Naovarat Srisantisang. The removal of colors in non-carbonated soft drinks using granular activated carbon for coliform detection by sanitary indicator medium. Master's Degree(Environmental Sanitation). Mahidol University. : Mahidol University, 2008.
The removal of colors in non-carbonated soft drinks using granular activated carbon for coliform detection by sanitary indicator medium
Abstract:
This research aimed to study GACs capacity to remove color from noncarbonated soft drinks; as well, it studied SI mediums capacity to detect coliform bacteria in non-carbonated soft drinks. GAC tends to increase the capacity of SI medium to detect the coliform bacteria, and coliform bacteria can be a cause of disease in humans. The study used 6 color tones of non-carbonated soft drinks (red, green, purple, blue, orange and yellow) in which the color was removed by using 3 GAC amounts (100, 200, 300 mg per soft drink 1 mL) at 2 contact times of color removal (30 and 60 minutes). The results showed that a higher amount of GAC brought about more color removal efficiency than a lower amount of GAC at p-value < 0.05. The increase of contact time significantly increased color removal efficiency at a p-value < 0.05 and the different color tones of soft drinks significantly affected different color removal efficiencies at p-value < 0.05. The orange color-tone soft drink showed the highest color removal efficiency, whereas the blue color-tone soft drink showed the lowest color removal efficiency. All color tones were removed by 300 mg per soft drink 1 mL of GAC amount and 60 minutes of contact time brought about the highest color removal efficiency, but these conditions were not the most suitable for every color tone. The most suitable condition for each color tone was selected from the lowest GAC amount and the shortest contact time for color removal that could affect the color of the
SI medium, as it changed to yellow for positive results and stayed purple for negative results (within 24 hours). 200 mg per soft drink 1 mL of GAC amount and 30 minutes of contact time were the most suitable conditions for red, green, purple and orange color tones. 300 mg per soft drink 1 mL of GAC amount and 30 minutes of contact time were the most suitable conditions for yellow color-tone. 300 mg per soft drink 1 mL of GAC amount and 60 minutes of contact time were the most suitable conditions for blue colortone. The validity of coliform bacteria detection by SI medium for these removed-color soft drinks compared with the standard MPN method were sensitivity value, pecificity value and efficiency of test more than 80%. Thus GAC can be used to remove the colors of soft drinks for coliform bacteria detection by SI medium in on efficient fashion.