| Summary: | 碩士 === 國立臺灣海洋大學 === 食品科學系 === 99 === The aim of this research are to investigate first the hydrolytic conditions for cellulase to hydrolyze the Ulva lactuca, to ferment the Ulva hydrolysate using lactic acid bacteria (LAB), and finally to investigate the anti-oxidant activity of LAB-fermented Ulva product. The optimal temperature and pH value for cellulose with 5 units/mL to hydrolyze 2% Ulva suspention are 45℃ and pH 6.0, respectively. Five strains including Lactococcus lactis subsp. Lactis BCRC 12315 ,12322, Lactobacillus bulgaricus BCRC 10696, Lb. Plantarum BCRC 10069 and Bifidobacterium parvulorum BCRC 14601 were used as the tested LAB. Except BCRC 12322, the bacteria counts for the rest 4 LAB strains were above 108 CFU/mL after inoculation in Ulva hydrolysate at 37℃ for 8hr. The ferrous-ion chelating activities of Ulva hot extract and Ulva hydrolysate were 81.54% - 97.25%, which were significantly higher than those LAB – formented product (31.41% - 43.29%)
. DPPH scavenging activities of Ulva hydrolysate and LAB – formented Ulva product were very low (3.54% ~ 6.05%). Trolox equivalent antioxidant capacity (TEAC) of raw materials and lactics-fermented Ulva hydrolysate were 290 - 1080μM, Inhibition of ascorbate auto-oxidation the fermented product were 75.06 - 184.33μg (Vit. C Equivalent / mL), total phenolic contcent of the fermented product were 75.50 - 126.89μg/mL. Adding with 3% soybean milk or black bean milk as supplement promoted the growth of LAB obviously and the effects were better than adding 3% red bean milk. In addition, supplanting with 3% black bean milk, the ferrous-ion chelating activity, DPPH scavenging activity, TEAC, inhibition of ascorbate auto - oxidation and total phenolic content were all higher than Ulva hydrolusate supplemented with red and soy beans . All two stains combination contented BCRC 14601 fermented products were above 108 CFU / mL, pH lower than 4.5 after 2 to 4 hours incubation. The fermented products of BCRC 14601 and BCRC 10696 had best flavor, reduction activities, TEAC and all estimated activities were greater than the unfermented raw materials and Ulva hydrolysate significantly. The total phenolic content was 484.02 μg / mL, ferrous-ion chelating activity, DPPH scavenging activity, TEAC and Inhibition of ascorbate auto-oxidation of this combination were 52.57% , 34.92%, 540 μM, and 722.86 μg (Vit. C Equivalent / mL), respectively. This combination had best flavor scores when supplemented with 3% black bean milk , the scores were falvor 6.78 ± 0.89, taste 7.02 ± 0.81, and overall acceptability 7.64 ± 1.05 respectively.
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