Fate of Escherichia coli O157 cells was evaluated when inoculated into each step after production... more Fate of Escherichia coli O157 cells was evaluated when inoculated into each step after production of lightly pickled Chinese cabbage. The efficacy of surface sterilization by 100 mg/L of chlorine water for 10 min on raw leaves (6.0 log CFU/g) was 2.2 log CFU/g reduction. No meaningful change of the population of E. coli O157 (3.5 log CFU/g to 1.5 log MPN/g) contaminated into 19 kinds of products was observed. These results indicated the difficulty of estimating the viable count of the cells between contaminated on farms and further processing and storage steps. The population of E. coli O157 (3 log CFU/g to 1 log MPN/g) inoculated into the Chinese cabbage products was reduced less than 0.6 log CFU/g after 2 h-incubation at 37℃ in artificial gastric juice. Prevention from initial contamination of E. coli O157 on the ingredients of Chinese cabbage products is important to reduce the risk of food poisoning because the reduction of the bacterial counts after processing and consumption a...
Commons Attribution (CC BY) license, which allows users to download, copy and build upon publishe... more Commons Attribution (CC BY) license, which allows users to download, copy and build upon published articles, as long as the author and publisher are properly credited, which ensures maximum dissemination and a wider impact of our publications. The book as a whole is distributed by MDPI under the terms and conditions of the Creative Commons license CC BY-NC-ND.
The modern food industry has developed and expanded because of its ability to deliver a wide vari... more The modern food industry has developed and expanded because of its ability to deliver a wide variety of high quality food products to consumers on a nationwide and worldwide basis. This feat has been accomplished by building stability into the products through processing, packaging, and additives that enable foods to remain fresh and wholesome throughout the distribution process. Total quality is the paramount importance and consumer's perception on the product is the ultimate measure of total quality. The quality of most foods decreases over time; in other words, there is a continual loss of quality from the time they leave the food processor until they are consumed, even under ideal handling conditions. Shelf-life studies can provide important information to minimize the extent of quality degradation to product developers enabling them to ensure that the consumer will see a high quality product for a significant period of time after production. Review ῌ305῍8642 ῎῍῏ΐῐ̮ 2῍1῍12
The majority of the seed sprout-related outbreaks have been associated with Escherichia coli O157... more The majority of the seed sprout-related outbreaks have been associated with Escherichia coli O157:H7. Therefore, it is necessary to find an effective method to inactivate these organisms on the seeds prior to sprouting. This study was conducted to assess the effectiveness of repeated quick hot-and-chilling treatments with various chemicals to inactivate E. coli O157:H7 populations inoculated onto mung bean and radish seeds intended for sprout production and to determine the effect of these treatments on seed germination. The treatment time was 20 sec for quick hot and 20 sec for quick chilling in one repeat. Likewise up to five repeats were done throughout the experiments. The chemicals used for this study were electrolyzed acidic (EO) water, phytic acid (0.05%), oxalic acid (3%), surfcera(R), and alpha-torino water(R), and distilled water was used as control. The quick hot treatment was done with 75 degrees C, 70 degrees C, and 60 degrees C, and the chilling temperature was 0 degrees C. The treated seeds were then assessed for the efficacy of this treatment in reducing populations of the pathogens and the effects of repeated quick hot-and-chilling treatments on germination yield. It was found that repeating treatment at 75 degrees C for two or three repeats with phytic acid and oxalic acid could reduce 4.38-log colony-forming unit (CFU)/g of E. coli O157:H7 in mung bean seeds. EO water and distilled water were found equally effective at 75 degrees C for four or five repeats to inactivate E. coli O157:H7 in mung bean seeds. However, alpha-torino water(R) and surfcera(R) were not found effective in comparison to other sanitizers used in this experiment. Irrespective of sanitizer used, the germination yield of the mung bean seed was not affected significantly. On the other hand, distilled water, EO water, and alpha-torino water(R) at 75 degrees C for five repeats were found effective in reducing 5.80-log CFU/g of E. coli O157:H7 in radish seeds; however, the germination yield of the seed was affected significantly. Therefore, repeated quick hot-and-chilling treatments could be useful to decontaminate mung bean seeds intended for sprout production.
