The objective of this study was to increase the efficiency of starch extraction from potato sludge by different concentration of food-grade hemicellulase. The potato sludge, which is a by-product of potato processing industry, was treated with food-grade hemicellulase. Starch extraction efficiency displayed no significant difference in hemicellulase concentration. The purities of potato starch increased from 83.40 to 95.91, 97.44, 95.58, and 97.79%, with treated 0.5, 0.75, 1.0, and 1.5% hemicellulase, respectively. The physicochemical properties of the starches, such as granule structure, particle size, pasting, and thermal transition, were not affected by the concentration of hemicellulase. These results indicate that food-grade hemicellulase treatment is an efficient method for starch extraction from potato sludge.

The experiment fields consisted of five plots as follows; 2, 4, and 8 tonsㆍha⁻¹ citrus skin in combination with starch sludge and pig manure mixing compost (CSSP), 4 tonㆍha⁻¹ fermented pig manure compost (FPMC) treated plot, and untreated control. Plant height and stem diameter were significantly increased by CSSP. Most of all, average tuber weight and tuber yield per plant were significantly increased in 4 and 8 tonsㆍha⁻¹ CSSP plots compared to the other plots. Marketable tuber (＞50 g fresh weight) yield were superior in order of 4 and 8 tonsㆍha⁻¹ CSSP plot, 4 tonsㆍha⁻¹ FPMC plot, and 2 tonsㆍha⁻¹ CSSP plot.