422 Journal ofFood Protection, Vol. 45, No.5, Pages 422-429 (Aprill982) Copyright© International Association of Milk, Food, and Environmental Sanitarians Hazard Analyses of Char siu and Roast Pork in Chinese Restaurants and Markets FRANKL. BRYAN I*, CHARLES A. BARTLESON2, MITSUTO SUGI3, BEATRICE SAKAI3, LLOYD MIYASHIR03, STEVEN TSUTSUMI3 a.nd CLIFFORD CHUN3 U.S. Department a;f'Health and Human Services, Public Health Service, Centers for Disease Control, Washington State Department ofSocial and Health Services. and Hawaii State Department a;f'Health Downloaded from http://meridian.allenpress.com/jfp/article-pdf/45/5/422/1653753/0362-028x-45_5_422.pdf by guest on 28 September 2021 (Received for publication March 25, 1981 l ABSTRACT pork (ham) and barbecued pork that have been prepared in foodservice establishments other than Chinese Evaluations of time-temperature exposure of each stage of restaurants have often been identified as vehicles of the preparation of char siu (marinated roast pork) were made at six Chinese restaurants and a market. These evaluations were foodborne illness <;!,5,12,13). Char siu, which ts also made of roast pork at the market. Samples of these marinated roast pork but is often referred to as products at the various stages of preparation and swabs of barbecued pork, prepared in Chinese restaurants has equipment surfaces that the pork touched during preparation only rarely been incriminated (10,15). Yet, because this were tested for Clostridium perfringens, Salmonella and product is quite popular and consequently is kept Staphylococcus aureus. The water activity of other samples was available for serving, it often remains for long periods of also determined. Temperatures attained at the geometric time within a temperature range that is suitable for center of these pork products during roasting in ovens or after growth of food borne pathogenic bacteria. Whether this cooking ceased were such that vegetative pathogenic food borne apparent failure to be a vehicle in foodborne disease bacteria should have been killed, if present. The cooked outbreaks could be real or a result of the lack of reports products were often displayed in warming cabinets or window or incomplete investigations has not been examined. The counters at which time their temperatures were within a range that would permit rapid bacterial growth for several hours. purpose of this investigation was to (a) ascertain Reheating of leftover pork was inadequate to destroy hazardous operations associated with the preparation pathogenic microorganisms that grew or toxins that were and storage of pork products in several Chinese produced during storage. The water activity of char siu was restaurants and in a Chinese market, (b) to relate these frequently at a level that would increase the bacterial lag phase findings to the water activity of the product, and (c) to and slow the rate of growth of pathogenic bacteria from identify critical control points of typical preparation optimum. A few samples of char siu were contaminated by low activities. numbers of C. perfringens and a sample of raw and roast pork with S. aureus. There were opportunities for contamination of MATERIALS AND METHODS cooked pork products during preparation, particularly at the Operations market. Critical control points for these operations--handling Char siu is pork loin cut into rectangular strips approximately 3 em after cooking, hot-holding, cooling and reheating--are given (1.2 in) by 6 em (2.4 in) and 20 to SO em (8 to 20 in) long that is along with measures for controlling and monitoring these marinated in a solution of sugar. salt, spices, soy sauce and red dye. It is points. usually refrigerated overnight and is then roasted in a gas-fired oven. After cooking. the char siu is either left in the unheated oven, stored in pans in a walk-in refrigerator. held at room temperature in pans, or stored in a display cabinet or on counters by a window. This product is either sold whole for take out orders or thinly diced into small pieces Foods prepared in Chinese restaurants have been (<1 em thick) for use in won ton soup. fried rice or other dishes. reported as vehicles of foodborne disease outbreaks Sides of fresh hog carcasses were left overnight at room temperature. (6,7.10,12,13). Boiled rice and fried rice have often been Salt was rubbed over the surface and into cuts made in the flesh. After incriminated as vehicles, but, in many other investiga­ roasting in an oven. the sides were cut into chunks of roast pork and stored in glass cabinets until sold. tions, specific vehicles have not been identified. Cured Operations involved in preparing char siu were evaluated in six restaurants (A. B. C. D. E. F) and at a market (G) that were located 1 U.S. Department a;l Health and Human Services. Public Health in either the states of Hawaii or Washington. Operations for preparing Service, Centers for Disease Control. Atlanta. Georgia 30333. the cuts of roast pork were evaluated at the market. 