Ultrasound-Assisted Extraction, Identification, and Quantification of Antioxidants from 'Jinfeng' Kiwifruit.

Ying-Hui Mai,Ding-Tao Wu,Ren-You Gan,Fan Zhu,Qiao-Hong Li,Hua-Bin Li,Qi-Guo Zhuang,Yu Xia,Kui Du

doi:10.3390/foods11060827

Abstract

Kiwifruit (Actinidia chinensis) is a nutrient-dense fruit abundant in vitamin C and phenolic compounds, and it exhibits strong antioxidant capacity. However, the antioxidants in ‘Jinfeng’ kiwifruit have seldom been extracted and analyzed, and the conditions for the extraction of kiwifruit antioxidants by ultrasound-assisted extraction (UAE) have seldom been investigated. In this study, response surface methodology (RSM) was used to optimize UAE conditions to extract antioxidants from ‘Jinfeng’ kiwifruit. In addition, the antioxidant capacity, contents of total phenolics and total flavonoids, ascorbic acid, and the profiles of antioxidants were also analyzed. The results showed that the optimal UAE conditions included 68% ethanol, liquid/solid ratio at 20 mL/g, extraction time at 30 min, extraction temperature at 42 °C, and ultrasonic power at 420 W. Under these conditions, the ABTS value of kiwifruit was 70.38 ± 1.38 μM TE/g DW, which was 18.5% higher than that of the extract obtained by conventional solvent extraction. The total phenolic and flavonoid contents were 15.50 ± 0.08 mg GAE/g DW and 5.10 ± 0.09 mg CE/g DW, respectively. Moreover, 20 compounds were tentatively identified by UPLC–MS/MS, and the content of main compounds, such as procyanidin B2, neochlorogenic acid, and epicatechin, were determined by HPLC–DAD. This research revealed the profiles of antioxidant phytochemicals in ‘Jinfeng’ kiwifruit, which can be a good dietary source of natural antioxidants with potential health functions.

Highlights

IntroductionKiwifruit (Actinidia) is an edible berry reputed for its remarkable nutritional value and attractive taste [1]
Only a few cultivars from A. chinensis, A. deliciosa, A. arguta, and A. eriantha have been commercially cultivated by the international kiwifruit industry [3]
Ultrasound-assisted extraction has been optimized for recovering phytochemicals from ‘Jinfeng’ kiwifruit, and it resulted in an 18.5% increment in antioxidant activity compared with conventional extraction

Summary

Introduction

Kiwifruit (Actinidia) is an edible berry reputed for its remarkable nutritional value and attractive taste [1]. More than 70 species and 120 taxa have been recognized globally, including A. deliciosa, A. chinensis, A. arguta, A. kolomikta, A. eriantha, A. macrosperma, and A. polygama [2]. Only a few cultivars from A. chinensis, A. deliciosa, A. arguta, and A. eriantha have been commercially cultivated by the international kiwifruit industry [3]. Plenty of research has documented that consuming kiwifruit has a large number of health benefits, such as antioxidant [1,4], anti-inflammatory [5,6], anti-cancer [7], anti-obesity [8] and gastrointestinal function-improving [9,10] capacities.

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Conclusion