A comparative study on the structural and functional properties of water‐soluble and alkali‐soluble dietary fibres from rice bran after hot‐water, ultrasound, hydrolysis by cellulase, and combined pre‐treatments

Abstract

Summary The aim of the study was to estimate the optimum method to obtain water‐soluble (WS‐DF) and alkali‐soluble (AS‐DF) dietary fibres fibres from defatted rice bran (DRB) to develop functional components for food. The different pre‐treatments of DRB, such as ultrasound (US) treatment, hydrolysis by cellulase (HC) and combined treatment (HC‐US), were compared with hot‐water (HWT) treatment on yields, and structural, physicochemical, and functional properties of WS‐DF and AS‐DF. Results showed that amounts of WS‐DF (5.54–9.03 g/100 g) and AS‐DF (7.22–9.58 g/100 g), and total dietary fibre (TDF) (42.21–45.44 g/100 g) obtained from the DRB after US, HC and HC‐US treatments were significantly higher than that after HWT (6.36, 5.65 and 31.92 g/100 g, respectively). The FT‐IR indicated that the effect of applied treatments on the changes of the chemical structure of polysaccharides was stronger for the WS‐DF than that for the AS‐DF. Scanning electron microscopy (SEM) showed that the surfaces of US‐treated DFs particles were much more fractured than those after the HWT and HC. The combined HC‐US treatment at 50°C for 30 min significantly enhanced the purity (85–91%) and homogeneity of RB DFs structure resulting in increased water‐holding, swelling and glucose adsorption capacities compared to conventional processes maintaining acceptable bioactivity. Our study showed that conventional hot water extraction could be replaced with the ultrasonication technology as an effective tool for the modification of rice bran DFs’ structure and functional properties.

Optimization of ultrasonic‐assisted extraction of insoluble dietary fiber from wheat bran and its characterization

“…EC, viscosity, and SC were also increased showing unique characteristics of isolated IDF. Similar results were depicted in the study by Zadeike et al (2021), which showed ultrasonic treatment significantly enhancing the homogeneity and purity of rice bran up to 85%–91% consequently increasing the swelling and glucose adsorption capacity, water‐holding, swelling capacity in comparison to the conventional methods with acceptable bioactivity.…”

“…The levels of variables, final experimental values, and predicted values have been shown in remains intact (Li et al, 2016). In a comparative study on rice bran with different ultrasonic-assisted treatments FTIR proved efficient in clearly depicting similar capability for all dietary fibers from the variety of ultrasound-assisted treatments (Zadeike et al, 2021).…”

“…Like for “arabinoxylans” abundantly present in wheat barn could be efficiently extracted at 120–480 W and treatment time of 15–45 min and more importantly according to the FTIR spectroscopy, the major chemical composition of arabinoxylan remains intact (Li et al, 2016). In a comparative study on rice bran with different ultrasonic‐assisted treatments FTIR proved efficient in clearly depicting similar capability for all dietary fibers from the variety of ultrasound‐assisted treatments (Zadeike et al, 2021).…”

Impact of low-frequency ultrasound technology on physical, chemical and technological properties of cereals and pseudocereals

“…LFUS capability to shatter dietary fibre was evidenced by Vaitkeviciene et al [196] : they ultrasonicated rice bran and observed an average 10% decrease of insoluble fibre, and an increase of the soluble fraction; formation of resistant starch, likely due to chains rearrangement, was also detected. Similarly, Zadeike et al [197] , documented a coarse surface with multiple fractures in LFUS-treated rice bran and an increase in its absorption of water and oil.…”

Physicochemical Properties of Three Types of Rice Bran Meal Dietary Fiber and Their Hypolipidemic Effects on Rats

“…IDF contains free carboxyl and hydroxyl groups, and due to its high cation exchange capacity, IDF also has detoxifying effects [10]. Studies had shown that physical [11,12], chemical [13,14] and biological [15] methods can alter the structure of rice bran meal dietary fiber (RBDF), thus affecting its physicochemical and functional properties.…”