SINGAPORE - Four food caterers and a restaurant involved in a series of food poisoning cases last year that left more than 230 ill in total had their food hygiene grades lowered to a "C" on Thursday (March 21).

In notices on the National Environment Agency's (NEA) website, the four food caterers were named as Foodtalks Caterer and Manufacturer in Bedok North Street 5, One Family Catering at Food Xchange @ Admiralty, and The Orange Lantern Gourmet Kitchen and Sin Yong Huat Catering in Aljunied Avenue 4.

Foodtalks, One Family and Sin Yong Huat previously had a grade "B", while The Orange Lantern was an "A", according to information available on the NEA website.

The only restaurant listed was Imperial Herbal at the Four Points by Sheraton, Riverview hotel located in Havelock Street. The restaurant's previous grade was an "A".

NEA said that the food poisoning incidents occurred between July and November last year.

The case involving Foodtalks saw the most number of victims among them, with 110 people reported having gastroenteritis symptoms after eating food provided by the caterer, which operates from industrial complex Shimei East Kitchen.

The victims included Kindergarten 2 children and teachers who were attending a learning camp organised by Busy Bees Asia in November last year.

None of them were hospitalised.

The Ministry of Health, Agri-Food and Veterinary Authority and NEA had conducted a joint inspection of the caterer's premises after the cases were reported on Nov 26.

Last year, 27 people fell ill after eating food from The Orange Lantern on Sept 24, 38 people ate food from Sin Yong Huat on Aug 28, and 35 had food from One Family Catering on July 27.

There were 24 victims in the food poisoning case at Imperial Herbal on Nov 7.

Mr Wang Jin Hui, the owner of Imperial Herbal, told The Straits Times that the 24 belonged to a tour group from China, who ate five dishes at the restaurant for lunch.

Two vegetable dishes were found to have higher than usual levels of bacteria, said Mr Wang, 58.

The restaurant has since looked at replacing a plastic basket used to contain the vegetables before the dish is served to patrons.

It will be using aluminium or steel baskets instead, which can be cleaned in a high-temperature dishwasher, Mr Wang said.

"We will also adopt a more thorough cleaning process, including disinfecting our premises every week," he said.

The Orange Lantern director S. S. Lee said that the company had catered some meals for 350 Singapore Polytechnic foreign students over five days last year.

They were told on the fourth day of the event that two students had fallen ill on the first day.

Mr Lee said that the 27 students fell ill over the four-day period.

However, MOH investigations found no evidence of cross contamination or bacteria in the food. The ministry also could not find the cause of the food poisoning, he said.

Mr Lee added that he had earlier appealed NEA's decision, after the agency reported some lapses in hygiene during their inspection, such as flies in the kitchen and food scraps under the cooking wok.

"We have already carried out more cleaning routines in our kitchen, and also installed plastic curtain strips at all entrances and increased number of flies traps, so that there will be no further hygiene lapses," he said.

NEA said that it adjusted the caterers' and restaurant's food hygiene grade to "C" from March 21 after investigations.

The grade will be reviewed in 12 months, and NEA will be keeping the premises under surveillance in the mean time.

The public can view the revised grades after 12 months here, under "Search Track Records of Licensed Food Establishments".