Thisprocess could produce more acid and the pH would decrease. Itis inferred that OD and pH are negative correlation, which can beproved from Fig. 4(a). Fig. 4(b) shows the correlation between theOD and DP. It can be seen that the OD of culture medium is largerwith lower DP of inulin as carbon source, which means the inulinwith lower DP has a better prebiotic effect. The figure suggests thatthere is also a negative correlation between DP and OD. Regardingto inference, it should be positive correlation between pH and DP,which is just proved by Fig. 4(c). This indicates that inulin withlower DP can be better used by probiotics. In summary, inulin withlower DP is more active and shows higher degree of utilization. Thisis a significant guidance for the utilization of inulin in industrialproduction.According to these data, we can harvest the tubers at differenttimes to get inulin with different average DP and to improve theutilization of inulin for different purposes. The tubers of Jerusalemartichoke can be harvested at the beginning of flowering or afterthe drying up of leaves and stems to get inulin with low DP whichis reported to be the most active product. Nevertheless, the yieldof inulin should also take into account. In short, with comprehen-sive consideration of inulin content and DP, 50 days or even laterafter flowering may be supposed to be the optimum maturity inNortheastern China.