Comparison of different washing methods for bacteriological quality of freshly eaten leafy vegetable Centella asiatica

摘要

Different protocols have been used for washing and disinfecting leafy vegetables. Traditional methods and chemical methods are used for washing and disinfecting leafy vegetables in Sri Lanka. However its effect on microbial reduction was barely studied. The aim of this study was evaluated the effectiveness of washing and disinfecting protocols used by the people in Sri Lanka on Centella asiatica. The leaf samples were collected from cultivated land (Manipay) and Market (Thirunelveli). The samples were microbiologically analysed. Based on the results market sample contained high numbers of bacteria than cultivated land sample. Shigella sp. found in market sample which was absent in cultivated land sample. Market samples were subjected to different washing and disinfecting treatment techniques as Dipping and washing in portable tap water (T1); Dipping in turmeric solution and washing in portable tap water (T2); Dipping in Sodium chloride solution and washing in portable tap water (T3); Dipping in mixture of Sodium chloride and turmeric solution and washing in portable tap water (T4); Dipping in lime solution and washing in portable tap water (T5); Dipping in vinegar solution and washing in portable tap water (T6). After treatments, the samples were microbiologically evaluated to measure bacterial reductions. LSD test was performed to identify the significance between the treatments and to found the most effective treatment method. Results revealed that there was a significant difference among treatments. Based on the results, treatment T6 was the most effective method and treatment T5 was completely removing the Shigella sp. MIC test was done for lime and vinegar solution based on their effectiveness on bacterial reduction than other treatments on leafy vegetable Centella asiatica. According to the MIC results 1%(v/v) of lime solution and Vinegar solution well enough to inhibit the growth of E.coli , Shigella sp., test isolate-3, test isolate-4 which were isolated from the Centella leaves sample from market.