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食品安全国家标准 食品微生物学检验 霉菌和酵母计数
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GB 4789.15-2016
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标准编号: GB 4789.15-2016 (GB4789.15-2016)
中文名称: 食品安全国家标准 食品微生物学检验 霉菌和酵母计数
英文名称: National food safety standard - Food microbiological examination - Enumeration of moulds and yeasts
行业: 国家标准
中标分类: X09
字数估计: 8,884
发布日期: 2016-10-19
实施日期: 2017-04-19
旧标准 (被替代): SN/T 2552.3-2010; GB 4789.15-2010
标准依据: 国家卫生和计划生育委员会公告2016年第15号
GB 4789.15-2016
National food safety standard Food microbiological examination: Enumeration of moulds and yeasts
中华人民共和国国家标准
食品安全国家标准
食品微生物学检验 霉菌和酵母计数
2016-10-19发布
2017-04-19实施
中 华 人 民 共 和 国
国家卫生和计划生育委员会 发 布
前言
本标准代替GB 4789.15-2010《食品安全国家标准 食品微生物学检验 霉菌和酵母计数》和
SN/T 2552.3-2010《乳及乳制品卫生微生物学检验方法 第3部分:酵母、霉菌菌落计数》。
本标准与GB 4789.15-2010相比,主要变化如下:
---修改了设备和材料;
---修改了培养基和试剂;
---修改了检验程序和操作步骤;
---修改了结果与报告;
---修改了附录A;
---附录B修改为第二法。
食品安全国家标准
食品微生物学检验 霉菌和酵母计数
1 范围
本标准规定了食品中霉菌和酵母(mouldsandyeasts)的计数方法。
本标准第一法适用于各类食品中霉菌和酵母的计数,第二法适用于番茄酱罐头、番茄汁中霉菌的计数。
2 设备和材料
除微生物实验室常规灭菌及培养设备外,其他设备和材料如下:
2.1 培养箱:28℃±1℃。
2.2 拍击式均质器及均质袋。
2.3 电子天平:感量0.1g。
2.4 无菌锥形瓶:容量500mL。
2.5 无菌吸管:1mL(具0.01mL刻度)、10mL(具0.1mL刻度)。
2.6 无菌试管:18mm×180mm。
2.7 旋涡混合器。
2.8 无菌平皿:直径90mm。
2.9 恒温水浴箱:46℃±1℃。
2.10 显微镜:10倍~100倍。
2.11 微量移液器及枪头:1.0mL。
2.12 折光仪。
2.13 郝氏计测玻片:具有标准计测室的特制玻片。
2.14 盖玻片。
2.15 测微器:具标准刻度的玻片。
3 培养基和试剂
3.1 生理盐水:见A.1。
3.2 马铃薯葡萄糖琼脂:见A.2。
3.3 孟加拉红琼脂:见A.3。
3.4 磷酸盐缓冲液:见A.4。
第一法 霉菌和酵母平板计数法
4 检验程序
霉菌和酵母平板计数法的检验程序见图1。
GB 4789.15-2016
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
National Food Safety Standard –
Food Microbiological Examination.
Enumeration of Moulds and Yeasts
ISSUED ON. OCTOBER 19, 2016
IMPLEMENTED ON. APRIL 19, 2017
Issued by. National Health and Family Planning Commission of the PRC
3. No action is required - Full-copy of this standard will be automatically &
immediately delivered to your EMAIL address in 0~60 minutes.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Equipment and materials ... 4
3 Culture Medium and Reagents ... 5
4 Examination procedures ... 5
5 Operation Steps ... 6
6 Results and Report... 7
7 Operation Procedures ... 8
Appendix A Culture Medium and Reagents ... 10
Foreword
This Standard replaced GB 4789.15-2010 National Food Safety Standard – Food
Microbiological Examination. Enumeration of Moulds and Yeasts; and SN/T 2552.3-
2010 Microbiological Examination Method for Milk and Milk Products Hygiene – Part
3. Colony-Count Method of Yeast and Moulds.
Compared with GB 4789.15-2010, this Standard has the major changes as follows.
--- Modify the equipment and materials;
--- Modify the culture medium and reagents;
--- Modify the examination procedures and operation steps;
--- Modify the results and report;
--- Modify the Appendix A;
--- Modify the Appendix B into the second method.
