GB 4789.14-2014 PDF EnglishUS$115.00 · In stock · Download in 9 seconds
GB 4789.14-2014: National food safety standard - Food Contact Materials and Articles - Food Microbiological Examination - Bacillus Cereus Delivery: 9 seconds. True-PDF full-copy in English & invoice will be downloaded + auto-delivered via email. See step-by-step procedure Status: Valid GB 4789.14: Historical versions
Similar standardsGB 4789.14-2014: National food safety standard - Food Contact Materials and Articles - Food Microbiological Examination - Bacillus Cereus---This is an excerpt. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.), auto-downloaded/delivered in 9 seconds, can be purchased online: https://www.ChineseStandard.net/PDF.aspx/GB4789.14-2014 GB NATIONAL STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA National Food Safety Standard – Food Microbiological Examination - Bacillus Cereus Issued on. DECEMBER 1, 2014 Implemented on. MAY 1, 2015 Issued by. National Health and Family Planning Commission of the People’s Republic of China Table of ContentsForeword... 3 1 Scope... 4 2 Equipment and materials... 4 3 Culture media and reagents... 4 4 Plate count method of bacillus cereus (first method)... 5 5 MPN count method of bacillus cereus (second method)... 12 Annex A Culture media and reagents... 15 Annex B Retrieval table of bacillus cereus most probable numbers... 23ForewordThis Standard replaces GB/T 4789.14-2003, Microbiological examination of food hygiene - Examination of bacillus cereus. Compared with GB/T 4789.14-2003, the major changes of this Standard are as follows. -- it changes the Chinese name of the standard; -- it adds the second method, the MPN counting method of bacillus cereus; -- it changes the culture conditions for selective isolation medium (MYP), from culturing for 12 h ~ 20 h at 37°C to culturing for 24 h ~ 48 h at 30°C ± 1°C; -- it adds the lysozyme examination; -- it changes the operating procedures; -- it adds Annex A and Annex B. National Food Safety Standard – Food Microbiological Examination - Bacillus Cereus1 ScopeThis Standard specifies the examination method of bacillus cereus in food. The first method of this Standard applies to the count of bacillus cereus in food which has a high content of bacillus cereus; and the second method applies to the count of bacillus cereus in food which has a low content of bacillus cereus.2 Equipment and materialsIn addition to conventional sterilization and culture equipment for microbiology laboratories, the other equipment and materials are as follows. a) refrigerators. 2°C ~ 5°C; b) thermostatic incubators. 30°C ± 1°C, 36°C ± 1°C; c) homogenizers; d) electronic balances. sensitivity 0.1 g; e) sterile conical flasks. 100 mL, 500 mL; f) sterile pipettes. 1 mL (having 0.01 mL scale), 10 mL (having 0.1 mL scale) or micropipettes and tips; g) sterile plates. diameter 90 mm; h) sterile examination tubes. 18 mm ×180 mm; i) microscopes. 10× ~ 100× (oil immersion lens); j) L spreader.3 Culture media and reagents3.1 Phosphate buffer solution (PBS). see A.1 of Annex A. 3.2 Mannitol yolk polymyxin (MYP) agar. see A.2 of Annex A. 3.3 Trypticase soy polymyxin broth. see A.3 of Annex A. 3.4 Nutrient agar medium. see A.4 of Annex A. 3.11 Motility medium. see A.11 of Annex A. 3.12 Sugar fermentation tube. see A.12 of Annex A. 3.13 V-P medium. see A.13 of Annex A.4 Plate count method of bacillus cereus (first method)4.1 Examination procedures The examination procedures of the plate count method of bacillus cereus are as shown in Figure 1. 