Comprising culturing in a liquid medium citrate concentration is 20mM or more, a yeast, a method of culturing the yeast invention citric acid concentration in the liquid medium in the culture at the start and a 20mM less than initiation of culture and before the logarithmic growth phase at the end of the post, a method of culturing the yeast according to the above including the step of adjusting the 20~200mM citric acid concentration in the liquid medium well, and cultured in a culture method in yeast according any of the above from yeasts, including a step of extracting yeast extract, process for producing yeast extract yeast, and is selected from the group consisting of yeast extract prepared from these yeasts were cultured in the culture method of yeast according any of the above comprises using as a raw material of the product that one or more, a process for producing foods and beverages. In accordance with the present invention can provide a method for culturing yeast capable without performing genetic modifications, to increase the glutathione content of cells in the.本発明は、酵母を、クエン酸濃度が20mM以上である液体培地中で培養することを含む、酵母の培養方法;培養開始時における液体培地のクエン酸濃度が20mM未満であり、かつ、培養開始後から対数増殖期終了時までの間に、液体培地のクエン酸濃度を20~200mMに調整する工程を含む前記記載の酵母の培養方法;並びに、前記いずれか記載の酵母の培養方法で培養された酵母から、酵母エキスを抽出する工程を含む、酵母エキスの製造方法;前記いずれか記載の酵母の培養方法で培養された酵母、及びこれらの酵母から調製された酵母エキスからなる群より選択される1以上の製造物を原料として用いることを含む、飲食品の製造方法に関する。本発明によれば、遺伝的な改変を施すことなく、菌体中のグルタチオン含有量を高めることができる酵母の培養方法を提供できる。
