Salter Robert S, Durbin Gregory W, Bird Patrick, Fisher Kiel, Crowley Erin, Hammack Thomas, Chen Yi, Clark Dorn, Ziemer Wayne
Charm Sciences, Inc., 659 Andover St, Lawrence, MA 01843, USA.
J AOAC Int. 2016 Jan-Feb;99(1):143-52. doi: 10.5740/jaoacint.15-0253. Epub 2016 Feb 4.
Peel Plate™ AC (aerobic count) is a low-profile plastic 47 mm culture dish with adhesive top that contains a dried standard plate count medium with oxidation/reduction indicator triphenyl tetrazolium chloride (TTC) that turns red with dehydrogenase enzyme activity of growing aerobic bacteria. The method provides a conventional quantitative count with simple rehydration and incubation for 48 ± 3 h at 35 ± 1°C for most food matrixes and 32 ± 1°C for 48 ± 3 h for dairy products. Dairy matrixes claimed and supported with total aerobic count data are whole milk, skim milk, chocolate milk (2% fat), light cream (20% fat), pasteurized whole goat milk, ultra-high temperature pasteurized milk, nonfat dried milk, lactose-reduced milk, strawberry milk, raw cow milk, raw goat milk, raw sheep milk, condensed skim milk, and vanilla ice cream. Food matrixes claimed for aerobic count detection are raw ground beef, environmental sponge of stainless steel, raw ground turkey, dry dog food, liquid whole pasteurized eggs, milk chocolate, poultry carcass rinse, and large animal carcass sponge. The method has been independently evaluated for aerobic count in dairy products: whole milk, skim milk, chocolate milk, and light cream. The method was also independently evaluated for aerobic count in food matrixes: ground beef and sponge rinse from stainless steel surfaces. In the matrix study, each matrix was assessed separately at each contamination level in comparison to an appropriate reference method. Colony counts were determined for each level and then log10-transformed. The transformed data were evaluated for repeatability, mean comparison between methods with 95% confidence interval (CI), and r(2). A CI range of (-0.5, 0.5) on the mean difference was used as the acceptance criterion to establish significant statistical differences between methods. The evaluations demonstrate that the Peel Plate AC provides no statistical differences across most of the matrixes with r(2) > 0.96. In the case of skim milk, there were significant differences that may be explained by a matrix-related stress on the spiked organisms but were not repeated in subsequent experiments. Within method repeatability of Peel Plate AC was similar to reference method with relative standard deviations in the ranges of 2 to 5% when log10 means were ≥1.5. Quality control data support that Peel Plate AC is stable for at least 1 year refrigerated. Incubation temperature ranges 30-36°C and times 45 -51 h were not significantly different.
皮氏平板™AC（需氧菌计数）是一种外形低矮的47毫米塑料培养皿，顶部有粘性，其中含有干燥的标准平板计数培养基以及氧化还原指示剂氯化三苯基四氮唑（TTC），在生长的需氧菌脱氢酶活性作用下会变红。该方法通过简单复水并在35±1°C下培养48±3小时（大多数食品基质）或在32±1°C下培养48±3小时（乳制品）来进行常规定量计数。有需氧菌计数数据支持的乳制品基质包括全脂牛奶、脱脂牛奶、巧克力牛奶（2%脂肪）、淡奶油（20%脂肪）、巴氏杀菌全脂山羊奶、超高温灭菌牛奶、脱脂奶粉、低乳糖牛奶、草莓牛奶、生牛奶、生山羊奶、生绵羊奶、脱脂炼乳和香草冰淇淋。用于需氧菌计数检测的食品基质包括生牛肉末、不锈钢环境海绵、生火鸡肉末、干狗粮、液态全脂巴氏杀菌鸡蛋、牛奶巧克力、家禽胴体冲洗液和大型动物胴体海绵。该方法已针对乳制品中的需氧菌计数进行了独立评估：全脂牛奶、脱脂牛奶、巧克力牛奶和淡奶油。该方法还针对食品基质中的需氧菌计数进行了独立评估：牛肉末和不锈钢表面的海绵冲洗液。在基质研究中，与适当的参考方法相比，每种基质在每个污染水平下都单独进行了评估。对每个水平确定菌落计数，然后进行log10转换。对转换后的数据进行重复性评估、方法间均值比较及95%置信区间（CI）和r(2)评估。均值差异的CI范围为（-0.5, 0.5）用作接受标准，以确定方法之间的显著统计差异。评估表明，皮氏平板AC在大多数r(2)>0.96的基质中无统计差异。在脱脂牛奶的情况下，存在显著差异，这可能是由于加标微生物受到与基质相关的压力所致，但在后续实验中未重复出现。当log10均值≥1.5时，皮氏平板AC的方法内重复性与参考方法相似，相对标准偏差在2%至5%范围内。质量控制数据表明，皮氏平板AC在冷藏条件下至少1年稳定。培养温度范围为30 - 36°C，培养时间为45 - 51小时，无显著差异。
