Objective: Sous vide is a relatively new cooking method introduced in restaurants in British Columbia. Sous vide cooking involves placing vacuum sealed food inside a temperature controlled water bath or steam convection oven. Unlike conventional cooking, sous vide cooking involves cooking food at a lower temperature (usually < 65°C) with a longer cook time. The low temperature allows chefs to precisely control the changes within the food. Thus sous vide cooked dishes have consistent texture and color, with retained flavor, moistness and nutrients. With all the benefits, sous vide cooking does have some disadvantages. Lower cooking temperature may not be sufficient for bacterial count reduction, resulting in unsafe food. In addition, every validated sous vide menu requires chefs to precisely follow the cooking temperature and cook time. Any deviation can cause the food to not reach the required 6.5 log reduction in bacterial count. The purpose of this experiment was to determine the effect on the internal temperature of cooking-in-process pork loin packages when additional chilled pork loin packages with an internal temperature of 4°C are submerged into the water bath.
Methods: Two groups of pork loin packages with data loggers inside (SmartButton) at approximately 4°C were introduced into a 60°C water bath at different intervals. The first group (6 packages) was immersed inside the water bath at time = 0 minute, while the second group (6 packages) was immersed inside the water bath at time = 10 minutes. Both groups were taken out when they were cooked for 31 minutes (at time = 31 minutes and 41 minutes respectively). Water bath temperature was recorded using SPER Scientific 8000024 data logger. Temperature data for pork loin packages was used to calculate the mean lethality achieved by each group. One sample t-test and two sample t-test were used for statistical analysis.
Results: There was a more than 3 mean log lethality difference in group A and group B pork loins. Pork loins cooked sous vide style in group A achieved a mean lethality of 5.12 at 31 minutes (range 0.42 to 12.78) while group B pork loins achieved a mean lethality of 8.44 at 31 minutes (range 3.35 to 11.87). With the same cook time, group A had a statistically significantly lower mean lethality than group B pork loins with p value = 0.003. Although statistically inconclusive whether group A pork loins achieved a mean lethality of 6.5, group B pork loins did reach the recommended mean lethality of 6.5.
Conclusion: The result indicated when new cold pork loin packages at 4°C are introduced into a cooking-in-process sous vide water bath at 60°C, the lethality of the original pork loin packages in the bath will be lowered if the cook time remains unchanged. However, it is inconclusive on whether the original pork loin packages will reach 6.5 lethality recommended by BCCDC. The new pork loin packages will reach 6.5 lethality if the original cook time is used., Peer reviewed, Published., Project submitted in partial fulfillment of the requirement for the degree of Bachelor of Technology in Environmental Health, British Columbia Institute of Technology, 2018.
Background: Legionella is a pathogen that causes Legionnaires’ disease in high risk populations. The pathogen is known to exist in plumbing systems that do not have preventative factors in place to prevent its growth and proliferation. Legionella grows between 25˚C and 42˚C and is killed at 60˚C, yet long-term care facilities (LTCFs) reduce accessible hot water temperatures from 60˚C at the hot water tank to less than 49˚C at the taps in order to prevent scalding of their residents. Currently, prevention against scalding takes precedence as temperature at accessible taps is regulated within the Residential Care Regulation (RCR) of the Community Care and Assisted Living Act. It is thought that Legionella proliferation risk can be balanced with scalding in-part through the appropriate installation location of thermostatic mixing valves (TMVs).
Methods: Three LTCFs in Vancouver, British Columbia were selected for environmental sampling for Legionella proliferation risk. At each LTCF the author recorded the type of hot water tank, temperature of water within the hot water tank, the presence of a TMV and temperature of pipes before and after the TMV. As well, the author recorded hot water temperatures after one minute and free available chlorine concentration ([FAC]) at numerous resident-accessible taps throughout each LTCF.
