Production of bioactive compounds from ginger (Zingiber officianale) dregs through subcritical water extraction

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Abstract

Ginger (Zingiber officinale) dregs are industrial wastes that are only disposed of or used as fertilizer and fuel. Ginger dregs still have very high bioactive compounds containing gingerol, shogaol, zingerone, parasol, resin, and essential oils. Bioactive compounds can be used in the pharmaceutical, cosmetic, food, and beverage industries. In this case, extracting active compounds from ginger dregs has been developed through subcritical water extraction. The advantages of hydrothermal extraction using water are easy to obtain, cheap, abundant availability, high purity, non-toxic, and easy to handle. The study was carried out with a fixed variable of 1000 gr ginger dregs and a changing variable. The volume of distilled water is 5000–15000 mL as subcritical water. The time variable was 10–30 min, and the temperature variable was 120 °C–140 °C. The variables in this study were determined using the Response Surface Methodology (RSM). Ginger pulp extract was analyzed using GC-MS analysis. The bioactive compound contains zingiberene, E-Citral (geranial), Beta.-Sesquiphellandrene (CAS) 2-Methyl-6-(4-Methylenecyclohex-2-Enyl)-2-Heptene-HEPTENE, Benzene, 1-(1,5-dimethyl-4-hexenyl)-4-methyl-(CAS), Geranyl acetate, and Endo-Borneol. Analysis of the raw material of ginger dregs obtained the results of specific gravity were in accordance with quality standards, variable 4 is 0.89 gr, variable 10 is 0.91 gr, variable 15 is 0.89 gr, variable 13 and 16 is 0.91 gr, which is in accordance with ginger oleoresin quality standard set by LPYI and BP Kimia Bogor. The ash content of ginger pulp is 0.08% with a quality standard value of 8.0% and a water content of 0.16% with a quality standard value of 10%.

Introduction

Ginger (Zingiber officinale) dregs are industrial wastes of herbal medicine or instant drinks. So far, ginger dregs have only been disposed of or used as fertilizer and fuel. Ginger dregs still have very high bioactive compound [1], [2], thus it is recommended to be reused by processing it optimally Oleoresin contains gingerol, shogaol, zingerone, parasol, resin, and essential oil [2], [3], [4]. Bioactive compound is a fixed mixture of oil and essential oil obtained using organic solvents. In addition, bioactive compound is a processed product of spices that usually forms a paste at room temperature and at higher temperatures in thick oil. Bioactive compound can be obtained by extracting good quality dry spices with volatile organic solvents. In this case, solvent material is produced from the resulting bioactive compound [2].(See Fig. 1 and Table 1)

The development of the bioactive compound extraction process from ginger dregs can be done through several separation techniques, including leaching [5], subcritical water extraction [6], supercritical fluid extraction [7], microwave extraction [8], [10], enzymatic extraction [9], and ultrasonic extraction [2]. The extraction process uses various solvents such as ethanol, methanol, acetone, dichloromethane, hexane, water, CO2, and 1-decyl-3-methylimidazolium bromide. The active compounds extraction processes through maceration, hydrodistillation, and leaching methods using several solvents such as ethanol, methanol, acetone, dichloromethane, and hexane are considered effective processes. However, they can potentially leave toxic solvent residues, long extraction times, large solvent requirements, low selectivity, and thermal degradation of bioactive compounds [1], [10].

An alternative extraction process that is considered appropriate is the extraction process with the following criteria: using a non-toxic solvent; a solvent that is cheap, easy to obtain, the abundant availability, has high purity, can be recycled, and easy to handle; has a polarity close to that of alcohol; and has low viscosity and surface tension [11]. Hydrothermal extraction process is an extraction process using water solvent (green solvent) under subcritical conditions. The use of water in the subcritical area for the extraction process will be effective at a high temperature. This is because, at high temperatures, the viscosity and surface tension of water will decrease so that it will encourage the mass transfer rate, absorption into the particle-matrix, and the selectivity to increase [6]. The use of water in subcritical conditions functions as a green solvent and can be used in selective extraction processes [12]. Subcritical water attracts a lot of attention because of its diverse propertiesAlthough water has polar properties at room conditions, when applied at high pressure and temperature, the properties can change to similar to non-polar solvents such as acetone, ethanol, or dimethyl-sulphoxide (DMSO). Water in subcritical conditions has various properties, such as polarity equivalent to organic solvents, has low viscosity and surface tension, is able to increase diffusivity up to 10 times, is able to reduce hydrogen bonds in water, and the dielectric constant value decreases to encourage mass transfer rates, absorption of particles in the matrix, and high selectivity of the extraction process [1], [13], [14].

This study is designed to determine the bioactive compound in ginger dregs by using a hydrothermal extractor. In addition, it aims to examine the optimum conditions of the extraction process for the bioactive compound in ginger waste through Response Surface Methodology (RSM). It uses a factorial design at level 2 with license of Stat Stoff Inc 1984–2011 to determine the most influential variable and analysis of the raw material of ginger dregs. The results show that specific gravity is in accordance with quality standards, water content, and ash content. Furthermore, this study measures the interaction between variables and determines the content of bioactive compounds using GC-MS analysis.

Section snippets

Material

The materials used in this study were obtained from the waste of MSME production of herbal medicine by Mrs. Herlin, Ungaran, Semarang, Central Java. Distilled water was purchased from PT. Bratachem Semarang, and used as a subcritical water extraction solvent. Nitrogen was used to remove air, and dissolved oxygen was obtained from PT. Bratachem Semarang. The research tool uses a subcritical water extractor.

Variable preparation

This study used three process variables, namely 1000-gram ginger dregs as fixed variable

Result and discussion

Oleoresin is a fixed mixture of oil and essential oil obtained using organic solvents. Oleoresin is a processed product of spices that usually forms a paste at room temperature and at higher temperatures in thick oil. Oleoresin is obtained by extracting good quality dry spices with volatile organic solvents. Solvent material is then produced from the resulting oleoresin. Ginger oleoresin is a dark brown liquid containing 15–35% essential oil, and flavor-forming compositions, namely gingerol,

Conclusion

The development of the bioactive compound extraction process from ginger dregs uses a hydrothermal extractor. The optimum conditions for the extraction of bioactive compound from ginger waste uses Response Surface Methodology (RSM) with a factorial design at level 2 to determine the most influential variables investigated. GC-MS analysis shows bioactive compounds from ginger dregs contain zingiberene, E-Citral (geranial), Beta.-Sesquiphellandrene (CAS)

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

This Research Has Been Funded by Research Fund Development & Application (RPP) 2021.

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