菌落總數(shù) 英文

1、logostandard operation proceduredoc. no.: micro. sop- m02 aerobic bacterial countissue date: jan. 16, 2006菌落總數(shù)測定reference gb4789.2revision date:1. scope and field of application 適用范圍this li describes routine methods for the detection of aerobic bacterial count in foods.本操作描述了食品中菌落總數(shù)的檢驗方法aerobic bact

2、erial count is commonly used as microbiological indicator for contaminant evaluation in food. this method also can be used for evaluate the trend of bacteria increase in food and provide the evidence for hygiene evaluation of the test sample.菌落總數(shù)主要作為判定食品被污染程度的標(biāo)志，也可以應(yīng)用這一方法觀察細菌在食品中繁殖的動態(tài)，以便對被檢樣品進行衛(wèi)生學(xué)評價

3、時提供依據(jù)。2. definitions 定義under appropriate condition (media, temperature, time, ph and aerobic culture etc.), the total plate count of forming colonies in 1 ml (g) treated food sample. 食品檢樣經(jīng)過處理，在一定條件下培養(yǎng)后（如培養(yǎng)基成分、培養(yǎng)溫度和時間、ph、需氧性質(zhì)等），所得1ml(g)檢樣中所含菌落的總數(shù)。3. principle of the method 原理aliquots of decimal dilut

4、ions of the sample are mixed with culture medium in petri dishes. colonies are counted after incubation at 361 oc for 482h and the number of microorganisms per gram or ml of the sample is calculated.吸取樣品稀釋液，使之在平板內(nèi)與培養(yǎng)基混合，361 oc培養(yǎng)482小時，然后計數(shù)。4. reagent and media 培養(yǎng)基和試劑 nutrition agar 營養(yǎng)瓊脂5. procedure 步

5、驟5.1 preparation of samples 樣品準(zhǔn)備weight 25g(ml) sample in 225ml sterilized buffer liquid, homogenized if necessary. 稱25克（毫升）樣品到225毫升緩沖液，如有必要將樣品打勻。5.2 plating 接種和倒板aliquots of 1ml of the dilutions to be analyzed are placed into petri dishes. add about 15ml of liquid na (cooled to 461 oc in water bath)

6、 within 15 minutes after preparation of dilutions. mix carefully inoculum and medium and allow the agar to cool and solidify. test two parallel plates for each dilution. 吸1ml樣品稀釋液到平板中，然后倒15毫升營養(yǎng)瓊脂（在水浴鍋內(nèi)冷卻至461 oc)進去, 從樣品稀釋至倒平板不應(yīng) 超過15分鐘, 小心混勻, 待其凝固. 每個稀釋度做兩個平皿。5.3 incubation 培養(yǎng)plates are inverted and i

7、ncubated for 482h at 361 oc. do not stack more than 6 plates.倒放于361 oc，培養(yǎng)482小時。把板壘成一疊時，一疊不要超過6塊。5.4 reading 讀板after incubation colonies are counted. examine the plates carefully, if necessary with a lens, to avoid mistaking particle or precipitates for pinpoint colonies. count the weighted mean of e

8、ach dilution.板上所有菌落都數(shù)出來，如有必要可用放大鏡。算出同稀釋度的各平板平均菌落總數(shù)。* note 注意use counts from all plates containing between 30 and 300 colonies, calculate the weighted mean of two plates for each dilution. the plate should not be counted which contains a big flake colony exceed half of dish, only the other be counted

9、 with no flake colony; if the flake colony is not meet half of dish and the colonies distribute equably in another half, the total plate count is two times of half dish number. if catenulate colonies (no clear border) presence, count each catenulate colony as one.選取菌落數(shù)在30-300之間的平板作為菌落總數(shù)測定標(biāo)準(zhǔn)。一個稀釋度使用兩

