The effect of extrusion of soybean (Glycine max), yellow lupin (Lupinus luteus), and linseed (Linum usitatissimum) on the activity of porcine pancreatic lipase (PPL) was evaluated through pH-Stat methodology with tributyrin emulsions in which the seed meals [extruded (E) and non-extruded (NE)] were dispersed. The seed meals affected PPL activity in a concentration-dependent fashion; at 2.3 mg/mL the meals reduced PPL activity (11.7–45.0% reduction) while the opposite was true (3.1–28.0% increase) at 6.8 mg/mL. PPL activity in the assays containing E-lupin, E-soybean and E-linseed meals at 2.3 mg/mL was 109.7 and 11.3% higher and 25.5% lower than the activity in the emulsions containing the NE-meals, respectively. The differences between the PPL activity in emulsions containing the extruded and NE-meals could be due to changes in the emulsifying properties of the meals after extrusion; extrusion increased (10.2%) the emulsification capacity of lupin meal and for linseed meal this property was reduced (9.2%). In spite of the low PPL activity at low meal concentrations, the percentage of free fatty acids released after 30 min was similar to the theoretical maximum (66.6%) with two exceptions – NE-soybean meal (59.5 ± 2.7%) and E-linseed meal (57.9 ± 1.2%).
Practical applications: Feed and food industries use plant protein sources that contain inhibitors of digestive enzymes. Various proteases inhibitors are inactivated during extrusion being less known the effect of extrusion on lipase inhibitors. Reduction of lypolysis rate, carried out mainly by pancreatic lipase in human and other animals, could influence feed and food consumption because satiety is controlled – at least in part – by undigested lipids. Our results show that extrusion can be used to reduce the inhibitory activity of lupin and soybean on PPL. On the other hand, extrusion of linseed increased the negative effect of this meal on PPL activity effect that could have applications in the development of food and ingredients for weight control.