The survival of gram-positive and gram-negative foodborne pathogens in both commercial and labora... more The survival of gram-positive and gram-negative foodborne pathogens in both commercial and laboratory-prepared kimchi (a traditional fermented food widely consumed in Japan) was investigated. It was found that Escherichia coli O157:H7, Salmonella Enteritidis, Staphylococcus aureus, and Listeria monocytogenes could survive in both commercial and laboratoryprepared kimchi inoculated with these pathogens and incubated at 10ЊC for 7 days. However, when incubation was prolonged, the S. aureus level decreased rapidly from the initial inoculum level to the minimum detectable level within 12 days, whereas Salmonella Enteritidis and L. monocytogenes took 16 days to reach similar levels in commercial kimchi. On the other hand, E. coli O157:H7 remained at high levels throughout the incubation period. For laboratory-prepared kimchi, the S. aureus level decreased rapidly from the initial inoculum level to the minimum detectable level within 12 days, and L. monocytogenes took 20 days to reach a similar level. E. coli O157:H7 and Salmonella Enteritidis remained at high levels throughout the incubation period. The results of this study suggest that the contamination of kimchi with E. coli O157:H7, Salmonella Enteritidis, S. aureus, or L. monocytogenes at any stage of production or marketing could pose a potential risk.
Process hygiene plays a major role in the production of high quality food. Knowledge of microorga... more Process hygiene plays a major role in the production of high quality food. Knowledge of microorganisms found in food processing environment and the control of microbial fouling are both essential in the prevention of microbial deterioration of food. Food industries must maintain their premises at a high standard of cleanliness and hygiene to ensure that there is no accumulation of garbage, recycled matter, food waste, dirt, grease, or other visible matter. Food utensils and equipment must be cleaned and sanitized before each use and between being used for raw food and ready to eat food. Numerous and costly cases of food spoilage and unacceptable contamination with pathogenic bacteria have been traced back to failures or insufficiencies of these procedures. Therefore, high standards of hygiene are required to avoid such problems.
In this study, we evaluated the ability of waste shell powder (WSP) and moringa seed powder (MSP)... more In this study, we evaluated the ability of waste shell powder (WSP) and moringa seed powder (MSP) individually or in combination to eliminate dye, heavy metal and resistant bacteria from the industrial wastewater (IWW). The presence of dyes, heavy metals, approximately 7.0 log CFU/ml of aerobic bacteria and 3.0-4.0 log CFU/ml of other pathogens including Escherichia coli, Pseudomonas aeruginosa, Citrobacter freundii, Serratia liquefaciens and Bacillus cereus was evident in IWW of both tannery and textile industries. In addition, depending on the type of bacterial species each bacterium was resistant to as high as 50 ppm of multi-metal (Cr 6+ , Cd 2+ and Pb 2+ or its combination) and even multi-drug resistant (amoxicillin, ampicillin, cefixime, ceftazidime, and tazobactam). Combined use of MSP (0.8 gm/100 ml IWW) and WSP (0.2 gm/100 ml IWW) treatment was able to discolor the IWW within 4 h and took 24 h to eliminate heavy metals and pathogenic bacteria to non-detectable level from the IWW, simultaneously. On the other hand, individual use of MSP or WSP was not found effective enough to remove or eliminate dye, heavy metal and bacteria simultaneously from the IWW. Similar experimental results were observed in the challenge test with laboratory-prepared effluent water containing 35.0 ppm Remazol Brilliant Blue R dye and maximum 50 ppm Cr 6+. Thus, the combination of these two bio-sorbents could be applicable in IWW treatment before being discharged into the environment.
We investigated the heat resistance of a four-strain mixture of Escherichia coli O157:H7 in raw g... more We investigated the heat resistance of a four-strain mixture of Escherichia coli O157:H7 in raw ground beef in both the absence and presence of white and green tea powders and an apple skin extract. Inoculated meat was cooked using the sousvide technique, i.e., the meat was packaged in sterile bags and completely immersed in a circulating water bath at low temperature for a period of time. The bags were cooked for 1 h to an internal temperature of 55, 58, 60, or 62.5ЊC, and then held from 240 min at 55ЊC to 10 min at 62.5ЊC. The surviving bacteria were enumerated by spiral plating onto tryptic soy agar overlaid with sorbitol-MacConkey agar. Inactivation kinetics of the pathogens deviated from first-order kinetics. D-values (time, in minutes, required for the bacteria to decrease by 90%) in the control beef ranged from 67.79 min at 55ЊC to 2.01 min at 62.5ЊC. D-values determined by a logistic model ranged from 36.22 (D 1 , the D-value of a major population of surviving cells) and 112.79 (D 2 , the D-value of a minor subpopulation) at 55ЊC to 1.39 (D 1) and 3.00 (D 2) at 62.5ЊC. A significant increase (P Ͻ 0.05) in the sensitivity of the bacteria to heat was observed with the addition of 3% added antimicrobials. D-value reductions of 62 to 74% were observed with apple powder and 18 to 58% with tea powders. Thermal death times from this study will assist the retail food industry to design cooking regimes that ensure the safety of beef contaminated with E. coli O157:H7.
