Ultrasound as a physical treatment of stillage for lactic acid fermentation

In this study, the stillage from the bioethanol production on wasted bread has been used as a substrate for fermentation by lactic acid bacteria. Ultrasound has been studied as a physical treatment of wasted bread stillage before fermentation by Lactobacillus rhamnosus ATCC 7469. In the ultrasound treated sample a 15 % higher lactic acid concentration compared to control sample and lactic acid yield of 0.87 g g-1 were obtained. Ultrasound could significantly increase LA productivity without effect on cell growth. Moreover, the number of viable L. rhamnosus ATCC 7469 cells was found higher in ultrasound treated samples. The study indicated that the ultrasound pretreatment could be effectively applied and used as an alternative to sterilization in lactic acid fermentation of distillery stillage.