台灣甘藷胰蛋白酶抑制能力分析

Trypsin Inhibitor Activity Analysis of Taiwanese Sweet Potato Varieties

甘藷可加入飼料中作為畜禽類的食物，但甘藷中所含的胰蛋白抑制劑會降低甘藷蛋白質的代謝利用率，進而限制甘藷作為飼料的應用性，過去的研究結果建議選擇胰蛋白抑制劑活性較低的甘藷供人類及動物食用。本研究調查台灣常見的食用及飼料用甘藷的胰蛋白抑制活性，結果顯示在食用甘藷中，台農57號擁有最高的胰蛋白抑制活性（約65%），其次為台農73號（約22%），至於台農64及66號甘藷其胰蛋白抑制活性均相當低(<5%)，而飼料甘藷台南18號、台農17與31號甘藷的胰蛋白抑制活性均高於70%，台農10號是目前台灣飼料甘藷使用最普遍的品種，其胰蛋白抑制活性為52.6%，飼料甘藷的胰蛋白抑制活性普遍高於食用甘藷。本研究進一步探討3種加熱處理法（包括水煮、微波及烘烤），對甘藷胰蛋白抑制活性的影響，結果顯示水煮處理可有效地降低甘藷的胰蛋白抑制活性，但有些甘藷品種仍會保有部份胰蛋白抑制活性。在飼料甘藷中，實驗品系CYY99-68具備產量高(66.12±0.85 ton/ha)且胰蛋白抑制活性低(32.4%)的優點，可作為飼料用甘藷選、育種時的參考。

Sweet potatoes have been used to feed animals. However, the trypsin inhibitor of sweet potatoes prevents animals from metabolizing proteins, and that reduces the practical application of using sweet potatoes as animals’ food. Thus, previous studies recommended selecting sweet potatoes with lower trypsin inhibitor activity for food applications. The trypsin inhibitor activity of Taiwanese sweet potato varieties was analyzed in this study. For human dietary sweet potatoes, TNG57 had the highest trypsin inhibitor activity (approximately 65%). In addition, the trypsin inhibitor activity of TNG64 and TNG66 was less than 5%. For animal feed sweet potatoes, the trypsin inhibitor activity of TN18, TNG17, and TNG31 was higher than 70%. On the other hand, the trypsin inhibitor activity of TNG10, the most popular animal feed sweet potato variety in Taiwan, was approximately 52.6%. The trypsin inhibitor activity of animal feed sweet potatoes was generally higher than that of human dietary sweet potatoes. The influence of thermal processing including boiling, microwaving, and baking on the trypsin inhibitor activity of sweet potatoes was also analyzed in this study. The boiling treatment successfully reduced the trypsin inhibitor activity of sweet potatoes. However, some sweet potatoes retained partial trypsin inhibitor activity after boiling treatment. An experimental variety named CYY99-68 had high yield (66.12 ± 0.85 ton/ha) and low trypsin inhibitor activity (approximately 32.4%). Therefore, CYY99-68 was a good sweet potato variety for undergoing further selecting and cultivation studies.