Spoilage Levels in Poultry Meat: A Microbiological Analysis

Purpose of the Lab

The purpose of this lab was to observe psychrotrophs and what levels of spoilage did they form throughout the course of two lab sessions.

Introduction

In poultry processing, there are many different microorganisms that will cause the meat itself to spoil (Iñiguez-Moreno, et al. (2019). Spoilage of meat often is the cause of Psychrotrophs (Iñiguez-Moreno, et al. (2019). Psychrotrophs are bacteria that are generated within cold temperatures. Such psychrotrophs are pseudomonas (Iñiguez-Moreno, et al. (2019). For instance, pseudomonas is considered the most common bacteria that causes spoilage within poultry.

However, pseudomonas is not included in any HACCP simply because Pseudomonas does not cause illness itself, but it does lead to the spoilage of the poultry meat (Almeida C. et al 2011). In return, with there being a presence of pseudomonas, there is more than likely a chance of Campylobacter jejuni will develop due to that presence.

To avoid such bacteria, the atmosphere is modified for the poultry to enhance shelf life.

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With the consideration that poultry meat has been the 2nd most consumable product within the past years, there Within the microorganism community, a collective group of microorganisms are called biofilms. Biofilms have been such a major issue, that they have been known to contaminate surfaces, damage water systems and even be a contributing factor to food spoiling very quickly in post process and later on shelf life. Foodborne illnesses have been a major issue in biofilms as well.

As stated in (V.O. Adetunji, T.O. Isola (2011), biofilms are far more resistant to antimicrobials.

They have different stages in which they form. Things to take in to consideration when it comes to spoilage of poultry include the temperate in which the meat is tested, pH levels, amount of nutrients, and the surface contents. (H. Meredith, V. et. al (2014). Every year, roughly 600 million people become sick due to foodborne illnesses. Of the 600 million, 350 of those people who were sick were caused by pathogen bacteria. As stated in 2019, 1.2 million people contracted salmonella (Iniguez- Moreno, 2019.)

Materials and Methods

Tools:

• Gloves: to prevent surface/cross contamination
• Sharpie: used to write with dilution of peptone water was smeared
• Chicken breast: to observe bacterial growth (10g)
• Homogenizer bag that holds the peptone water and chicken sample with the initial amount of 10-1
• Test tubes (9mL): holds peptone water for dilutions 10-2-10-7
• Pump was used to retrieve the peptone from the bag of homogenized water within the pipette
• Pipette was used to retrieve the peptone water and placed in the test tubes (9mL)
• TSA petri plate was used to induce the bacterial growth with homogenized water (14).
• Spreader Rod used to spread the bacteria all over the plate
• Incubator stimulated growth of bacteria on the plate
• Refrigerator used to slow the growth of the bacteria

Methods

In this lab, each group received a number of fourteen plates with a volume of 0.1 mL, in which a meat sample of 10 grams and peptone water were smeared on each plate in circular motion. The plates were divided into two separate sides. The sides were “plates 1 and plates 2.” It was conscious to keep the homogenized bag closed to prevent inaccurate data as the experiment went further and further. To retrieve the peptone, we used a pump and pipette to retrieve it from the homogenized bag of water. We retrieved each amount of peptone water from each of the previous 9mL test-tube to increase the number of dilutions.

We then wrote with a sharpie on each level of dilution increasing on each plate. As the plates were incubated and refrigerated over the course of a seven-day period until the next lab, the bacteria were set to grow. After the bacteria was incubated and moved to the refrigerator, the group had to keep in mind that whatever bacteria is on the plates, that is what needs to be slowed down during the cool time.

The desired temperature of the plates would be set at the desired number of colonies between each plate was between 25-250. The group counted all colonies and grouped all colonies that were tightly together as one with the sharpie. However, not all plates will have the same amounts of colonies, and some will have those colonies in which they were unable to count will be known as TNTC (too numerous to count). If the plates had a lesser amount that required, that number with be recorded as well. The desired amount was then recorded and then the CFU calculation was made. The CFU is calculated between the two different sets of colonies per plate. One level of CFU will fall 25-250 if the calculations were done correctly. That is the one that will fall in to the equation. The calculation was then calculated and compared with others to compare and observe who had the most spoilage.

Results

Bacterial Growth of Group 4

Table 1

Psychrotrophic count: 1.144 x 10^8 CFU/g

Calculation of Psychotropic Count

(CFU/g)

114.4* 105

= 1.144 x 108 CFU/g

0.1

Listed Below are all of the participants in lab and their spoilage levels:

• Group 1: 4.3 x 108 CFU/g
• Group 2: 2.7 x 108 CFU/g
• Group 3: 1.13 x 107 CFU/g
• Group 4: 1.144 x 108 CFU/g
• Group 5: 3.9 x 107 CFU/g
• Group 6: 1.155 x 107 CFU/g

Discussion

As the experiment was conducted and concluded, we predicted that the spoilage would be prominent after the fifth dilution. As listed the CFU level per gram was calculated, it was for certain that we were not the only group that witnessed spoilage after the fifth dilution. Groups 1 and 2 also witnessed spoiled at the fifth dilution. However, groups 3, 5, and 6 had spoiled sooner than the previous listed results. A possible reason this may have occurred is because the samples were not incubated at the same amount of time and that amount of spoilage was refrigerated and that is where the bacteria was slowed down at.

Another factor could be that different amounts of homogenized water amounts in the pipette. To prevent inaccurate amounts of spoilage, a faster reaction time to put the plates in the incubators and refrigerator could be taken in to consider action. Also, it could be possible to be more accurate with the controlled group of peptone water 0.1 mL. There may have been errors in reading the pipette at eye level, not taking in the fact that the pipette in fact, has a meniscus reading level as just like many other cylindrical tubes.

Conclusion

In conclusion, this lab has informed the group that that psychrotrophs do from in poultry if certain temperatures are not met. The groups were very pleased with their results and the methods were very useful as well. The CFU calculation showed where the amount of spoilage was averaged out. This lab has made it known that refrigeration does not stop spoilage, but rather slows it down. It can still ruin over time.