The Centre for Food Safety (CFS) and the Consumer Council (CC) have conducted a study on the microbiological quality of buns and sandwiches in Hong Kong. This study aimed to give an overview of the microbiological quality of some buns and sandwiches which may have higher microbiological risks and are commonly available at local food premises. It also aimed to increase awareness of safe preparation and hygienic handling of these products in the food industry.
2. In this study, a total of 113 buns and sandwiches were collected from food premises, supermarkets and bakery shops, including chain and individual stores, located in different districts in Hong Kong from June to August 2011. All samples were subject to microbiological examination including aerobic colony count (ACC), Escherichia coli (total), Staphylococcus aureus and Bacillus cereus analyses conducted by the Public Health Laboratory Services Branch of the Centre for Health Protection, Department of Health. For items containing meat/egg, Salmonella spp. was also analysed whereas for those containing seafood, Vibrio parahaemolyticus was also analysed. The microbiological quality of the samples was assessed against the criteria stipulated in the Microbiological Guidelines for Ready-to-eat Food (The Guidelines) issued by the CFS in 2007.
3. The Guidelines stipulate microbiological criteria of the food concerned so as to reflect their hygienic and safety quality. According this set of Guidelines, microbiological quality of food can be classified into one of four classes* , namely Class A, B, C and D.
4. Among the 113 samples taken, the majority (96%) were of Class A or Class B quality. However, 4 samples, including 3 coconut and cream buns and a hot dog, were of Class C quality due to excessive ACC and/or Staphylococcus aureus organism. This may indicate sub-optimal hygienic condition and a need for improvement in hygienic condition of the concerned premises.
5. As revealed in the study, post-baking contamination, prolonged storage at room temperature and unhygienic handling were the likely causes for the poor microbiological quality in the samples; highlighting the importance of good hygiene practices in the food industry. In order to help food trade implement food safety measures in their operations so as to produce and sell wholesome and safe buns and sandwiches, the CFS has drafted a set of Guidelines on Safe Production of Buns and sandwiches. After consulting with the trade, the Guidelines will be distributed and uploaded to the CFS website for trade reference.
Advice to the Public
- Patronise reliable and licensed food premises.
- Consume buns and sandwiches as soon as possible.
- Except certain buns, e.g. plain rolls and pineapple buns, with lower microbiological risk and are safe to store at room temperature for a longer period of time, keep perishable buns and sandwiches (including home-made ones) in the refrigerator at or below 4 oC if they are not consumed immediately, and consume them within 1 or 2 days or within shelf-life.
Advice to Trade
- Purchase food ingredients from reliable sources.
- Estimate the demand for buns and sandwiches as well as their fillings carefully to avoid over-production.
- Store perishable fillings at or below 4 oC and avoid cross-contamination.
- Except certain buns, e.g. plain rolls and pineapple buns, with lower microbiological risk and are safe to store at room temperature for a longer period of time, keep perishable buns and sandwiches in the refrigerator at or below 4 oC or discard them after storing at room temperature for more than 4 hours.
- Plan the production schedule ahead to avoid preparing buns and sandwiches too far in advance.
- Always follow good personal hygiene practices.
The related article is published in the CHOICE MAGAZINE (Issue 422 released on 15 December 2011) (Chinese only).
the microbiological status of the food sample is satisfactory.
the microbiological status of the food sample is less than satisfactory but still acceptable for consumption.
the microbiological status of the food sample is unsatisfactory. Licensees of food premises should be advised to investigate and find out the causes and to adopt measures to improve the hygienic conditions.
the microbiological status of the food sample is unacceptable. The food sample contains unacceptable levels of specific pathogens that is potentially hazardous to the consumer.
Risk Assessment Section
Centre for Food Safety
Food and Environmental Hygiene Department