Susceptibility of sweet potato (Ipomoea batatas) peel proteins to digestive enzymes

Abstract

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.

Bound form terpenes in sweet potatoes and their distribution in flesh and peel of different cultivars

“…Sweet potato peels exhibited a lower moisture content compared to flesh. A proximal analysis of sweet potato peels from the Beauregard and Jewel cultivars revealed that the primary components of sweet potato peel were carbohydrates (Maloney et al ., 2014).…”

Preharvest Fruit Drop of Date Palm ( Phoenix dactylifera L.) Cv. Deglet Nour at Kimri Stage: Development, Physico-chemical Characterization, and Functional Properties

“…Concentration of total polyphenols and antioxidant activities of fruits at Kimri and Tamar stages are also reported in Table 7. Significant difference was observed between stages with a highest mean value were recorded in dropped fruits (341.61 ± 29.39 mg GAE/100 g fresh weight and 1076.57 ± 9.11 mg AAE/100 g fresh Rania et al (2014) reported that, phenolic compounds possess antioxidant, anticarcinogenic, antimicrobial and anti-inflammatory properties. Jemni et al (2014) found that total polyphenols in dates of cv.…”

<p>Comparative study on antidiabetic, cytotoxicity, antioxidant and antibacterial properties of biosynthesized silver nanoparticles using outer peels of two varieties of <em>Ipomoea batatas</em> (L.) Lam</p>

“…[50][51][52] The sweet potato peels are abundant in storage proteins, identified as sporamins, which are resistant to simulated gastric digestion and present promising antioxidant and antiproliferative properties. [53][54][55][56] Sporamins function as trypsin inhibitors, also after incubation with pepsin or trypsin.…”