Study on the Acetic Acid Fermentation from Eucheuma sp. and Bioactivities of Its Product

• Main Authors: Cheng, Jingyue, 鄭景龠
• Other Authors: Pan, Chorng-Liang
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/wt6wxv

碩士 === 國立臺灣海洋大學 === 食品科學系 === 107 === The aim of this study is to produce acetic acid from Eucheuma sp. by fermentation and to analyze bioactivities of its fermentation product. The experiment is divided into three-stage fermentation, the first stage is monosaccharification, the second stage is fermentation of ethanol, and the third stage is fermentation of acetic acid. In the first stage, using 0.4 N HCl hot acid extract for 30 min , 0.5% cellulase treatment for 24 h then using induced crude enzyme (2.5% from Pseudomonas vesicularis MA103 and 2.5% from Aeromonas salmonicida MAEF108) treatment on 5% (w/v) Eucheuma sp. powder for 24 h, the composition of total and reducing sugar in Eucheuma sp. hydrolysate were 18.98 and 16.36 mg/mL, respectively. However, the total sugar required for ethanol fermentation and acetic acid fermentation from Eucheuma sp. is greater than that measured by Eucheuma sp. hydrolysate. Therefore, the polysaccharides in Eucheuma sp., including agar, carrageenan, and cellulose, were tested by phenol-sulfuric acid assay, the control group was potato starch. The OD480nm of agar, carrageenan, and cellulose were 90%, 58-89% and 40% of the control group, respectively. It is speculated that some substances degraded by sulfuric acid not be colored with phenol or sulfuric acid, so the concentration of total sugar should be 20-45 mg/mL. Because Acetobacter orleanensis BCRC 11070 and A. pasteurianus BCRC 10938 can not grow in broth with 1% NaCl, the Eucheuma sp. hydrolysate was treated with electrodialysis with 18.2 voltage, and the salt content droped from 11.03 to 0.03 g/L meansure by mohr method, and the concentrations of total and reducing sugar were not statistically significantly different. In the second stage, the desalted hydrolysate of Eucheuma sp. inoculate with various groups of Saccharomyces cerevisiae including strains BCRC 21550, BCRC 21686, and BCRC 21812 to produce ethanol, and the ethanol concentrations of 72 h fermented solution showed 1.19-1.45 mg/mL, and the yield were between 19.0-23.1%. In the third stage, different strains of Acetobactor sp. were inoculated into desalted Eucheuma sp. ethanol fermentation broth, 6% A. orleanensis BCRC 11070 and 12% A. pasteurianus BCRC 10938 resulted higher acetic acid yields, which were 17.55% and 3.05%, respectively. Euc-AA-42 was product of acetic acid fermentation from Eucheuma sp., which fermemted by 4% A. orleanensis BCRC 11070 and 2% A. pasteurianus BCRC 10938. Euc-AA-42 as compered to other group present higher acetic acid concentration and yield, which were 0.76% and 18.70%, respectively. In bioactivities experiments, Euc-AA-24 was product of acetic acid fermentation from Eucheuma sp., which fermemted by 2% A. orleanensis BCRC 11070 and 4% A. pasteurianus BCRC 10938. Euc-AA-24 in 50% concentration showed higher DPPH free radicals scavenging effect 74.94%. Euc-AA-66 was product of acetic acid fermentation from Eucheuma sp., which fermemted by 6% A. orleanensis BCRC 11070 and 6% A. pasteurianus BCRC 10938. Euc-AA-66 in 100% concentration showed higher reducing power that is equal to 425.80 μg/mL Trolox. Euc-AA-66 was product of acetic acid fermentation from Eucheuma sp., which fermemted by 6% A. orleanensis BCRC 11070. Euc-AA-66 in 25% concentration showed higher ACE inhibition rate, which was 94.00%. In conclusion, for Eucheuma sp. could produce 0.76% acetic acid, and Eucheuma sp. acetic acid fermentation product showed antioxidative and ACE inhibition activity.