Enzymo-chemical preparation, physico-chemical characterization and hypolipidemic activity of granular corn bran dietary fibre

Abstract

Corn bran dietary fibre (CF) was paid more attention for its anticancer and hypolipidemic activities. In this paper, corn bran was firstly decomposed to the threadlike fibre (CF1) by multiple enzymes and then further modified to the granular fibre (CF2) by alkali under high pressure and high temperature (APT). The two types of fibres were characterized by scanning electron microscope (SEM) and near-infrared spectrophotometer (IR), and investigated by hydration measurements and nitrite adsorption assays. The results showed that CF2 had more much specific surface area, and displayed 4.7, 6.3 and 30-fold increases in water retention (WR), swelling capacity (SC) and nitrite absorption (NA), compared with CF1, respectively. The rat feeding trials showed that the granular fibre could decrease total cholesterol (TC), triglyceride (TG) and low density lipoprotein-cholesterol (LDLC) by 41.4 %, 20.7 % and 56.5 %, respectively. These excellent physiological activities indicate that CF2 will be a potentially available dietary ingredient in functional food industries, and meanwile imply that the enzymochemical method is a desired strategy for CF processing.

Keywords: Corn bran; Dietary fibre; Functional ingredient; Process.

Fig. 1

Physiognomies of two fibres, CF₁ (a) and CF₂ (b), showed by scanning electron micrographs. CF₁: Threadlike corn bran dietary fibre prepared by processing corn bran with multiple enzymes; CF₂: Granular corn bran dietary fibre prepared by processing corn bran with multiple enzymes and with alkali under high pressure and high temperature, respectively

Fig. 2

Hydroxyl group absorptions of CF₂ (—) and CF₁ (-·-) at 3,340 cm⁻¹, showed by infrared spectra. CF₁: Threadlike corn bran dietary fibre prepared by decomposing corn bran with multiple enzymes; CF₂: Granular corn bran dietary fibre prepared by processing corn bran with multiple enzymes and with alkali under high pressure and high temperature (0.6 % NaOH, 105 kpa and 121 °C), respectively

Fig. 3

Swelling capacity (SC) and water retention (WR) values of CF₂ processed by alkali under high pressure and high temperature (APT). CF₂ sample 1–8: Granular corn bran dietary fibre prepared by processing corn bran with multiple enzymes and with alkali (0.1 %, 0.3 %, 0.6 %, 1.0 %, 3.0 %, 5.0 %, 7.0 % or 10 % NaOH) under high pressure and high temperature (105 kpa and 121 °C), respectively; The SC and WR values are mean ± SD of replicative experiments (n = 3)

Fig. 4

Absorbance of ingrained nitrite solution after adsorbed by CF₁ (white square) or CF₂ (black square) for some time. CF₁: Threadlike corn bran dietary fibre prepared by decomposing corn bran with multiple enzymes; CF₂: Granular corn bran dietary fibre prepared by processing corn bran with multiple enzymes and with alkali under high pressure and high temperature (0.6 % NaOH, 105 kpa and 121 °C), respectively. All assays were performed repeatedly (n = 3) and average values were taken