Effect of Cooking Methods on Bioactivity of Polyphenols in Purple Potatoes

Qi Sun,Min Du,Duroy A Navarre,Meijun Zhu

doi:10.3390/antiox10081176

Abstract

Purple-fleshed potato (Solanum tuberosum L.) is a good dietary source of anthocyanins, flavonols, and polyphenolic acids, mostly chlorogenic acid. The objective of this study was to examine the impacts of cooking methods including boiling, steaming, and the newly developed vacuum-sealed boiling (VSBoil) on extractability and bioactivity of polyphenolic compounds in a purple potato (PP) cultivar, Purple Pelisse. Data showed that boiling and steaming reduced the total polyphenolic content in PP. High-performance liquid chromatography analysis showed that steaming slightly reduced the extractable chlorogenic acid content, while VSBoil increased it. For DPPH free radical scavenging activities, VSBoil and steaming effectively preserved the antioxidant activity of a polyphenol-rich extract of PP, while boiling resulted in a significant reduction compared to raw potato extract. All extracts effectively suppressed bursts of intracellular reactive oxygen species in human colonic epithelial cells upon hydrogen peroxide induction, of which the extract from the VSBoil group showed the highest antioxidant potential. In addition, all extracts showed anti-inflammatory effects in Caco-2 cells induced with tumor necrosis factor-α. In conclusion, the content and bioactivity of extractable polyphenols were largely retained in PP subjected to different cooking processes. VSBoil resulted in the highest content of extractable polyphenolic compounds and bioactivity among tested cooking methods.

Highlights

Potatoes, the carbohydrate-rich tubers of Solanum tuberosum L., are widely grown and consumed around the world
Potato tubers are enriched in phytonutrients such as dietary fibers and polyphenols [1]
The extractable Total polyphenolic content (TPC) of purple potato (PP) after boiling, vacuum-sealed boiling (VSBoil), or steaming was compared to that of raw PP by using the Folin–Ciocalteu assay, where gallic acid (GA) and chlorogenic acid (CGA) were used as equivalent standards

Summary

Introduction

The carbohydrate-rich tubers of Solanum tuberosum L., are widely grown and consumed around the world. Potato tubers are enriched in phytonutrients such as dietary fibers and polyphenols [1]. Pigmented potato tubers, such as purple-fleshed potatoes, contain anthocyanins that are responsible for their red, blue, or purple color. Purple potato (PP) is rich in polyphenolic acids, including chlorogenic acid (CGA) and caffeic acid, which are higher than those in white potato [2]. Purple Pelisse, the variety we used in this study, was first cross bred in 2000 and yielded purple skin and dark purple flesh tubers [3]

Objectives

Methods

Results

Discussion

Conclusion