Potato starch was hydrolyzed in the presence of HCl and citric or tartaric acids at 130 degrees C for 2 or 3 h, resp., to dexstrins processed then by fermentation by Lactobacillus or Bifidobacterium genus bacteria. Scattering molecular masses of the dextrins were detd. by using exclusion chromatog., while their ay. length of carbohydrate chains by using anion-exchange chromatog. The fermentation yielded MeCH(OH)COOH, AcOH, and, in some cases, HCOOH. Some amts. of EtCOOH, AcH and EtOH were also found in the fermentation products.