Microbiological Quantitative Testing Overview
📌 The video demonstrates quantitative microbiological testing for E. coli, *Staphylococcus aureus*, and *Bacillus cereus* counts in food using a ready-to-use rapid kit.
🧪 The core principle involves growing and counting specific bacterial colonies after inoculation into the ready-to-use medium (RUM) using a Peptone Saline Solution (PSS) for sample homogenization.
⏱️ Testing for *E. coli*, *B. cereus*, and *S. aureus* can be performed simultaneously because the homogenization solvent is the same (PSS).
🔬 Required incubation is typically 35–37°C for 24 hours or according to the specific kit instructions.

Sample Preparation and Dilution Protocol
🧼 Begin by cleaning the sample container with 70% alcohol.
⚖️ Aseptically weigh 25 grams (g) of the composited food sample into a sterile stomacher bag.
💧 Add 225 milliliters (mL) of PSS solvent to the bag and homogenize to achieve a $10^{-1}$ dilution.
🔁 Further serial dilutions are prepared by pipetting 1 mL of the homogenized sample into 9 mL of PSS, creating a $10^{-2}$ dilution, and continuing as needed for inoculation.

Rapid Kit Inoculation and Interpretation
🧪 Inoculate 1 mL from each dilution level into the respective ready-to-use media tubes for *E. coli*, *B. cereus*, and *S. aureus*.
👯 It is standard practice to perform the inoculation testing in duplicate (Duplo).
🟦 Colony results are interpreted based on color changes provided by the kit: *E. coli* typically yields blue or light blue colonies, while *B. cereus* and *S. aureus* both typically yield blue colonies.

Key Points & Insights
➡️ Standard analytical methods referenced include Pusat Pengembangan Pengujian Obat dan Makanan Nasional (P3OMN) guidelines for reference numbers (e.g., *E. coli* methods 35 and 37 of 2019).
➡️ Accurate aseptic technique is crucial during sample weighing and dilution steps to ensure reliable quantitative results.
➡️ Final count determination must follow the specific calculation methods outlined in the P3OMN analysis for *E. coli*, *B. cereus*, and *S. aureus*.

📸 Video summarized with SummaryTube.com on Dec 01, 2025, 01:47 UTC