Data about modification of structural and physicochemical properties of palm kernel expeller dietary fibres with carboxymethylation, acidic treatment, hydroxypropylation and enzymatic hydrolysis combined with heating

The data presented in this article are related to the research article entitled “Effects of carboxymethylation, acidic treatment, hydroxypropylation and enzymatic hydrolysis combined with heating on structural and physicochemical properties of palm kernel expeller dietary fibres.” This article describes the effects of carboxymethylation, acidic treatment, hydroxypropylation and enzymatic hydrolysis combined with heating on the structural and physicochemical properties of palm kernel expeller dietary fibres (PKEDF). Our data is made publicly available to the potential re-use of palm kernel expeller in food and other industries. Moreover, this dataset provides a reference about how to improve physicochemical and functional properties of dietary fiber.


Value of the Data
The data provide the potential re-use of palm kernel expeller in the food or other industries. The data provide information on how to improve some functional properties of palm kernel expeller dietary fiber. This data may serve as a reference for other works to develop other dietary fiber resource unutilized.

Data Description
The Fig. 1 shows the particle size distribution of PKE, PKEDF and the modified PKEDFs (PKEDF-A, PKEDF-HE, PKEDF-C and PKEDF-H). The data referring to water swelling capacity, emulsifying capacity, emulsion stbility, amylolysis kinetics and α-amylase activity inhibition ration ( α-AAIR) of DFs are shown in Tables 1-3 , repscetiviely. The data referring to X-ray diffraction, Fourier-transformed infrared spectroscopy can be seen in the Ref. [1] .

Heating treatment followed by enzymatic hydrolysis
PKEDF (50 g) was heated at 121 °C for 45 min. The heated PKEDF was suspended in deionized water (dH 2 O) (1: 15, m/v), and then 0.3 g of hemicellulase and 0.45 g of cellulase were added. The mixture was adjusted to pH 4.5 and incubated at 50 °C for 3 h. Afterwards the mixture was incubated in boiling water for 10 min, and then cooled and filtered. The residue was collected  Table 3 Effect of palm kernel expeller dietary fibres on amylolysis kinetics and α-amylase activity inhibition ration.

Acidic treatment
1 mol/L NaOH (1: 10, w/v) at 60 °C for 2 h, and then treated by 1 mol/L HCl at 60 °C for 30 min. Afterwards, the mixture was neutralized and filtrated, the residue was washed with dH 2 O and dried at 60 °C for 4 h. Then PKEDF treated by acidic (PKEDF-A) was obtained [2] .

Carboxymethylation
PKEDF (8 g) were suspended in 80 mL of ethanol (85%, v/v). The suspension was gently stirred at room temperature (RT) for 30 min. Then 50 mL of NaOH (0.676 mol/L) were gradually added with vigorously stirring at 35 °C for 60 min. Afterwards 9.7 mL of chloroacetic acid (3.38 mol/L) pre-treated with NaOH (3.38 mol/L) were added and gently stirred at 35 °C for 30 min. Then the mixture was incubated at 53 °C for 3.5 h, and cooled to RT, neutralized to pH 7.0 with acetic acid and centrifuged at 40 0 0 g for 15 min. The precipitate was collected, washed with anhydrous ethanol and dried at 45 °C for 4 h to obtain carboxymethylated PKEDF (PKEDF-C) [3] .

Hydroxypropylation
5 g of PKEDF were suspended in 50 mL of dH 2 O and then mixed with 50 mL of Na 2 SO 4 (20 mg/mL). The mixture was adjusted to pH 11.0 and 2 mL of propylene oxide were added.