Effects of dietary fibre source and content and extrusion conditions on the physicochemical composition and physical quality of fibre-enriched lentil snacks

Abstract

The growing recognition of the health benefits associated with dietary fibre and the deficit in its daily intake are propelling the food industry to develop a variety of fibre-enriched products including puffed snacks. Incorporating rich sources of fibre into pulse-based foods can supplement the insufficient daily dietary fibre intake. To produce fibre-enriched puffed pulse snacks and ready-to-eat breakfast cereals, three different fibre sources, namely carrot powder (CP), wheat bran (WB) and red lentil hulls (LH), were added to red lentil (RL) flour at 0%, 10% and 20% levels (w/w) and extruded at three extrusion moisture contents (MC), i.e., 18%, 20% and 22% (db). Incorporation of all three fibres into RL flour significantly (P ≤ 0.05) increased the total and insoluble dietary fibre contents and hardness and decreased the expansion index, brightness and crispiness of extrudates. Scanning electron microscopy images revealed that the fibre-enriched extrudates had thicker cell walls with smaller cells when qualitatively compared to RL extrudates with no fibre addition. CP containing extrudates had significantly (P ≤ 0.05) higher soluble dietary fibre (SDF) content compared to extrudates containing WB and LH. WB containing extrudates were significantly (P ≤ 0.05) harder and less expanded than CP and LH containing extrudates at the same MC. The increase in fibre incorporation level increased the hardness of CP and WB containing extrudates but did not affect LH containing extrudates. Fibre incorporation level also increased the colour differences between RL extrudates with and without fibre enrichment. Increasing MC significantly (P ≤ 0.05) increased the SDF and hardness and decreased the expansion index of extrudates. These results can potentially pave the way for the production of fibre-enriched pulse-based puffed products, namely, snacks and ready-to-eat breakfast cereals, that are texturally and structurally appealing to consumers.