Study on Cooling Methods and Their Influence on Outgrowth of Clostridium perfringens Spores in Black Pepper Sauce

• Main Authors: GAN SOO WAH, 顏素華
• Other Authors: Chang, Cheng-Ming
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/9s95ab

碩士 === 國立臺灣海洋大學 === 食品科學系 === 102 === Chilling in “cook-chill” procedure of catering operation should be completed quickly to prevent the germination and growth of pathogen spores that survived from the cooking procedure. Slow cooling operation or inefficient refrigeration storage were major factors for food poisoning cases. Therefore, this study intended to investigate the sufficiency of cooling methods that applicable to small and medium sized catering kitchens, which included ice bath cooling, tap-water cooling, fan cooling and room cooling, and to validate if these cooling methods could perform a good cooling time-temperature control. To estimate the efficiencies of these cooling methods, this study used 0, 3.5%, 4.0%, 4.5% and 5.0% starch contents of black pepper sauce as the study samples. Results showed that starch contents and the initial viscosity had no significant effects on the average cooling rate of different cooling methods. The cooling process of the three types of cooling methods (including ice bath, tap-water, and fan cooling) could be distinguished into two sections by a turning point on each cooling time-temperature curve. The results showed that the cooling rates of first section had a positive correlation with moisture content, and moderate negatively correlated with the initial viscosity and starch contents. This study compared the cooling efficiency of these cooling methods. Ice bath cooling (CM1, CM2 with average cooling rate of 0.47 ~ 0.48 ℃/min) had the best cooling performance, followed by tap-water cooling (CM3, CM4 with average cooling rate of 0.33 ℃/min) and fan cooling (CM5, CM6 with average cooling rate of 0.32 ℃/min), which were much greater than room cooling method (average cooling rate of 0.14℃/min). CM2 (wave, ice bath) had much higher cooling rate than CM1 (still, ice bath), which suggested that shaking and stirring could increase the cooling rate of the sample. The order of the cooling rate, from fastest to slowest were CM1, CM2, CM3, CM4, CM5, CM6 and CM7. Except for ice bath cooling, the other cooling methods were limited by environmental factors, which caused them failed to cool the sample into 21℃ or less. The safety time limit of the cooling process is six hours for the sample starting to be cooled from 60℃. As consideration of the cost-effectiveness of the products cooling, this study recommend the combination of different cooling methods for achieving a better cooling time-temperature control. The control strategies of different cooling methods were established as a reference for small and medium sized catering kitchen. The effect of cooling methods and refrigeration storage were tested by using Reinforced Clostridial agar Medium (RCM) and black pepper sauces with inoculation of C. perfringens. Because of the cold shock due to the magnitude of cooling rate in the first cooling section, C. perfringens did not proliferate in the samples. Levels of C. perfringens decreased 1.23 – 1.84 log CFU/ml in RCM within 12 hours; 1.0 – 1.86 log CFU/g in black peper sauce within 168 hours. C. perfringens survived under refrigeration temperatures for more than 7 days with the levels of less than 106-107 CFU/g.