Question

Which of the following statements is TRUE with respect to the use of Petrifilm method for the enumeration of aerobic plate count in foods?

• A. Reduces incubation time
• B. Eliminates the preparation of diluents
• C. Eliminates media preparation
• D. Requires large incubation space

Hint:

Petrifilm Advantages: ELIMINATES MEDIA PREPARATION and autoclaving; sample-ready rehydratable film with built-in indicator dyes; saves incubator space.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Rapid microbiological enumeration technologies: 3M Petrifilm plates contain pre-coated, cold-water-soluble gelling agents, nutrients, and triphenyltetrazolium chloride (TTC) indicator dyes, completely eliminating traditional agar media boiling and sterilization.

Step 2: Detailed Explanation:
In rapid microbiological testing methods for dairy and food products (AOAC Official Method Petrifilm):
- The Petrifilm Method is a standardized, dry rehydratable sample-ready culture plate system:
1. Eliminates Media Preparation (C) (TRUE): The films come factory pre-coated with standardized culture nutrients, cold-water-soluble selective gelling agents, and TTC redox dye indicators. The laboratory analyst completely eliminates the labor, autoclaving, tempering, and pouring of traditional agar media.
2. Misconceptions: It uses standard incubation time ($48\text{ h}$ at $32^\circ - 35^\circ ext{C}$, does not reduce incubation), standard sample serial dilution diluents are still required, and it saves $> 85\%$ incubator space due to thin stacking.

Step 3: Final Answer:
Therefore, the statement 'Eliminates media preparation' is TRUE, matching option (C).