National food safety standard

Transcription

1 Translated English of Chinese Standard: GB Translated by: Wayne Zheng et al. ICS GB B 40 NATIONAL STANDARD OF THE PEOPLE S REPUBLIC OF CHINA GB National food safety standard Food microbiological examination - Commercial sterility Issued on: November 11, 2013 Implemented on: June 01, 2014 Issued by: National Health and Family Planning Commission of the People s Republic of China Page 1 of 21

2 Table of Contents Foreword Scope Terms and definitions Equipment and materials Medium and reagent Examination procedure Operation procedure Determination of results... 9 Annex A Medium and reagent Annex B Abnormal causes analysis (Optional items) Page 2 of 21

3 Foreword This Standard replaces GB/T Food Microbiological Examination - Commercial Sterility Examination of Canned Food. Compared with GB/T , the major changes of this Standard are as follows: Modified the name of this Standard; Modified the scope; Deleted the normative references; Deleted [Translator: some of] the terms and definitions; Modified the equipment and materials; Modified the medium and reagents; Added the examination procedure diagram; Modified the examination procedure; Modified the determine of the results; Modified Annex A and Annex B. Page 3 of 21

4 National food safety standard Food microbiological examination Commercial sterility 1 Scope This Standard specifies the basic requirements, operation procedure and determination of results of the commercial sterility examination of food. This Standard applies to the commercial sterility examination of food. 2 Terms and definitions For the purpose of this standard, the following terms and definitions apply. 2.1 Low acid canned food Besides alcoholic beverage, all canned food of which the balance ph value is more than 4.6 and water activity value is more than 0.85 after sterilization; those original low acid fruit, vegetables or vegetable products - of which the ph value is lower after adding acid so as to meet the requirement of heat sterilization - are considered as low acid canned food. 2.2 Acid canned food Canned food of which the balance ph value equals to or less than 4.6 after sterilization. Tomatoes, pears and pineapples and their juices of which the ph value is less than 4.7, and figs of which the ph value is less than 4.9 are all considered as acid canned food. 3 Equipment and materials In addition to the biology laboratory routine sterilization and cultivation equipment, other equipment and materials are as follows: a) Refrigerator: 2ºC-5ºC; b) Constant temperature incubator: 30ºC±1ºC; 36ºC±1ºC; 55ºC±1ºC; c) Thermostat water bath: 55ºC±1ºC; d) Homogenizer and sterile homogeneous bags, homogeneous cup or mortar; e) Potential ph meter (accuracy of ph 0.05 units); Page 4 of 21

5 f) Microscope: 10 times times; g) Can opener and can hole puncher; h) Electronic scales or bench balance; i) Clean bench or 100-grade clean laboratory. 4 Medium and reagent 4.1 Sterile saline solution: See A.1 in Annex A. 4.2 Crystal violet staining solution: See A.2 in Annex A. 4.3 Xylene. 4.4 Ethanol solution containing 4% iodine: 4g of iodine is dissolved in 100ml of 70% ethanol solution. Page 5 of 21

6 opened using sterile scissors, without damage to the interface elevation. Smell immediately above the open mouth and make a record. Note: Severe expanded samples may explode with spewing toxic substances. The prevention measures, for example, cover a sterile towel on the expanded samples or a sterile funnel on the samples can be taken to prevent the occurrence of such hazards. 6.5 Retained samples After opening, take out the content of at least 30mL (g) with a sterile pipette or other appropriate tools in sterile operation and put it into the sterile container for storage in the refrigerator of 2ºC-5ºC or for further test as required; this batch of samples can be discarded after the test conclusions are drawn. The sample opened can be properly stored for future use of checking the container. 6.6 Sensory examination In a test room with well-lit, clean air and without odor, pour the content of sample into the white enamel tray, observe and smell the texture, morphology, color and smell; press the food to examine the product traits and verify whether the food is rotten and deteriorated, meanwhile, observe the situation inside and outside of the packaging container and make a record. 6.7 Determination of ph value Sample preparation Mixing the liquid products for future use; for the samples with both solid phase and liquid phase, the mixing liquid phase shall be taken as the standby For thick and semi-thick products as well as those products from which it is difficult to separate juice (such as syrup, jam, jelly, grease, etc.), take part of the sample and grind it in the homogenizer or mortar; if the grinded sample is still too thick, add the same amount of sterile distilled water and mix for use Determination Insert the electrode in the sample solution to be examined, and adjust the temperature corrector of the ph meter to the temperature of examination solution. If the instrument is without a temperature correction system, the temperature of the examined sample shall be adjusted to be within the range of 20ºC±2ºC, and adopt the steps that are suitable to the ph meter used to perform determination. When the reading is stable, read the ph values directly from the instrument scale, accurate to: ph 0.05 units At least two determinations shall be done for the same prepared sample. The difference Page 8 of 21

