# Optimization of Xylose Recovery in Oil Palm Empty Fruit Bunches for Xylitol Production
## 3 Results
### The Effects of SL, Temperature, and Time on Xylose Recovery  
The effects of SL, temperature, and time on xylose recovery in the hydrolysate of solid and liquid pretreated OPEFB are shown in Figure 1a,b, respectively. Figure 1: The factorial plot of the main effects of solid loading (SL), temperature, and pretreatment time on (**a**) xylose recovery in solid pretreated oil palm empty fruit bunch (OPEFB) hydrolysate and (**b**) xylose recovery in liquid pretreated OPEFB hydrolysate. The results in Figure 1a,b showed that SL, temperature, and pretreatment time affected the xylose recovery in solid and liquid pretreated OPEFB hydrolysate. Every single line showed a slope that represented effects of magnitude, where a steeper slope designates greater magnitude of the effects. The SL of 10% was associated with the maximum xylose recovery in the hydrolysate of solid pretreated OPEFB (Figure 1a), and the pretreatment time of 37.5 min was associated with the highest xylose recovery in solid pretreated OPEFB hydrolysate (Figure 1a). A temperature of 165 \({}^{\circ}\)C was associated with the highest xylose recovery as shown in Figure 1a,b. The SL of 10% and pretreatment time of 37.5 min showed the highest xylose recovery on the hydrolysate of solid pretreated OPEFB. On the contrary, the SL of 10% and pretreatment time of 37.5 min in Figure 1b showed the lowest xylose recovery in the hydrolysate of liquid pretreated OPEFB. To ensure the main effect in the plot, the ANOVA result is shown in Table 2.  
Analysis of variance (Table 2) showed that temperature had a significant effect with a \(p\)-value of 0.001 on the square model of the ANOVA test, which explained the curvature of xylose recovery and clear maximum recovery as responses in Figure 1a. However, the maximum xylose recovery in solid pretreated OPEFB hydrolysate associated with SL and pretreatment time may be due to random chance as the \(p\)-value was higher than 0.05. The linear model of ANOVA test showed that SL, pretreatment time, and temperature were not statistically significant for xylose recovery in solid pretreated OPEFB hydrolysate as the \(p\)-values were 0.786, 0.423, and 0.721, respectively. Likewise, the square model on xylose recovery showed that SL and pretreatment time were not as significant as temperature because the \(p\)-values were 0.258 and 0.293, respectively. Furthermore, there was no interaction effect between the effects and only a two-way interaction between temperature and time with a \(p\)-value of 0.314, which was not significant, as can be seen in Table 2.  
The minimum xylose recovery in liquid pretreated OPEFB hydrolysate associated with SL and pretreatment time may be due to random chance (Figure 1b). This was supported by the ANOVA test shown in Table 2. The analysis of variance showed that SL, temperature, and pretreatment time effects were not statistically significant as the \(p\)-values were 0.917, 0.041, and 0.817, respectively. There was no interaction effect between these three parameters on xylose recovery in solid and liquid pretreated OPEFB hydrolysate.