Preparation of Insoluble Dietary Fiber from Forest Waste and Its Physiological Function in Rat Fed High Cholesterol Diets

Abstract

This study investigated the production of insoluble dietary fiber using forest waste, the dietary effect of manufactured insoluble fiber on physiological function in rat fed high cholesterol diets. Insoluble dietary fiber was prepared from the wood chips of oak (Quercus mongolica). The best condition for steam-explosion treatment for the preparation of insoluble dietary fiber was 25 kg/㎤ pressure for 6 minutes. In the chemical analysis of insoluble dietary fiber pretreated by 1% sodium hydroxide solution with steam-exploded wood, α-cellulose content was 61.7% in the insoluble dietary fiber, which contained 7.6% residual lignin. In order to compare insoluble dietary fiber with commercial α-cellulose of physiological function, Sprague-Dawley male rats weighing 100±10 g were randomly assigned to one normal diet, five high cholesterol diet containing 1% cholesterol. The high cholesterol diet groups were classified as fiber free diet (FF group), 5% commercial α-cellulose diet (5C group), 10% commercial α-cellulose (10C group), 5% insoluble dietary fiber diet (5M group),, 10% insoluble dietary fiber (10M group). The rats were fed ad libidum for 4 weeks. Food intake, weights gain,, food efficiency ratio in high cholesterol groups were higher than those of normal group, but there were no significant differences between the experimental groups. There were not any significant differences in the weights of liver, kidney,, small intestine of insoluble dietary fiber supplemented groups, but weight of cecum in all insoluble dietary fiber group were significantly higher than those of FF group. A gastrointestinal transit time was decreased by supplementation of insoluble dietary fiber. Weight, water contents of feces in the insoluble dietary fiber supplemented groups were significantly higher than those of the FF group. There were not any significant differences in the activities of the glutamic pyruvic transaminase (GPT), glutamic oxaloacetic transaminase (GOT) between the experimental groups. In conclusion, the manufactured insoluble dietary fiber, commercial insoluble fiber have the same physiological effects. The preparation method of the insoluble dietary fiber from the oak chips suited its purpose.