Comparison of physicochemical and functional characteristics of insoluble dietary fibre from okara by separate and co‐fermentation with lactic acid bacteria and Kluyveromyces marxianus

Summary Okara, a natural source of dietary fibre (DF), is recognised as an edible and safe material. In this study, lactic acid bacteria (LAB) and Kluyveromyces marxianus were used to ferment okara in separately or in combination, and the physicochemical and functional characteristics of obtained insoluble dietary fibre (IDF) excluded from okara were compared. The result showed that compared with non‐fermented okara, the content of IDF from co‐fermented okara by LAB and K. marxianus increased by 6.8%, while separate fermentations were 2.4% and 4.0%. Scanning electron microscopy result showed that the structure of co‐fermented okara IDF was looser and porous with the edge disappeared compared to separate and non‐fermented okara. All the fermentation treatment groups effectively reduced the particle size and affected the cellulose and hemicellulose functional groups of IDF. Furthermore, compared with non‐fermented okara, processing performance, and the activities of hypoglycaemic and hypolipidaemic of IDF were greatly improved in fermented okara.