Improvement in soluble fiber content of wheat fiber through enzymic modification

Abstract

The influence of fiber purification and conditions of enzymatic modification on soluble fiber content of wheat fiber were examined. Crude wheat fiber was purified by a modified enzymatic extraction. Crude wheat bran contained 16% soluble dietary fiber by weight. Purification of the crude wheat bran did not alter soluble fiber content nor result in a significant loss of total dietary fiber. A technical grade hemicellulase was used to enzymatically modify the purified wheat fiber. The yield varied considerably with enzyme concentration and time. The optimized modification conditions utilized were 0.1 M acetate buffer (pH 5.0) and 60 HCU/mL per g of PIFF hemicellulase a t 30 "C for 40 min. The enzymatic modification of wheat fiber resulted in an 87% increase in soluble fiber content up to 30%.A number of studies have demonstrated that the use of soluble fibers may be an important adjunct in the treatment of diabetes. Jenkins et al. (Jenkins et al., 1977a(Jenkins et al., ,b, 1980 demonstrated that the addition of soluble types of dietary fiber such as pectin and guar into test meals reduced postprandial glycemia in normal, non-insulindependent and insulin-dependent subjects. This was attributed in part either t o an increased mouth to cecum transit time, to the decreased rate of gastric emptying, or to a slower rate of duodenal absorption, all factors associated with an increase in solubility and/or viscosity (Blackburn et ai., 1984;Jenkins e t al., 1977b Jenkins e t al., , 1979.Insoluble fibers such as cellulose or less soluble fibers such as wheat bran have been shown to be less effective as agents for lowering serum glucose values. In contrast, they have been shown to increase fecal bulk and inhibit colon tumors. Although wheat bran is a less soluble type of fiber, a number of studies have reported the use in the treatment of diabetics (Simpson e t al., 1979a,b).The objective of the present investigation was to determine the conditions under which the soluble fiber content of wheat fiber could be increased. This would increase the potential for clinical usage under circumstances requiring a more soluble type of fiber. PROCEDURESPurification of Wheat Bran. A modification of Prosky et al. (1984) and Monte and Maga (1980) was utilized for determination and purification of a commercial grade of crude wheat bran. The purification method developed is described in Figure 1.Sample Pretreatment-Extraction of Lipids. The extraction of lipid from crude wheat bran (CWB) was performed three times with use of reagent grade petroleum ether (PET) (6:l = PET:CWB) at room temperature. The defatted wheat bran (DWB) was dried overnight at 105 "C in an air oven to a constant weight. It was then passed through a Wiley mill (Model No. 4) equipped with a 0.5-mm-mesh screen.Removal of Soluble Complex Carbohydrate. DWB was incubated in a 0.08 M Na2P0, buffer (pH 6.0 DWB), containing Termamyll20 L (120 KNU (Novo-a-amylase unit)/mL per 10 g of DWB; heat-stable a-amylase; Novo Laboratories, Inc., Wilton, CT 06897) for 30 min in a hemisphe...

Phytochemical Profile, Bioactivity, and Prebiotic Potential of Bound Phenolics Released from Rice Bran Dietary Fiber during in Vitro Gastrointestinal Digestion and Colonic Fermentation

“…Preparation of RBDF. The preparation of RBDF was performed according to the previously described procedure 13 with some modification. Freshly prepared rice bran was obtained from Guangzhou Liquan Food Co. Ltd, Guangdong, China.…”

Improving the nutritional value of wheat bran by a white‐rot fungus

“…In fact soluble dietary fibre, by increas-ing the viscosity of the stomach contents, has been demonstrated to influence the rate of gastric emptying, to lower the rate of nutrient adsorption and to reduce post-prandial glycaemia and plasma cholesterol level. Enzymic treatments with the aim of increasing the soluble fibre content of wheat bran and other food by-products rich in insoluble dietary fibre have been reported (Caprez et al, 1987;Oh & Grundleger, 1990).…”

Extraction of Soluble Fiber from Distillers' Grains

“…Dietary fibers are further classified into two groups according to solubility in water: SDF and insoluble dietary fibers (IDF). Research has shown that SDF can be extracted from corn, wheat, and rice through chemical and biological treatment of the hemicellulosic fractions [5][6][7]. Potential products derived from SDF extracted from hemicellulose include emulsifiers, adhesives, thickeners, and stablizers [8,9].…”

“…Other studies have shown reaction time and temperature to be key factors in the formation and extraction of soluble fiber from hemicellulosic sources using chemical and enzymatic treatments [2,6]. Oh et al [6] used a technical grade hemicellulase to enzymatically modify the soluble fiber content of a purified wheat fiber substrate.…”

“…Oh et al [6] used a technical grade hemicellulase to enzymatically modify the soluble fiber content of a purified wheat fiber substrate. The yield was found to be considerably dependent on enzyme concentration and time.…”