National Food Safety Standard –
Food Microbiological Examination.
Enumeration of Moulds and Yeasts
1 Scope
This Standard specifies the enumeration method of moulds and yeasts in the food.
The first method in this Standard is applicable to the enumeration of moulds and yeasts
in various foods; while the second method is applicable to the enumeration of moulds
in the canned tomato sauce and tomato juice.
2 Equipment and materials
In addition to the biological laboratory routine sterilization and cultivating equipment,
other equipment and materials are as follows.
2.1 Incubator. 28°C±1°C.
2.2 Beat-type homogenizer and homogeneous bag.
2.3 Electronic balance. sensitivity of 0.1g.
2.4 Sterile conical flask. capacity of 500mL.
2.5 Sterile pipette. 1mL (with 0.01mL scale), 10mL (with 0.1mL scale).
2.6 Sterile test tube. 18mm × 180mm.
2.7 Vortex mixer.
2.8 Sterile flat plate. diameter of 90mm.
2.9 Constant temperature water batch. 46°C±1°C.
2.10 Microscope. 10× ~ 100×.
2.11 Micro-pipettor and tip. 1.0mL.
2.12 Refractometer.
bottle) containing sterile diluent (distilled water or normal saline or phosphate buffering
solution) or into the sterile homogeneous bag; sufficiently shake, or use beat-type
homogenizer to beat for 1min ~ 2min; and 1.10 sample homogenous solution is
prepared.
5.1.3 Take 1mL of 1.10 sample homogenous solution to inject into the test tube
containing 9mL of sterile diluent; change another 1mL sterile pipette to blow and
absorb repeatedly; or mix evenly on the vortex mixer; such solution is 1.100 sample
homogenous solution.
5.1.4 Operate as per 5.1.3, prepare the 10 times incremental serial sample
homogenous solution. Once incrementally dilute, replace 1 piece of 1mL sterile pipette.
5.1.5 According to the evaluation of the sample pollution, select the sample
homogenous solution (liquid sample can include the stock solution) with 2 ~ 3
appropriate dilution; when performing the 10 times incremental dilution, absorb 1mL of
respectively. Meanwhile, take 1mL of sterile diluent and add into 2 sterile flat plates to
make the blank control.
5.1.6 Timely cool off the 20mL ~ 25mL of potato dextrose agar or rose Bengal agar
(can place into a 46°C±1°C constant temperature water bath for thermal insulation) to
46°C, then pour into the flat plate; rotate the flat plate to make it mix evenly. Place on
the horizontal platform till the culture medium is completely solidified.
5.2 Cultivation
After agar solidification, upright the flat plat, and place into 28°C±1°C incubator for
cultivation; observe and record the cultivation results to the first 5d.
Perform visual examination; if necessary, use magnifier or low power lens to record
dilution factor, and corresponding number of moulds and yeast colonies. It is expressed
by the Colony-Forming Unit (CFU).
Select the flat plate with number of colonies 10CFU ~ 150CFU, count the moulds and
yeasts, respectively according to the colony morphology. When the moulds spreading
and growing over the whole flat plate, it can be recorded as the colony spread.
6 Results and Report
6.1 Results
6.1.1 Calculate the average value of two flat plate colonies at the same dilution, then
Appendix A
Culture Medium and Reagents
A.1 Normal saline
A.1.1 Components
Sodium chloride 8.5g
Distilled water 1000mL
A.1.2 Preparation
Add sodium chloride into 1000mL of distilled water, mix till it is fully dissolved; after
packaging separately, sterilize for 15min at 121°C, then backup.
A.2.1 Components
Potato (peeled and cut into blocks) 300g
Dextrose 20.0g
Agar 20.0g
Chloromycetin 0.1g
Distilled water 1000mL
A.2.2 Preparation
Peel the potato and cut it into blocks; add 1000mL of distilled water, and boil for 10min
~ 20min. Use gauze to filter, add distilled water to 1000mL. Add dextrose and agar,
backup.
A.3 Rose Bengal agar
Peptone 5.0g
Dextrose 10.0g
Potassium dihydrogen phosphate 1.0g
Magnesium sulfate (anhydrous) 0.5g
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