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 $IT_{50}$ (time required to reach 50% inhibition of TIA) values were decreased as heating temperature and time increased. The ITso of moist heating was estimated to be 0.34 min at $100^{\circ}C$, whereas for deep-fat frying the $IT_{50}$ was 0.13 min at $180^{\circ}C$ and 5.28 min for oven baking at $100^{\circ}C$. The $IT_{50}$ value of microwave cooking was 0.194 min at medium heat, and which was similar to that of pressure cooking at $120^{\circ}C$ (0.185 min). Moreover, there was a negative relationship between temperature (${\geq}80^{\circ}C$) and $IT_{50}$ values ($R^2=0.99$, p<0.01). The TIA of potato was completely inactivated by moist heating at $100^{\circ}C$ within 5 min, whereas the pressure cooking at $120^{\circ}C$ and deep-fat frying at $180^{\circ}C$ within 60 and 30 sec, respectively. Based on our results, deep-fat frying is the most effective cooking method to reduce TIA in potatoes.