ISO 14461-2-2005 奶和奶制品.微生物实验室内质量控制.第2部分:平行板和后续稀释步骤的菌落计数可靠性测定

标准号：ISO 14461-2-2005
中文标准名称：奶和奶制品.微生物实验室内质量控制.第2部分:平行板和后续稀释步骤的菌落计数可靠性测定
英文标准名称：Milk and milk products - Quality control in microbiological laboratories - Part 2: Determination of the reliability of colony counts of parallel plates and subsequent dilution steps
标准类型：X16
发布日期：1999/12/31 12:00:00
实施日期：1999/12/31 12:00:00
中国标准分类号：X16
国际标准分类号：07.100.30
适用范围：This part of ISO 14461 | IDF 169 describes a routine procedure for the evaluation of results of the enumeration of microorganisms using colony-count methods with subsequent 10-fold dilution steps and one plate or two parallel plates within each dilution step. This routine procedure is applied regularly in each laboratory performing colony counts. It provides criteria for the acceptability of differences between the results from parallel plates and subsequent dilution steps, as follows. a) The results (colony counts) obtained from parallel plates are compared with tabulated limits for given colony counts. If these limits are exceeded, a technical problem when performing the parallel determinations may be indicated. b) The results (sums of colony counts) of two parallel plates of two subsequent 10-fold dilution steps are compared with tabulated limits for given sums of colony counts. If these limits are exceeded, a technical problem when performing the dilutions may be indicated. c) If the limits mentioned above are exceeded in more cases than expected, this indicates that the test procedure lacks reliability. NOTE The formulae for calculating the values in Table 1 and 2 are given and explained in Clause 7.