or cans with plastic liners) are used to discard contaminated materials. These materials include all disposable gloves, culture‐containing disposable Petri plates, and disposable test tubes. Contaminated materials (i.e., those exposed to laboratory microorganisms) are typically autoclaved or incinerated. Contaminated broken glassware should be disposed of in the sharps container. Broken, uncontaminated glassware should be placed in a receptacle designated for that purpose (e.g., the broken glass box). If syringes are used for a laboratory exercise, they should be disposed of in the sharps container designated by the instructor.
Spilling or splashing of cultures can happen. In case of small spills, the student needs to encircle and flood the area with excess disinfectant, allow disinfectant to sit for the proper amount of time, and wipe the area with paper towels or other provided absorbent towels, wiping toward the center to prevent spread of the contaminant. These towels are considered contaminated and should be disposed of in the biohazard container. In case of larger spills, the instructor should be notified immediately. Any broken glassware should be disposed of in a sharps container. Appropriate disposable gloves should be worn during the cleaning process and should be discarded after the spill has been addressed.
It is recommended that students tape their inoculated agar plates together at the end of each exercise or keep them in a designated group container (small plastic bin) to make retrieving the group’s plates easier at the beginning of the subsequent session and make them easier to handle and inspect by instructors. Plates should be placed in the correct orientation and in the designated location for incubation.
PRACTICAL ASPECTS
In addition to keeping yourself and other laboratory members safe, the proper exercise of safety protocols and etiquette allows for the timely completion of laboratory sessions. Lack of preparation before arriving to the laboratory may prevent students from finishing the exercise within the allotted time.
Before the Laboratory Session
1 Carefully read the laboratory exercise and understand why and how it is executed.
2 Summarize the practical steps to be carried out during the session on a single sheet of paper. This “exercise summary” should be one of only two papers allowed on the bench during the execution of the exercise. The second is a blank paper for writing observations and recording results. As indicated earlier, the exercise summary (plus the recording sheet) are ideally kept in a plastic sleeve and placed on the bench while executing the exercise. The 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.
REFERENCE
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.
CHAPTER 2 SAMPLING FOR MICROBIOLOGICAL ANALYSIS OF FOOD AND PROCESSING ENVIRONMENT
It is a challenge to be able to assess the microbiological quality and safety of food accurately. The approach often used is a stepwise procedure that includes sampling, sample preparation, laboratory analysis, data collection, and result interpretation. Errors in each of these steps cumulatively determine the reliability of the overall procedure. Sampling can be an elaborate exercise (Figure 2.1), and analysts consider it the most error‐prone step. Poorly planned and executed sampling operations compromise the analyst’s ability to assess the quality or safety of food. This chapter includes two main sections: “Theoretical
