TABLE 2.
Effect of operational variables (temperature, total initial sugars concentrations, reactor enzyme loading and feed flow rates) on lactulose yield with respect to total lactose reacted (YLu*) and lactulose concentration (CLu) in the synthesis of lactulose in continuous stirred-tank reactor with glyoxyl agarose immobilized A. oryzae β-galactosidase.
| Molar Ratio of Fructose to Lactose |
4 |
8 |
16 |
24 |
||||||
| YLu* | CLu | YLu* | CLu | YLu* | CLu | YLu* | CLu | |||
| (gLu/gLactose total) | (g/L) | (gLu/gLactose total) | (g/L) | (gLu/gLactose total) | (g/L) | (gLu/gLactose total) | (g/L) | |||
| Inlet concentrations of sugar substrates (% w/w) | ||||||||||
| 10 | − | − | − | − | 0.064 | 4.15 | − | − | ||
| 20 | − | − | − | − | 0.137 | 7.51 | − | − | ||
| 30 | − | − | − | − | 0.193 | 8.39 | − | − | ||
| 40 | − | − | − | − | 0.228 | 10.52 | − | − | ||
| 50 | − | − | − | − | 0.246 | 9,19 | − | − | ||
| 60 | − | − | − | − | 0.209 | 7.27 | − | − | ||
| Temperature (°C) | ||||||||||
| 50 | − | − | − | − | 0.246 | 9.14 | − | − | ||
| 60 | − | − | − | − | 0.185 | 7.79 | − | − | ||
| 70 | − | − | − | − | 0.162 | 0.53 | − | − | ||
| Reactor enzyme loading (IUH⋅mL–1) | ||||||||||
| 17.4 | 0.143 | 28.99 | 0.182 | 22.20 | 0.208 | 13.93 | − | − | ||
| 29.06 | 0.149 | 30.19 | 0.193 | 23.60 | 0.246 | 16.43 | − | − | ||
| 58.12 | 0.171 | 34.58 | 0.221 | 26.89 | 0.259 | 17.37 | − | − | ||
| Feed flowrate (mL⋅min–1) | ||||||||||
| 3 | 0.165 | 33.43 | 0.216 | 26.24 | 0.259 | 17.28 | − | − | ||
| 6 | 0.149 | 30.18 | 0.193 | 23.55 | 0.246 | 16.42 | 0.277 | 13.00 | ||
| 9 | 0.122 | 24.76 | 0.183 | 22.24 | 0.245 | 16.40 | 0.276 | 12.87 | ||
| 12 | 0.161 | 32.32 | 0.214 | 26.02 | 0.22 | 15.13 | 0.238 | 11.11 | ||