blender Stomacher 400, Seward, England) for two minutes. Incubation temperature and time for other microbiological analyses were as follows: For counting total aerobic mesophilic bacteria (TAMB), Plate Count Agar (Oxoid) was used. Colonies were counted at the end of incubation for 48 h at 30℃ under aerobic conditions. Lactic acid bacteria (LAB) were incubated at 30℃ anaerobically for 2 d by using De Man Rogosa Sharpe Agar (Oxoid). Micrococcus/Staphylococcus (M/S) were counted using Mannitol Salt Phenol-Red Agar (Oxoid) incubated aerobically at 30℃ for 2 d. Mould-yeast (M-Y) were incubated at 25℃ aerobically for 5 d by using Potato Dextrose Agar (Oxoid). Enterobacteriaceae was incubated on Violet Red Bile Dextrose Agar (Merck) at 30℃ anaerobically for 2 d.
5
Quantifying Spoilage Bacteria in Fish
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In order to determine the microbial load in the tested fish samples, 10 g of representative fish sample was homogenized with 90 mL of sterilized Ringer solution (Merck, Darmstadt, Germany) in an appropriate sterile stomacher bag for 60 s using a Stomacher (BagMixer®, interscience, St Nom la Bretèche, France). Then, 0.1 mL of 10-fold serial dilutions of fish homogenates were transferred and spread on the surface of appropriate culture media in Petri dishes for spoilage bacteria enumeration. Plate count agar (PCA, Merck, Darmstadt, Germany) was used for the enumeration of total viable count (incubation at 25 °C for 72 h). For the enumeration of Pseudomonas spp., cetrimide–fucidin–cephaloridine (CFC) agar (Merck, Darmstadt, Germany) was used (incubation at 25 °C for 48 h). Violet Red Bile Dextrose agar (VRBD, Merck, Darmstadt, Germany) was used for the enumeration of Enterobacteriaceae spp. using the pour plate method (incubation at 25 °C for 48 h).
Two replicates of at least three appropriate dilutions were enumerated. Microbial growth modeling was carried out using the Baranyi growth model [21 (link)], by fitting curves using the DMFit program (http://www.combase.cc/index.php/en/ ). Different kinetic parameters, i.e., the rate (k) of the microbial growth, lag phase (Lag), and the final microbial population (Nmax) were estimated at the tested processing conditions.
Two replicates of at least three appropriate dilutions were enumerated. Microbial growth modeling was carried out using the Baranyi growth model [21 (link)], by fitting curves using the DMFit program (
6
Enumeration of Microbial Populations in Food Samples
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Twenty-five grams of each sample was placed into sterile stomacher bags, and 225 mL of sterile physiological saline (0.85% NaCl) was added. After homogenizing in a stomacher (Lab Stomacher Blender 400-BA 7021, Seward, West Sussex, UK), appropriate dilutions were spread on selective agar plates.
de Man–Rogosa–Sharpe agar (Oxoid, Basingstoke, England) was used for the enumeration of lactic acid bacteria, and the plates were incubated under anaerobic conditions (Anaerocult A, Merck, Darmstadt, Germany) for 48 h at 30°C. Micrococcus/Staphylococcus was enumerated on mannitol salt phenol-red agar (Oxoid, Basingstoke, England) for 48 h at 30°C; Enterobacteriaceae was enumerated on Violet Red Bile Dextrose agar (Merck, Darmstadt, Germany) for 48 h at 30°C under anaerobic conditions (Anaerocult A, Merck, Darmstadt, Germany); molds–yeasts were enumerated on Rose Bengal chloramphenicol agar (Merck, Darmstadt, Germany) for 5 D at 25°C.
de Man–Rogosa–Sharpe agar (Oxoid, Basingstoke, England) was used for the enumeration of lactic acid bacteria, and the plates were incubated under anaerobic conditions (Anaerocult A, Merck, Darmstadt, Germany) for 48 h at 30°C. Micrococcus/Staphylococcus was enumerated on mannitol salt phenol-red agar (Oxoid, Basingstoke, England) for 48 h at 30°C; Enterobacteriaceae was enumerated on Violet Red Bile Dextrose agar (Merck, Darmstadt, Germany) for 48 h at 30°C under anaerobic conditions (Anaerocult A, Merck, Darmstadt, Germany); molds–yeasts were enumerated on Rose Bengal chloramphenicol agar (Merck, Darmstadt, Germany) for 5 D at 25°C.
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