Results: The hot water tank temperatures were set at 60.6˚C, 73.0˚C and 62.0˚C for LTCF #1, LTCF #2 and LTCF #3, respectively. All three LTCFs had installed a TMV within the boiler room immediately after the hot water tank. It was found that LTCF #1’s plumbing system water temperature was reduced from 60.6˚C (at the tank) to 48.9˚C after the TMV. LTCF #2’s plumbing system water temperature was reduced from 73.0˚C (at the tank) to 43.3˚C after the TMV. LTCF #3 was an older plumbing system that did not have thermometers within the boiler room to check the drop in temperature after the TMV. Water temperatures at taps were compared to a standard of 49°C and [FAC] levels at taps to a standard of 0.2 mg/L. The mean hot water temperature and mean [FAC] residual for all three LTCFs were 40.2˚C and 0.27 mg/L, respectively. For all three LTCFs, it was statistically significant that mean water temperatures were less than the comparison value of 49˚C (LTCF #1 p = 0.00000, LTCF #2 p = 0.00022, LTCF #3 p = 0.00110). It was also statistically significant that the mean [FAC] of all three LTCFs were greater than the comparison vale of 0.20 mg/L (LTCF #1 p = 0.00042, LTCF #2 p = 0.00000, LTCF #3 p = 0.00107).
Conclusion: It was found that all three LTCFs had set preventive measures in place to protect their residents. Water was heated to at least 60˚C to prevent Legionella and lowered to less than 49˚C to prevent scalding. [FAC] residual was also adequate to prevent growth of Legionella. However, the location of the TMV in the boiler room was suspected to be a possible contributing factor to Legionella growth, especially if cold water temperatures were to reach 20˚C or above, as they could in warm summer months. Further research is needed to determine the significance of the TMV location and the presence of Legionella., Peer reviewed, Peer-reviewed article, Published., Project submitted in partial fulfillment of the requirement for the degree of Bachelor of Technology in Environmental Health, British Columbia Institute of Technology, 2018., Legionella pneumophila, Legionnaires’ disease, Pontiac fever, Community care facility, Long-term care facility, High risk population, Free available chlorine concentration, Hot water temperature, Hot water, Thermostatic mixing valve
Background & Purpose: The seasonal demand for shellfish such as oysters is on the rise. Shellfish are nutritious foods that may be enjoyed in a variety of ways, from slurping raw oysters to cooking oysters by means of boiling, steaming, pan frying and baking. Most consumers of oysters are aware of potential food safety issues with shellfish. Raw or undercooked shellfish can carry bacteria, viruses and toxins, potentially resulting in foodborne illness. Past outbreaks associated with the consumption of raw and undercooked oysters, prompted the British Columbia Centre for Disease Control (BCCDC) to develop guidelines for those preparing, cooking and consuming shellfish. The recommended cooking temperature and time from the guideline was compared with the temperature and time of standard cooking methods from the Fanny Bay Oyster Market restaurant. The purpose of this project was to determine whether standard cooking methods from restaurants attain the guideline’s recommended 90oC for 90 seconds.
Method: Four common cooking methods of Oysters were chosen based on recommendation from Chef Chris Andraza and BCCDC researcher Lorraine McIntyre. Oysters were pan fried, deep fried, baked and grilled. Internal temperatures of cooked oysters were then measured with a probe thermometer. Results for each method were analyzed and compared with the standard of 90oC using the one sample t-test from the statistical software package, NCSS11.
Results: One sample t-tests showed statistically differences from the deep fried, baked and grilled methods when compared to the standard of 90oC (p = 0.000). The power for all three methods was 100%, therefore there is confidence that the findings reflect the truth. Experimental temperatures were consistently less than the standard. The pan fried method showed no statistically significant difference when compared to the standard of 90oC (p = 135). The power for pan fried method was 29.2%, therefore there is limited confidence that the findings reflect the truth. Therefore the deep fried, baked and grilled methods required additional cooking time to raise internal temperatures of the oysters. Whereas the pan fried method had achieved the standard but further experimentation is required to eliminate the chance of a type II error.
Conclusion: It can be concluded that three out of the four cooking methods (deep fried, baked and grilled) can have significantly different mean temperatures. However, different thermal preparation methods prior to final thermal processing requires consideration to determine cooked oyster consumption safety. One out of the four cooking methods (pan fried) attained the standard temperature 90oC. Therefore, it is recommended for deep fried, baked and grilled cooking methods that the cooking time be extended to achieve an internal temperature of 90oC or higher., Peer reviewed, Peer-reviewed article, Published., Project submitted in partial fulfillment of the requirement for the degree of Bachelor of Technology in Environmental Health, British Columbia Institute of Technology, 2018., Cooked Oyster, Temperature, Recipes, Restaurant