brain drain: Assessment of Total Coliform and Treatment Effects...
- Sunday, August 25, 2013
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1 Shrestha pratiksha, 2 Rai KP
1 College of Applied Food and Dairy Technology- Kathmandu, Nepal
2 Department of Food Technology and Quality Control- Babarmahal, Kathmandu Nepal.
Abstract:
The purpose of the study was to access the microbiological quality of different fresh vegetables, irrigated by water of Manohora River in Kathmandu-Nepal collected from commercial farming area in Mulpani VDC, and effectiveness of washing with water and chlorine water in reducing total coliform load in the sample.
Salad vegetables; lettuce( Lactusa sativa), radish(Raphanus sativus,), and turnip (Brassica rapa rapa) were taken as test samples for the study. Sample vegetable was washed with municipality water and chlorinated water. To verify the effectiveness of chlorine on the vegetable sanitation, three different concentration of chlorine solution (50, 100 and 150 ppm) were used. Lettuce was used as a test vegetable because its leaves are most popular and widely used in salad preparation and also used in hamburgers and other fast foods, which is very popular among young generation in Kathmandu .
Enumerations were done using the Most Probable Number (MPN) technique with LST and BGLB media. The microbiological analysis revealed high rates of contamination by Total coliforms. River water sample contained Total Coliform of 3.02 log CFU/ml, while the Total coliform concentrations ranged from 3.02 log CFU/ml to 2.04 log CFU/ml in all untreated salad vegetables. The total coliform concentrations was 0.90 log cfu/ml in the salad vegetables, washed with KUKL (Kathmandu Upatyaka Khanepani Limited) tap water , while it was 0.11 cfu/ml to 0.48 CFU/ml in chlorine treated fresh salad vegetables. Washing alone was able to obtain log reduction of 1.14 cycles.
Chlorine dip was significantly (p < 0. 05) more effective than water rinsing in reducing Total coliform. The treatment with chlorine solution – 150 ppm resulted in the highest Reductions. It resulted in 1.93 log cycle reduction in total coliform. While no significant statistical difference was identified in the tested solutions (treated with 100 ppm chlorine and 150 ppm chlorine). Log reduction of 1.74 cycles was obtained with treatment of chlorine solution-100ppm.Therefore optimum reduction was determined determined to be at 100 ppm chlorination. Besides, FRC ( Free residual chlorine) in wash water was found to be 6ppm which is within permissible limit as defined by Canadian Horticulture guidelines- 2010. Therefore best dose of chlorination for fresh salad vegetables of Kathmandu, irrigated by Bagmati Tributary - Manohora river was found to be 100 ppm.
In conclusion, ——Bagmati tributary; Manohora river, is heavily contaminated and is not suitable for drinking, irrigation or recreational purpose. All the samples exceed the guidelines for unrestricted irrigation.(1 log cfu/ml).
—Fresh salad vegetables irrigated by Manohora river water is not safe for consumption without any treatment.
—Chlorine treatment is more effective in reducing microbial load than water rinsing alone.
Considering upon the effectiveness and residual level, the best concentration for chlorine treatment has been found to be 100 ppm for effective disinfection of salad vegetables.There is also need to improve hygiene practices and enforce laws preventing the discharge of wastes into streams. The important control measures are: to wash and disinfect all vegetables thoroughly before consumption; and to use potable or treated water for irrigation of vegetable gardens especially where salad crops that are eaten raw are cultivated.This findings can be suggested and applied in sanitation of such fresh vegetables for salad preparation in any food processing establishment.
corresponding Author: Shrestha Pratiksha, College of Applied Food and Dairy Technology,Kathmandu . Email: pratiksha.shrestha2001@gmail.com , Tel: 977- 9844783411
