The Link between Polyphenol Structure, Antioxidant Capacity and Shelf-Life Stability in the Presence of Fructose and Ascorbic Acid.

Inbal Hanuka Katz,Eden Eran Nagar,Avi Shpigelman,Zoya Okun

doi:10.3390/molecules25010225

Inbal Hanuka Katz, Eden Eran Nagar + Show 2 more

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https://doi.org/10.3390/molecules25010225

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Abstract

Polyphenols play an important role in the sensorial and health-promoting properties of fruits and vegetables and display varying structure-dependent stability during processing and shelf-life. The current work aimed to increase the fundamental understanding of the link between the stability of polyphenols as a function of their structure, presence of ascorbic acid and fructose and total antioxidant capacity (TAC), using a multi-component model system. Polyphenol extract, used as the multi-component model system, was obtained from freeze-dried, high polyphenol content strawberry (Fragaria × ananassa ‘Nerina’) and twenty-one compounds were identified using high-performance liquid chromatography-mass spectrometry (HPLC-MS). The TAC and the first-order degradation kinetics were obtained, linking the polyphenol stability to its chemical structure, with and without the presence of fructose and ascorbic acid. The TAC (measured by oxygen radical absorption capacity (ORAC) and ferric reducing antioxidant potential (FRAP) assays) was not dramatically affected by storage temperatures and formulation, while polyphenol stability was significantly and structure dependently affected by temperature and the presence of ascorbic acid and fructose. Anthocyanins and phenolic acids were more unstable in the presence of ascorbic acid, while flavonol stability was enhanced by its presence. Shelf life study performed at 37 °C revealed significantly higher stability of purified polyphenols vs. the stability of the same polyphenols in the strawberry extract (multi-component system).

Highlights

Polyphenols are a diverse group of molecules naturally occurring in fruits and vegetables
Polyphenol stability in a complete food matrix is influenced by oxidizing enzymes that are naturally found in strawberries, such as polyphenol oxidase (PPO) and peroxidase (POD) [35]
Extract total antioxidant capacity (TAC) was not affected by the addition of AA or fructose during shelf-life at 37 ◦ C, measured by FRAP and or a hydrogen atom transfer reaction (ORAC), while the stability of the polyphenolic compounds was significantly and structure dependently affected

Summary

Introduction

Polyphenols are a diverse group of molecules naturally occurring in fruits and vegetables. These compounds contain multiple phenolic functional groups with sensory, health-promoting and industrial values. Recent reviews report the substantial evidence that specific polyphenols benefit health status, especially in the field of prevention and possible management of certain chronic diseases [1]. The biological potential was suggested to derive from their antioxidant capacity, iron chelation capacity and direct modulation of cell signaling pathways. Polyphenols were shown to inhibit cell proliferation and angiogenesis, modulate transcription factors and their associated kinases, and prevent various signaling pathways [2]. Polyphenols’ general structure consists of aromatic rings with hydroxyl groups, organic acids (phenolic or aliphatic), sugars and acylated sugars that are often conjugated to the polyphenolic primary structure. The conjugated sugars can be mono-, di- or oligosaccharides [3]

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