Analytical Food Microbiology. Ahmed E. Yousef

Analytical Food Microbiology - Ahmed E. Yousef


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plastic sleeve should be sanitized properly before leaving the laboratory.

      Immediately Before Entering the Laboratory

      1 Finish or dispose of any food or drink items/containers.

      2 Turn off electric devices (e.g., mobile phones, laptop computers, tablets, etc.); these should be stowed appropriately for the duration of the laboratory session.

      Immediately After Entering the Laboratory

      1 Enter the teaching laboratory when the instructor/supervisor is available; more than one instructor should be available to supervise the session.

      2 Keep your belongings (e.g., backpack, winter coat, etc.) in the designated area, which is preferably outside the laboratory; bring only the exercise summary and a blank sheet of paper to the bench.

      3 Put the exercise summary (and the blank sheet) in the provided plastic sleeve; this is a sanitizable pocket for protection against spills. Present the exercise summary on the bench to be reviewed by the instructor.

      4 Hair that is longer than shoulder length must be tied up.

      5 Wash hands in the laboratory sink using the soap and disposable towels provided.

      6 Put on a lab coat; when not in use, these should be stored in the laboratory throughout the course.

      7 Put on disposable gloves and sanitize the bench; a quaternary ammonium solution or alcohol is often used for bench sanitization.

      8 Listen carefully to the instructor’s short presentation; this presentation may include seating chart, assignment for the food to be analyzed, potential pitfalls, etc.

      9 Start the exercise when instructed to do so.

      While Executing the Exercise

      1 Be aware of whether you are working individually or in groups of two or more. If working in groups, part of the work could be carried out individually and the other part is done cooperatively. If working in a group, make sure you communicate clearly with laboratory partner(s) before starting the exercise.

      2 Start the laboratory exercise and observe the safety rules described earlier.

      3 Do your best to complete the work efficiently and diligently.

      4 Make sure you share the progress of the exercise or problems encountered with one of the instructors.

      5 Record your observations or results. The exercise summary sheet or a separate sheet of paper may be used for recording. Alternatively, hand‐held electronic notepads may be provided by instructors for note taking and data collection.

      Immediately After Completing the Laboratory Exercise

      1 Show your work (mounted microscope slide, reaction results, colony counts, etc.) to the instructor.

      2 If asked, transfer the data collected to the class computer or class data sheet.

      3 Dispose of work items correctly.

      4 Sanitize the bench using the sanitizer provided (often a quaternary ammonium sanitizer or alcohol).

      5 Remove disposable gloves and place them in the biohazard container.

      6 Store lab coat appropriately.

      7 Wash hands.

      8 Take your belongings and exit the laboratory.

      1 Centers for Disease Control and Prevention. (2020). Biosafety in microbiological and biomedical laboratories. 6th ed. U.S. Department of Health and Human Services, Washington, DC, USA.

      This section covers the theoretical principles of sampling and sample‐size calculations. Additionally, techniques that may be followed during sampling and sample preparation of food or processing environment are covered.

      Sampling Principles

      Introduction

      Although food is emphasized in this book, sampling and analysis of water and processing environment will also be addressed. A sample of water from a stream is described as a “specimen.” Similarly, samples from circulating cleaning or rinsing solution or swabs from a moving conveyer belt are also considered specimens. In these situations, the population sampled is not static and thus getting a representative portion is a challenging task.

      Preparing A Sampling Plan

      Sampling is an essential step in any procedure


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