The degradation rate of Volatile Fatty Acids (VFAs) produced predominantly in the acidogenesis stage is a key process parameter to be optimised to ensure a successful Anaerobic digestion (AD). Thermodynamically, the o...The degradation rate of Volatile Fatty Acids (VFAs) produced predominantly in the acidogenesis stage is a key process parameter to be optimised to ensure a successful Anaerobic digestion (AD). Thermodynamically, the oxidation of the VFAs are energetically unfavourable, and as such external energy source apart from the energy derived from the hydrolysis of Adenosine Triphosphate (ATP) is needed for the initial activation of the VFAs, initial growth of the methanogens in AD process and improved degradation rate of the VFAs. Thus, this research investigated the influence of polyphosphate hydrolysis on the degradation rate of the VFAs at high concentration. Sodium-propionate, Sodium-butyrate and Sodium-acetate salts were added at the start of experiments in order to increase the concentration of the VFAs. The polyphosphate salts used were;Na-hexametaphosphate, Na-tripolyphosphate and potassium pyrophosphate. The control experiment was polyphosphate free and three process parameters (degradation rate, cumulative biogas production and specific methane content) of anaerobic digestion were investigated. The experiments were carried out at a mesophilic temperature of 37.5°C for 41 days. The results of the investigation showed that the treated reactors with the polyphosphate salt solution in low concentration performed better than the reactors with high concentration of the polyphosphate salts solution. All the treated reactors with poly-P salts performed better than reactor Nr-9 (control experiment), but reactor Nr-1 was outstanding with an improved degradation rate of 47%, cumulative biogas production of 21% and specific methane content of 23%.展开更多
为探究发酵温度对低盐虾酱中风味物质的影响,分别在10、15、20℃和25℃进行虾酱的自然发酵,分别使用高效液相色谱法、气相色谱法和气相色谱-离子迁移谱测定虾酱中的游离氨基酸、游离脂肪酸和挥发性化合物。结果表明,在低盐虾酱中均检测...为探究发酵温度对低盐虾酱中风味物质的影响,分别在10、15、20℃和25℃进行虾酱的自然发酵,分别使用高效液相色谱法、气相色谱法和气相色谱-离子迁移谱测定虾酱中的游离氨基酸、游离脂肪酸和挥发性化合物。结果表明,在低盐虾酱中均检测出17种游离氨基酸和26种游离脂肪酸,10℃发酵的虾酱中呈味氨基酸含量最高,20℃发酵的虾酱中游离脂肪酸含量最高。在低盐虾酱中共鉴定出69种挥发性化合物,包括醇类19种、醛类13种、酮类13种、酯类12种、烯类2种、醚类2种、酸类1种和其他化合物7种。10℃和15℃发酵的虾酱中醇类、酮类的相对含量较高;20℃和25℃发酵的虾酱中氨的相对含量较高。挥发性化合物的主成分分析表明,不同温度发酵的低盐虾酱中挥发性化合物可显著区分。通过正交偏最小二乘判别分析,结合变量投影重要性(variable importance in projection,VIP),共筛选出6种差异挥发性化合物(VIP>1,P<0.05),分别为3-甲基丁醇(单体及二聚体)、乙酸乙酯二聚体、丙烯酸乙酯、2-甲基丁醛二聚体和氨。聚类热图分析表明,10℃和15℃发酵的低盐虾酱风味较相似,20℃和25℃发酵的低盐虾酱风味较相似。该研究结果为推进商品化低盐虾酱的恒温发酵提供了理论参考。展开更多
文摘The degradation rate of Volatile Fatty Acids (VFAs) produced predominantly in the acidogenesis stage is a key process parameter to be optimised to ensure a successful Anaerobic digestion (AD). Thermodynamically, the oxidation of the VFAs are energetically unfavourable, and as such external energy source apart from the energy derived from the hydrolysis of Adenosine Triphosphate (ATP) is needed for the initial activation of the VFAs, initial growth of the methanogens in AD process and improved degradation rate of the VFAs. Thus, this research investigated the influence of polyphosphate hydrolysis on the degradation rate of the VFAs at high concentration. Sodium-propionate, Sodium-butyrate and Sodium-acetate salts were added at the start of experiments in order to increase the concentration of the VFAs. The polyphosphate salts used were;Na-hexametaphosphate, Na-tripolyphosphate and potassium pyrophosphate. The control experiment was polyphosphate free and three process parameters (degradation rate, cumulative biogas production and specific methane content) of anaerobic digestion were investigated. The experiments were carried out at a mesophilic temperature of 37.5°C for 41 days. The results of the investigation showed that the treated reactors with the polyphosphate salt solution in low concentration performed better than the reactors with high concentration of the polyphosphate salts solution. All the treated reactors with poly-P salts performed better than reactor Nr-9 (control experiment), but reactor Nr-1 was outstanding with an improved degradation rate of 47%, cumulative biogas production of 21% and specific methane content of 23%.
文摘为探究发酵温度对低盐虾酱中风味物质的影响,分别在10、15、20℃和25℃进行虾酱的自然发酵,分别使用高效液相色谱法、气相色谱法和气相色谱-离子迁移谱测定虾酱中的游离氨基酸、游离脂肪酸和挥发性化合物。结果表明,在低盐虾酱中均检测出17种游离氨基酸和26种游离脂肪酸,10℃发酵的虾酱中呈味氨基酸含量最高,20℃发酵的虾酱中游离脂肪酸含量最高。在低盐虾酱中共鉴定出69种挥发性化合物,包括醇类19种、醛类13种、酮类13种、酯类12种、烯类2种、醚类2种、酸类1种和其他化合物7种。10℃和15℃发酵的虾酱中醇类、酮类的相对含量较高;20℃和25℃发酵的虾酱中氨的相对含量较高。挥发性化合物的主成分分析表明,不同温度发酵的低盐虾酱中挥发性化合物可显著区分。通过正交偏最小二乘判别分析,结合变量投影重要性(variable importance in projection,VIP),共筛选出6种差异挥发性化合物(VIP>1,P<0.05),分别为3-甲基丁醇(单体及二聚体)、乙酸乙酯二聚体、丙烯酸乙酯、2-甲基丁醛二聚体和氨。聚类热图分析表明,10℃和15℃发酵的低盐虾酱风味较相似,20℃和25℃发酵的低盐虾酱风味较相似。该研究结果为推进商品化低盐虾酱的恒温发酵提供了理论参考。
