Bound Form Terpenes in Sweet Potatoes and Their Distribution in Flesh and Peel of Different Cultivars

Six prevalent sweet potato cultivars, New Orleans, Beauregard, Japanese, Hannah, Garnet and Jewel, were selected to determine the distribution of terpenes in their flesh and peel. Free-form terpenes were not detected in both flesh and peel in all the cultivars by using a solid phase microextraction (SPME) and gas chromatography-mass spectrometer (GC-MS) method. Major terpenes in the sweet potatoes were linalool and & alpha;-terpineol and existed in bound form in flesh and peel. They were released as free-form and determined after acid hydrolysis treatment. However, ultrasonication-assisted acid hydrolysis decreased the levels of terpenes with increased treatment time because the broken-down free-form terpenes were volatile and rapidly evaporated or oxidised. For the selected cultivars, the Garnet, Jewel and Japanese cultivars had the greatest levels of linalool, while the Beauregard and New Orleans cultivars had the greatest level of & alpha;-terpineol. Also, the concentration of linalool or & alpha;-terpineol in the peel of each cultivar was approximately two times greater than in its flesh. This study revealed the bound form terpenes and their distribution in sweet potatoes. The results explored the potential utilisation of sweet potato peel as a natural source of terpenes. Bound form terpenes in sweet potatoes image