portant; word-wrap: break-word !important; font-size: 18px;”>GB 4789.2-2016 食品安全国家标准 食品微生物学检验 菌落总数测定
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portant; word-wrap: break-word !important;”>portant; word-wrap: break-word !important;”>（1）固体或半固体：称取25g样品于均质袋中，加入已灭菌的生理盐水225g，稍捏碎（特别是糕点/面包及其他淀粉制品），放入拍击式均质器均质1min，此时即制备成1：10的样品匀液。以移液器或灭菌吸取该液体至9mL灭菌生理盐水试管中，换上新的灭菌移液器枪头，缓缓吸取液体后反复吹打2次，此时即制备成1：100的匀液，以此类推，制备10倍系列稀释匀液。
portant; word-wrap: break-word !important;”>（2）液体样品：直接吸取原液进行检验，稀释时可直接吸取1mL原液到9mL灭菌生理盐水试管中按照“固体或半固体”的方式稀释。
portant; word-wrap: break-word !important;”>portant; word-wrap: break-word !important; color: rgb(157, 87, 202);”>三、稀释度的选取：
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portant; word-wrap: break-word !important;”>portant; word-wrap: break-word !important;”>空白对照：分别吸取1mL灭菌生理盐水到平皿中做空白对照。（若空白有菌落生长则该实验无效）。
portant; word-wrap: break-word !important;”>portant; word-wrap: break-word !important; color: rgb(157, 87, 202);”>五、平板计数琼脂（PCA）：
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portant; word-wrap: break-word !important; color: rgb(157, 87, 202);”>portant; word-wrap: break-word !important;”>常采用0.85%氯化钠溶液（生理盐水），121℃、15min高压灭菌后冷却备用。
portant; word-wrap: break-word !important;”>portant; word-wrap: break-word !important; color: rgb(157, 87, 202);”>八、倾注培养基时，根据对样品污染情况的估计（同一类型样品的微生物检测经验），若样品有表面蔓延生长的可能性，则待第一次倾注的琼脂凝固后，可在表面再覆盖一层琼脂以避免菌落蔓延而难以计数。
portant; word-wrap: break-word !important;”>portant; word-wrap: break-word !important; color: rgb(157, 87, 202);”>九、水产品30±1℃培养72±3h；其它样品36±1℃培养48±2h。注意：此处的“水产品”是指生鱼片、鱿鱼干等未经深度加工的水产品。
portant; word-wrap: break-word !important;”>portant; word-wrap: break-word !important; color: rgb(157, 87, 202);”>十、本标准的重难点为菌落计数及计算。
portant; word-wrap: break-word !important;”>portant; word-wrap: break-word !important;”>（1）菌落计数时，从低稀释度的平板开始计数。若所有平板上的菌落数均小于30CFU，则须计数所有平板上的菌落数，但仅采用最接近30CFU的两个平板的菌落数来计算最终菌落总数。
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portant; word-wrap: break-word !important;”>以固体样品举例，菌落数选取、计算过程及结果修约如下：
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portant; word-wrap: break-word !important;”>以固体样品举例，根据标准中给定的公示，菌落数选取、计算过程及结果修约如下：
portant; word-wrap: break-word !important;”>（4）若所有稀释度的平板菌落数都大于300，则不能所有都计为TNTC，必须将最高稀释度的两个平板上的菌落逐一地计数，再计算平均数，该平均数为该梯度的菌落总数，其余平板上的菌落数可记为TNTC。
portant; word-wrap: break-word !important;”>portant; word-wrap: break-word !important;”>（5）计算菌落总数时，须严格按照标准要求进行计算。
portant; word-wrap: break-word !important;”>特殊情况：
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portant; word-wrap: break-word !important;”>举例如下：
portant; word-wrap: break-word !important;”>portant; word-wrap: break-word !important; color: rgb(157, 87, 202);”>十一、对于水产品、冷冻食品、速冻食品等菌落总数含量较高、限量值较大的食品类别，建议多增加稀释梯度（可稀释至10-4甚至10-5），避免稀释度较低、浓度较大导致培养后平板上菌落蔓延、弥散而难以计数甚至无法计数。
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portant; word-wrap: break-word !important; color: rgb(54, 65, 173);”>portant; word-wrap: break-word !important;”>GB 4789.10-2016 食品安全国家标准 食品微生物学检验 金黄色葡萄球菌检验
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portant; word-wrap: break-word !important; font-size: 16px; color: rgb(241, 136, 35);”>1、7.5%氯化钠肉汤增菌培养：
portant; word-wrap: break-word !important; font-size: 16px;”>（1）若样品本身在均质后清澈，培养18h观察呈现一定程度的浑浊（与培养前相比），则接种平板；若18h后仍无变化，继续培养至24h后无论浑浊与否都接种至平板；
