Generating functional property variation in lentil (Lens culinaris) flour by seed micronization: Effects of seed moisture level and surface temperature

The effects of micronization temperature (115, 130, 150 or 165. °C seed surface) in combination with lentil (green var. Eston) seed moisture level (natural moisture 8% and tempered to 16 or 23% moisture) on the physico-chemical and functional properties of the resulting flour were investigated. An increase in the water holding capacity of the resulting lentil flour was observed at 16 and 23% seed moisture and micronizing temperatures above 130. °C. Higher oil absorption capacity was observed for flours from 16 and 23% seed moisture levels than micronization at 8% moisture. Starch gelatinization was observed only when seeds were micronized at 23% seed moisture level and 18-25% gelatinized starch was found depending on the temperature achieved. Resistant starch percentage and protein dispersibility index of flours decreased with all micronizing temperatures and tempering levels. Endogenous enzyme activities of lentil flour decreased with increasing micronization temperatures as indicated by reduced lipoxygenase and peroxidase activities. The trypsin inhibitory activity was also reduced due to micronization. Differential scanning calorimetry results did not show changes in peak denaturation temperatures for starch and protein except in the flours from micronization treatments above 150. °C. However, decreases in the enthalpy values (8-90%) were observed for both starch and protein peaks. Very low final viscosity values were observed for the flours of lentil seed tempered to 23% moisture and micronized to 150 or 165. °C surface temperatures indicating possible changes in seed protein and starch. Micronization of tempered lentil seed resulted in changes in functional parameters of the resulting flours thereby allowing entry into different applications than the flour of untreated seeds.