Grains and legumes.
Partially by cooking, sprouting.
Growth inhibition and pancreatitis.
Protease inhibitors: Protease inhibitors are widely distributed within the plant kingdom, including the seeds of most cultivated legumes. Protease inhibitors have the ability to inhibit the activity of proteolytic enzymes within the gastrointestinal tract of animals (Liener and Kakade, 1980). Trypsin inhibitor and chymotrypsin inhibitor are protease inhibitors occurring in raw legume seeds. Protease inhibitors are the most commonly encountered class of antinutritional factors of plant origin. These inhibitors have been reported to be partly responsible for the growth-retarding property of raw legumes. The retardation has been attributed to inhibition of protein digestion but there is evidence that pancreatic hyper- activity, resulting in increased production of trypsin and chymotrypsin with consequent loss of cystine and methionine is also involved (McDonald et al., 1995). Trypsin inhibitors have been implicated in reducing protein digestibility and in pancreatic hypertrophy (Liener, 1976). Trypsin inhibitors are polypeptides that form well characterized stable complexes with trypsin on a one-to-one molar ratio, obstructing the enzymatic action (Carlini and Udedibie, 1997). Protease inhibitors are inactivated by heat especially moist heat, because of even distribution of heat (Bressani and Sosa, 1990; Liener, 1995).