4.2 Operating procedures 4.2.1 Sample treatment Frozen samples shall be unfrozen not exceeding 15 min below 45°C and not exceeding 18 h at 2°C ~ 5°C. If they can’t be examined promptly, they shall be stored at - 10°C ~ -20°C. Non-frozen, perishable samples shall be examined as soon as possible; and if they can’t be examined promptly, they shall be stored in a refrigerator at 2°C ~ 5°C and examined within 24 h. 4.2.3 Sample dilution Absorb 1 mL of the 1.10 sample homogeneous solution of 4.2.2 to add to a dilution tube containing 9 mL of PBS or normal saline; fully mix up to make 1.100 sample homogeneous solution. In accordance with the estimation of sample contamination degree, operate as above and make into ten-fold incremental serial dilution sample homogeneous solution in succession. After each dilution, replace one 1 mL sterile pipette or tip. 4.2.5 Isolation and culture 4.2.5.1 Isolation Under normal conditions, allow plates to stand for 10 min after applying. If sample solution is difficult to absorb, it can be placed in an incubator to culture for 1 h at 30°C ± 1°C; turn over plates after sample homogeneous solution is evenly absorbed; place them upside down in the incubator; culture for 24 h ± 2 h at 30°C ± 1°C. If the colonies are not typical, continue culturing for 24 h ± 2 h before observing. On MYP agar plates, typical colonies are of a faint pink colour (indicating unfermented mannitol) and there are white to pale orchid pink precipitation ring (indicating the production of lecithinase). 4.3 Confirmatory appraisal 4.3.1 Dyeing microscopic examination Pick single colonies of pure culture for Gram’s microscopic examination. Bacillus cereus is Gram positive bacillus of size (1 μm ~ 1.3 μm) ×(3 μm ~ 5 μm); the spore is oval which is located at the centre or one end of thallus, not expanding on thallus; both ends of thallus are flat, normally arranged in the shape of short chains or long chains. 4.3.2 Biochemical identification 4.3.2.4 Root growth test Item Bacillus cereus Bacillus thuringiensis Bacillus mycoides Bacillus anthracis Bacillus megaterium 4.3.2.6 Protein toxin crystal test 4.4 Calculation of results 4.4.1 Count and confirmation of typical colonies 4.4.1.1 Select plates having typical bacillus cereus colonies and plates of a total colony count between 20 CFU ~ 200 CFU on three plates of the same dilution degree; count typical colonies. In case of the phenomena of a) ~ f), calculate in accordance with Equation (1) of 4.4.2.1.In case of the phenomenon of g), calculate in accordance with Equation (2) of 4.4.2.2.5 MPN count method of bacillus cereus (second method)5.1 Examination procedures The examination procedures of the MPN count method of bacillus cereus is shown in Figure 2. 5.2 Operating procedures 5.2.1 Sample treatment As in 4.2.1. 5.2.2 Sample preparation As in 4.2.2. 5.2.3 Sample dilution As in 4.2.3. 5.2.5 Culture Use an inoculating loop to transfer 1 loop from each tube; inoculate on MYP agar plates by streaking; culture for 24 h ± 2 h at 30°C ± 1°C. If colonies are not typical, continue to culture for 24 h ± 2 h before observation. 5.2.6 Confirmatory appraisal Select 5 typical colonies from each plate (select all if less than 5); inoculate them on nutrient agar plates for pure culture by streaking; culture for 24 h ± 2 h at 30°C ± 1°C; carry out confirmatory test. See 4.3.Annex ACulture media and reagents A.1 Phosphate buffer solution (PBS) A.1.1 Composition Potassium dihydrogen phosphate 34.0 g Distilled water 500.0 mL A.3 Trypticase soy polymyxin broth A.4 Nutrient agar A.6 Motility medium A.7 Nitrate broth A.7.1 Ingredients Peptone 5.0 g Potassium nitrate 0.2 g Distilled water 1,000.0 mL A.8 Casein agar ......Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al. Tips & Frequently Asked Questions:Question 1: How long will the true-PDF of English version of GB 4789.14-2014 be delivered?Answer: The full copy PDF of English version of GB 4789.14-2014 can be downloaded in 9 seconds, and it will also be emailed to you in 9 seconds (double mechanisms to ensure the delivery reliably), with PDF-invoice.Question 2: Can I share the purchased PDF of GB 4789.14-2014_English with my colleagues?Answer: Yes. 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