Susceptibility of sweet potato (Ipomoea batatas) peel proteins to digestive enzymes
Article first published online: 1 APR 2014
© 2014 The Authors. Food Science & Nutrition published by Wiley Periodicals, Inc.
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Food Science & Nutrition
Volume 2, Issue 4, pages 351–360, July 2014
How to Cite
Food Science & Nutrition 2014; 2(4): 351–360
- Issue published online: 11 JUL 2014
- Article first published online: 1 APR 2014
- Manuscript Accepted: 22 FEB 2014
- Manuscript Revised: 16 FEB 2014
- Manuscript Received: 27 NOV 2013
- North Carolina Sweet Potato Commission
- North Carolina Biomanufacturing Training and Education Center
- National Institute of Food and Agriculture. Grant Number: NC02271
- amylase inhibitor;
- sweet potato peel;
- trypsin inhibitor
Sweet potato proteins have been shown to possess antioxidant and antidiabetic properties in vivo. The ability of a protein to exhibit systemic effects is somewhat unusual as proteins are typically susceptible to digestive enzymes. This study was undertaken to better understand how digestive enzymes affect sweet potato proteins. Two fractions of industrially processed sweet potato peel, containing 6.8% and 8.5% protein and 80.5% and 83.3% carbohydrate, were used as a source of protein. Sweet potato proteins were incubated with pepsin, trypsin, and chymotrypsin and protein breakdown was visualized with SDS-PAGE. After pepsin digestion, samples were assayed for amylase inhibitory activity. Sporamin, the major storage protein in sweet potatoes, which functions as a trypsin inhibitor as well, exhibited resistance to pepsin, trypsin, and chymotrypsin. Sporamin from blanched peel of orange sweet potatoes was less resistant to pepsin digestion than sporamin from outer peel and from extract of the white-skinned Caiapo sweet potato. Trypsin inhibitory activity remained after simulated gastric digestion, with the Caiapo potato protein and peel samples exhibiting higher inhibitory activity compared to the blanched peel sample. Amylase and chymotrypsin inhibitory activity was not present in any of the samples after digestion.