DOX system (DOX-60F/DOX-30F) rapidly evaluates the total number of microorganisms, coliforms and Escherichia coli

#15 Pseudo retort food and Clostridium botulinum


Professor Emeritus at Hokkaido University

Advisor at Japan Food Research Laboratories

Biography of Dr. Isshiki


In late April, Clostridium botulinum caused a group food poisoning at a church in Ohio, United States.  Among more than 50 people who attended the luncheon, one woman died.  21 people were diagnosed as botulism, and 10 as suspect patients.  The causative food was a home-made canned potato salad.  Although Japanese people do not have a custom to make canned or bottled food at home, people in some regions of Western countries have a longtime culture of such diet.


What Japanese people should be concerned about is pseudo retort food, a group of vacuum-packaged foods so-called “semi-retort” or “soft retort”.  You can buy a film bag (pouch) and a household device for easy vacuum packaging at DIY stores.




Some food-processing companies ship enormous amounts of food products without taking measures against Clostridium botulinum such as thorough heat sterilization or adding preservatives.  They misunderstand that distribution at low temperature is enough to prevent Clostridium-botulinum food poisoning.  Also, some distributors and retailers do not understand the difference between retort and pseudo retort foods.


Retort (pouch) foods are described as “contained or packaged foods sterilized by pressure or heat” in the Food Sanitation Act.  As for these types of foods, measures against Clostridium botulinum are required so that they can be handled at ordinary temperature.  Especially, foods with pH over 4.6 and Aw over 0.94 need to be powerfully sterilized.


In 1984, a Clostridium-botulinum mass food poisoning case occurred caused by vacuum-packaged lotus root with mustard manufactured in Kumamoto prefecture.  Along with the opening of the Kumamoto Airport, mustard lotus roots were brought back to all over Japan as a souvenir, and the outbreak of food poisoning spread to 13 cities sickening 31 people and killed 9.



In 2012, a pseudo retort food, azuki-batto, caused a tragedy in Tottori Prefecture (Figure2).  Azuki-batto is a kind of noodle in red-bean soup.  It was produced and vacuum-packaged in Aomori Prefecture designed to be distributed at low temperature.  It was not heated at high temperature which is a requirement for retort foods.  It as a pseudo retort food.  Both of the couple who ate the azuki-batto became seriously ill and they are still in hospital.


Ministry of Health, Labour and Welfare raised an alert over Clostridium-botulinum food poisoning, and Consumer Affairs Agency notified food manufacturers to clearly indicate the need for low-temperature distribution and refrigeration on the packages of pseudo retort foods.  It is necessary for the entire nation to realize a difference between retort and pseudo-retort foods.  Let us avoid repeating the same tragedy through risk communication about refrigeration-needed foods.


A precondition for the safety of pseudo retort foods is securing seamless cold chain (distribution at low temperature).  It is necessary to strive toward transparency by disclosing such efforts as implementing low-temperature storage in the back yards of supermarkets.  Not only Product Liability Act, but other laws making distributors/retailers responsible might need to be prepared.


References (all in Japanese)

1) Kokubo, Y. ed., Genba de Yakudatsu Shokuhin Biseibutsu Q&A (Q&A on food microorganism useful on the spot), 3rd ed., Chuohoki Publishing, p.65 (2011). 

2) Ministry of Health, Labour and Welfare: Measures for vacuum-packaged foods (packaged low-acid foods) against Clostridium-botulinum food poisoning (2012)

 3) Japan Food Research Laboratories: We must remember the threat of Clostridium botulinum, JFRL News, 4 (11), 1-8(2012)

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