Influence of different soaking and drying treatments on anti-nutritional composition and technological characteristics of red and green lentil (Lens culinaris Medik.) flour

Abstract

This study aimed to produce lentil flour with reduced antinutritional factors, acceptable color, and improved techno-functional properties. To obtain lentil flour, red and green lentil seeds were subjected to soaking in distilled water (with/without ultrasound at 80, 100% amplitude for 2 or 4 h) and drying treatments [oven-drying (50, 100 degrees C) or microwave-drying (600, 900 W)]. The influence of process parameters on phytic acid content (PAC), trypsin inhibitor content (TIC), water absorption capacity (WAC), oil absorption capacity (OAC), and color of lentil flours were investigated. During soaking, the water absorption and hardness of the seeds and pH, soluble solid content, and turbidity of the soaking water varied depending on the soaking parameters and the type of lentil. Lentil flours had WAC and OAC values ranging from 108.5 to 358.9 g water/100 g and from 80.2 to 98.7 g oil/100 g, respectively. Microwave-dried lentil flours had 2.0-2.8 times higher WAC compared to oven-dried ones. Higher microwave power level and oven drying temperature provided higher WAC values. Effect of soaking treatment on color and techno-functional properties of flours varied depending on the type of lentil flour and the applied drying method. Soaking and subsequent drying of lentil seeds yielded 14.5-43.8% reduction in PAC and 58.2-80.1% reduction in TIC. Soaking followed by microwave drying at 900W may be recommended as a rapid and effective method to obtain lentil flour with good color, high WAC, reduced PAC, and TIC. Application of ultrasound during soaking for 4 h prior to drying further enhances the potential of reducing antinutritional factors.