Effect of cultivars and cooking methods on the trypsin inhibitor activities of potatoes

The trypsin inhibitor activities (TIA) of various potato cultivars were evaluated by measuring the inhibition of trypsin inhibitor activity using N-benzoyl-DL-arginine-p-nitroanilide (BAPNA) as substrate. The TIA values of 5 potato cultivars (1.99 to 2.88 mg/g) were significantly different among cultivars (p < 0.05). When the TIA values of commercially processed potatoes were determined, no TIA was detected. During cooking, the IT50 (time required to reach 50% inhibition of TIA) values were decreased as heating temperature and time increased. The IT50 of moist heating was estimated to be 0.34 min at 100 degrees C, whereas for deep-fat frying the IT50 was 0.13 min at 180 degrees C and 5.28 min for oven baking at 100 degrees C. The IT50 value of microwave cooking was 0.194 min at medium heat, and which was similar to that of pressure cooking at 120 degrees C (0.185 min). Moreover, there was a negative relationship between temperature (>= 80 degrees C) and IT50 values (R-2 = 0.99, p < 0.01). The TIA of potato was completely inactivated by moist heating at 100 degrees C within 5 min, whereas the pressure cooking at 120 degrees C and deep-fat frying at 180 degrees C within 60 and 30 see, respectively. Based on our results, deep-fat frying is the most effective cooking method to reduce TIA in potatoes.