10、個平板，應(yīng)采用兩個平板平均數(shù)。其中一個平板有較大片狀菌落生長時，則不宜采用，而應(yīng)以無片狀的菌落生長的平板作為該稀釋度的菌落數(shù)；若片狀菌落不到平板的一半，而其余一半中菌落分布又很均勻，即可計算半個平板后乘2以代表全平皿菌落數(shù)。平板內(nèi)如有鏈狀菌落生長時（菌落至今無明顯界限），若僅有一條鏈，可視為一個菌落；如果有不同來源的幾條鏈，則應(yīng)將每條鏈作為一個菌落計。6. calculation 計數(shù)6.1 general case 一般情況calculate the amount as the weighted mean from the successive dilutions, which contai

11、n between 30 and 300 colonies. (see example 1 in attached sheet 1). the calculate result is the weighted means of the successive dilution multiply by dilution factor.應(yīng)選擇平均菌落數(shù)在30-300之間的稀釋度，乘以稀釋倍數(shù)報告之（見表1中例1）。6.2 special case 特殊情況i. if all weighted means are between 30 and 300 of two different dilution

12、s, the calculate result should be decided by the ratio of two weighted means. if the ratio less than or equal to 2, the calculate result is the mean value of two weighted means; if the ratio more than 2, the calculate result is the smaller value of the two weighted means. (see example 2&3 in attache

13、d sheet 1)若有兩個稀釋度，其生長的菌落數(shù)均在30-300之間， 則視兩者之間的比值如何來決定。若其比值小于或等于2，應(yīng)報告其平均數(shù)；若大于2則報告其中較小的數(shù)字（見表1中例2及例3）。ii. if all weighted means are more than 300, the calculate result is the weighted means of the highest dilution multiply by dilution factor. (see example 4 in attached sheet 1)若所有稀釋度的平均菌落數(shù)均大于300，則應(yīng)按稀釋度最高

14、的平均菌落數(shù)乘以稀釋倍數(shù)報告之（見表1中例4）。iii. if all weighted means are less than 30, the calculate result is the weighted means of the lowest dilution multiply by dilution factor. (see example 5 in attached sheet 1)若所有稀釋度的平均菌落數(shù)均小于30，則應(yīng)按稀釋度最低的平均菌落數(shù)乘以稀釋倍數(shù)報告之（見表1中例5）。iv. if none of the petri dishes contains any coloni

15、es, the result expressed as less than 1 multiply the lowest dilution factor. (see example 6 in attached sheet 1)若所有稀釋度的均無菌落數(shù)生長，則以小于1乘以最低稀釋倍數(shù)報告之（見表1中例6）。v. if not all weighted means are between 30 and 300, some value more than 300 or less than 30, the calculate result is the weighted means which clos

16、ed 30 or 300 multiply by dilution factor. (see example 7 in attached sheet 1)若所有稀釋度的平均菌落數(shù)均不在30-300之間，其中一部分大于300或小于30時，則以最接近30或300的平均菌落數(shù)乘以稀釋倍數(shù)報告之（見表1中例7）。6.3 result reporting 結(jié)果報告if the calculate result less than 100, report the actual result; otherwise round off the results calculated to two signifi

17、cant figures. also can expressed as a number between 1.0 and 9.9 times the appropriate power of 10. (see attached sheet 1)菌落數(shù)在100以內(nèi)時，按其實有數(shù)報告；大于100時，采用兩位有效數(shù)字，在兩位有效數(shù)字后面的數(shù)值，以四舍五入方法計算。也可用10的指數(shù)法來表示（見表1）。表1 稀釋度選擇及菌落數(shù)報告方式例次 example稀釋液及菌落數(shù)dilution and colony number兩稀釋液之比number ratio of two dilution菌落總數(shù)calculate result報告方式report result10-110-210-3cfu/g(ml)cfu/g(ml)1多不可計tntc16420-16 40016 000 或 1.6 x 1042多不可計tntc295461.6