ピザ用チーズ中のＬｉｓｔｅｒｉａ ｍｏｎｏｃｙｔｏｇｅｎｅｓの保存および加熱調理時の挙動 Behavior of Listeria monocytogenes in Shredded Cheese During Strage and Cooking.
<I>Listeria monocytogenes</I> (<I>L. m</I>. ) in shredded cheese was examined for its growth behavior during cold storage and cooking. During storage at 5°C, the concentration after inoculation decreased up to day 20 and thereafter increased. On day 77, the concentration was recovered to almost the same level as that at the time of inoculation, in shredded cheese inoculated with 10<SUP>4</SUP> or 10<SUP>6</SUP>/g <I>L.m</I>. and increased by 1-2 orders in shredded cheese inoculated with 10<SUP>1</SUP>/g <I>L .m</I>. . Also during storage at 10°, the inoculated <I>L.m</I>. decreased up to day 20 and thereafter increased, each bacterial concentration increased by 1-4 orders. Organoleptically, fungigenesis occurred from days 20 and 15 at 5° and 10°, respectively. The number of bacteria surviving in the pizza inoculated with 10<SUP>6</SUP>/g <I>L.m</I>. was 3.6-23/100 g after heating at 200°C for 5 min, while heating at 250°C for 5 min caused the death of all the inoculated bacteria, that is 10<SUP>6</SUP>/g. The change of the temperature at the center of the pizza while cooking tended to decrease with the increases in the temperature of storage and in the volume of ingredients, and these changes were also macroscopically recognizable.<BR>The above findings suggested that <I>L. m</I>. in shredded cheese dose not proliferate during the allowable period of storage before consumption and becomes extinct with general methods of cooking.
日本食品微生物学会雑誌 11(1), 29-33, 1994