Validation of the Peel Plate™ AC for Detection of Total Aerobic Bacteria in Dairy and Nondairy Products

Abstract

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.

Comparative effect of gamma and electron beam irradiation on some food borne pathogenic bacteria contaminating meat products

“…-E. coli was discovered and isolated on the Charm peel plate (EC) microbiological test (kit: code; PP EC look). This test has been certified as a performance test method O7150 by the Association of Analytical Community's Research Institute [13] .…”

Detection of tetracycline and streptomycin in beef tissues using Charm II, isolation of relevant resistant bacteria and control their resistance by gamma radiation

“…While, E. coli count (EC) plates (kit code: PP-EC-100 k) to detect the coliform isolates. This test has been certificated by the Association of Analytical Communities (AOAC) research Institute as a performance tested method 071501 [51]. Briefly, 25 g of ground meat or liver were homogenized for 2 min with 225 ml of peptone saline solution (0.1% peptone and 0.85% NaCl), samples were then 10-fold serially diluted, 1 ml sample dilutions (10 − 4 -10 − 7 ) were added to distinct Charm Peel Plates and incubated at 35 ± 1°C for 18-24 h. Pink or blue/ violet colonies on the AC (Fig.…”