2Washington State Department a;( Social and Health SeT'I!ices, O{vmpia, Washington 98504. i\1 easureme,1ts 'Hawaii State Department ofHealth. Honolulu. Hawaii 96801. Water activity (aw) was evaluated with an electric hygrometer. JOURNAL OF FOOD PROTECTION. VOL. 45, APRIL 1982 HAZARD ANALYSES OF CHAR SIU 423 Specifications for this instrument have been published (6). Recordings cooking are summarized in Table 1 and examples are were usually made at 25 C (77 F), however, a few recordings were made illustrated in Fig. 3-7. The highest temperatures attained at other temperatures. Several samples were frozen and thawed before at the geometric centers of pieces of char siu ranged from analysis for~- Time-temperature measurements were obtained with thermocouples 61 C (142 F) to 91 C (195 F). Internal temperatures of the and recorded on a recording potentiometer. Specifications for this roast pork reached 74 C (166 F) and 81 C (178 F). The instrument have been published 0-6). Necdle·point thermocouples temperatures rose as much as 4 C (7 F) after cooking were inserted into the meat so that the sensing end was located near the ceased. According to established D-values for various geometric center. Welded-junction thermocouples were used to measure air temperatures. pathogenic bacteria in similar substrates (1,8), the time-temperature values attained in these products Laboratory should have killed most vegetative pathogenic foodborne Samples for laboratory analysis were taken as described by Bryan et al. (4.6). bacteria that might have been present. Laboratory procedures for the isolation of Clostridium perfringens, Salmonella and Staphylococcus aureus are described in the Bacteriological Analytical Manual (} 6). Oven a;r RESULTS AND DISCUSSION Downloaded from http://meridian.allenpress.com/jfp/article-pdf/45/5/422/1653753/0362-028x-45_5_422.pdf by guest on 28 September 2021 Storage ofraw products Temperature changes in a side of raw pork (at the center of a thigh) held overnight at room temperature are Out of oven and to refrigerator shown in Fig. 1. The temperatures were such that * psychrotrophic and mesophilic microorganisms could have multiplied for several hours. ---165°F -- 150° F. Temperatures of strips of raw pork, during marinating in a refrigerator, are shown in Fig. 2. During this period, usual pathogenic foodbome bacteria would not be expected to multiply because of the combined effects of low temperature and salt concentration. Hours Figure 3. Temperatures at geometric center of char siu during cooking in an oven and during cooling in a walk-in refrigerator (F;stablishment A). >-fot:rs Figure 1. Temperatures at center of thigh of side of uncooked pig carcass during hanging at room temperature (F;stablishment G). Hours Figure 4. Temperatures at geometric center of char siu during cooking and during cooling at room temperature and in a walk·in refrigerator I,F;stablishment C). Handling cooked products Hours Cooked pork products were often handled by workers Figure 2. Temperatures of0.6-lb strip of char siu marinating who had previously handled raw meat or raw poultry. in a walk· in refrigerator (F;stablishment F). The cooked products were chopped and sliced on cutting boards with cleavers and knives that were also used for Cooking other purposes. The cooked pork could easily have Time-temperature exposures of char siu during become contaminated during this operations because S. JOURNAL OF FOOD PROTECTION, VOL. 45, APRIL 1982 424 BRYANETAL. ~~~IT 175 325 ~ / :Oven air 150 lL ~~~J~.250 . 125 0 . Q) 225 . 0 0 ~ .2 200 . 1100 ~ 0 . I ~ Q; 175 75 ~ 150j'_ ----150° F----------------------65socl l Char siu E r-- 125 50 100 ~ 75 25 Room air 50 25 0 Downloaded from http://meridian.allenpress.com/jfp/article-pdf/45/5/422/1653753/0362-028x-45_5_422.pdf by guest on 28 September 2021 0~,,-,,-,-,-,,-,-,-,,-"-,~1 0 2 3 4 56 7 8 9101 11213141516171819 Hours Figure 5. Temperatures at geometric center of char siu during cooking and during subsequent holding at room temperature (Establishment E). 500 475 250 450 Oven a1r 225 425 400 375 350 r~7050 lL 325 0 300 I S1de 1 t150 ~ ~ out of oven Q) 2 275 0 • Pork s 1 de 1, S1de 1 .... d 125 250 2 .2 0:; Char stu ( center of cutdup . Q. 225 ~~~eat ~ oolfllflOOOO-VlN t-- E ;emoved th1gh meat ~noved oven 100 E -,olflOO-.D-.D-.D0\"<1" -.D 200 rom ~ven to the ._ i OJ 175 market ; I- '"' '~ • [-75 -------- 150 150o F--.~- -~,~~~=:~/,(;~$;~- =~ -, 65 soc! SO 125 ~ -==.:::::--. Porks1deZ,centerr 100 ----'---- -- =-·- -·of shoulder meat 1 • Center of t ' 25 75 t Meat removed Char stu Side 2 50 from oven and 1nto oven 25 holes poked 0 through sk1n 0 0 4 Hours Figure 6.