Exploring extrusion technology in developing value-added products from Montana lentils

Abstract

This study seeks to demonstrate that lentil flour and its fractionates are viable ingredients for use in the development of lentil puffs, lentil couscous and lentil texturized vegetable protein with a twin-screw pilot-scale extruder (Buhler-30 mm). Regarding the development of lentil puffs, an experimental design with three formulation factors of lentil flour (x1), lentil starch concentrate (x2) and lentil protein concentrate (x3) was created. The overall acceptance and texture liking score of lentil puff formulations was found to be dependent on all three formulation factors. An optimum lentil puff formulation was therefore predicted at a 50% ratio of lentil starch concentrate to 25% ratios of both lentil flour and lentil protein concentrate to be produced at an extrusion feed .rate of 20 kg/h, a moisture rate of 10% and a screw speed of 350 rpm. For the development of lentil couscous, an experimental design with factors of the ratio of lentil protein concentrate to lentil flour (x1) and the extruder screw speed (x2) was created. Increasing the ratio of lentil protein concentrate to lentil flour decreased the water absorption index, cohesiveness, chewiness, and resilience texture of lentil couscous formulations. Higher sensory acceptance, appearance, flavor and texture scores for lentil couscous samples were observed for formulations with lentil protein concentrate levels at 20% and a screw speed of 250 rpm. Clustering sensory results revealed that participants who issued higher sensory score were willing to buy the presented lentil couscous at $3.37 for 10 oz of lentil couscous with lentil protein concentrate levels at 20% and produced at a screw speed of 250 rpm. The development of a lentil TVP with lentil protein concentrate revealed that the techno functional properties of lentil TVPs were dependent on the total protein content, extrusion conditions and pH. Adding pea protein isolate to lentil protein concentrate in formulations increased the protein content to levels ideal for texturization. Increasing the extrusion dry feed rate and screw speed also increased the degree of texturization of ingredient mixes. Despite exploring the addition of gums, salts, transglutaminase as well as cross-linking agents, a change in pH, with additives of citric acid and calcium hydroxide, was the only strategy observed to influence the techno functional properties of lentil TVP samples. In comparison to the reference soy TVP produced from soy protein concentrate, lentil TVP samples produced from trials with higher contents of pea protein isolate (> or = 30%, w/w, d.b. in the dry feed) presented higher instrumental springiness, cohesiveness, and chewiness texture.