Application of Chromatographic and Spectroscopic Methods towards the Quality Assessment of Ginger (Zingiber officinale) Rhizomes from Ecological Plantations.

Wojciech Koch,Lucyna Wyszogrodzka-Koma,Wirginia Kukula-Koch,Zbigniew Marzec,Wojciech Szwerc,Elwira Kasperek,Yoshinori Asakawa

doi:10.3390/ijms18020452

Abstract

The usefulness of ginger in the food industry and pharmacotherapy is strictly related to its content of various components. The study elucidates the chemical composition of Zingiber officinale rhizomes cultivated on ecological plantations on Shikoku Island (Japan). GC-MS analysis of terpene content, LC-MS determination of phenolic content, and the determination of 12 elements using AAS spectrometry were performed to give more detailed insight into the samples. Ninety-five percent of terpene composition was elucidated, with zingiberene as the most abundant sesquiterpene (37.9%); the quantification of gingerols and shogaols was performed, showing the highest contribution of 6-gingerol (268.3 mg/kg); a significant K (43,963 mg/kg of dry mass) and Mn (758.4 mg/kg of dry mass) content was determined in the elemental analysis of the rhizomes and low concentration of toxic elements (Cd, Ni and Pb) remaining below the safe level values recommended by European Commission Directives. The main phenolic compound was (6)-gingerol, which is characteristic of fresh rhizomes and is responsible for their taste and aroma. Surprisingly, high amounts of (6)-shogaol were determined, even though this phenolic compound usually occurs in old or processed material and not in fresh rhizomes. Sesquiterpenes were the major fraction of volatiles. The highest concentrations were determined for α-zingiberene, β-sesquiphellandrene, (E,E)-α-farnesene, geranial, and ar-curcumene. The volatiles composition of ginger cultivated on Shikoku Island is specific and strongly differs from plants cultivated in China, Nigeria, or Australia. The elemental composition of ginger rhizomes grown in ecological plantations is more beneficial for human health compared to products grown in normal cultivars, as the products contain high amounts of potassium and manganese and are characterized by low sodium content and lower levels of toxic heavy metals.

Highlights

Interest in nutrition, natural healing methods, and the use of medicinal plants is increasing every year
Our study revealed several important differences in chemical composition between gingers obtained from ecological plantations and in the traditional way
LC-MS analysis of the obtained ethanolic extract revealed that the main phenolic compound was (6)-gingerol, which is characteristic of fresh rhizomes and is responsible for their taste and aroma

Summary

Introduction

Natural healing methods, and the use of medicinal plants is increasing every year. The use of ginger in traditional medicine has been reported since antiquity, as early as 3500 BC [1]. The ginger rhizome is appreciated for its taste qualities; it is used as a spice, flavoring agent, and as an additive in the preparation of meals [3]. It is used as an ingredient in dietary supplements such as pills, syrups, or teas. The confirmed antimicrobial action of the rhizomes (including antibacterial, antiviral, antifungal, and antiparasitic activity) justify its traditional use in cold treatment [5,6,7]. The two major groups of active compounds from ginger, which are responsible for most of the biological actions of this plant, are polyphenols (gingerols, shogaols, and paradols) and volatiles such as zingiberole, zingiberone, and zingiberene [12]

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Conclusion