Alkaline, acid and acid-wet ball milling extraction of dietary fiber from kiwi berry (Actinidia arguta): Structural, rheological, physicochemical and functional properties

Abstract

Dietary fiber (DF) has gained significant attention due to its potential health benefits, highlighting the need for optimized extraction techniques from various plant sources. In this study, the objective of the study was to evaluate the effects of several extraction techniques, such as alkaline (AL), acid (AC) and acid-wet ball milling (ACWB) on structural, rheological, physicochemical and functional characteristics of dietary fiber (DF) extracted from kiwi berry. The alkaline method involved using a NaOH solution, while the acid extraction utilized citric acid. The acid-wet ball milling method combined acid treatment with ball-milling to enhance fiber extraction. AL-DF had higher total dietary fiber and thermal stability than AC-DF and ACWB-DF. The Fourier transform infrared spectroscopy (FT-IR) spectra indicated peak intensity variation in three extracted DF fractions. The scanning electron microscopy (SEM) observation indicated that ACWB-DF exhibited a looser microstructure, and ACWB-DF had the smallest particle size (359.1 nm) as compared to those of AL-DF and AC-DF. In addition, ACWB-DF exhibited the lowest ζ-potential (−23.40 mV) and maximum viscosity (19.11 mPa s) among all samples. Furthermore, ACWB-DF has stronger water holding (3.91 g/g), oil holding (1.78 g/g), water swelling (6.47 mL/g), bile acid adsorption (387.75 mg/g), nitrite ion adsorption (720–785 μg/g) and glucose adsorption (193.41–374.87 mg/g) capacities than AL-DF and AC-DF fractions. Hence, ACWB-DF may have tremendous potential to be functional food additives in the food industry.