Fate of Escherichia coli O157 cells was evaluated when inoculated into each step after production... more Fate of Escherichia coli O157 cells was evaluated when inoculated into each step after production of lightly pickled Chinese cabbage. The efficacy of surface sterilization by 100 mg/L of chlorine water for 10 min on raw leaves (6.0 log CFU/g) was 2.2 log CFU/g reduction. No meaningful change of the population of E. coli O157 (3.5 log CFU/g to 1.5 log MPN/g) contaminated into 19 kinds of products was observed. These results indicated the difficulty of estimating the viable count of the cells between contaminated on farms and further processing and storage steps. The population of E. coli O157 (3 log CFU/g to 1 log MPN/g) inoculated into the Chinese cabbage products was reduced less than 0.6 log CFU/g after 2 h-incubation at 37℃ in artificial gastric juice. Prevention from initial contamination of E. coli O157 on the ingredients of Chinese cabbage products is important to reduce the risk of food poisoning because the reduction of the bacterial counts after processing and consumption a...
Commons Attribution (CC BY) license, which allows users to download, copy and build upon publishe... more Commons Attribution (CC BY) license, which allows users to download, copy and build upon published articles, as long as the author and publisher are properly credited, which ensures maximum dissemination and a wider impact of our publications. The book as a whole is distributed by MDPI under the terms and conditions of the Creative Commons license CC BY-NC-ND.
The modern food industry has developed and expanded because of its ability to deliver a wide vari... more The modern food industry has developed and expanded because of its ability to deliver a wide variety of high quality food products to consumers on a nationwide and worldwide basis. This feat has been accomplished by building stability into the products through processing, packaging, and additives that enable foods to remain fresh and wholesome throughout the distribution process. Total quality is the paramount importance and consumer's perception on the product is the ultimate measure of total quality. The quality of most foods decreases over time; in other words, there is a continual loss of quality from the time they leave the food processor until they are consumed, even under ideal handling conditions. Shelf-life studies can provide important information to minimize the extent of quality degradation to product developers enabling them to ensure that the consumer will see a high quality product for a significant period of time after production. Review ῌ305῍8642 ῎῍῏ΐῐ̮ 2῍1῍12
The majority of the seed sprout-related outbreaks have been associated with Escherichia coli O157... more The majority of the seed sprout-related outbreaks have been associated with Escherichia coli O157:H7. Therefore, it is necessary to find an effective method to inactivate these organisms on the seeds prior to sprouting. This study was conducted to assess the effectiveness of repeated quick hot-and-chilling treatments with various chemicals to inactivate E. coli O157:H7 populations inoculated onto mung bean and radish seeds intended for sprout production and to determine the effect of these treatments on seed germination. The treatment time was 20 sec for quick hot and 20 sec for quick chilling in one repeat. Likewise up to five repeats were done throughout the experiments. The chemicals used for this study were electrolyzed acidic (EO) water, phytic acid (0.05%), oxalic acid (3%), surfcera(R), and alpha-torino water(R), and distilled water was used as control. The quick hot treatment was done with 75 degrees C, 70 degrees C, and 60 degrees C, and the chilling temperature was 0 degrees C. The treated seeds were then assessed for the efficacy of this treatment in reducing populations of the pathogens and the effects of repeated quick hot-and-chilling treatments on germination yield. It was found that repeating treatment at 75 degrees C for two or three repeats with phytic acid and oxalic acid could reduce 4.38-log colony-forming unit (CFU)/g of E. coli O157:H7 in mung bean seeds. EO water and distilled water were found equally effective at 75 degrees C for four or five repeats to inactivate E. coli O157:H7 in mung bean seeds. However, alpha-torino water(R) and surfcera(R) were not found effective in comparison to other sanitizers used in this experiment. Irrespective of sanitizer used, the germination yield of the mung bean seed was not affected significantly. On the other hand, distilled water, EO water, and alpha-torino water(R) at 75 degrees C for five repeats were found effective in reducing 5.80-log CFU/g of E. coli O157:H7 in radish seeds; however, the germination yield of the seed was affected significantly. Therefore, repeated quick hot-and-chilling treatments could be useful to decontaminate mung bean seeds intended for sprout production.