7 Annex A Medium and reagent A.1 Sterile saline solution A.1.1 Ingredient Sodium chloride 8.5g Distilled water. 1,000.00mL A.1.2 Preparation Weigh 8.5g of sodium chloride and dissolve it into 1,000mL distilled water, and autoclave at 121ºC for 15min. A.2 Crystal violet staining solution A.2.1 Ingredient Crystal violet 1.0g 95% Ethanol 20.0mL 1% Ammonium oxalate solution 80.0mL A.2.2 Preparation Completely dissolve 1.0g of crystal violet into 95% ethanol, and mix it with 1% ammonium oxalate solution. A.2.3 Staining method Fix the smear on the alcohol-lamp flame, drop the crystal violet dye on it, dyeing for 1min, and then wash it. Page 10 of 21

8 the ph to 7.8±02. B Veal residue airs to semi-dry after washing, distribute and put it in several test tubes of 15mm 150mm (for about 2cm - 3cm height in the tubes), and add 0.1g-0.2g of reduced iron powder or little scrap irons into each tube. Put the liquid medium prepared in B to each tube separately, exceeding the surface of the meat residue for about 1cm. Cover the melted Vaseline or liquid paraffin on it for 0.3cm-0.4cm. Sterilize at 121ºC for 15min. B.1.3 Nutrient agar medium B Ingredient Peptone 10.0g Veal extract 3.0g Sodium chloride 5.0g Agar Distilled water. 15.0g-20.0g 1,000.0mL B Preparation Dissolve the ingredients, except for the agar, in the distilled water; add about 2mL 15% sodium hydroxide solution, and correct the Ph to Add the agar and heat it to boiling, so that the agar dissolves. Put it in the flask or test tube of 13mm 130mm, autoclave at 121ºC for 15min. B.1.4 Acid broth B Ingredient Polypeptone 5.0g Yeast extract 5.0 g Dextrose 5.0g Potassium phosphate (Potassium dihydrogen 5.0g phosphate) Distilled water. 1,000.0mL B Preparation Heat and stir the ingredients in B to dissolve, correct the ph to 5.0 ± 0.2, autoclave at 121ºC for 15min. B.1.5 Malt extract broth B Ingredient Page 12 of 21

9 generate carbon dioxide, this particularly concentrating and occurring in foods containing sugar and some acid, such as tomato sauce, molasses, mincemeat, as well as sugary fruit can. This decomposition rate is accelerated with increase of temperature. B If any microorganism is separated from direct smear of the sterilized vacuum-packed and normal products, it may be due to the laboratory pollution. In order to verify laboratory pollution, inoculate the separated live microorganism on another normal control sample under sterile condition, sealing and cultivating it for 14d at the temperature of 36ºC. If the expansion or product spoilage occurs, these microorganisms may not come from the original sample. If the sample is still flat, open the sample packaging by sterile operation and cultivate again in accordance with the above steps; if the same kind of microorganism is found again and the product is normal, the product will be considered to be commercially sterile, because such microorganism does not grow under normal storage and transit. B If the food itself has turbidity, it may not make a definitive conclusion through broth cultivation, it shall be further cultivated to determine whether there is microbial growth under this situation. B.4 Leak test method for tinned steel sheet food empty cans B.4.1 Leakage check by reducing the pressure Wash packaging can for samples, then dry at the temperature of 36ºC. Pour clean water with the volume of 80%-90% into the empty can and properly place a perspex sheet with rubber ring at the roll rim of open end of the can, keeping the can tight. Start up vacuum pump, closing deflation valve, pressing the cover plate with hands, controlling air exhaust to make the time of vacuum meter rising from 0 Pa to Pa (510mmHg) for more than 1min and keeping this vacuum degree for more than 1 min. Make it incline and carefully observe whether there is presence of bubbles in the can, especially roll rims and weld joints. Where bubbles are continuously generated from the same part, it shall be judged as leakage, while recording leaking time and vacuum degree and marking leaking part. B.4.2 Leakage check by increasing the pressure Wash packaging can for samples, then dry at the temperature of 36ºC. Inserting rubber plug tightly into the opening in the empty can, and immersing the empty can in the aquarium with water; then starting the air compressor, slowly opening the valve so that pressure in the can is gradually increased, and maintaining 2min until the pressure is increased to 6.8X10 4 Pa. Carefully observe whether there is presence of bubbles in the can, especially roll rims and weld joints. Where bubbles are continuously generated from the same part, it shall be judged as leakage, while recording leaking time and pressure and marking leaking part. Page 21 of 21