| Summary: | 碩士 === 國立虎尾科技大學 === 生物科技系碩士班 === 105 === In this study, the water extract from 1:10 in w/w of black soybean (Glycine max (L) Merr.)/water was determined to be the culture medium (defined as black soybean water extract; BSWE) for the growth of Lactobacillus plantarum BCRC 10069. The effects of fermentation btime, starter concentration (1%, 5%, 10% (v/v)) and sucrose addition (0, 5, 10, 20 g/L) on the cell viability (defined as viable cell counts; VCCs in CFU/mL) of L. plantarum and on pH value and antioxidant activity (DPPH radical scavenging, total phenolic content (TPC) and reduced power (RP)) of the fermented BSWE were investigated. For starter concentration with different concentrations of sucrose addition, the growth of L. plantarum with 10% starter was litter better than that with 5% one, but much better than that with 1% one. There were no clearly corresponding effect of sucrose addition concentration on VCCs of L. plantarum and medium pH of BSWE for each starter concentration. The VCCs obtained at the 15th hour (hr) fermentation time for 0, 5, 10, 20 g/L sucrose addition with 10% starter rapidly increased up to 1.51, 1.50, 1.54 and 1.56 × 108 CFU/mL, respectively, of L. plantarum with pH values ranging around from 5.5~6.0 (at the 0th hr) to 4.5~4.6 (during the last 15 hr fermentation from 15th hr to 30th hr). There were effects of initial starter concentration that the Therefore, the unfermented BSWE without sucrose addition (0 g/L sucrose) was a prospect media for the growth of L. plantarum BCRC 10069 with 10% starter and the supernatant of the fermented BSWE was collected to estimate its antioxidant activity (DPPH scavenging activity, TPC and RP). The DPPH scavenging activity of the fermented BSWE increased with fermentation time at the first 9 hours (hr) fermentation up to the highest value (81.2%) from 75.4% (at the 0th hr), and then it was kept at an approximate constant value (its range was around 81.2%~83.3%) during the fermentation time of 9 hr to 24 hr. Both of the TPC (defined as gallic acid equivalent; GAE) and RP (defined as vitamin C equivalent; Vit.CE) decreased with fermentation time. The corresponding values were obtained from 0.082 mg GAE/mL and 0.28 mg Vit.CE/mL, respectively (at the 0th hr), to 0.053 mg GAE/mL and 0.24 mg Vit.CE/mL), respectively (at the 24th hr). However, the BSWE is the suitable culture medium for the growth of L. plantarum and the supernatant of the unfermented BSWE may be someday used as a health-value favorite beverage without probiotics of lactic acid bacteria.
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