Optimization of mannanase hydrolysis of steamed palm kernel cake to improve nutritional quality

Palm kernel cake (PKC), an abundant and healthy feed alternative to soybean meal and yellow corn, has been used in animal diets. The use of PKC in monogastric nutrition is limited due to its high fibre content. Although it has been demonstrated that steamed PKC is easily digestible by mannanase, the impact of the operation variables is unknown. Steamed PKC was enzymatically hydrolyzed to improve its efficient when used as feed by multi-response criteria based on the Taguchi orthogonal array. On the basis of a L9 orthogonal array, nine experimental runs were carried out. The percentage of substrate, incubation duration, and enzyme units were optimized, focusing on protein and carbohydrate content. The predicted and experimental results of optimal conditions to produce steamed PKC hydrolysate based on the Nine Taguchi design were 20%, 6 h, and 750 units. Optimum conditions yielded reducing sugar, total sugar, and protein release at 655.85 mg/mL, 875.75 mg/mL, and 1,631.86 mg/mL, respectively. Protein content was considerably decreased during pepsin digestion in all runs when compared to raw PKC. The chemical analysis of steam hydrolysate demonstrated that B. amyloliquefaciens NT6.3 mannanase increased the amount of neutral detergent soluble (NDS) components while decreasing non-starch polysaccharide components. This study identified the optimal conditions for improving the functionality of steamed PKC for efficient use as a feedstuff.