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portant; word-wrap: break-word !important; font-size: 16px; color: rgb(241, 136, 35);”>2、血平板：portant; word-wrap: break-word !important;”>portant; word-wrap: break-word !important;” />
portant; word-wrap: break-word !important; font-size: 16px; color: rgb(241, 136, 35);”>3、接种原则：
portant; word-wrap: break-word !important; font-size: 16px;”>（1）革兰氏染色后还剩余10个或10个以上菌落，则NA、BHI分别接种5管；
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portant; word-wrap: break-word !important; font-size: 16px;”>（3）5个及以下则全部接种BHI，不接种NA。
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portant; word-wrap: break-word !important;”>portant; word-wrap: break-word !important; font-size: 16px;”>36±1℃培养24h后观察，有菌落生长则取出，无菌落生长则继续培养至48h后再观察。若血平板已挑取菌落进行证实试验，则不必再挑取BP平板上的菌落进行实验。 若血平板上无菌落生长，则应在24h～48h内逐步观察BP平板是否长菌或有无长菌迹象，有则需配置BHI及NA，挑取BP上的菌落进行纯化、增菌，36±1℃培养24h。
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portant; word-wrap: break-word !important; font-size: 16px;”>（2）同时取金黄色葡萄球菌标准菌株（ATCC 6538以及CMCC（B）26003各一支）制成菌悬液后作为阳性对照、以灭菌生理盐水为阴性对照，分别接种至BHI中同步培养后进行血浆凝固酶试验。
portant; word-wrap: break-word !important; font-size: 16px;”>（3）若血浆凝固酶试验结果可疑，则挑取NA上的菌落接种BHI再次进行试验。
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portant; word-wrap: break-word !important;”>portant; word-wrap: break-word !important; font-size: 16px;”>第二法 金黄色葡萄球菌平板计数法
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portant; word-wrap: break-word !important; font-size: 16px;”>2、涂布时不要触及平板边缘（会导致样液涂抹不均匀，大部分汇集于边缘）。
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portant; word-wrap: break-word !important; font-size: 16px;”>4、涂布完成后应稍微放置一段时间使培养基吸收样品匀液。
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portant; word-wrap: break-word !important; font-size: 16px;”>6、36±1℃培养24h后观察，有典型菌落生长则进行证实试验（革兰氏染色镜检、血浆凝固酶试验、划线血平板）。若无菌落生长则继续培养至48h后再观察，有典型菌落生长则进行证实试验，无典型菌落生长则试验终止。
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portant; word-wrap: break-word !important; font-size: 16px;”>1、样品稀释同菌落总数，取3个连续稀释度稀释液（或包括液体样品原液），每个稀释度接种3管7.5%氯化钠肉汤，每管接种1mL，36±1℃培养18h后观察，若出现浑浊则接种至BP平板，若无变化则继续培养至24h后再接种至BP平板。
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portant; word-wrap: break-word !important; font-size: 16px;”>3、根据证实后的阳性管数差MPN表得出结果。
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portant; word-wrap: break-word !important; color: rgb(54, 65, 173); font-size: 18px;”>portant; word-wrap: break-word !important;”>GB 4789.15-2016 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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portant; word-wrap: break-word !important;”>第一法 霉菌和酵母平板计数法
portant; word-wrap: break-word !important;”>1、孟加拉红培养基灭菌条件比较特殊：121℃，20min。
portant; word-wrap: break-word !important;”>2、稀释液可选择生理盐水、磷酸盐缓冲液，还可选择无菌水。
portant; word-wrap: break-word !important;”>3、正置平板培养。为避免孢子扩散、菌落蔓延，可选择使用一次性塑料培养皿。
portant; word-wrap: break-word !important;”>4、“观察并记录培养至第5d的结果”，意味着需要从培养的第二天开始逐日观察并记录霉菌和（或）酵母的生长情况，且原始记录须体现“逐日观察”。
portant; word-wrap: break-word !important;”>5、特别注意：“菌落数在10以内时，采用一位有效数字报告，菌落数在10～100之间时，采用两位有效数字报告”，即：在直接吸取原液检验时，若两个平板上的平均菌落数小于10，则四舍五入后的数值直接记为最终结果（不可四舍五入为10），若1：10的两个平板上一个长1个菌落，另一个无菌落生长，则平均数为0.5，最终计算结果为5，结果报告为5，而不是10。
