and white liquor according to the invention the first retention time for the wood chips between the start of the cooking process i e both the impregnation and cooking zone and the withdrawal of the first withdrawal xyl 1 is shorter than the retention time of the wood chips in the cooking process between the start of the cooking process and the second withdrawal in the figure xyl 1 is drawn off directly at the start of the cooking zone and xyl 2 is drawn off partly into the cooking zone a suitable first retention time is at least 30 minutes in the cooking process and for cooking liquor withdrawn in a subsequent withdrawal these cooking liquors have had increasing retention times between the beginning of the cooking process and the subsequent withdrawal the amount of cooking liquor withdrawn is at least 0 5 1 5 cubic meters comprising dissolved hemicellulose from each withdrawal position and reintroduced to the last phase of the cooking process due to the fact that the first dissolved hemicellulose has a longer chain length and has been in the cooking process the shortest time the first withdrawn cooking liquor xyl 1 with a first content of dissolved hemicellulose may be allowed a longer retention time in the last phase of the cooking process than the cooking liquors which have been withdrawn in subsequent withdrawals and which have also been reintroduced to the last phase of the cooking process the withdrawn cooking liquor xyl 1 of the first withdrawal with a first content of dissolved hemicellulose may also be allowed a longer retention time.