Abstract: Objective: Mixed tumorous stem mustard and carrot juices and skim milk were fermented by mixed lactic acid bacteria to develop a fermented milk beverage. Methods: The fermentation starter was composed of Streptococcus thermophiles, Lactobacillus planetarium and Lactobacillus acidophilus. One-factor-at-a-time experiments and a five-variable, four-level orthogonal array design were used to determine optimal fermentation conditions based on acid production and viable lactic acid bacterial count. Results: The optimal fermentation starter was a 1:1:1 mixture of Streptococcus thermophiles, Lactobacillus planetarium and Lactobacillus acidophilus. The optimal fermentation conditions were 6:4 of ratio of tumorous stem mustard to carrot juices, 4% skim milk, 2% of inoculum size, 40 ℃ of fermentation temperature and 24 h of fermentation time. The optimal amounts of sucrose, citric acid, sodium carboxy methyl cellulose (CMC-Na) and xanthan gum added to the fermentation broth were 4%, 0.04%, 0.2% and 0.03%, respectively.

Key words: tumorous stem mustard, carrot, lactic acid bacteria, fermentation