conditions to reduce the water content to no higher than 8 thirty kilograms of dried soy beans are then ground into particles of no smaller than 20 mesh and added to 130 l of sterile water the mixture is stirred under sterile conditions at room temperature for twelve hours and then centrifuged at 1000 rpm to remove insoluble residues to make the culture medium these extracts are mixed according to the above recipe and the mixture is autoclaved at 121 u00b0 c for 30 minutes and cooled to below 40 u00b0 c before use one thousand grams of the activated yeast powder prepared as described above section v supra is added to 1000 l of the mixed fruit extract solution and the yeast solution is transferred to the first container 1 shown in fig2 the yeast cells are then cultured in the presence of an alternating electric field having a frequency of 18223 mhz and a field strength of about 390 420 mv cm e g 403 407 mv cm at 28 32 u00b0 c under sterile conditions for 16 hours the yeast cells are further incubated in an alternating electric field having a frequency of 18227 mhz and a field strength of 320 350 mv cm e g 333 337 mv cm the culturing continues for another 12 hours the yeast culture is then transferred from the first container 1 to the second container 2 which contains 1000 l of culture medium if need be a new batch of yeast culture can be started in the now available first container 1 and subjected to an alternating electric field having a.