Enhancement of gamma-aminobutyric acid in a fermented red seaweed beverage by starter culture Lactobacillus plantarum DW12

Lactobacillus plantarum DW12, a gamma-aminobutyric acid (GABA) producing strain, was used as a starter culture to produce a functional fermented red seaweed beverage (FSB). Optimal conditions for producing FSB were established using Central Composite Design by varying the amounts of monosodium glutamate (MSG), sucrose and the initial pH in MRS medium. After a verification test, 1 percent MSG, 6 percent sucrose and an initial pH of 6 were selected. Four treatments were tested: traditional formula (A), red seaweed-cane sugar-potable water = 3:1:10, w/w/v, initial pH 6; the traditional formula with a 5 percent starter culture consisting of 4.1 x 10(9) CFU of DW 12/ml (B); formula A modified by changing the amounts of cane sugar and MSG to 6 percent and 1 percent, respectively (C); formula C with a 5 percent starter culture added (D). Comparison among the 4 treatments showed that the treatment D produced the highest amount of GABA (4000 mg/L) during days 45-60 while the GABA content of A, B and C treatments was 340, 730 and 1690 mg/L, respectively. However, the results of the sensory test for the treatments C and D showed that the presence of MSG produced an unsatisfactory salty taste. All finished products from the 4 treatments met Thai standard guidelines for chemical and microbiological qualities after 120 days. The results indicated that enrichment of the GABA content in FSB is possible by adding MSG and the GABA producing strain DW12; however, the appropriate amount of MSG addition should be further studied.

Characterization of the antiyeast compound and probiotic properties of a starter lactobacillus plantarum DW3 for possible use in fermented plant beverages

Lactobacillus plantarum DW3 produced antifungal compounds that inhibited the growth of Rhodotorula mucilaginosa DKA, contaminating yeast in fermented plant beverages (FPBs) and various potential human pathogens. Phenyllactic acid (PLA) identified by gas chromatography- mass spectrometry (GC-MS) was produced at 31 mg/L PLA in MRS medium and 5 mg/ml inhibited growth of the target yeast in vitro by 90 percent. Other inhibitors were also present but not specifically identified. Results of in vitro tests showed that DW3 also had probiotic properties as it survived various human biological barriers resistance to pH 3, bile salts, growth without vitamin B12 and the presence and absence of oxygen. Its inhibitory effect against food borne pathogenic bacteria and spoilage organisms was higher than that found for a commercial strain Lactobacillus casei R. An acute oral toxicity test on ICR mice at a high single dose of either 10(9) and 10(12) cells per mouse for 14 days showed that DW3 had no adverse effect on the general health status and there was no evidence of bacteremia. Mice fed DW3 had a reduced weight gain compared to the control. No significant difference (p > 0.05) was found for the spleen weight index (SWI) among the treatment and control groups whereas there was a significant difference (p < 0.05) for the liver weight ratio (LWR) in a group fed with 10(12) cells per mouse when compared with the control group.