INVESTIGATING THE CHANGE IN GRAM NEGATIVE AND POSITIVE BACTERIA NUMBER PRESENT ON TOP OF THE BEVERAGE CANS BEFORE AND AFTER CLEANING THE REGION AND COMPARING THE NUMBERS WITHIN THE CLEANING METHODS WHICH ARE CLEANING WITH TISSUE, WET WIPE, TAP WATER AND SOAPY WATER

摘要

Beverage cans encounter with external contacts which causes microorganismsudincluding pathogenic bacteria dispersed. Found on top region of the cans, these bacteriaudincrease the contamination risk of diseases to human beings. The purpose of this study is toudcompare the bacteria amount (CFU/ml) on top region of the beverage cans before and afterudcleaning the area with four methods (cleaning with tissue, wet wipe, tap water and soapyudwater). Additional aim is to investigate which cleaning method is most effective in reducingudthe bacteria amount (CFU/ml).udThe research question of this study is: ‘‘Is there a significant difference on theudamount of bacterial colonies of gram negative and positive bacteria found at the surface ofudthe steel beverage cans before and after cleaning the top surface region with differentudmethods as cleaning with tissue, wet wipes, distilled water and water with soap?’udBacteria count from the samples is done by taking cultures from the surface, dilutingudand leading them to stay 24 hours at 37°C in petri dishes containing sheep blood agar inudincubation. Then colony number count is done for five groups and used in data analysis.udMean values are 280, 29, 8.8, 21.2 and 3.2 CFU/ml for the controlled and the cleanedudgroups (with tissue, wet wipe, tap and soapy water) respectively. ANOVA test supports theudhypothesis that there is difference between the bacteria amount before and after cleaningudthe top region of the cans (P=5.3825x10‐6). The second ANOVA test is done to see theuddifference between the cleaning methods. It shows the most effective method is cleaningudwith soapy water (P=1.36x10‐4). The conclusion is that after cleaning the top region of theudcan there is a decrease in bacteria number and the most decrease is seen when it is cleanedudwith soapy water.