The survival of gram-positive and gram-negative foodborne pathogens in both commercial and labora... more The survival of gram-positive and gram-negative foodborne pathogens in both commercial and laboratory-prepared kimchi (a traditional fermented food widely consumed in Japan) was investigated. It was found that Escherichia coli O157:H7, Salmonella Enteritidis, Staphylococcus aureus, and Listeria monocytogenes could survive in both commercial and laboratoryprepared kimchi inoculated with these pathogens and incubated at 10ЊC for 7 days. However, when incubation was prolonged, the S. aureus level decreased rapidly from the initial inoculum level to the minimum detectable level within 12 days, whereas Salmonella Enteritidis and L. monocytogenes took 16 days to reach similar levels in commercial kimchi. On the other hand, E. coli O157:H7 remained at high levels throughout the incubation period. For laboratory-prepared kimchi, the S. aureus level decreased rapidly from the initial inoculum level to the minimum detectable level within 12 days, and L. monocytogenes took 20 days to reach a similar level. E. coli O157:H7 and Salmonella Enteritidis remained at high levels throughout the incubation period. The results of this study suggest that the contamination of kimchi with E. coli O157:H7, Salmonella Enteritidis, S. aureus, or L. monocytogenes at any stage of production or marketing could pose a potential risk.
Process hygiene plays a major role in the production of high quality food. Knowledge of microorga... more Process hygiene plays a major role in the production of high quality food. Knowledge of microorganisms found in food processing environment and the control of microbial fouling are both essential in the prevention of microbial deterioration of food. Food industries must maintain their premises at a high standard of cleanliness and hygiene to ensure that there is no accumulation of garbage, recycled matter, food waste, dirt, grease, or other visible matter. Food utensils and equipment must be cleaned and sanitized before each use and between being used for raw food and ready to eat food. Numerous and costly cases of food spoilage and unacceptable contamination with pathogenic bacteria have been traced back to failures or insufficiencies of these procedures. Therefore, high standards of hygiene are required to avoid such problems.
In this study, we evaluated the ability of waste shell powder (WSP) and moringa seed powder (MSP)... more In this study, we evaluated the ability of waste shell powder (WSP) and moringa seed powder (MSP) individually or in combination to eliminate dye, heavy metal and resistant bacteria from the industrial wastewater (IWW). The presence of dyes, heavy metals, approximately 7.0 log CFU/ml of aerobic bacteria and 3.0-4.0 log CFU/ml of other pathogens including Escherichia coli, Pseudomonas aeruginosa, Citrobacter freundii, Serratia liquefaciens and Bacillus cereus was evident in IWW of both tannery and textile industries. In addition, depending on the type of bacterial species each bacterium was resistant to as high as 50 ppm of multi-metal (Cr 6+ , Cd 2+ and Pb 2+ or its combination) and even multi-drug resistant (amoxicillin, ampicillin, cefixime, ceftazidime, and tazobactam). Combined use of MSP (0.8 gm/100 ml IWW) and WSP (0.2 gm/100 ml IWW) treatment was able to discolor the IWW within 4 h and took 24 h to eliminate heavy metals and pathogenic bacteria to non-detectable level from the IWW, simultaneously. On the other hand, individual use of MSP or WSP was not found effective enough to remove or eliminate dye, heavy metal and bacteria simultaneously from the IWW. Similar experimental results were observed in the challenge test with laboratory-prepared effluent water containing 35.0 ppm Remazol Brilliant Blue R dye and maximum 50 ppm Cr 6+. Thus, the combination of these two bio-sorbents could be applicable in IWW treatment before being discharged into the environment.
We investigated the heat resistance of a four-strain mixture of Escherichia coli O157:H7 in raw g... more We investigated the heat resistance of a four-strain mixture of Escherichia coli O157:H7 in raw ground beef in both the absence and presence of white and green tea powders and an apple skin extract. Inoculated meat was cooked using the sousvide technique, i.e., the meat was packaged in sterile bags and completely immersed in a circulating water bath at low temperature for a period of time. The bags were cooked for 1 h to an internal temperature of 55, 58, 60, or 62.5ЊC, and then held from 240 min at 55ЊC to 10 min at 62.5ЊC. The surviving bacteria were enumerated by spiral plating onto tryptic soy agar overlaid with sorbitol-MacConkey agar. Inactivation kinetics of the pathogens deviated from first-order kinetics. D-values (time, in minutes, required for the bacteria to decrease by 90%) in the control beef ranged from 67.79 min at 55ЊC to 2.01 min at 62.5ЊC. D-values determined by a logistic model ranged from 36.22 (D 1 , the D-value of a major population of surviving cells) and 112.79 (D 2 , the D-value of a minor subpopulation) at 55ЊC to 1.39 (D 1) and 3.00 (D 2) at 62.5ЊC. A significant increase (P Ͻ 0.05) in the sensitivity of the bacteria to heat was observed with the addition of 3% added antimicrobials. D-value reductions of 62 to 74% were observed with apple powder and 18 to 58% with tea powders. Thermal death times from this study will assist the retail food industry to design cooking regimes that ensure the safety of beef contaminated with E. coli O157:H7.
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