RESUMEN
We conducted a microbiological assessment of Indian Rojak, a popular deep fried food in Singapore to evaluate its overall microbial quality, assess the effectiveness of reheating and identify key food items that could contribute to the microbial load of the dish. In 2009, an outbreak of foodborne illness associated with this food led to 154 reported cases of acute gastroenteritis, 48 were hospitalized and 2 died. Vibrio parahaemolyticus was isolated from the patients. We evaluated 455 Indian Rojak ingredients from 35 stalls; no Salmonella spp, Vibrio cholerae/parahaemolyticus or Escherichia coli O157:H7 were recovered from the studied samples. The reheating by the food handlers significantly reduced the overall median Standard Plate Count (SPC) of food from 4.5 to 2.7 log colony forming units (CFU)/g (p<0.05). The cooked ingredients with the highest microbial loads were tofu and fish cake, with those purchased from wet markets having significantly higher bacterial loads than those purchased from supermarkets (p<0.05). The Rojak gravy had the lowest median bacterial load (1.9 log CFU/g). Raw, ready-to-eat vegetables, namely green chillis, cucumbers and onions had higher levels ranging from 5.9 to 6.1 log CFU/g. Contamination with E. coli, Staphylococcus aureus, and Bacillus cereus was seen with some of the ready-to-eat raw vegetables. Repeated education of food handlers with emphasis on good hygiene practices should be conducted to reduce the risk of foodborne illnesses.